EX-99.1 2 d159182dex991.htm EX-99.1 EX-99.1

Exhibit 99.1

 

 

LOGO

BARRICK GOLD CORPORATION

 

 

TECHNICAL REPORT ON THE

CORTEZ JOINT VENTURE OPERATIONS,

LANDER AND EUREKA COUNTIES,

STATE OF NEVADA, U.S.A.

NI 43-101 Report

Qualified Persons:

Kathleen Ann Altman, Ph.D., P.E.

R. Dennis Bergen, P.Eng.

Stuart Collins, P.E.

Chester Moore, P.Eng.

Wayne Valliant, P.Geo.

 

March 21, 2016

 

RPA Inc. 55 University Ave. Suite 501   |   Toronto, ON, Canada M5J 2H7   |   T + 1 (416) 947 0907   www.rpacan.com


LOGO

Report Control Form

 

Document Title  

Technical Report on the Cortez Operations, State of Nevada, U.S.A.

 

   
Client Name & Address  

Barrick Gold Corporation

Brookfield Place, TD Canada Trust Tower

Suite 3700, 161 Bay Street, P.O. Box 212

Toronto, Ontario M5J 2S1

 

                 
Document Reference  

Project#2471                      

 

    Status &
Issue No.
       

FINAL

Version                                         

        
                         
Issue Date  

March 21, 2016

     
                 
Lead Author  

Wayne Valliant

Dennis Bergen

Stuart Collins

Chester Moore

Kathleen A. Altman

      (Signed)

(Signed)

(Signed)

(Signed)

(Signed)

           
Peer Reviewer  

Deborah McCombe

 

      (Signed)

 

           
Project Manager Approval        

Wayne Valliant

 

      (Signed)

 

           
Project Director Approval  

Graham Clow

 

      (Signed)

 

                 
Report Distribution  

Name

 

  No. of Copies
 
 

Client

   
 

 

RPA Filing

 

 

 

1 (project box)

 

      Roscoe Postle Associates Inc.      

55 University Avenue, Suite 501      

Toronto, ON M5J 2H7      

Canada      

Tel: +1 416 947 0907      

Fax: +1 416 947 0395      

mining@rpacan.com      


FORWARD-LOOKING INFORMATION

This report contains forward-looking statements. All statements, other than statements of historical fact regarding Barrick or Cortez, are forward-looking statements. The words “believe”, “expect”, “anticipate”, “contemplate”, “target”, “plan”, “intend”, “project”, “continue”, “budget”, “estimate”, “potential”, “may”, “will”, “can”, “could” and similar expressions identify forward-looking statements. In particular, this report contains forward-looking statements with respect to cash flow forecasts, projected capital, operating and exploration expenditure, targeted cost reductions, mine life and production rates, potential mineralization and metal or mineral recoveries, and information pertaining to potential improvements to financial and operating performance and mine life at the Cortez mine that may result from the Cortez Underground Expansion Project and certain other Value Realization Initiatives. All forward-looking statements in this report are necessarily based on opinions and estimates made as of the date such statements are made and are subject to important risk factors and uncertainties, many of which cannot be controlled or predicted. Material assumptions regarding forward-looking statements are discussed in this report, where applicable. In addition to such assumptions, the forward-looking statements are inherently subject to significant business, economic and competitive uncertainties and contingencies. Known and unknown factors could cause actual results to differ materially from those projected in the forward-looking statements. Such factors include, but are not limited to: fluctuations in the spot and forward price of commodities (including gold, copper, silver, diesel fuel, natural gas and electricity); the speculative nature of mineral exploration and development; changes in mineral production performance, exploitation and exploration successes; risks associated with the fact that the Cortez Underground Expansion Project and certain other Value Realization Initiatives are still in the early stages of evaluation and additional engineering and other analysis is required to fully assess their impact; diminishing quantities or grades of reserves; increased costs, delays, suspensions, and technical challenges associated with the construction of capital projects; operating or technical difficulties in connection with mining or development activities, including disruptions in the maintenance or provision of required infrastructure and information technology systems; damage to Barrick’s or Cortez’s reputation due to the actual or perceived occurrence of any number of events, including negative publicity with respect to the handling of environmental matters or dealings with community groups, whether true or not; risk of loss due to acts of war, terrorism, sabotage and civil disturbances; uncertainty whether the Cortez Underground Expansion Project or any of the other Value Realization Initiatives will meet Barrick’s capital allocation objectives; the impact of global liquidity and credit availability on the timing of cash flows and the values of assets and liabilities based on projected future cash flows; the impact of inflation; fluctuations in the currency markets; changes in interest rates; changes in national and local government legislation, taxation, controls or regulations and/or changes in the administration of laws, policies and practices, expropriation or nationalization of property and political or economic developments in the United States; failure to comply with environmental and health and safety laws and regulations; timing of receipt of, or failure to comply with, necessary permits and approvals; litigation; contests over title to properties or over access to water, power and other required infrastructure; increased costs and physical risks, including extreme weather events and resource shortages, related to climate change; and availability and increased costs associated with mining inputs and labor. In addition, there are risks and hazards associated with the business of mineral exploration, development and mining, including environmental hazards, industrial accidents, unusual or unexpected formations, pressures, cave-ins, flooding and gold bullion, copper cathode or gold or copper concentrate losses (and the risk of inadequate insurance, or inability to obtain insurance, to cover these risks).

Many of these uncertainties and contingencies can affect Barrick’s actual results and could cause actual results to differ materially from those expressed or implied in any forward-looking statements made by, or on behalf of, Barrick. All of the forward-looking statements made in this report are qualified by these cautionary statements. Barrick and RPA and the Qualified Persons who authored this report undertake no obligation to update publicly or otherwise revise any forward-looking statements whether as a result of new information or future events or otherwise, except as may be required by law.


LOGO    www.rpacan.com

 

TABLE OF CONTENTS

 

     PAGE  

1 SUMMARY

     1-1   

 Executive Summary

     1-1   

 Technical Summary

     1-9   

2 INTRODUCTION

     2-1   

3 RELIANCE ON OTHER EXPERTS

     3-1   

4 PROPERTY DESCRIPTION AND LOCATION

     4-1   

 Land Tenure

     4-1   

 Royalties

     4-2   

5 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY

     5-1   

 Accessibility

     5-1   

 Climate

     5-1   

 Local Resources

     5-2   

 Infrastructure

     5-2   

 Physiography

     5-3   

6 HISTORY

     6-1   

7 GEOLOGICAL SETTING AND MINERALIZATION

     7-1   

 Regional Geology

     7-1   

 Local Geology

     7-5   

 Property Geology

     7-9   

 Mineralization

     7-12   

8 DEPOSIT TYPES

     8-1   

9 EXPLORATION

     9-1   

 Exploration Potential

     9-1   

10 DRILLING

     10-1   

 Reverse Circulation Drilling Methods

     10-3   

 Core Drilling Methods

     10-3   

 Conventional and Mud Drilling Methods

     10-4   

 Collar Surveys

     10-4   

 Down Hole Surveys

     10-4   

 Sample Recovery

     10-5   

 Geotechnical and Hydrological Drilling

     10-5   

 Grade Control Drilling

     10-6   

 Mineral Resource Delineation Drilling

     10-6   

 Sampling Method and Approach

     10-21   

 Bulk Density Determination

     10-25   

 Logging, Sampling, and Sample Storage facilities

     10-26   

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page i    


LOGO    www.rpacan.com

 

 

 RPA Comments on Sampling Method and Approach

     10-26   

 Quality Assurance and Quality Control

     10-27   

 Cortez Laboratory

     10-31   

 RPA’s Comments on QA/QC

     10-32   

11 SAMPLE PREPARATION, ANALYSES AND SECURITY

     11-1   

 Analytical Laboratories

     11-1   

 Sample Preparation

     11-2   

 Analysis

     11-3   

 Sample Security

     11-4   

 RPA’S Comments on Sample Preparation, Analysis, and Security

     11-6   

12 DATA VERIFICATION

     12-1   

 Databases

     12-1   

 Barrick Reviews

     12-1   

 External Reviews

     12-3   

 RPA Database Review

     12-3   

 RPA Opinion

     12-2   

13 MINERAL PROCESSING AND METALLURGICAL TESTING

     13-1   

 Introduction

     13-1   

 Metallurgical Testing

     13-1   

 Ore Routing

     13-2   

 Gold Recovery Estimates

     13-2   

 Deep South Zone Metallurgical Testing

     13-7   

 Summary and Conclusions

     13-9   

14 MINERAL RESOURCE ESTIMATE

     14-1   

 Summary

     14-1   

 Pipeline Complex

     14-2   

 Cortez Hills Complex

     14-20   

 Cortez Pits

     14-39   

 Gold Acres

     14-43   

15 MINERAL RESERVE ESTIMATE

     15-1   

 Summary

     15-1   

 Open Pit Mineral Reserves

     15-6   

 Underground Mineral Reserves

     15-20   

 Reconciliation

     15-26   

 RPA Opinion

     15-36   

16 MINING METHODS

     16-1   

 Recent Production History

     16-1   

 Underground Mine

     16-15   

 Cortez Life of Mine Plan

     16-41   

17 RECOVERY METHODS

     17-1   

 Introduction

     17-1   

 Oxide Ore Milling

     17-1   

 Oxide Ore Heap Leaching

     17-3   

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page ii    


LOGO    www.rpacan.com

 

 

 Refractory Ore Treatment

     17-4   

18 PROJECT INFRASTRUCTURE

     18-1   

 Roads

     18-1   

 Tailings Storage Facility

     18-1   

 Dumps

     18-1   

 Stockpiles

     18-4   

 Leach Pads

     18-4   

 Power

     18-4   

19 MARKET STUDIES AND CONTRACTS

     19-1   

 Markets

     19-1   

 Contracts

     19-1   

20 ENVIRONMENTAL STUDIES, PERMITTING, AND SOCIAL OR COMMUNITY IMPACT

     20-1   

 Environmental Studies

     20-1   

 Mine Permitting

     20-1   

 Social and Community Requirements

     20-9   

 Mine Closure Requirements

     20-15   

21 CAPITAL AND OPERATING COSTS

     21-1   

 Capital Cost Estimate

     21-1   

 Operating Costs

     21-2   

22 ECONOMIC ANALYSIS

     22-1   

23 ADJACENT PROPERTIES

     23-1   

24 OTHER RELEVANT DATA AND INFORMATION

     24-1   

25 INTERPRETATION AND CONCLUSIONS

     25-1   

26 RECOMMENDATIONS

     26-1   

27 REFERENCES

     27-1   

28 DATE AND SIGNATURE PAGE

     28-1   

29 CERTIFICATE OF QUALIFIED PERSON

     29-1   

LIST OF TABLES

 

          PAGE  

Table 1-1

  

Mineral Resources – December 31, 2015

     1-3   

Table 1-2

  

Mineral Reserves – December 31, 2015

     1-4   

Table 1-3

  

Capital Costs

     1-18   

Table 1-4

  

LOM Operating Costs

     1-18   

Table 6-1

  

History of Exploration and Mining at Cortez Site

     6-2   

Table 6-2

  

Annual Production, 1969–2015

     6-6   

Table 10-1

  

Drill Hole Types

     10-1   

Table 10-2

  

RC Sample Reduction

     10-22   

Table 10-3

  

Blast Hole Sample Reduction

     10-25   

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page iii    


LOGO    www.rpacan.com

 

 

Table 11-1

  

Chain of Custody Summary

     11-6   

Table 13-1

  

Cortez Oxide Mill Gold Recovery Equations

     13-3   

Table 13-2

  

Cortez Heap Leach Ultimate Gold Recovery Equations

     13-3   

Table 13-3

  

Refractory Ore Gold Recovery Equations

     13-4   

Table 13-4

  

Production Data 2013-2015

     13-5   

Table 13-5

  

Heap Leach Gold Production

     13-6   

Table 13-6

  

Deep South Zone Test Results (Au Recovery)

     13-8   

Table 13-7

  

Deep South Zone Optimization Samples Analytical Results

     13-9   

Table 14-1

  

Mineral Resource Summary – December 31, 2015

     14-1   

Table 14-2

  

Cortez Mineral Resource Models

     14-2   

Table 14-3

  

Pipeline Complex Mineral Resource Summary – December 31, 2015

     14-3   

Table 14-4

  

Pipeline Complex Mineral Resource Reporting Cut-off Grades

     14-4   

Table 14-5

  

Pipeline Complex Block Model Parameters

     14-6   

Table 14-6

  

Search Ellipse Orientations Of Structural Domains – Pipeline Complex

     14-8   

Table 14-7

  

Summary of Gold Grade Caps – Pipeline Complex

     14-9   

Table 14-8

  

Low Grade Omnidirectional Variogram Models – Pipeline Complex

     14-10   

Table 14-9

  

Estimation Pass Summary – Pipeline Complex

     14-12   

Table 14-10

  

Summary of Composite Weights – Pipeline Complex

     14-13   

Table 14-11

  

Bulk Density – Pipeline Complex

     14-14   

Table 14-12

  

Comparison of Basic Statistics of Gold Values – Pipeline Complex

     14-18   

Table 14-13

  

Cortez Hills Complex Mineral Resource Summary – December 31, 2015

     14-20   

Table 14-14

  

Cortez Hills Complex Mineral Resource Reporting Cut-off Grades

     14-21   

Table 14-15

  

Cortez Hills Complex Block Model Parameters

     14-23   

Table 14-16

  

Cortez Hills Complex CapPing

     14-25   

Table 14-17

  

Cortez Hills Complex - Bulk Density

     14-27   

Table 14-18

  

Cortez Hills Complex - Classification Distance Criteria

     14-29   

Table 14-19

  

Cortez Pits Mineral Resource Summary – December 31, 2015

     14-40   

Table 14-20

  

Cortez Pits - Estimation Pass Summary

     14-42   

Table 14-21

  

Cortez Pits - Bulk Density

     14-42   

Table 14-22

  

Gold Acres Refractory Mineral Resource Summary – December 31, 2015

     14-44   

Table 14-23

  

Gold Acres Indicator Model Estimation Parameters

     14-45   

Table 14-24

  

Interpolation Passes Inside and Outside the Gold Acres 0.50 Indicator Model

     14-46   

Table 14-25

  

Gold Acres Bulk Density

     14-47   

Table 14-26

  

Gold Acres Untransformed Gold Statistics

     14-47   

Table 15-1

  

Total Mineral Reserves – December 31, 2015

     15-2   

Table 15-2

  

Proportion of Reserves by Deposit

     15-5   

Table 15-3

  

Processing as Percent of Total Tons/Ounces

     15-6   

Table 15-4

  

Open Pit Leach Cut-Off Grades

     15-15   

Table 15-5

  

Open Pit Mill Cut-Off Grades

     15-16   

Table 15-6

  

Open Pit Refractory Cut-Off Grades

     15-17   

Table 15-7

  

Mill Leach Inter-Process Cut-Off Grade

     15-18   

Table 15-8

  

Cortez Hills and Pediment Whittle Pit Optimization Parameters

     15-19   

Table 15-9

  

Pipeline and Crossroads Whittle Pit Optimization Parameters

     15-19   

Table 15-10

  

Underground Cut-off Grade Calculations

     15-23   

Table 15-11

  

Cortez Hills Open Pit Reconciliation

     15-28   

Table 15-12

  

Cortez Hills Open Pit Reconciliation by Process Type

     15-29   

Table 15-13

  

Pipeline Open Pit Reconciliation

     15-31   

Table 15-14

  

Pipeline Open Pit Reconciliation By Process Type

     15-32   

Table 15-15

  

Underground Mineral Reserve Reconciliation

     15-33   

Table 16-1

  

Mine Operations Summary 2012-2015

     16-1   

Table 16-2

  

Cortez Operation – LOM Open Pit Production

     16-11   

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page iv    


LOGO    www.rpacan.com

 

 

Table 16-3

  

Cortez Hills/Pediment – LOM Open Pit Production

     16-12   

Table 16-4

  

Pipeline/Crossroads – LOM Open Pit Production

     16-12   

Table 16-5

  

Percentages of Mined Processing Ore Types

     16-13   

Table 16-6

  

Major Open Pit Equipment

     16-14   

Table 16-7

  

Rock mass characterization for the Deep South Zone

     16-22   

Table 16-8

  

Summary of Proposed Hydraulic Radii by Geotechnical Domain

     16-23   

Table 16-9

  

Underground Equipment Fleet

     16-36   

Table 16-10

  

Key Factors Deep South Zone PFS

     16-37   

Table 16-11

  

Underground LOM Production

     16-40   

Table 16-12

  

Underground LOM Ore Types

     16-40   

Table 16-13

  

Underground Ore Source By Zone

     16-41   

Table 16-14

  

Cortez Operation – LOM Mining

     16-42   

Table 16-15

  

LOM Ore Processed - Roaster

     16-43   

Table 16-16

  

LOM Ore Processed – Pipeline Mill

     16-43   

Table 16-17

  

LOM Ore Processed – Heap Leach

     16-44   

Table 16-18

  

LOM Total Ore Processed

     16-44   

Table 20-1

  

Important Environmental Documents and Plans of Operations for Pipeline and Cortez Hills

     20-3   

Table 20-2

  

Major Environmental Permits

     20-8   

Table 20-3

  

Surface Disturbance Authorization

     20-16   

Table 21-1

  

Capital Costs

     21-1   

Table 21-2

  

LOM Operating Costs

     21-2   

Table 21-3

  

Manpower

     21-2   

LIST OF FIGURES

 

          PAGE  

Figure 4-1

  

Location Map

     4-3   

Figure 4-2

  

Land Ownership Map

     4-4   

Figure 4-3

  

Deposit Locations

     4-5   

Figure 4-4

  

Cortez Hills Infrastructure

     4-6   

Figure 4-5

  

Pipeline Complex Infrastructure

     4-7   

Figure 7-1

  

Regional Geology

     7-4   

Figure 7-2

  

Local Geology

     7-7   

Figure 7-3

  

Local Stratigraphy

     7-8   

Figure 10-1

  

Drill Hole Map

     10-2   

Figure 10-2

  

Pipeline Complex Drill Hole Plan

     10-8   

Figure 10-3

  

Pipeline Deposit – Cross Section 58000N (A-A’)

     10-9   

Figure 10-4

  

Crossroads Deposit - Cross Section 52800N (B-B’)

     10-10   

Figure 10-5

  

Gold Acres Drill Hole Plan

     10-11   

Figure 10-6

  

Gold Acres Deposit - Cross Section 59800N (A-A’)

     10-12   

Figure 10-7

  

Cortez Hills Drill Hole Plan

     10-14   

Figure 10-8

  

Cortez Hills – Cross Section 28600N (A-A’) Breccia, Middle and Lower Zones

     10-15   

Figure 10-9

  

Pediment - Long-Section B-B’

     10-16   

Figure 10-10

  

Lower Zone - Long-Section C-C’

     10-17   

Figure 10-11

  

Cortez Pits Area (NW Deeps) Drill Hole Plan

     10-19   

Figure 10-12

  

Cortez Pits Area – Cross Section 38200N

     10-20   

Figure 13-1

  

Historical Heap Leach Data

     13-7   

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page v    


LOGO    www.rpacan.com

 

 

Figure 14-1

  

Resource Estimation Domains Pipeline Complex

     14-7   

Figure 14-2

  

Low Grade, Omnidirectional Variograms at Pipeline Complex

     14-11   

Figure 14-3

  

Mineral Resource Classification, Crossroads Deposit, Pipeline Complex

     14-15   

Figure 14-4

  

Section 52600 N: Comparison of Block and Composite Gold Grades at Crossroads Deposit, Pipeline Complex

     14-19   

Figure 14-5

  

Resource Estimation Domains Cortez Hills Complex

     14-24   

Figure 14-6

  

Comparison of Block and Composite Grades at Pediment Deposit, Cortez Hills Complex

     14-32   

Figure 14-7

  

Comparison of Block and Composite Grades within the Breccia Zone, Open Pit Portion, Cortez Hills Complex

     14-33   

Figure 14-8

  

Comparison of Block and Composite Grades within the Breccia Zone, Underground Portion, Cortez Hills Complex

     14-34   

Figure 14-9

  

Comparison of Block and Composite Grades within the Middle Zone, Cortez Hills Complex

     14-35   

Figure 14-10

  

Comparison of Block and Composite Grades within the Lower Zone, including Deep South, Cortez Hills Complex

     14-36   

Figure 14-11

  

CHUG Lower Zone Comparison of Block and Composite Mean by Middle Zone one

     14-37   

Figure 14-12

  

CHUG Middle Zone Comparison of Block and Composite Mean by Middle Zone one

     14-37   

Figure 14-13

  

CHUG Breccia Zone Comparison of Block and Composite Mean by Middle Zone one

     14-38   

Figure 14-14

  

CHOP Breccia Zone Comparison of Block and Composite Mean by Middle Zone one

     14-38   

Figure 14-15

  

CHOP Pediment Zone Comparison of Block and Composite Mean by Middle Zone one

     14-39   

Figure 15-1

  

Deposit Locations

     15-4   

Figure 15-2

  

Cortez Hills and Pediment Ultimate Pit Areas

     15-9   

Figure 15-3

  

Cortez Hills Open Pits, Waste Dumps, and Infrastructure

     15-10   

Figure 15-4

  

Pipeline and Crossroads Ultimate Pit Areas

     15-12   

Figure 15-5

  

Pipeline Pits and Phases

     15-13   

Figure 15-6

  

Schematic View of the Cortez Hills Underground

     15-22   

Figure 15-7

  

Total Underground Ore Reconciliation 2014-2015

     15-34   

Figure 15-8

  

Underground Oxide Ore Reconciliation 2014-2015

     15-35   

Figure 15-9

  

Underground Roaster Ore Reconciliation 2014-2015

     15-36   

Figure 16-1

  

Site Layout

     16-3   

Figure 16-2

  

Cortez Hills Open Pit Recommended Pit Slope Design

     16-7   

Figure 16-3

  

Crossroads Recommended Slope Design

     16-8   

Figure 16-4

  

CHUG LOM Mine Production Rate

     16-16   

Figure 16-5

  

CHUG LOM Gold Production and Head Grade

     16-17   

Figure 16-6

  

Geotechnical Domains

     16-23   

Figure 16-7

  

Main Ramp Layout Relative to Geological Features, Looking North

     16-24   

Figure 17-1

  

Pipeline Mill Process Flow Sheet

     17-6   

Figure 17-2

  

Simplified Heap Leach Flow Sheet

     17-7   

Figure 17-3

  

Goldstrike Roaster Flow Sheet

     17-8   

Figure 18-1

  

Pipeline Complex Infrastructure

     18-2   

Figure 18-2

  

Cortez Hills Complex Infrastructure

     18-3   

Figure 20-1

  

Boundaries and Permit Areas

     20-2   

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page vi    


LOGO    www.rpacan.com

 

1 SUMMARY

EXECUTIVE SUMMARY

Roscoe Postle Associates Inc. (RPA) was retained by Barrick Gold Corporation (Barrick) to prepare an independent Technical Report on the Cortez Open Pit and Underground Mine Operations (the Cortez Operations or the Mine), in Eureka and Lander Counties, Nevada, USA. The purpose of this report is to support public disclosure of Mineral Resources and Mineral Reserves at Cortez as of December 31, 2015. This Technical Report conforms to NI 43-101 Standards of Disclosure for Mineral Projects. RPA visited the operations between May 5 and 7, 2015.

Barrick is a Canadian publicly traded mining company with a portfolio of operating mines and projects across five continents. The Cortez Operations are located in northeastern Nevada approximately 62 mi west and south of Elko.

The Cortez Mine is a joint venture between two wholly-owned subsidiaries of Barrick, Barrick Cortez Inc. (60%) and Barrick Gold Finance Inc. (40%). The Cortez Operations consist of the Pipeline, Crossroads, Gap, Cortez Hills (CHOP), and Pediment open pits, the Cortez Hills underground (CHUG) mine, a 13,000 ton per day (stpd) carbon-in-leach (CIL) gold plant, heap leach pads and heap leach processing plants, the planned Crossroads open pit, with additional Mineral Resources contained in the Cortez Pits and Gold Acres open pits. The nearby deposit of Hilltop is also part of the Mine but does not have reportable resources at this time.

The open pit is a large scale operation utilizing a conventional truck and shovel fleet and mining approximately 400,000 stpd of ore and waste. Mining operations move between the various pits over the Life of Mine (LOM) plan. The underground mine is a 2,000 stpd mechanized mine. Ore from the mines is treated at an oxide mill at the site, on leach pads, and refractory ore is shipped to Barrick’s Goldstrike operation for processing.

Barrick completed a Pre-feasibility Study (PFS) for underground mining in the Deep South Zone (the Cortez Underground Expansion Project), below currently permitted areas of the CHUG. The PFS indicated that the project has the potential to contribute average underground production of more than 300,000 ounces per year between 2022 and 2026 at average all-in

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-1    


LOGO    www.rpacan.com

 

 

sustaining costs of approximately $580 per ounce. More detailed planning, subsequent to the PFS, has resulted in the current LOM beginning underground gold production from the Deep South Zone in 2022 and producing 300,000 ounces per year between 2023 and 2027. Initial capital costs are estimated to be $153 million. The PFS supports conversion of approximately 1.7 million ounces of Measured and Indicated Resources in the Deep South Zone to Proven and Probable Reserves as of December 31, 2015.

The PFS timeline assumes that permitting will take approximately three to four years and Barrick expects to commence this process in the first half of 2016. On this basis, following the receipt of permits, dewatering and development work could begin as early as 2019 or 2020, with initial production from the Deep South Zone commencing in 2022. The expansion of the underground mine is expected to offset the impact of the end of mining in the Cortez Hills open pit, which is scheduled to conclude in 2018.

Table 1-1 summarizes the Cortez Mineral Resources as of December 31, 2015. Table 1-2 summarizes the Cortez Mineral Reserves as of December 31, 2015.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-2    


LOGO    www.rpacan.com

 

TABLE 1-1 MINERAL RESOURCES – DECEMBER 31, 2015

Barrick Gold Corporation – Cortez Operations

 

    Measured Resources     Indicated Resources     Measured + Indicated     Inferred Resources  

Mine

  Tons
(000 st)
    Grade
(oz/st
Au)
    Contained
Gold

(000 oz)
    Tons
(000 st)
    Grade
(oz/st
Au)
    Contained
Gold

(000 oz)
    Tons
(000 st)
    Grade
(oz/st
Au)
    Contained
Gold

(000 oz)
    Tons
(000 st)
    Grade
(oz/st
Au)
    Contained
Gold

(000 oz)
 

Open Pit

                       

Pipeline

    1,231        0.022        27        14,617        0.019        275        15,848        0.019        302        1,698        0.03        44   

Gap

    167        0.025        4        2,402        0.019        47        2,569        0.020        51        —          —          —     

Crossroads

    1,530        0.014        22        17,500        0.014        237        19,030        0.014        259        12,220        0.01        167   

Gold Acres

    213        0.124        26        3,266        0.104        340        3,479        0.105        367        305        0.10        32   

Cortez Hills

    —          —          —          —          —          —          —          —          —          3,440        0.04        122   

Pediment

    —          —          —          —          —          —          —          —          —          411        0.01        3   

Cortez Pits

    472        0.094        45        3,611        0.051        183        4,083        0.056        227        1,283        0.02        27   

 

 

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

 

Sub-Total

    3,613        0.034        124        41,395        0.026        1,082        45,009        0.027        1,206        19,359        0.02        395   

Underground

                       

Cortez Hills Breccia

    167        0.339        56        335        0.329        110        502        0.332        167        9        0.47        4   

Cortez Hills Middle

    —          —          —          1,065        0.328        350        1,065        0.328        350        82        0.35        28   

Cortez Hills Lower

    —          —          —          942        0.273        257        942        0.273        257        541        0.25        133   

Cortez Deep South

    —          —          —          663        0.255        169        663        0.255        169        710        0.42        301   

 

 

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

 

Sub-Total

    167        0.339        56        3,005        0.295        886        3,172        0.297        943        1,341        0.35        466   

 

 

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

   

 

 

 

Total

    3,780        0.048        181        44,400        0.044        1,969        48,180        0.045        2,149        20,700        0.04        861   

Notes:

 

1.

CIM definitions were followed for Mineral Resources.

2.

Mineral Resources are estimated at various cut-off grades depending on material type and processing stream.

3.

Mineral Resources are estimated using an average gold price of US$1,300 per ounce.

4.

A minimum mining width of 10 ft was used.

5.

Mineral Resources are additional to and exclusive of Mineral Reserves.

6.

Numbers may not add due to rounding.

 

 

    Barrick Gold Corporation – Cortez Joint Venture, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-3    


LOGO    www.rpacan.com

 

TABLE 1-2 MINERAL RESERVES – DECEMBER 31, 2015

Barrick Gold Corporation – Cortez Operations

 

     Total Proven    Total Probable           Total Proven + Probable  

Zone

   Tons
(000)
     Grade
(oz/st)
     Contained
Gold
(000 oz)
          Tons
(000 st)
     Grade
(oz/st Au)
     Contained
Gold
(000 oz)
          Tons
(000 st)
     Grade
(oz/st Au)
     Contained
Gold
(000)
 

Open Pit

                                  

Pipeline

     1,470         0.019         28             15,985         0.017         266             17,455         0.017         294   

Crossroads

     8,135         0.035         287             86,613         0.033         2,880             94,749         0.033         3,167   

Cortez Hills

     1,564         0.127         198             17,145         0.116         1,984             18,709         0.117         2,182   

Pediment

     762         0.032         24             20,506         0.027         547             21,268         0.027         571   

Open Pit Subtotals

     11,931         0.045         537             140,249         0.040         5,677             152,181         0.041         6,214   

Underground

                              

Breccia Zone

     120         0.514         62             205         0.486         100             324         0.497         161   

Middle Zone

                  3.544         0.365         1,292             3,544         0.365         1,292   

Lower Zone

                  3.777         0.351         1,324             3,777         0.351         1,324   

Deep South

                  5.266         0.322         1,697             5,266         0.322         1,698   

Underground Subtotals

     120         0.514         62             12,792         0.345         4,414             12,912         0.347         4,476   

Stockpiles

                                  

Mill Stockpiles

     1,510         0.096         145                             

Leach Stockpiles

     57         0.014         1                             

Refractory Stockpiles

     2,248         0.130         293                             

Stockpile Subtotals

     3,814         0.115         438                          3,814         0.115         438   

Total

     15,866         0.065         1,037             153,042         0.066         10,092             168,908         0.066         11,129   

Notes:

 

1.

CIM definitions were followed for Mineral Reserves.

2.

Mineral Reserves are estimated at cut-off grades that range from 0.004 oz/st Au to 0.205 oz/st Au depending on deposit, mining method, and process type.

3.

Mineral Reserves are estimated using an average gold price of US$1,000 per ounce to year 2020 and US$ 1,200 per ounce thereafter.

4.

A minimum mining width of 15 ft was used.

5.

Bulk density varies from 0.052 st/ft3 to 0.091 st/ft3, depending on material type.

6.

Numbers may not add due to rounding.

 

 

    Barrick Gold Corporation – Cortez Joint Venture, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-4    


LOGO    www.rpacan.com

 

 

CONCLUSIONS

Based on the site visit and review of the documentation available, RPA offers the following interpretation and conclusions:

GEOLOGY AND MINERAL RESOURCES

 

   

The Cortez deposits are “Carlin” style porphyry/epithermal deposits hosted by sedimentary rocks.

 

   

The sampling, sample preparation, analyses, security, and data verification meet or exceed industry standards and are appropriate for Mineral Resource estimation.

 

   

The parameters, assumptions, and methodology used for Mineral Resource estimation are appropriate for the style of mineralization.

 

   

Mineral Resources are reported exclusive of Mineral Reserves and are estimated effective December 31, 2015.

 

   

Total Mineral Resources at the Cortez Operations are:

 

   

Measured - 3.78 million tons, grading 0.048 oz/st Au, containing 181,000 oz Au.

 

   

Indicated - 44.40 million tons, grading 0.044 oz/st Au, containing 1,969,000 oz Au.

 

   

Inferred - 20.7 million tons, grading 0.04 oz/st Au, containing 861,000 oz Au.

 

   

Open Pit Mineral Resources at the Cortez Operations are:

 

   

Measured - 3.61 million tons, grading 0.034 oz/st Au, containing 124,000 oz Au.

 

   

Indicated - 41.40 million tons, grading 0.026 oz/st Au, containing 1,082,000 oz Au.

 

   

Inferred - 19.4 million tons, grading 0.02 oz/st Au, containing 395,000 oz Au.

 

   

Underground Mineral Resources at the Cortez Operations are:

 

   

Measured - 0.17 million tons, grading 0.339 oz/st Au, containing 56,000 oz Au.

 

   

Indicated - 3.01 million tons, grading 0.295 oz/st Au, containing 886,000 oz Au.

 

   

Inferred - 1.34 million tons, grading 0.35 oz/st Au, containing 466,000 oz Au.

MINING AND MINERAL RESERVES

 

   

The Mineral Reserves are contained within four open pit deposits, four zones in one underground deposit, and surface stockpiles.

 

   

The December 31, 2015 Mineral Reserves as stated by Cortez are estimated in a manner consistent with industry practices.

 

   

Total Mineral Reserves at the Cortez Operations are:

 

   

Proven: 15.9 million tons, grading 0.065 oz/st Au, containing 1.03 million oz Au.

 

   

Probable: 153.0 million tons, grading 0.066 oz/st Au, containing 10.09 million oz Au.

 

   

Open Pit Mineral Reserves at the Cortez Operations are:

 

   

Proven: 11.9 million tons, grading 0.045 oz/st Au, containing 0.54 million oz Au.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-5    


LOGO    www.rpacan.com

 

 

   

Probable: 140.2 million tons, grading 0.040 oz/st Au, containing 5.67 million oz Au.

 

   

Underground Mineral Reserves at the Cortez Operations are:

 

   

Proven: 0.1 million tons, grading 0.514 oz/st Au, containing 0.06 million oz Au.

 

   

Probable: 12.8 million tons, grading 0.345 oz/st Au, containing 4.41 million oz Au.

 

   

The open pit mine is a conventional operation that currently has 400 st and 345 st class off-highway haul trucks which are loaded by one 35 yd3 hydraulic shovel and five 48 yd3 to 77 yd3 size electric shovels.

 

   

The Cortez operation is permitted to dewater up to approximately 36,000 gpm from the underground and open pit mine areas.

 

   

Mine production rates are projected to average 157 million tons per year (Mstpa) of total material from 2016 to 2022. Average open pit ore mining rate is approximately 19.1 Mstpa.

 

   

CHUG is a mechanized decline access underground mine operating at approximately 2,000 stpd of ore.

 

   

The Breccia, Middle, and Lower Zones of the underground mine are mined or planned to be mined using drift and fill mining methods.

 

   

The mining methods and equipment are considered to be suitable for the deposits.

 

   

In the Deep South Zone, Measured and Indicated Mineral Resources were converted to approximately 1.7 million oz of Proven and Probable Mineral Reserves as of year-end 2015 on the basis of a positive PFS.

 

   

The conclusions and recommendations of the Deep South Zone PFS are reasonable and appropriate for the deposit.

 

   

The Deep South Zone PFS work included re-evaluation of the geotechnical characteristics and the design for the mining of the Deep South includes long hole stoping which is expected to be more productive and lower cost than the drift and fill mining.

 

   

The Deep South Zone has the potential to be a standalone expansion of the CHUG.

PROCESS

 

   

RPA is of the opinion that metallurgical test work completed for the Mine has been appropriate to establish optimal processing routes for the different mineralization styles encountered in the deposits and that the gold recovery calculations for all of the processing options are currently appropriate to estimate the amount of gold that will be recovered over the LOM.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-6    


LOGO    www.rpacan.com

 

 

   

The mill and heap leach operations at Cortez are well run, cost effective processing facilities for oxide ore.

 

   

There are no appropriate processes for single and double refractory ore at Cortez. Therefore, these ore types are shipped to Goldstrike for processing. Limits to the transportation rates imposed by environmental permits restrict the amount of ore that can be shipped to 1.2 Mstpa. If additional refractory ore is mined, it must be stockpiled.

 

   

Total Carbonaceous Material (TCM) processing at Goldstrike is advanced technology that provides additional capacity for processing carbonaceous, preg-robbing ore without displacing material that is processed in the roaster. It also allows processing of ore with elevated concentrations of arsenic. The TCM technology uses calcium thiosulfate (CaTs) to leach the gold after pressure oxidation rather than cyanide and resin-in-pulp to recover the gold from the leach solution.

ENVIRONMENTAL CONSIDERATIONS

 

   

One of the risks to the Mine is the receipt of permit approvals from the various government agencies.

 

   

Cortez is diligent in managing its permitting and all environmental requirements for the property.

 

   

RPA is not aware of any environmental issues that could materially impact Barrick’s ability to extract the Mineral Resources or Mineral Reserves at this time.

ECONOMIC ANALYSIS

 

   

RPA has performed an economic analysis of the Cortez Operations using the estimates presented in this report and confirms that the outcome is a positive cash flow that supports the statement of Mineral Reserves.

RECOMMENDATIONS

Based upon its work, RPA provides the following recommendations.

GEOLOGY AND MINERAL RESOURCES

 

   

Continue to revise and update the Mineral Resource modelling procedures, with specific consideration to the potential additional mineralization trend in the Crossroads pit and the incorporation of an ordinary kriging run as an additional validation check at Cortez Hills.

 

   

Review the classification criteria, with consideration to variogram models based on single mineralization domains at Cortez Hills, and the inclusion of classification wireframe shells, particularly for the Measured component, or the incorporation of classification smoothing scripts.

MINING AND MINERAL RESERVES

 

   

Continue ore reconciliation tracking and attempt to identify and report the causes of any large changes on a monthly basis.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-7    


LOGO    www.rpacan.com

 

 

   

Present the reconciliation results showing the percentage differences and not the absolute differences.

 

   

Develop a set of orebody characteristics (width, height, grade, rock conditions) considered appropriate for long hole stoping and identify the quantity and location of those portions of the orebody amenable to long hole stoping.

 

   

Consider the Lower Zone rock bin capacity to ensure that a smooth ore feed from the mine can be maintained.

 

   

Review the small amounts of Inferred material within stope designs with a view to changing the classification of these small areas so that Inferred Mineral Resources are not included in the stope plans.

 

   

Modify the LOM and Mineral Reserve estimation process to include:

 

   

a reconciliation between the LOM plan and the Mineral Reserve estimate

 

   

a tabulation of the Mineral Resources converted by classification including the Inferred Mineral Resources

 

   

a review of those Inferred Mineral Resources within the LOM plan to determine whether any can or should be reclassified as Indicated Mineral Resources

 

   

the impact on the LOM plan of including the Inferred Mineral Resources within the plan at zero grade

 

   

Prepare detailed reconciliations and comparisons for any future conversions to new or different software packages to identify any issues in the process.

 

   

Continue the mine dewatering and careful highwall slope monitoring.

 

   

Re-evaluate the use of blast movement monitoring to improve grade control.

 

   

Develop detailed grade control accounting and stockpile management procedures.

 

   

Refine use of cross over grades, and standardize the Mineral Reserve reporting with the LOM production schedule.

 

   

Implement ore drive width increases to increase the productivity and/or production rate of the drift and fill mining.

 

   

Assess areas of the Lower Zone for the application of long hole stoping methods and implement trials if suitable areas can be identified.

Continue to advance the planning of the Deep South Zone, which is included in the LOM plan, to optimize the production and development schedules in future years.

 

   

Continue to evaluate the initiative to process mineralized waste concurrently with material from the underground resource.

PROCESSING

 

   

Continue to evaluate new ore types and to optimize the processes to increase recovery and/or to decrease costs.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-8    


LOGO    www.rpacan.com

 

 

   

Continue to work collaboratively with the Goldstrike staff to maintain and improve the metallurgical accounting for treatment of Cortez ore in the roaster and the TCM process.

ENVIRONMENTAL

 

   

Continue to expedite environmental permitting as required to support the changes in operations and development of new areas of the Mine.

COSTS

 

   

Continue to evaluate and implement opportunities for cost savings and profitability improvements.

ECONOMIC ANALYSIS

Under NI 43-101 rules, producing issuers may exclude the information required in this section on properties currently in production, unless the technical report includes a material expansion of current production. RPA notes that Barrick is a producing issuer, the Cortez Mine is currently in production, and a material expansion is not being planned. RPA has performed an economic analysis of the Cortez Mine using the estimates presented in this report and confirms that the outcome is a positive cash flow that supports the statement of Mineral Reserves.

TECHNICAL SUMMARY

PROPERTY DESCRIPTION AND LOCATION

The Cortez Operations are located 62 mi southwest of Elko, Nevada, USA, in Eureka and Lander Counties.

All Mineral Reserves and Mineral Resources, in addition to existing and future facilities to be used to exploit the Mine’s deposits, are on public lands administered by the Battle Mountain or Elko Field Offices of the U.S. Department of Interior, Bureau of Land Management (BLM).

At Cortez, Barrick directly controls approximately 216,124 acres of mineral rights with ownership of mining claims and fee lands. There are 10,461 claims consisting of:

 

   

9,630 unpatented lode claims

 

   

575 unpatented mill-site claims

 

   

104 patented lode claims

 

   

125 patented mill-site claims

 

   

27 unpatented placer claims and 185 patented mill-site claims

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-9    


LOGO    www.rpacan.com

 

 

All lease agreements and claim holdings are current and in good standing.

EXISTING INFRASTRUCTURE

There is extensive infrastructure in place to support the Cortez Operations including:

 

   

The 13,000 stpd No. 2 Mill complete with run-of-mine (ROM) pad and crushing circuit

 

   

Pipeline leach pad areas (Area 28 and Area 30) and gold recovery plant

 

   

Area 34 leach pad and gold recovery plant for the CHOP and Pediment

 

   

A tailings management facility

 

   

A gyratory crusher at the CHOP and an 11 mi long conveyor to the No. 2 Mill

 

   

Existing open pit mines at CHOP, Cortez, and Pipeline

 

   

Pit dewatering wells and pumps for the open pits and the CHUG

 

   

Infiltration ponds for the disposal of water

 

   

An existing underground mine at CHUG

 

   

Batch plant for shotcrete and cemented rock fill preparation

 

   

Stockpile areas for an assortment of ore types

 

   

Office complexes at the Mill No. 2, Mill No. 1, CHUG, and CHOP

 

   

Equipment maintenance shops at CHOP, CHUG, and adjacent to the Mill No. 2

 

   

Exploration offices, core handling and core storage warehouse

 

   

System of public and private roads connecting the facilities

 

   

Shared business support services from the business unit offices in Elko

HISTORY

Mining in the Cortez Mining District began with the discovery of silver ore in 1862. Underground silver mining was conducted in the area until the 1930s. Mineralization at Hilltop was also identified during the 1860s. Gold mineralization at Gold Acres was discovered in the late 1920s and mined by a small mining company from 1935 to 1960.

In 1959, American Exploration & Mining Co. (AMEX), a wholly-owned US subsidiary of Placer Development Ltd. (subsequently Placer Dome Inc.), entered into a lease-option agreement on the properties and started extensive exploration. In 1964, AMEX formed the Cortez Joint Venture (CJV).

The CJV initiated open pit mining in the Cortez open pits from 1968 to 1972 and moved to the Gold Acres North and South pits in 1973. Leaching and milling of Gold Acres stockpiles and

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-10    


LOGO    www.rpacan.com

 

 

dumps continued until 1983. Mill grade ores were mined from 1987 to 1996 and processed at Cortez Mill No. 1. In 2003, the CJV commenced shipping Gold Acres refractory stockpiles for toll processing at third-party facilities.

The Horse Canyon deposits were discovered in early 1976. Three pits, North, South, and South Extension, were mined in the period from 1984 to 1987. Exploration drilling campaigns at the Horse Creek deposit, originally discovered in the late 1960s, occurred in the mid-1980s and intermittently over the last ten years and are ongoing.

The Pipeline deposit was discovered by CJV geologists in March 1991 during drilling of deep condemnation holes. The Gap deposit was discovered in 1991 adjacent to the planned Stage 9 of the Pipeline pit.

In November 1991, CJV discovered the South Pipeline deposit. Construction of Mill No. 2 and pre-stripping of the first stage of the Pipeline pit began in 1996. Continued drilling resulted in the 1998 discovery of the Crossroads deposit beneath 550 ft of alluvium.

In 1996, CJV geologists began a program that led to the 1998 discovery of the Pediment deposit. The Cortez Hills deposit was discovered in October 2002. In 2004, the Cortez Hills Lower Zone was discovered. In November 2008, the Environmental Impact Statement (EIS) for the Cortez–Pediment development was approved. Production from underground began in late 2008, and the first ore production from CHOP occurred in late December 2009.

Barrick acquired an interest in Cortez through the 2006 acquisition of Placer Dome Inc. In March 2008, Barrick acquired its 100% interest in the Mine, purchasing the former Kennecott 40% interest, from Rio Tinto.

GEOLOGY AND MINERALIZATION

The Cortez gold district is in the eastern Great Basin of the Basin and Range Province. The Paleozoic basement rocks of northeastern Nevada are made up of a western deep-water, eugeoclinal siliclastic assemblage (Upper Plate) and an eastern shallow-water, miogeosynclinal carbonate assemblage (Lower Plate) of sedimentary strata. Cortez lies within the “Battle Mountain-Eureka Trend” (BMT), an alignment of gold mines and occurrences located in a northwest-southeast belt extending from the Marigold Mine some 50 mi northwest

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-11    


LOGO    www.rpacan.com

 

 

of Cortez, to Ruby Hill at Eureka 60 mi to the southeast. Paleozoic basement rocks have been folded and faulted, and cut by younger Jurassic and Tertiary aged intrusions.

The Cortez deposits are “Carlin” style sedimentary rock-hosted and porphyry/epithermal deposits. Carlin deposits form as structurally and/or stratigraphically controlled replacement bodies consisting of strata-bound, tabular, disseminated gold mineralization occurring in Silurian-Devonian carbonate rocks. Deposits are localized at contacts between contrasting lithologies, metamorphosed to varying extents. They can also be discordant or breccia-related. The deposits are hydrothermal in origin, are usually structurally controlled and at Cortez are hosted in Lower Plate carbonate strata exposed by two erosional windows through allochthonous Upper Plate siliclastic units; the windows are on either side of Crescent Valley.

Mineralization consists primarily of submicron to micrometre-sized gold particles, very fine sulphide grains, and gold in solid solution in pyrite. Gold is disseminated throughout the host rock matrix in zones of silicified and decarbonatized, argillized, silty calcareous rocks, and associated jasperoids. Gold may occur around limonite pseudomorphs of authigenic pyrite and arsenopyrite. Major ore minerals include native gold, pyrite, arsenopyrite, stibnite, realgar, orpiment, cinnabar, fluorite, barite, and rare thallium minerals. Gangue minerals typically comprise fine-grained quartz, barite, clay minerals, carbonaceous matter, and late-stage calcite veins.

In the Cortez district, the favoured host rocks for gold mineralization are the Devonian Wenban Limestone, followed by the Horse Canyon and Roberts Mountain Formations. Mineralization reflects an interplay between structural and lithological ore controls in which hydrothermal solutions from intrusives moved to favourable porous decalcified limestone.

Mineralized host rocks are predominantly characterized as oxides, along with sulphidic and carbonaceous refractory material. Carbon content in the deposits is highly variable and occurs generally in the Devonian Wenban Limestone and the Roberts Mountain Formation. Supergene alteration extends up to 656 ft depth resulting in oxide ores, which overlie the refractory sulphides. Alteration has liberated gold by the destruction of pyrite and resulted in the formation of oxide and secondary sulphate minerals, which include goethite, hematite, jarosite, scorodite, alunite, and gypsum.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-12    


LOGO    www.rpacan.com

 

 

EXPLORATION STATUS

Modern exploration commenced along the Battle Mountain–Eureka Trend in the 1960s, and has been nearly continuous since that time. Exploration in the Cortez district has been undertaken by Barrick and its predecessor companies such as the CJV and has included mapping, various geochemical and geophysical surveys, pitting, trenching, petrographic, and mineralogy studies, and various types of drilling.

Barrick has advanced stage exploration drilling projects at Cortez. Exploration projects include underground drilling programs at Cortez Hills Lower Zone (Deep South), Horse Canyon Cortez exploration project, and metallurgical testwork at Hilltop.

MINERAL RESOURCES

RPA considers the December 31, 2015 Mineral Resource estimate completed by Barrick to be reasonable, acceptable, and reported in compliance with Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves dated May 10, 2014 (CIM definitions) as incorporated by reference into NI 43-101. The Mineral Resources are exclusive of Mineral Reserves and are summarized in Table 1-1.

The Mineral Resources are estimated from three dimensional block models created using Vulcan software. Surfaces and solids representing topography, overburden, geological units, and gold mineralization were incorporated into the resource block models. Resource estimates utilize drill hole, survey, geological, analytical and bulk density information entered, validated and maintained in a centralized acQuire SQL Server database. Industry standard best practices were used to obtain the data; quality assurance and quality control (QA/QC) protocols, as well as data validation procedures, were employed to ensure that the quality and quantity of data used for the resource estimates were appropriate and acceptable.

MINERAL RESERVES

The Mineral Reserves for Cortez as of December 31, 2015 are summarized in Table 1-2. These Mineral Reserves are a combination of the open pit and underground operations and the stockpiles.

RPA considers the Mineral Reserve estimate, completed by Barrick, to be reasonable, acceptable, and reported in accordance with CIM definitions and NI 43-101. The Mineral

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-13    


LOGO    www.rpacan.com

 

 

Reserves are generated based upon the mine designs applied to the Measured and Indicated Mineral Resources. The design methodology uses both the cut-off grade estimation and economic assessment to design and validate the Mineral Reserves.

MINING METHOD

The current Cortez site has been operating since 1988. Currently, the active mining areas are the Cortez Hills and Pediment pits, the Pipeline and Crossroads pits, and the Cortez Hills underground.

Open pit mining at Cortez Hills and Pipeline is by conventional open pit methods using hydraulic and electric front shovels and large, off-highway dump haul trucks. The open pit mine life is estimated to be three years for Cortez Hills (2016 through 2018) and eight years for the Pipeline Complex (2016 through 2023). The open pit operations has an estimated current daily material movement capacity of 400,000 stpd.

Underground mining is being carried out in the Breccia, Middle, and Lower zones. The underground mine is operating at a rate of 2,000 stpd with all ore hauled to surface by truck. The mining is all by drift and fill mining method. Management are working on plans to increase the mine production by improving the productivity of the drift and fill mining and implementing long hole stoping in some areas of the Lower Zone. Under the current mine plan, which includes the Deep South Zone project, underground mining at Cortez Hills is scheduled through 2028.

As a result of a positive PFS completed in 2015, approximately 1.7 million ounces of Measured and Indicated Mineral Resources in the Deep South Zone, a down dip extension of the Lower Zone below the 3,800 ft level, were converted to Proven and Probable Mineral Reserves as of year-end 2015. Under the current mine plan, which incorporates the Cortez Underground Expansion Project, the Deep South Zone is proposed to be mined using long hole stoping methods and will use extensions to the planned Lower Zone infrastructure for the movement of rock, men, and materials. Mining of the Deep South Zone requires dewatering below the 3,800 ft level and this requires an amendment to the Plan of Operations (PoO). The permitting process is expected to take three to four years. This permit amendment application is planned to be submitted in 2016. On this basis, following the receipt of permits, dewatering and development work could begin as early as 2019 or 2020, with initial production from the Deep South Zone commencing in 2022. The expansion of the underground mine will help to offset

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-14    


LOGO    www.rpacan.com

 

 

the impact of the end of mining in the Cortez Hills open pit, which is expected to conclude in 2018. The majority of the ore in the Deep South Zone is oxide ore which is proposed to be treated in the Pipeline Mill or at heap leach facilities at Cortez after the Pipeline Mill operation ceases in 2023.

Over the past four years, the underground mine production has been steady at approximately 2,000 stpd to 2,200 stpd ore. Over the same period, the grade has decreased from 1.07 oz/st Au to 0.63 oz/st Au.

In 2015, 23.4 Mst of ore was mined and 24.7 Mst was processed at a head grade of 0.50 oz/st Au. Gold production was 999,278 oz.

MINERAL PROCESSING

Ore from Cortez is either processed on site in the oxide processing facilities or transported to Barrick’s Goldstrike operation for refractory ore treatment.

Mill No. 2, or the Pipeline mill, is a nominal 13,000 stpd oxide processing plant with crushing, a semi-autogenous grinding (SAG) mill, a ball mill, grind thickener, a carbon-in-column (CIC) circuit for the grind thickener overflow solution, a CIL circuit, tailings counter-current-decantation (CCD) wash thickener circuit, carbon stripping and reactivation circuits, and a refinery to produce gold doré.

A primary gyratory crusher is located adjacent to the CHOP together with a series of overland conveyors that transport the ore to the coarse ore stockpile at Mill No. 2. There is a primary jaw crusher at Mill No. 2 that is used when processing ore from Pipeline and in the future, Crossroads.

Tailings are stored in a zero-discharge tailings storage facility. A double liner covers the entire tailings area, extending completely under the dam embankment.

Low-grade oxide material is leached as ROM ore on three prepared double-lined leach pads. Pregnant solution from the leach pads is fed to CIC columns for gold recovery. The loaded carbon from the heap leach operation is transported to the mill for gold recovery.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-15    


LOGO    www.rpacan.com

 

 

Area 28 heap leach circuit has a water balance that is interlinked with the Pipeline mill circuit since it uses the tailings pond under-drain solution as leach solution and excess pad effluent is processed in the mill CIC circuit. Area 28 is at maximum capacity for ore stacking and is no longer an operating leach pad. The Area 30 heap leach circuit is independent of the Pipeline mill. Ore delivery to the pad recommenced in 2013 and is set to continue through 2023. Area 34 heap leach is a third pad that was designed to treat CHOP ore. The first cells were placed under leach during March 2011 and ore deliveries are scheduled to continue through 2018 based on the current LOM plan.

Ores that have a cyanide soluble (shake test) to fire assay gold (AA/FA) ratio of less than 50% are transported to Goldstrike for processing in either the pressure oxidation (POX) circuit or the roaster. Haulage of refractory ore to Goldstrike is currently limited by permit to 1.2 Mstpa. At Goldstrike, two options are currently available for processing refractory ore. It will either be processed in the roaster followed by a CIL circuit or in the TCM process, which includes POX followed by resin-in-leach with CaTs.

MARKET STUDIES

Gold is the principal commodity at Cortez and is freely traded, at prices that are widely known, so that prospects for sale of any production are virtually assured. Prices are usually quoted in US dollars per troy ounce.

ENVIRONMENTAL, PERMITTING, AND SOCIAL CONSIDERATIONS

Cortez and Barrick have environmental groups and management systems to ensure that the necessary permits and licences are obtained and maintained. These groups also carry out the required monitoring and reporting required. Cortez has developed an environmental management system (EMS) to help manage the environmental requirements.

The BLM issued the original EIS and Record of Decision (ROD) in November 2008 and a supplemental EIS and ROD in March 2011. In October 2012, Cortez submitted a second proposed amendment to the existing PoO (APO2). All components of the APO2 application were approved by the BLM on February 24, 2014.

Cortez submitted additional proposed modifications to the PoO in August 2014 and then, following a revision, in October 2014. The proposed modifications include:

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-16    


LOGO    www.rpacan.com

 

 

   

Deepen the Gap Pit from 4,400 ft amsl to 4,360 ft amsl

 

   

Construct the Range Front Declines and associated infrastructure

 

   

Expand the Area 30 heap leach facilities by 240 acres

 

   

Modify mining rate between the Cortez Hills and Pipeline

 

   

Add a water treatment plant and infrastructure to reduce naturally occurring arsenic concentrations in the dewatering water

 

   

Allow off-site ore haulage up to approximately 1.2 Mstpa site wide

 

   

Reconfigure the Pipeline, Canyon, and Gap waste rock facilities

 

   

Infrastructure additions

An APO-3 was approved by the BLM and a ROD was completed in 2015.

A number of permits are required to operate the Cortez Mine. Cortez adheres to permitting guidelines from the BLM, the Nevada Revised Statutes (NRS), the Nevada Administrative Code (NAC), and other federal government requirements.

CAPITAL AND OPERATING COST ESTIMATES

The total capital expenditure in the 2016 LOM plan is $2,011 million broken down as shown in Table 1-3.

This total includes capital required to expand underground mining into the Deep South Zone below currently permitted levels. The project has the potential to contribute underground production beginning in 2022 and will average more than 300,000 ounces per year between 2023 and 2027 at average all-in sustaining costs of approximately $580 per ounce. Initial capital costs are estimated to be $153 million and sustaining capital is estimated to be $58 million, for the Deep South Zone project total of $211 million.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-17    


LOGO    www.rpacan.com

 

 

TABLE 1-3 CAPITAL COSTS

Barrick Gold Corporation – Cortez Operations

 

Year

          Deferred
Operating
     Expansion      Exploration      Fixed
Equipment
     Mobile
Equipment
     Regulatory      Grand
Total
 

2016

   US$  M         58.6         222.1         9.8         43.5         7.4         9.1         350.5   

2017

   US$  M         50.7         284.1         8.1         19.8         9.3         5.0         376.9   

2018

   US$ M         145.5         169.3         11.8         22.5         12.8         37.8         399.7   

2019

   US$ M         253.8         61.5         11.0         22.5         6.1         7.4         362.2   

2020

   US$ M         131.7         29.5         11.3         13.8         12.4         1.8         200.5   

2021

   US$ M         19.7         21.7         6.1         13.4         7.9         1.6         70.5   

2022

   US$ M         12.9         6.8         4.0         7.5         10.7         1.6         43.6   

2023

   US$ M         29.5         5.7         2.9         2.2         5.9         1.6         47.8   

2024

   US$ M         46.2         7.7         2.6         0.4         8.4         1.6         67.0   

2025

   US$ M         41.4         29.4         1.8         0.4         9.8         1.7         84.5   

2026

   US$ M         0.9         2.3         1.6         0.3         —           1.6         6.7   

2027

   US$ M         —           —           —           —           —           0.5         0.5   

2028

   US$ M         —           —           —           —           —           0.5         0.5   

Total

   US$  M         791         840         71         146         91         72         2,011   

The LOM operating costs are shown in Table 1-4.

TABLE 1-4 LOM OPERATING COSTS

Barrick Gold Corporation – Cortez Operations

 

     Unit      Open Pit      Underground  

Mine $/t mined

   US$ /st mined         1.79         86.59   

Mine $/t milled

   US$ /st milled         12.60         104.82   

Process

   US$ /st milled         7.43         22.87   

G&A

   US$ /st milled         2.40         24.02   

Refine freight

   US$ /st milled         0.01         0.09   

Royalty

   US$ /st milled         2.21         4.90   

Total

   US$ /st milled         24.66         156.70   

VALUE REALIZATION INITIATIVES

In addition to the Cortez Underground Expansion, i.e., expanding underground mining into the Deep South Zone, below currently permitted levels, Barrick has recently conducted a technical review of the Cortez Operations with the objective of identifying potential opportunities to increase production capacity. The opportunities that have been identified so far include:

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-18    


LOGO    www.rpacan.com

 

 

CORTEZ PITS MINING

The Cortez Pits area is located to the north of the current Cortez Hills underground portal and the area was previously mined between 1969 and 1993. There is a remaining resource below the historic Cortez Pits that is a continuation of the mined-out portion of the Cortez deposit. The current reported Measured plus Indicated Mineral Resources total 4.1 Mt at a grade of 0.056 oz/st Au with 227,000 oz of contained gold. Pending the appropriate level of studies to convert the mineralization to Mineral Reserves, mining would be by open pit methods of the primarily heap leach grade material. A total of 163,000 oz is expected to be recovered using a process recovery of 74.1%.

There is sufficient drilling information associated with this deposit to model the resource in terms of gold grade, however, additional drilling information is required for geotechnical guidance and metallurgical testing. The deposit also allows for resource upgrades at gold prices greater than US$1,400.

HAULAGE CAPACITY INCREASE

The Cortez Hills operation currently ships refractory ores via over-the-highway haul trucks to the Goldstrike operation for processing. Haulage is currently limited by permit to 1.2 Mstpa. An opportunity exists to expand the shipping rate to 2.2 Mstpa during the APO-4 permitting process, allowing increased shipping to begin upon permit receipt in 2020. Permit submittal is currently scheduled for Q1 2016.

Additional technical studies are underway to determine increased haulage parameters including fleet sizing and road base suitability.

Increased shipping rates will allow advancing the current LOM production stream of refractory material.

PRODUCTION CAPACITY INCREASE BY 10%

Cortez Hills operation has identified an opportunity to increase production capacity by an approximately 10% increase of the CIL process plan and heap leach (HL) capacity. This will be achieved as follows:

 

   

Partial solution recycle is pursued applying pregnant leach solution to new material for the first 30 days of leaching.

 

   

CIL process plant throughput is achieved by maximizing SAG and ball mill power draw along with improved secondary grinding circuit control strategies.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-19    


LOGO    www.rpacan.com

 

 

   

Increased capacity will advance production and cash flow streams along with slight reduction in unit costs. Implementation is currently underway (10% complete) as the majority of infrastructure is in place. Capital cost is estimated to be $10 million (conceptual level) for solution distribution. Improvements in throughput are estimated to be 10% to 20% for HL and 5% to 12% for CIL.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 1-20    


LOGO    www.rpacan.com

 

 

2 INTRODUCTION

Roscoe Postle Associates Inc. (RPA) was retained by Barrick Gold Corporation (Barrick) to prepare an independent Technical Report on the Cortez Open Pit and Underground Mine Operations (the Cortez Operations or the Mine), in Eureka and Lander Counties, Nevada, USA. The purpose of this report is to support the public disclosure of Mineral Resources and Mineral Reserves at Cortez as of December 31, 2015. This Technical Report conforms to NI 43-101 Standards of Disclosure for Mineral Projects.

Barrick is a Canadian publicly traded mining company with a portfolio of operating mines and projects across five continents. The Cortez Operations are located in northeastern Nevada approximately 62 mi west and south of Elko.

The Cortez Mine is a joint venture between two wholly-owned subsidiaries of Barrick, Barrick Cortez Inc. (60%) and Barrick Gold Finance Inc. (40%). The Cortez Hills Project is 100% owned by Barrick Cortez Inc. The Cortez Operations consist of the Pipeline, Crossroads, Gap, Cortez Hills (CHOP), and Pediment open pits, the Cortez Hills underground (CHUG) mine, a 13,000 short ton per day (stpd) carbon-in-leach (CIL) gold plant, heap leach pads and heap leach processing plants, and the planned Crossroads open pit, with additional Mineral Resources contained in the Cortez Pits and Gold Acres open pits. The nearby deposit of Hilltop is also part of the Mine but does not have reportable resources at this time.

The open pit is a large scale operation utilizing a conventional truck and shovel fleet and mining approximately 400,000 stpd of ore and waste. Mining operations move between the various pits over the Life of Mine (LOM) plan. The underground mine is a 2,000 stpd mechanized mine. Ore from the mines is treated at an oxide mill at the site and on leach pads and refractory ore is shipped to Barrick’s Goldstrike operation for processing.

Barrick completed a Pre-feasibility Study (PFS) for underground mining in the Deep South Zone (the Cortez Underground Expansion Project), below currently permitted areas of the CHUG. The PFS indicated that the project has the potential to contribute underground production of more than 300,000 ounces per year between 2022 and 2026 at average all-in sustaining costs of approximately $580 per ounce. More detailed planning, subsequent to the PFS, has resulted in the current LOM beginning underground gold production from the Deep

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 2-1    


LOGO    www.rpacan.com

 

 

South Zone in 2022 and producing 300,000 ounces per year between 2023 and 2027. Initial capital costs are estimated to be $153 million. The PFS supports conversion of approximately 1.7 million ounces of Measured and Indicated Resources in the Deep South Zone to Proven and Probable Reserves as of December 31, 2015.

The PFS timeline assumes that permitting will take approximately three to four years and Barrick expects to commence this process in the first half of 2016. On this basis, following the receipt of permits, dewatering and development work could begin as early as 2019 or 2020, with initial production from the Deep South Zone commencing in 2022. The expansion of the underground mine is expected to offset the impact of the end of mining in the Cortez Hills open pit, which is scheduled to conclude in 2018.

SOURCES OF INFORMATION

Site visits were carried out by Wayne Valliant, P.Geo., RPA Principal Geologist, Chester Moore P.Eng., RPA Principal Geologist, Dennis Bergen, P.Eng., RPA Associate Principal Mining Engineer, Stuart Collins, P.E., RPA Principal Mining Engineer, and Kathleen Ann Altman, Ph.D., P.E., RPA Principal Metallurgist, from May 5 to 7, 2015.

Discussions were held with personnel from Barrick and Cortez:

 

   

Larry Snider, Senior Resource Geologist

 

   

Roger Bond, Senior Geologist

 

   

Andrew Ostendorf, Resource Geologist

 

   

Felipe Salamanca, Open Pit Chief Engineer

 

   

Robert Dudley, Accounting Supervisor

 

   

Jim MacPherson, Senior Mine Engineer

 

   

Dave Pierce, Water Management Superintendent

 

   

Lynnette Hutson, Senior Business Analyst

 

   

Patrick Jenks, Chief Geotechnical Engineer

 

   

Mark D. Miller, Environmental Manager

 

   

Nick Atiemo, Environmental Superintendent

 

   

Brian D. Taylor, Environmental Specialist III (Public Lands)

 

   

Amiee Keys, Environmental Specialist II (Environmental Management System)

 

   

Steve Cashin, Process Manager

 

   

Jon Kamensky, Superintendent Metallurgical Services & Heap Operations

 

   

Jeff Olson, Metallurgist

 

   

Emrah Yalcin, Senior Metallurgist

 

   

Pamela Moyo, Senior Metallurgical Engineer

 

   

Erin Lee Buck, Metallurgist

 

   

James (Sam) Edens, Metallurgical Coordinator

 

   

Brandon Cooper, Metallurgist

 

   

Theo Kandawasvika, Technical Services Superintendent

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 2-2    


LOGO    www.rpacan.com

 

 

   

Beverley O’Malley, Cortez Hills Underground, Chief Geologist

Mr. Valliant is responsible for the overall preparation of this report and reviewed the geology, sampling, assaying, and resource estimate of the open pit part of the operation described in Sections 7 to 12 and 14 as well as the general information in Sections 4, 5, and 6. Mr. Moore reviewed the geology, sampling, assaying, and resource estimate of the underground part of the operation described in Sections 7 to 12 and 14. Mr. Collins reviewed the mining practices, reserve estimate, and economics of the open pit division and is responsible for the open pit portions of Sections 15, 16, 18, 19, 21, and 22. Mr. Bergen reviewed the mining practices, reserve estimate, and economics of the underground division and is responsible for the underground portions of Sections 15, 16, 18, 19, 21, and 22. Dr. Kathleen Ann Altman reviewed the metallurgical and environmental aspects of the operation and is responsible for Sections 13, 17, and 20. All authors share responsibility for Sections 1, 2, 3, 24, 25, 26, and 27.

The documentation reviewed, and other sources of information, are listed at the end of this report in Section 27 References.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 2-3    


LOGO    www.rpacan.com

 

 

LIST OF ABBREVIATIONS

Units of measurement used in this report conform to the imperial system. All currency in this report is US dollars (US$) unless otherwise noted.

 

A

 

annum

 

kWh

 

kilowatt-hour

amsl

 

average mean sea level

   

A

 

ampere

 

L

 

litre

bbl

 

barrels

 

lb

 

pound

btu

 

British thermal units

 

L/s

 

litres per second

°C

 

degree Celsius

 

m

 

metre

C$

 

Canadian dollars

 

M

 

mega (million); molar

cal

 

calorie

 

m2

 

square metre

cfm

 

cubic feet per minute

 

m3

 

cubic metre

cm

 

centimetre

 

µ

 

micron

cm2

 

square centimetre

 

µg

 

microgram

d

 

day

 

m3/h

 

cubic metres per hour

dia

 

diameter

 

mi

 

mile

dmt

 

dry metric tonne

 

min

 

minute

dwt

 

dead-weight ton

 

µm

 

micrometre

°F

 

degree Fahrenheit

 

mm

 

millimetre

ft

 

foot

 

mph

 

miles per hour

ft2

 

square foot

 

MVA

 

megavolt-amperes

ft3

 

cubic foot

 

MW

 

megawatt

ft/s

 

foot per second

 

MWh

 

megawatt-hour

g

 

gram

 

oz

 

Troy ounce (31.1035g)

G

 

giga (billion)

 

oz/st

 

ounce per short ton

Gal

 

Imperial gallon

 

ppb

 

part per billion

g/L

 

gram per litre

 

ppm

 

part per million

Gpm

 

Imperial gallons per minute

 

psia

 

pound per square inch absolute

g/t

 

gram per tonne

 

psig

 

pound per square inch gauge

gr/ft3

 

grain per cubic foot

 

RL

 

relative elevation

gr/m3

 

grain per cubic metre

 

s

 

second

ha

 

hectare

 

st

 

short ton

hp

 

horsepower

 

stpa

 

short ton per year

hr

 

hour

 

stpd

 

short ton per day

Hz

 

hertz

 

t

 

metric tonne

in.

 

inch

 

tpa

 

metric tonne per year

in2

 

square inch

 

tpd

 

metric tonne per day

J

 

joule

 

US$

 

United States dollar

k

 

kilo (thousand)

 

USg

 

United States gallon

kcal

 

kilocalorie

 

USgpm

 

US gallon per minute

kg

 

kilogram

 

V

 

volt

km

 

kilometre

 

W

 

watt

km2

 

square kilometre

 

wmt

 

wet metric tonne

km/h

 

kilometre per hour

 

wt%

 

weight percent

kPa

 

kilopascal

 

yd3

 

cubic yard

kVA

 

kilovolt-amperes

 

yr

 

year

kW

 

kilowatt

   

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 2-4    


LOGO    www.rpacan.com

 

 

3 RELIANCE ON OTHER EXPERTS

This report has been prepared by Roscoe Postle Associates Inc. (RPA) for Barrick Gold Corporation (Barrick). The information, conclusions, opinions, and estimates contained herein are based on:

 

   

Information available to RPA at the time of preparation of this report,

 

   

Assumptions, conditions, and qualifications as set forth in this report, and

 

   

Data, reports, and other information supplied by Barrick and other third party sources.

For the purpose of this report, RPA has relied on ownership information provided by Barrick. RPA has not researched property title or mineral rights for Cortez and expresses no opinion as to the ownership status of the property.

RPA has relied on Barrick for guidance on applicable taxes, royalties, and other government levies or interests, applicable to revenue or income from Cortez.

Except for the purposes legislated under provincial securities laws any use of this report by any third party is at that party’s sole risk.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 3-1    


LOGO    www.rpacan.com

 

 

4 PROPERTY DESCRIPTION AND LOCATION

The Cortez Gold Mine is located 62 mi southwest of Elko, Nevada, USA. The Mine is located in Eureka and Lander Counties (Figure 4-1). The Cortez property is surrounded by the Cortez Joint Venture Area of Interest (CJVAOI) that covers approximately 1,053 mi2 (Figure 4-2). The deposits and infrastructure are illustrated in Figures 4-3, 4-4, and 4-5.

The CJVAOI includes private land, patented, and unpatented mineral claims and fee land and land controlled by competitors. The co-ordinates of the Pipeline open pit are approximately 40°15’ North latitude and 116°43’ West longitude.

LAND TENURE

At Cortez, Barrick directly controls approximately 216,124 acres of mineral rights with ownership of mining claims and fee lands. There are 10,461 claims consisting of:

 

   

9,630 unpatented lode claims

 

   

575 unpatented mill-site claims

 

   

104 patented lode claims

 

   

125 patented mill-site claims

 

   

27 unpatented placer claims and 185 patented mill-site claims

All lease agreements and claim holdings are current and in good standing.

The 2015 holding costs for the Cortez property include $1.7 million in holding costs and $496,015 in lease payments.

Unpatented lode and mill-site claims are held under the 1872 mining law as amended, which requires the annual payment of $155 per claim on or before noon on the first of September each year. If the annual payment is not made for that specific claim, the claim will lapse and be subject to forfeiture. Patented ground or claims are surveyed by a certified mineral surveyor, and appropriate monuments placed in the ground. Each unpatented claim is marked on the ground, and does not require a mineral survey.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 4-1    


LOGO    www.rpacan.com

 

 

All Mineral Reserves and Mineral Resources, in addition to existing and future facilities to be used to exploit the Mine deposits, are on public lands administered by the Battle Mountain or Elko Field Offices of the U.S. Department of Interior, Bureau of Land Management (BLM).

ROYALTIES

The Cortez operation is subject to a number of royalties. All production at Cortez is subject to a 1.28595% gross smelter return (GSR) royalty payable to the former shareholders of Idaho Mining Corporation. This was originally a 2.5% GSR royalty covered by a capping of ounces produced; the production limit has been met and the royalty reduced to a 1.28595%. GSR is defined as 100% of smelter revenue before deductions for refining and transportation. The Idaho Mining Corporation royalty pertains to any production from the Pipeline, South Pipeline, Crossroads, Gap, Gold Acres, Cortez NW Deep, Cortez Hills, Pediment, and Hilltop deposits.

Royal Gold Inc. (Royal Gold) holds a sliding-scale GSR royalty over the Pipeline/South Pipeline deposits ranging from 0.40% to 5.0%. An additional sliding-scale GSR royalty is held over the undeveloped Crossroads deposit.

ECM Inc. (ECM) holds a net value royalty of 3.75% of gold sales from the South Pipeline deposit.

Rio Tinto holds a sliding-scale royalty (of 0% at gold prices less than $400/oz to 3% at gold prices greater than $900/oz) on 40% of all Cortez production in excess of 15 million ounces on and after January 1, 2008, which has not yet occurred.

The State of Nevada imposes a 5% net proceeds tax on the value of all minerals severed in the State. This tax is calculated and paid based on a prescribed net income formula which is different from book income. RPA is not aware of any environmental liabilities on the property. Barrick has all required permits to conduct work on the property. RPA is not aware of any other significant factors and risks that may affect access, title, or the right or ability to perform work on the property.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 4-2    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 4-3    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 4-4    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 4-5    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 4-6    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 4-7    


LOGO    www.rpacan.com

 

 

5 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY

ACCESSIBILITY

The Mine is reached by travelling approximately 32 mi east from Battle Mountain, Nevada, on US Interstate 80. Alternative access is from Elko, Nevada, approximately 45 mi west to the Beowawe exit, then approximately 35 mi south on Nevada State Route 306, which extends southward from US Interstate 80. Both US Interstate 80 and Nevada State Route 306 are paved roads.

The mining district is also crossed by a network of gravel roads, providing easy access to various portions of the Mine. All roads are suitable for all weather conditions; however, in extreme winter conditions, roads may be closed for short periods for snow removal.

The Union Pacific Rail line runs parallel to US Interstate 80 to the north of the Mine. Elko, the closest city to the Mine, is serviced by daily commercial airline flights to Salt Lake City, Utah.

CLIMATE

The Mine is located in the high desert region of the Basin and Range physiographic province. There are warm summers and generally mild winters, however, overnight freezing conditions are common during winter. The mean annual temperature is 51°F. Precipitation averages six inches per year, primarily derived from snow and summer thunderstorms. Typically, the months with the greatest precipitation are March, May, and November. During the winter months at elevations above approximately 5,500 ft amsl, precipitation generally occurs as snow. Evaporation is estimated at 39 in. per year.

Operations continue on site year-round and are not materially impacted by weather.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 5-1    


LOGO    www.rpacan.com

 

 

LOCAL RESOURCES

Cortez is located in a major mining region and local resources including labour, water, power, contractors and suppliers, and local infrastructure for transportation of supplies are well established. The majority of the workforce lives in the nearby towns of Elko, Spring Creek, Carlin, and Battle Mountain.

Electric power is provided to the Cortez site by NV Energy via an approximately 50 mi long radial transmission line originating at their Falcon substation. The incoming NV Energy line terminates at the Barrick owned Pipeline Substation. Two 120 kV lines that tap onto the NV Energy power line feed Barrick owned 120 kV power lines: an approximately 9 mi extension to serve the Cortez Hills development and an approximately 3 mi extension to serve the South Pipeline and Crossroads pits.

Water for process use at Cortez Mill No. 2 is supplied from the Pipeline open pit dewatering system. Approximately 1,450 gallons per minute of the pit dewatering volume is diverted for plant use. Additional water can be sourced as needed from wells at Mill No. 1.

Process water supply for Cortez Hills will be drawn in whole or in part from dewatering operations. If sufficient volume cannot be produced by dewatering, process water will be supplied by existing production wells at the Pipeline and/or Cortez facilities.

Water from the CHUG is pumped across Crescent Valley to an existing surface re-infiltration area.

INFRASTRUCTURE

There is an extensive infrastructure in place to support the Cortez Operations including:

 

   

The 13,000 stpd No. 2 Mill complete with run-of-mine (ROM) pad and crushing circuit (including a primary jaw crusher)

 

   

Pipeline leach pad and gold recovery plant

 

   

Area 34 leach pad and gold recovery plant for Cortez Hills and Pediment

 

   

A tailings management facility

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 5-2    


LOGO    www.rpacan.com

 

 

   

A gyratory crusher at the Cortez Hills open pit (CHOP) and an 11 mi long conveyor to the No. 2 Mill

 

   

Existing active open pit mines at CHOP, Cortez, Pipeline, and Crossroads

 

   

Pit dewatering wells and pumps for the open pits

 

   

Infiltration ponds for the disposal of water

 

   

An existing underground mine at Cortez Hills Underground (CHUG)

 

   

Batch plant for shotcrete and cemented rock fill preparation

 

   

Stockpile areas for an assortment of ore types

 

   

Office complexes at the Mill No. 2, Mill No. 1, CHUG, and CHOP

 

   

Equipment maintenance shops at CHOP, CHUG, and adjacent to the Mill No. 2

 

   

Exploration offices, core handling, and core storage warehouse

 

   

System of public and private roads connecting the facilities

 

   

Shared business support services from the business unit offices in Elko

PHYSIOGRAPHY

The Pipeline mine and Mill No. 2 are located at the southern end of the Crescent Valley in Lander County, Nevada. The Cortez Hills deposits and operations are located at the northern end of Eureka County. The Crescent Valley is a structural and topographic basin between the Northern Shoshone Range on the west and the Cortez Range on the east. Most mine facilities are on the west side of the valley at an elevation of approximately 5,000 ft amsl. This includes the original workings of the Gold Acres mine, now inactive, the Pipeline pit, the Gap pit and the proposed Crossroads pit.

The property is located at elevations between 4,500 ft amsl and 6,000 ft amsl on the valley floor and up the side of Mount Tenabo.

The Cortez Mine and Mill No. 1 (both inactive) are located along the northern edge of the Cortez Range seven miles southeast of the Pipeline pit. The Cortez Hills and Pediment deposits are located in the Cortez Hills approximately three miles south of the Cortez Pits and at an elevation of approximately 6,000 ft amsl.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 5-3    


LOGO    www.rpacan.com

 

 

The vegetation consists primarily of shrubs and grasses, such as sagebrush, rabbitbrush, cheatgrass, and grama. Juniper trees, pinion pine, mountain mahogany, and a variety of grasses are also present. In general, vegetation is relatively sparse. The valley floor is sparsely vegetated while the mountain slopes have small pinion pine and juniper trees. No endangered or threatened species, BLM-sensitive species, or plants proposed for listing have been identified in the Mine area.

Fauna that have been observed in the Mine area are typical of those of the Great Basin area, and include jackrabbits, cottontail rabbits, mule deer, antelope, coyotes, various rodents, and reptiles. No proposed threatened, or endangered species are considered to exist within the Mine area.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 5-4    


LOGO    www.rpacan.com

 

 

6 HISTORY

Mining in the Cortez Mining District began with the discovery of silver mineralization in 1862 along the quartzite outcroppings at the western base of Mount Tenabo, some four miles to the southeast of the Cortez Mill No. 1 complex. Underground silver mining was conducted in the area until the 1930s. Mineralization at Hilltop was also identified during the 1860s. The majority of production occurred between 1915 and 1951 from underground sources, with approximate production of 18,000 ounces of gold, 360,000 ounces of silver and subordinate amounts of lead, copper, and antimony. Gold mineralization at Gold Acres was discovered in the late 1920s and mined by a small mining company from 1935 to 1960. The mine was one of the few gold operations to remain open during World War II.

In 1959, American Exploration & Mining Co. (AMEX), a wholly-owned US subsidiary of Placer Development Ltd. (subsequently Placer Dome Inc. (Placer Dome) and Barrick), entered into a lease-option agreement on the properties of the Cortez Metals Co. and started extensive exploration of the mine workings and surrounding area. In 1963 AMEX entered into an exploration agreement with Idaho Mining Corp., which had acquired large areas of mineralized ground adjoining the AMEX holdings. In 1964, AMEX formed the Cortez Joint Venture (CJV) with the added participation of the Bunker Hill Co., Vernon F. Taylor, Jr., and Webb Resources Inc.

The US Geological Survey found anomalous gold in altered outcrops at the base of the Cortez Range in 1966. The CJV shortly afterwards discovered the Cortez deposit. Production at Cortez began in 1969 and continued until 1972, and then resumed from 1988 to 1993. Production was from the F-Canyon, Cortez, and Ada 52 pits. Waste dumps from the operations were reclaimed during the 1990s. The Cortez process facilities include three inactive heap leach pads, West, East and 91-C leach pads, constructed in 1972, 1984, and 1990 respectively. The leach pads have been inactive since 1994. Seven tailings storage areas are situated in the Cortez area, TA 1 to TA 7, inclusive.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 6-1    


LOGO    www.rpacan.com

 

 

TABLE 6-1 HISTORY OF EXPLORATION AND MINING AT CORTEZ SITE

Barrick Gold Corporation – Cortez Operations

 

Period

  

Activity

1862–1932

  

Cortez Silver mine in operation

1912–1921

  

Mining of gold, lead, copper and antimony at Hilltop

Late 1920s

  

Gold Acres deposit discovered

1935–1960

  

Gold mined from the Gold Acres deposit by other companies. Gold Acres mined as an open pit operation

1964

  

CJV formed

1966

  

Cortez deposit discovered

1968

  

Horse Creek (formerly Red Hill) discovered by Homestake Mining Co.

1969–1972; 1988–1993

  

Cortez deposit mined

1973–1976

  

New southern extension of the Gold Acres deposit mined and Horse Canyon deposit discovered

1976–1983

  

Low-grade oxide ores from Cortez and Gold Acres heap leached

1983–1987

  

Horse Canyon deposit mined

1987–1996

  

Mining resumed in the Cortez and Gold Acres deposits

1989

  

Acquisition of Hilltop deposit

1991

  

Pipeline, South Pipeline, Crescent and Gap deposits discovered

1994

  

Commenced mining the Crescent pit within the north western portion of the South Pipeline deposit

1996

  

Mining commenced on the Pipeline deposit

1997

  

Production at Mill No. 2 commenced. Total development and capital costs were $250 million.

1998

  

Crossroads and Pediment deposits discovered.

1999

  

Mill No. 1 was placed on care and maintenance.

2001

  

Plan of Operations was submitted for Pipeline expansion and Pediment

2002

  

South Area heap leach facility was commissioned

2003

  

Cortez Hills deposit discovery announced

2004–2009

  

Infill drilling continued at Cortez Hills and Pediment deposits Discovery of Lower Zone at Cortez Hills

2005

  

Completion of positive internal Feasibility Study on Cortez Hills

2006

  

Barrick acquires Placer Dome; commencement of mining at the South Gap deposit

2008

  

Acquisition of remaining 40% interest in the Mine through Barrick purchase of Kennecott interest from Rio Tinto. Positive Record of Decision received for Cortez Hills development

2009

  

Development of open pit commences at Cortez Hills. Mining halted at the Pipeline Complex.

2011

  

Goldrush deposit discovered.

2013

  

Production resumed at Pipeline Complex.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 6-2    


LOGO    www.rpacan.com

 

 

The CJV initiated exploration drilling around the pre-existing Gold Acres deposit in 1969, and obtained exploration rights to the former mining area in 1969. Open pit mining began in 1973, from the North and South pits. Low-grade ores from Gold Acres were mined and processed by heap leaching until 1976. Leaching and milling of Gold Acres stockpiles and dumps continued until 1983. The Gold Acres heap leach facility is associated with the deposits. Drilling resumed, resulting in the discovery of refractory gold mineralization in the vicinity of the North pit. Mill-grade ores were mined from 1987 to 1996 and processed at the Cortez Mill No. 1. Total production from this deposit (historic and recent) is estimated to exceed 500,000 ounces of gold. In 2003, the CJV commenced shipping Gold Acres refractory stockpiles for toll-processing at third-party facilities.

The Horse Canyon deposits were discovered in early 1976. Three pits, North, South, and South Extension were mined in the period from 1984 to 1987. Approximately 3.5 million tons were mined with approximately 385,000 ounces of gold recovered.

The Pipeline, South Pipeline, and Crossroads gold deposits occur in sequence from northwest to southeast and were entirely concealed beneath pediment gravels up to 300 ft thick. The Pipeline deposit was discovered by CJV geologists in March 1991 during drilling of deep condemnation holes on the pediment east of Gold Acres. The Gap deposit was discovered in 1991 adjacent to the planned Stage 9 of the Pipeline pit.

The Pipeline South area was initially controlled by association placer claims under the control of the CJV since the early 1970s. Only scattered sub-ore grade gold has been identified. The area was over-staked with lode claims by ECM in early 1987. By May 1987, Royal Gold had leased this property, known as the GAS claims, from ECM. The claim conflict was resolved by the formation of the Royal/Cortez Joint Venture between Royal Gold and the CJV later that year.

Royal Gold completed geophysical surveys and drilling programs between 1987 and 1989 that led to the identification of additional sub-economic gold grades, primarily in an anomaly known as GAS 2. Although a mineral resource was estimated no further work was undertaken by Royal Gold or by CJV due to the limited amount of drill data available. No further drilling by Royal Gold occurred due to lack of funding.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 6-3    


LOGO    www.rpacan.com

 

 

In August 1991, the Royal/Cortez Joint Venture was terminated and the CJV leased the property directly from ECM. A later dispute between Royal Gold and the CJV concerning termination of the Royal/Cortez Joint Venture led to the formation of the South Pipeline Project and the royalty structure.

In November 1991, the CJV discovered the South Pipeline deposit. Additional gold was identified in August 1992. Step-out and in-fill drilling continued through July 1994. This drilling confirmed the presence of a relatively shallow gold occurrence above the water table, the Crescent deposit. Mining of the Crescent pit (northwest part of the South Pipeline deposit) commenced in May 1994 and was completed in 1997. The Crescent pit has since been subsumed by the Pipeline pit.

An internal Feasibility Study (FS) covering the Pipeline and South Pipeline deposits was completed by Placer Dome Technical Services in 1995. Construction of Mill No. 2 and pre-stripping of the first stage of the Pipeline pit began in 1996. The Pipeline pit has estimated Mineral Reserves and is included in Barrick’s current LOM plan. Two waste dumps are permitted (Gap and Pipeline). Associated infrastructure includes the integrated Pipeline heap leach and tailings facility, South Area heap leach facility, and Mill No. 2.

Continued drilling along northwest-southeast structural trends at Pipeline in 1998 resulted in discovery of the Crossroads deposit southeast of the South Pipeline deposit. Crossroads is concealed beneath 550 ft of alluvium. It represents a continuation of mineralization from South Pipeline.

In 1996, CJV geologists began a program to test for concealed mineralization south of the Cortez Mine. Geochemical and geophysical surveys were used to guide deep reverse circulation (RC) drilling, initially focusing on an area immediately west of the Cortez Fault. In 1998, the Pediment deposit was discovered in a deep RC drilling program designed to test potential for bedrock mineralization in the central and western portions of the alluvium-covered Cortez Fault Corridor. Subsequent RC and core drilling programs through 2002 defined the Pediment deposit.

The Cortez Hills deposit was discovered in October 2002 as part of an RC drilling exploration program investigating a steep gravity gradient anomaly near the projected intersection of north–northwest-trending Cortez Fault Corridor structures and west–northwest-trending faults

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 6-4    


LOGO    www.rpacan.com

 

 

beneath alluvial cover immediately to the north of the Pediment deposit. In 2004, the Cortez Hills Lower Zone was discovered as part of the step-out drilling to the west of the Cortez Hills deposit.

In November 2008, the Environmental Impact Statement (EIS) for the Cortez–Pediment development was approved. The project was developed as two open pits and a concurrent underground development of a high-grade portion underlying the pits. Production from underground began in late 2008, and the first ore production of CHOP phases one through three occurred in late December 2009.

In March 2008, Barrick acquired a 100% interest in the Mine, purchasing the former Kennecott 40% interest for a consideration of $1.695 billion in cash, an additional $50 million payable if and when an additional 12 million ounces of contained gold Mineral Resources were added to Barrick’s December 31, 2007 Mineral Reserve statement for Cortez, and a sliding-scale royalty payable to Rio Tinto on 40% of all Cortez production in excess of 15 million ounces on and after January 1, 2008. In 2012, the threshold of an additional 12 million ounces added to Mineral Resources was reached, and the $50 million payment was made to Rio Tinto.

Production from the Mine in the period 1969 to 2015 is summarized in Table 6-2.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 6-5    


LOGO    www.rpacan.com

 

 

TABLE 6-2 ANNUAL PRODUCTION, 1969–2015

Barrick Gold Corporation – Cortez Operations

 

Year Ended

   Gold
(000 oz)

    1969

   166

    1970

   209

    1971

   120

    1972

   190

    1973

   76

    1974

   104

    1975

   74

    1976

   28

    1977

   2

    1978

   2

    1979

   2

    1980

   8

    1981

   21

    1982

   25

    1983

   47

    1984

   49

    1985

   56

    1986

   62

    1987

   51

    1988

   42

    1989

   40

    1990

   54

    1991

   58

    1992

   77

    1993

   67

    1994

   70

    1995

   111

    1996

   161

    1997

   407

    1998

   1,138

    1999

   1,328

    2000

   1,010

    2001

   1,188

    2002

   1,082

    2003

   1,065

    2004

   1,052

    2005

   904

    2006

   427

    2007

   323

    2008

   428

    2009

   518

    2010

   1,140

    2011

   1,421

    2012

   1,370

    2013

   1,337

    2014

   901

 

  

 

    2015

   999

 

  

 

    Total

   20,010

Note: Production from 1969 to 2005 is total production, reported on a 100% basis, sourced from corporate annual reports. Production from April to December 2006, 2007, and January to February 2008 is the Barrick interest only, at 60% of production. Barrick production at 100% is included from March 2008 onwards.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 6-6    


LOGO    www.rpacan.com

 

 

7 GEOLOGICAL SETTING AND MINERALIZATION

REGIONAL GEOLOGY

The Mine is located in the eastern Great Basin (Basin and Range Province) at the southern closure of Crescent Valley, a northeast trending structural and topographic basin between the Northern Shoshone Range on the west and the Cortez Range on the east. The Mine lies within the “Battle Mountain-Eureka Trend” (BMT), an alignment of gold mines and occurrences located in a northwest-southeast belt extending from the Marigold Mine some 50 mi northwest of Cortez, to Ruby Hill at Eureka 60 mi to the southeast.

Two regionally recognized Paleozoic assemblages comprise the basement sedimentary strata of northeastern Nevada. These assemblages were deposited on the western continental margin of North America. The western assemblage is a deep water marine package of siliciclastic rocks consisting of mudstone, chert, siltstone, sandstone, and minor limestone. The eastern shallow water sedimentary assemblage consists predominantly carbonate rocks including limestone, dolomite, and some quartzite units. The eastern assemblage underlies all other stratigraphic units in eastern and central Nevada.

Jurassic to Cretaceous intrusive rocks of granitic composition intrude the Paleozoic sedimentary rock and are locally exposed as stocks, sills, and dikes. Tertiary extrusive rocks unconformably overlie the older packages and are dominated by a bimodal suite of rhyolite and basaltic flows with associated felsic tuffs and lesser amounts of intermediate volcanic rocks. Post-mineralization Eocene to Oligocene quartz porphyry dikes and sills have been emplaced along low angle thrust faults as well as high angle structures, in some cases intruding the gold deposits. Late Tertiary and Quaternary erosional products have partially filled the valley basins with coalescing alluvial fan deposits marginal to the mountains and finer-grained alluvium in the valley centres.

The Antler orogeny extensively deformed Paleozoic rocks of the Great Basin in Nevada and western Utah during Late Devonian and Early Mississippian time. In the late Devonian about 350 million years ago, the Antler volcanic island arc terrane collided with what was then the west coast of North America and the North American Plate. The collision zone is marked by

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-1    


LOGO    www.rpacan.com

 

 

the Roberts Mountains Thrust, a system of low-angle thrust faults along which the Upper Plate clastic rocks were thrust some 90 miles eastward over the Lower Plate carbonates. Mesozoic compressional deformation was also important regionally as indicated by various east and west as well as north-northeast and south-southwest verging thrusts. Tertiary faulting developed basins and ranges with the former subsequently filled with volcanic and sedimentary rocks during Tertiary time. Gold mineralization occurred at the onset of Tertiary volcanism, approximately 39 million years ago.

The stratigraphic section is cut by a series of north-northwest, northwest, northeast, and north-northeast striking high- and low-angle faults with extensive fracturing, brecciation, and folding. These faults both control and displace mineralization, with evidence for both dip-slip and oblique-slip displacements. Jurassic and Tertiary intrusive rocks utilized both high and low-angle faults as they intruded the Paleozoic section. Cenozoic Basin and Range deformation most likely reactivated the majority of faults in the area.

In terms of their regional tectonic setting, the BMT gold deposits are hosted in carbonate rocks within a thick sequence of Paleozoic miogeosynclinal sedimentary rocks coincident with:

 

   

the thinned western margin of the North American craton in early Paleozoic times,

 

   

the west-central portion of the Lower Devonian Antler foreland basin,

 

   

the east edge of deformation related to the late Paleozoic Humboldt orogeny,

 

   

an area of Jurassic plutonism, metamorphism and deformation,

 

   

the hinterland of the early Tertiary Sevier orogenic belt, and

 

   

the broad zone of Eocene to Miocene calc-alkaline magmatism and tectonic extension that occurred throughout much of the Great Basin.

The collision between the Antler terrane and the North America Plate induced higher crustal temperatures and pressures, which produced numerous hot springs along the suture zone. Several episodes of subsurface magmatism are known to have occurred subsequent to the collision. During these episodes, and particularly during the Eocene epoch, hot springs brought dissolved minerals toward the surface, precipitating them out along fissures. Among these minerals were gold and silver. Most of the largest gold deposits lie within approximately 300 ft of the Roberts Mountain Thrust at the base of the Upper Plate allochthon. Geochronologic study indicates that most of the gold in the BMT was emplaced over a short interval of time between approximately 42 Ma and 36 Ma. Analyses of the sulphosalt galkhaite

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-2    


LOGO    www.rpacan.com

 

 

from the Rodeo deposit at Barrick’s Goldstrike Mine (Carlin Trend) have yielded a mineralization age of 39.8 ± 0.6 Ma.

The regional geology is shown in Figure 7-1.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-3    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-4    


LOGO    www.rpacan.com

 

 

LOCAL GEOLOGY

Both the western and eastern Paleozoic assemblages are present in the Cortez area. At Cortez the western assemblage, termed the Upper Plate, includes:

 

   

Devonian Slaven Formation cherts and argillites

 

   

Silurian Elder Formation sandstone and Fourmile Canyon Formation

 

   

Ordovician Vinini and Valmy Formations siliclastic rocks

The eastern assemblage, or Lower Plate, consists of:

 

   

Devonian Horse Canyon Formation laminated calcareous siltstone, mudstones with interbedded chert and silicified siltstones

 

   

Early Devonian Wenban Formation carbonate turbidites, debris flows, micrites, and silty limestones

 

   

Silurian-Devonian Roberts Mountains Formation laminated silty limestones

 

   

Ordovician Eureka Formation quartzites and Hanson Creek Formation sandy dolomites

 

   

Cambrian Hamburg dolomite

Two erosional windows of Lower Plate rocks are mapped in the Cortez area both located at the southern end of Crescent Valley (Figure 7-2). The Gold Acres window on the eastern flank of the Shoshone Range, is buried to the east beneath the alluvial fill of Crescent Valley, and presumably is offset by the Crescent fault located on the south side of the valley near the Cortez Mine. South of the Crescent fault is the Cortez window, which appears to be a continuation of the Gold Acres window. The Cortez window is a two to three mile-wide, north–south trending zone that extends from the margin of Crescent Valley near the existing Cortez Mine south through the Cortez Hills area and into the northern Grass Valley area.

Aeromagnetic studies indicate that intrusive rocks underlie most of the Cortez Mountains. Outcrops of igneous intrusions in the Cortez district are granodiorite of Jurassic-cretaceous age (104 Ma to 150 Ma) and the Jurassic-age quartz monzonite Mill Canyon Stock. Felsic and mafic and dikes of similar age occur primarily in north to northwest striking faults. Contact metamorphism affects the sedimentary rocks adjacent to the larger igneous bodies and is evident in the formation of marble, calc-silicates, hornfels, and skarn. Post-mineral porphyry dacite and rhyodacite dikes and sills of Tertiary age are present and notable where they cross-cut mineralized zones.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-5    


LOGO    www.rpacan.com

 

 

The local geology and stratigraphy of the Cortez Mine area is shown in Figures 7-2 and 7-3, respectively.

The Gold Acres, Pipeline, Gap, and Crossroads gold deposits are at the south end of the Shoshone Range located on the west side of Crescent Valley within the Gold Acre Lower Plate window. Gold Acres mineralization is hosted within the Roberts Mountains thrust fault, which is up to 400 feet thick in the mine. The Pipeline, South Pipeline, Gap, and Crossroads deposits occur within Lower Plate Horse Canyon, Wenban, and Roberts Mountains Formations.

The Hilltop gold deposit, located approximately 10 mi north of Gold Acres is hosted by an Eocene porphyry and surrounding brecciated, Upper Plate siliciclastic sedimentary rocks of the Ordovician Valmy Formation along a northwest-trending belt of similar aged intrusions.

The Cortez Pits, Cortez Hills, and Pediment gold deposits are on the south side of Crescent Valley associated with the Cortez Lower Plate window. The Cortez Hills mineralized breccia, thrust fault related Middle and Lower zones are within Horse Canyon, Wenban, and Roberts Mountains units. The Pediment deposit appears to be contained within Miocene-age conglomeratic sediments located immediately southwest of the Cortez Hills deposit. The Horse Canyon deposit is in the Cortez Range approximately four miles east of Cortez Hills and is emplaced in Horse Canyon and Wenban units.

The Buckhorn gold mine, approximately seven miles east of Cortez, is a past producer that shut down in 1991 with historical production of 250,000 ounces of gold. It is a low-sulphidation epithermal vein and replacement mineralization localized by structures and permeable horizons in Tertiary basalts and underlying fanglomerate.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-6    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-7    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-8    


LOGO    www.rpacan.com

 

 

PROPERTY GEOLOGY

Deposit descriptions for the Pipeline Complex, Gold Acres, Pediment, and Cortez Pits deposits were extracted in whole or in part from the Scott Wilson RPA Cortez 2010 Audit Report and modified where required for this Report to reflect the current geological understanding of these areas.

PIPELINE COMPLEX

PIPELINE/SOUTH PIPELINE/CROSSROADS

The Pipeline, South Pipeline, and Crossroads deposits are separate zones of one gold-mineralized system, which collectively strike approximately N20W for over 8,000 ft and extend up to 5,000 ft wide E-W. Economic gold grades do not occur over the full expanse of this system, but variable degrees of hydrothermal alteration are evident including oxidation, decalcification, weak contact metamorphism, argillization, silicification, and carbonization. Mineralization at the Pipeline Complex occurs just outboard of the metamorphic aureole associated with the Gold Acres intrusive. Alluvial cover is absent in the northwest, but thickens up to 450 ft in the eastern Pipeline pit area and ranges from 315 ft to 770 ft over the Crossroads deposit to the south.

The area is characterized by folded and low-angle faulted Paleozoic carbonates. The primary host rocks are variably altered, thin- to thick-bedded, carbonate turbidites, debris flows, micrites, and silty limestones of the Devonian Wenban Limestone and thin-bedded, planar-laminated calcareous siltstones, mudstones, inter-bedded chert, and silicified siltstones of the Devonian Horse Canyon Formation overlying. At depth, planar laminated, silty limestones of the Silurian Roberts Mountains Formation also host mineralization.

Initial porosities in the turbidites, siltstones, and silty limestones were enhanced through argillization and decarbonitization along structural and stratigraphic controls. Thrust and normal faulting have shattered the more brittle cherty and silicified beds creating a secondary porosity. The highest and most continuous gold grades occur in the inter-bedded cherts and silicified turbidites of the Horse Canyon Formation and in the Wenban Formation either where capped by the Horse Canyon Formation or in areas of more intense decarbonitization. Host formations have been thickened and repeated by low-angle thrusting largely associated with the Late Devonian Antler Orogeny.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-9    


LOGO    www.rpacan.com

 

 

GAP

The Gap deposit is hosted in Devonian Wenban Limestone and lies west of the Pipeline Deposit. Mineralization occurs where north-northwest and northeast, high-angle faults intersect thermally altered Devonian Wenban Limestone in the axis of the Gold Acres antiform. Bedding in the Devonian Wenban Limestone is sub-horizontal to gently east-dipping. Portions of the limestone host-rocks of the deposit that lie within the metamorphic aureole of the Gold Acres Stock have been altered to calc-silicate marble, hornfels, skarn, and gossan. Skarn within the Gap pit can be correlated with the upper skarn in the Gold Acres deposit.

GOLD ACRES

The Gold Acres pit is centred on the axis of a low-amplitude, north-northwest trending antiform. The primary host rocks to the mineralization are sheared Upper Plate siliciclastics and greenstones of the Ordovician Valmy Formation and cherts and quartz siltstone of the Devonian Slaven Formation, sheared Lower Plate silty limestone with discontinuous thin phosphatic black lenses of the Silurian Roberts Mountains Formation and micrite to silty micrite of the Devonian Wenban Limestone. The intensity of metamorphism associated with the Gold Acres Stock varies depending on original lithology and ranges from hornfels to calc-silicate marble to skarn. Drill hole intercepts indicate that the pluton is 400 ft to 600 ft below the current Gold Acres pits.

Two discrete horizons, referred to as “Upper Skarn” and “Lower Skarn,” have been mapped at Gold Acres. The Upper Skarn unit is a bleached felsic sill-like body with endoskarn development and is presumed to be associated with the granodioritic Gold Acres Stock of Jurassic-Cretaceous (104 Ma to 150 Ma) age. The “Lower Skarn” is a garnet–diopside skarn believed to be lower Wenban Limestone. The two skarn horizons are separated by an 80 ft to 200 ft thick zone comprising slices of Upper and Lower plate rocks known as the Imbricate Thrust Zone (ITZ).

CORTEZ HILLS COMPLEX

The Cortez Hills Complex includes the Cortez Hills Breccia, Middle and Lower zones, and the Pediment deposit.

BRECCIA, MIDDLE AND LOWER ZONES

The upper levels of mineralization in the Cortez Hills deposit are hosted in the Horse Canyon Formation. The bulk of the deposit is hosted in the Devonian Wenban Limestone. At depth,

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-10    


LOGO    www.rpacan.com

 

 

mineralization is also hosted by Roberts Mountains Formation as well as Hanson Creek Dolomite. The range-bounding Cortez Fault is located just east of the deposit.

The location of Breccia gold mineralization appears to have been emplaced on hydrothermal brecciated and fractured rocks that are centred on a northwest striking and moderately southwest dipping fault and its attendant structures, named the Voodoo Fault. At depth the stratigraphy has been deformed by thrust faulting leading to both folding and fracturing. Gold mineralization at depth occurs as tabular, sub-horizontal to shallow dipping zones associated with calcareous rocks subject to preparation by alteration and deformation; this deeper mineralization forms the Middle and Lower zones at Cortez Hills. Post-mineral quartz porphyry dikes and sills intrude the Cortez Hills deposits. A northwest trending swarm of steely dipping dikes defines the limits between the Middle and Lower zones.

PEDIMENT

The Cortez Pediment deposit is located in a Tertiary gravel-filled canyon immediately south of Cortez Hills and appears to have originated from material and gold eroded from the top of the Cortez Hills deposit. In contrast to rock formations, the gravels at Pediment display inverted stratigraphy in that the deepest unit is a 50 ft to 200 ft thick siltstone-dominated gravel sourced from the gold mineralized Horse Canyon Formation and it underlies a limestone-dominated gravel (100 ft to 800 ft thick) derived from the erosion of uplifted, barren Devonian Wenban Limestone. The gravels are covered by thin, unconsolidated fanglomerate composed of Eureka Quartzite fragments, the quartzite having been exposed by later uplift east of the Cortez Fault. There are no obvious structural controls, although the Pediment deposit is strongly elongated north–northeast.

CORTEZ PITS (NW DEEPS)

The Cortez NW Deeps deposit is hosted by strongly altered, thin- to medium-bedded silty limestone of the Roberts Mountains Formation and by sheared and altered interbedded dolomite and limestones of the underlying Ordovician Hanson Creek Formation. Devonian Wenban Limestone caps most ridges and hills around the NW Deeps deposit and locally appears to have acted as a cap rock over alteration systems in the underlying Roberts Mountains Formation. Prior to mining, Quaternary alluvium formed a thin veneer of cover over the deposit. Alluvium thickens abruptly to the north across the Cortez range-front normal fault.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-11    


LOGO    www.rpacan.com

 

 

Quartz monzonites of the Jurassic Mill Canyon Stock are present east of the deposit on the uplifted side of a north–northwest-trending normal fault. Numerous Oligocene quartz porphyry dikes and sills intrude the deposit. These dikes are considered to be post-mineralization.

A series of north–northwest-trending and northeast-trending faults cut the Roberts Mountains Formation at the deposit. Mineralization occurs where these faults intersect shallow east-dipping thrust breccia zones (thrust duplexes) within the Roberts Mountains Formation.

MINERALIZATION

With the exception of Cortez Hills, the description of mineralization for this section is taken largely from the July 2010 Scott Wilson RPA Cortez audit report with modifications as required for this report.

Gold mineralization is reported as Mineral Resources for the following nine deposits in the Cortez area:

 

   

Pipeline Complex (3 deposits) – Pipeline, Gap and Crossroads

 

   

Gold Acres

 

   

Cortez Hills Complex (4 zones) – Breccia, Middle, Lower and Pediment

 

   

Cortez Pits (NW Deeps)

Mineralization consists primarily of submicron to micrometre-sized gold particles, very fine sulphide grains, and gold in solid solution in pyrite. Mineralization occurs disseminated throughout the host rock matrix in zones of silicified and decarbonatized, argillized, silty calcareous rocks, and associated jasperoids. Gold may occur around limonite pseudomorphs of authigenic pyrite and arsenopyrite. Major ore minerals include native gold, pyrite, arsenopyrite, stibnite, realgar, orpiment, cinnabar, fluorite, barite, and rare thallium minerals. Gangue minerals typically comprise fine-grained quartz, barite, clay minerals, carbonaceous matter, and late-stage calcite veins.

Argillization is characterized by removal of kaolinite and growth of illite in proximity to controlling faults. Arsenic, antimony, iron, and copper accompany gold in north–northwest oriented fault structures and silver, arsenic, manganese, and lead in northeast trending faults.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-12    


LOGO    www.rpacan.com

 

 

In the Cortez district, the favoured host rocks for gold mineralization are the Wenban Limestone, followed by the Horse Canyon and Roberts Mountain Formations. Mineralization reflects an interplay between structural and lithological ore controls in which hydrothermal solutions from intrusives moved to favourable porous decalcified limestone.

Mineralization is predominantly characterized by oxides, and sulphidic and carbonaceous refractory material. Carbon content in the deposits is highly variable and occurs generally in the Devonian Wenban Limestone and Roberts Mountain Formation.

Supergene alteration extends up to 656 ft depth resulting in oxide ores, which overlie the refractory sulphides. Alteration has liberated gold by the destruction of pyrite and resulted in the formation of oxide and secondary sulphate minerals, which include goethite, hematite, jarosite, scorodite, alunite, and gypsum.

PIPELINE COMPLEX

Mineralization at Pipeline occurs where an east-dipping thrust duplex crosses a deep-seated 305° striking fracture system. The majority of the mineralization is tabular and stratiform with a shallow easterly dip.

The main Pipeline deposit is 50 ft to 300 ft thick, tabular zone at 500 ft to 600 ft beneath the surface; it dips at a low angle to the east and extends 750 ft north-south by 1500 ft east-west. South Pipeline consists of two zones 1) a shallow zone starting at 65 ft to 150 ft depth and 2) a deep zone starting at 1,000 ft. The shallow zone occupies an area of approximately 1,800 ft by 2,000 ft, north and east respectively, and exhibits both low-angle and high-angle structural controls on gold distribution. The deep zone occupies an area 200 ft north-south by 600+ ft east-west, is up to 250 ft thick and is more closely associated with high-angle structures. Drill depths average 1,000 ft although drill holes up to 1,400 ft are not uncommon in the centre of the deposit where mineralization ranges from 400 ft to over 1,000 ft thick.

Crossroads lies at the south end of the Pipeline trend and is deeper, varying in thickness from less than 10 ft to greater than 300 ft with a primary control of low-angle structures sub-parallel to bedding and an overall 20o easterly dip. The zone is intensely sheared, shattered, and/or brecciated, with minor offsets along the high-angle faults. Oxidation extends to depths in excess of 1,300 ft. Crossroads consists of two mineralized zones: an upper stratiform zone

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-13    


LOGO    www.rpacan.com

 

 

along the Horse Canyon–Wenban contact and a deeper zone controlled by an east-northeast striking, west dipping (20° to 25°) structural zone that cuts across stratigraphy.

At Gap, mineralization occurs where north-northwest and northeast, high-angle faults intersect thermally altered Wenban Formation in the axis of the Gold Acres antiform. A northern zone of mineralization is primarily hosted within gossan horizons cut by high-angle faults in thermally altered Devonian Wenban Limestone. The southern zone is outside the metamorphic aureole; mineralization occurs within a 1,000 ft wide corridor of strong fracturing bounded on the northeast side by a high-angle, N45W northeast-dipping fault. Gold mineralization is post-metamorphic and strongly oxidized. Carbon alteration is prevalent and increases with depth.

GOLD ACRES

At Gold Acres, the mineralized area is approximately 6,000 ft long by 2,500 ft wide with an average thickness ranging from 80 ft to 200 ft. Mineralization is mainly refractory; high gold grades (greater than 0.10 oz/st Au) are associated with secondary carbon and/or fine-grained sooty sulphide minerals. Minor oxide gold mineralization is hosted within the Upper Plate rocks overlying the Imbricate Thrust Zone (ITZ). The Lower Skarn is largely barren of gold, although it does host minor polymetallic mineralization (Zn–Mo–Cu) presumed to be coeval with intrusive emplacement and skarn formation.

The Gold Acres deposit was developed in two lobes, the north (London Extension Pit) and the south (Old Gold Acres Pit, or OGA). The London Extension Pit is bounded on the north by the northeast striking, moderately westward dipping (50° to 60°) Gold Acres Fault. The Gold Acres Fault down drops the ITZ and Gold Acres Stock approximately 200 ft to the northwest. The Island Fault separates the London Extension and OGA pits and strikes approximately to the north–northeast, dipping at 50° to the northwest. The Island Fault apparently down-drops mineralization in the London Extension Pit relative to the OGA Pit. Multiple northeast-trending faults between the Gold Acres and Island Faults incrementally down-drop mineralized stratigraphy to the north in a stair-step pattern. Both pits have been inactive since 1995 except for a small program in the London Extension Pit in 2000–2001 when refractory ore was mined to supply a third-party for processing.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-14    


LOGO    www.rpacan.com

 

 

CORTEZ HILLS COMPLEX

BRECCIA, MIDDLE AND LOWER ZONES

Breccia gold mineralization is hosted in hydrothermally brecciated and fractured rocks that are spatially associated with the Voodoo Fault and its attendant structures. Altered, matrix supported breccia bodies contain the highest gold grades and are surrounded by “crackle” breccias and highly fractured rock with moderate gold grades continuing outwards to less fractured rocks with lower grades. Most of the Breccia mineralization dips moderately southwest enveloping the Voodoo Fault. The upper portion has a northeast dip that possibly reflects control by an antithetic structure. Breccia Zone mineralization extends from a near surface elevation of 5,850 ft to 4,070 ft, terminating just east of the Middle Zone. It is approximately 1,000 ft wide with a northwest trend, and varies in width from 250 ft to 1,900 ft.

Mineralization of the Middle and Lower zones lie at depth to the west and southwest of the Breccia zone. These sub-horizontal, tabular zones are associated with alteration localized along a complex zone of thrust faulting and back thrusts in the Roberts Mountain Formation that has also incorporated slices of Devonian Wenban Limestone. A swarm of northwest trending post mineral quartz porphyry dikes separates the Middle from the Lower Zone. The Lower Zone has a distinct northwest-southeast trend in the Roberts Mountain and Hanson Creek Formations that is interpreted as the crest of a plunging antiform. The Middle zone occurs between elevations 4,235 ft and 3,825 ft, is approximately 1,800 ft wide northwest-southeast by 1,300 ft long northeast-southwest, and ranges in thickness from 10 ft to 270 ft. The Lower Zone lies at an elevation of 4,260 ft to the northwest and 3,060 ft to the southeast, extends 4,300 ft northwest-southeast, varies in width from 1,450 ft in the north to 500 ft in the south and ranges in thickness from 60 ft to 270 ft. Both the Middle and Lower zones are open to both the northwest and southeast.

Post-mineral dikes and sills are significant in that they are estimated to account for up to 10% of the waste rock volume within portions the Cortez Hills deposits.

Gold mineralization is often spatially associated with decalcification and to a lesser degree silicification. Deep oxidation at Cortez Hills is inferred to be related to deep, convection-driven circulation of mixed meteoric and spent hydrothermal fluids during the waning stages of the mineralizing event. The enhanced weathering phenomenon resulted in significant carbonate dissolution and clay formation as well as extremely deep oxidation of gold-bearing iron

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-15    


LOGO    www.rpacan.com

 

 

sulphide minerals. Arsenates of copper and zinc have been noted in, and adjacent to, oxidized mineralization.

PEDIMENT

Most of the gold in the Pediment deposit is present within the lower of the two gravel/ conglomerate units draped over a paleobasement of thermally altered limestone and marble. Two mineralized zones have been delineated 1) a shallow zone along the southern extent of the deposit, with a depth to the top of the zone ranging from 150 ft to 300 ft, and 2) a deeper zone at the northern part of the deposit, which begins at a depth of approximately 500 ft. Both mineralized zones exhibit a tabular geometry and occupy a general area of 3,000 ft north-south by 600 ft east–west. Gold mineralization is associated with clasts of strongly altered carbonate rocks that have been oxidized and are similar to mineralization found in situ in the near-surface portion of the Cortez Hills Complex.

CORTEZ PITS (NW DEEPS)

The Cortez NW Deep deposit is a continuation of the mined-out main Cortez deposit. The deposit consists of remnants of oxide mineralization in the east wall of the Bass Pond pit and deeper, sulphide and carbonaceous mineralization. A series of north–northwest trending and northeast trending faults cut the Roberts Mountains Formation at the deposit. Gold mineralization is localized where these faults intersect shallow east dipping thrust breccia zones (thrust duplexes). Most of the Cortez NW Deep higher-grade gold mineralization (less than 0.1 oz/st Au) occurs in two zones lying between the 4,200 ft and 4,500 ft elevations beneath the old Cortez open pit floor. Present surface elevations are between 4,800 ft and 5,300 ft. One zone consists of an oxidized and strongly altered thrust zone within the Roberts Mountains Formation and the other is an unoxidized, sulphide-bearing thrust zone at the top of the Hanson Creek Formation. Post mineral quartz porphyry dikes have been emplaced along high-angle faults.

Locally, silica overprints all lithologies, but does not show a strong correlation with gold at a local scale. Silicification occurs as massive fault fill, bedding replacements after decalcification and as micro-veinlets. Massive silicification fills both north–northwest and northeast trending faults. Bedding replacement by silica occurs along beds that were originally carbonate-rich.

Oxidation is pervasive at 4,700 ft elevation. Mineralization becomes dominantly refractory at 4,200 ft to 4,350 ft elevation.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 7-16    


LOGO    www.rpacan.com

 

 

8 DEPOSIT TYPES

The Cortez deposits are “Carlin” style sedimentary rock-hosted and porphyry/epithermal deposits. Carlin deposits form as structurally and/or stratigraphically controlled replacement bodies consisting of stratabound, tabular, disseminated gold mineralization occurring in Silurian-Devonian carbonate rocks. Deposits are localized at contacts between contrasting lithologies, metamorphosed to varying extents. They can also be discordant or breccia-related.

Host rocks are most commonly thinly bedded silty or argillaceous carbonaceous limestone or dolomite, commonly with carbonaceous shale. Although less mineralized, non-carbonate siliciclastic and rare metavolcanic rocks can locally host gold that reaches economic grades. Felsic plutons and dikes may also be mineralized at some deposits.

The deposits are hydrothermal in origin and are usually structurally controlled. The carbonate host rocks are part of an autochthonous miogeoclinal carbonate sequence (Lower Plate) exposed as tectonic windows beneath the Roberts Mountain allochthon. The lower Paleozoic allochthonous (Upper Plate) rocks are siliciclastic eugeoclinal rocks that were displaced eastward along the Roberts Mountain Thrust over younger units during the upper Paleozoic Antler Orogeny. Carlin deposits are localized along the thrust.

Current models attribute the genesis of the deposits to:

 

   

epizonal plutons that contributed heat and possibly fluids and metals;

 

   

meteoric fluid circulation resulting from crustal extension and widespread magmatism;

 

   

metamorphic fluids, possibly with a magmatic contribution, from deep or mid-crustal levels;

 

   

upper crustal orogenic-gold processes within an extensional tectonic regime.

The past-producing Buckhorn gold-silver mine and the Hilltop gold project are examples of different styles of mineralization in the Cortez District. Buckhorn is a typical example of a low-sulphidation epithermal system while Hilltop is an intrusive-related deposit. Hilltop is an Eocene-age system clearly associated with 38 Ma to 39 Ma felsic gold-copper porphyries, while Buckhorn is a Miocene occurrence, deposited during the initiation of 15 Ma to 17 Ma Northern Nevada Rift extension and associated bimodal volcanism.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 8-1    


LOGO    www.rpacan.com

 

 

9 EXPLORATION

Modern exploration commenced along the Battle Mountain–Eureka Trend in the 1960s, and has been nearly continuous since that time. Exploration in the Cortez District has been undertaken by Barrick and its predecessor companies such as the CJV and has included mapping, various geochemical and geophysical surveys, pitting, trenching, petrographic, and mineralogy studies, and various types of drilling. The description regarding drilling, sampling methods, and sample quality is discussed in Section 10 Drilling.

Many of the targets being investigated are partially or totally concealed by younger overburden and Tertiary rock cover or by allochthonous Upper Plate Paleozoic siliclastic rocks. Geophysical surveys are being used to help map buried bedrock features.    

EXPLORATION POTENTIAL

There is potential for further increases in Mineral Resources.

Barrick funds a multi-million dollar exploration budget each year for the Cortez area. Barrick has advanced stage exploration drilling projects at the mine. Exploration planned for 2015 includes:

 

  1.

Underground

 

  a.

Cortez Hills Lower Zone (Deep South) – $7.9M to complete a 42-hole infill drilling (11,600 m) program for resource advancement in the Cortez Hills Lower Zone below the 3,800 ft amsl elevation (Deep South Pre-feasibility Study (PFS) area).

 

  b.

CHUG Frontiers $2.7M to complete 12 step out holes (4,270 m) along potential southern extensions of the Deep South resource and to explore the Renegade Zone approximately 200 m below the current resource.

 

  c.

Deep Roberts $1.7M to complete five holes (2,700 m) to explore for potential deep mineralization in previously untested horizons up to 300 m below the current Deep South resource.

 

  2.

Surface

 

  a.

Barrick completed 49 holes for 19,000 ft of drilling at Hilltop, outlining a body of epithermal, intrusive-related gold mineralization. There is still potential to expand this target as it remains open in several directions. The next steps are to complete fill-in drilling for grade continuity, metallurgical test-work for recovery process options and extension drilling to expand the mineralization and establish a reportable mineral resource at Hilltop

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 9-1    


LOGO    www.rpacan.com

 

 

  b.

Mill Canyon South – $1.5M to complete three holes (2,750 m) to test targets north of the Horse Canyon Mine and Goldrush discovery.

 

  c.

Crescent Valley – $0.6M to complete one drill hole (+1,000m) to evaluate potential for extensions of Cortez mineral system on the hanging-wall side of the Crescent Fault.

 

  d.

Fourmile Canyon$0.3M to complete a surface evaluation/targeting program in the area north of the Goldrush discovery.

 

  e.

North Pipeline$0.1M to complete surface evaluation and targeting focusing on the area north of the Pipeline pit.

Longer-term exploration potential remains for deep underground targets in the Gold Acres Window, as well as for potential open-pit and underground-mineable targets in the southern and eastern Cortez Window.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 9-2    


LOGO    www.rpacan.com

 

 

10 DRILLING

This description of drilling is taken largely from a previous report entitled “Technical Report on the Cortez Joint Venture Operations, Lander and Eureka Counties, State of Nevada, USA”, dated March 2012. It has been updated based on RPA’s site visit and subsequent review of available documentation.

Exploration and drilling activities for resource development in the Cortez district span a period of more than 40 years and include a variety of drilling techniques and the use of numerous different drill contractors. Approximately 20,448 drill holes are currently in the Barrick Cortez database. This number is known to be incomplete, as a significant portion of the drilling completed by companies other than Barrick and the CJV have not been incorporated in the digital database. The drill hole types included in the database are summarized in Table 10-1. RPA notes that a small number of these holes have been completed since the latest Mineral Resource update.

TABLE 10-1 DRILL HOLE TYPES 

Barrick Gold Corporation – Cortez Operations

 

Drilling Type

   Number of Holes      %  

Reverse Circulation

     13,717         67   

Core

     4,345         21   

Other

     2,386         12   

 

  

 

 

    

 

 

 

Total

     20,448         100   

Figure 10-1 illustrates the distribution of drill holes contained in the database for the Cortez district. Drill hole collars included in this figure are not representative of the total drilling within the Mine. Many of the drill holes external to the Cortez and Gold Acre Windows were completed for reconnaissance purposes.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-1    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-2    


LOGO    www.rpacan.com

 

 

REVERSE CIRCULATION DRILLING METHODS

Reverse circulation (RC) drilling is currently used during the initial phases of exploration, condemnation drilling, and to pre-collar diamond coring holes through intervals of overburden and unaltered cap rocks. RC holes range in diameter from 4.5 in. to 7.0 in. Diameters of 6.5 in. and 6.75 in. are currently used for exploration.

Current practice is for RC holes encountering mineralization to be bracketed on four sides by core holes increasing the density of core holes in mineralized zones. RC pre-collar holes are cased with 4.5 in. casing and core drilling is continued through mineralization and footwall rocks. The depth to which RC drilling is used depends on the water table depth, which is in turn dependent on mining dewatering activity in the area. Since 1980, RC has been typically used for 600 ft to 3,500 ft holes. RC pneumatic hammers are used up to 1,800 ft. Auxiliary compressors are used to increase the effectiveness of the down-hole hammers. Tri-cone rock bits are used at depths below the working depth of hammer bits. Centre-return hammers and bits were used for RC drilling at Pipeline. The deepest RC hole at Pipeline reached a depth of 4,540 ft while the deepest at Cortez Hills has been 4,400 ft.

CORE DRILLING METHODS

Core sizes for wire-line diamond drilling are typically HQ (2.5 in. diameter) for resource development drilling. Occasionally, core holes are reduced from HQ size to NQ (1.9 in. diameter) size in difficult drilling conditions. Surface metallurgical core includes HQ and PQ-3 (3.27 in. diameter) sizes.

Conventional core handling methods and wax impregnated cardboard core boxes are used by the contractors who deliver the core to the logging facility on site. Core runs of 5 ft are typical in waste rock zones, but the shattered and broken nature of the Pipeline shear zone usually results in shorter runs. The drill crew inserts wooden blocks to mark the end of each core run. Manual versus natural breaks in the core are clearly marked with a wax crayon. Core is delivered to the logging shed by technicians or the drilling foreman at least once per shift.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-3    


LOGO    www.rpacan.com

 

 

CONVENTIONAL AND MUD DRILLING METHODS

These drilling method use air to pull the sample from the bit to the hole collar up the outside of the drill stem. Typically conventional air holes were short, and terminated at the water table. The drill diameter range was from 5.5 in. to 6.5 in. Conventional mud drilling used a similar sampling technique, with drill water-based bentonite clay/inorganic polymer muds employed facilitating drill sample return. Mud rotary drill holes range in diameter from 6 in. to 9 in. Mud-rotary drills have been used to drill relatively thick sections of alluvium over the Crossroads deposit or in areas being condemned for waste dumps and processing facilities. Core tools were used to complete the bedrock sections of these holes. Limited information remains on the drilling, logging, and sampling methodology for hole-types that were drilled prior to the mid-1990s.

COLLAR SURVEYS

Collar coordinates from the 1960s to the 1980s drilling were determined by optical surveys, field estimates, Brunton compass and pacing, or compass-and-string distance. Recent campaigns have hole collars surveyed with either Total Station electronic distance measurement (EDM) or geodetic-grade, global positioning system (GPS) instruments. Two separate reference grids (Pipeline Mine grid and Cortez grid) are maintained. Survey Data in remote areas is collected in Truncated Universal Transverse Mercator (TUTM) Coordinates and then converted to the appropriate mine grid.

DOWN HOLE SURVEYS

Down hole surveying began in 1991 at the Pipeline deposit. Significant deviations were shown in RC drilling and down hole surveying has been carried out since then. Most holes were surveyed with a recording gyroscope by a commercial contractor. Readings are taken every 50 ft down hole and digitally transferred to the database. Boyles Brothers Drilling used a multi-shot recording gyroscope (MSRG) tool until April 1993. Silver State Surveying later performed all MSRG surveys and currently contractors WelNav and International Directional Services LLC (Deep South) provide the surveys. Mahoney et al. (2009) reports that significant work has been carried out by Cortez to determine the accuracy of the instruments of each contractor.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-4    


LOGO    www.rpacan.com

 

 

Underground core holes drilled prior to May 2008 were surveyed down-hole by Deep South. Since then surveying has been done by Cortez personnel using Reflex magnetic instrumentation. Geotechnical holes have been drilled in each discovery to date using oriented tools. These normally use a plasticine, triple scribe, and down-hole camera system.

Down-hole surveys for a limited number of holes are incomplete where ground conditions such as caving restrict access for the survey instrument.

SAMPLE RECOVERY

In general, core-drilling practices at Pipeline, Crossroads, Gap, the Cortez Pits (NW Deeps), Cortez Hills and Pediment ensure a relatively high core recovery. Core recovery is sufficient to provide representative samples of a sedimentary rock-hosted gold deposit. Prior to 1991, core recovery values and RC sample weights were not routinely digitized or added to the general drill hole database. Wet drilling conditions for RC holes prohibit measurements of sample weights as a result recovery of RC materials cannot be calculated.

Core recoveries are maximized by use of triple-tube core barrels, face-discharge bits, and special drilling mud. Core recovery averaged 93% for 314 holes used in the Pipeline and South Pipeline FS (Placer Dome Technical Services, 1995). The median core recovery for the Cortez Hills deposit was 96%. Only four core holes in the Cortez Hills deposit had less than 80% core recovery and were located in an approximate 150 ft by 150 ft geographic area in the upper extreme eastern portion of the lower-grade mineralized area near the intersection of four faults.

GEOTECHNICAL AND HYDROLOGICAL DRILLING

Geotechnical and hydrological holes have been drilled to provide raw data for the hydrological and geotechnical portions of the PFS and FS on the Pipeline and Cortez Hills deposits, and subsequently to support mining operations. Thirty-two underground core holes have been drilled for geotechnical purposes. These holes were designed parallel to planned drifts and served to predict the character of the rock mass to be developed.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-5    


LOGO    www.rpacan.com

 

 

GRADE CONTROL DRILLING

OPEN PIT

Blast holes in rock on 50 ft ore benches are drilled on a staggered pattern approximately 22 ft by 25 ft with an 83/4 in. bit. This spacing has been decreased to 16 ft by 16 ft in carbonaceous ore. On 40 ft waste benches, blast hole (83/4 in. bit) spacing ranges from 22 ft by 22 ft up to 27 ft by 27 ft. Blast holes in alluvium employ a 83/4 in or 97/8 in bit and are spaced from 22 ft by 22 ft up to 27 ft by 27 ft apart on a square grid as determined by the blast engineer. All blast holes have a four foot sub-drill.

UNDERGROUND

Initial core drilling for the breccia zone was completed with flat fans of HQ core holes drilled to nominal 50 ft spacing across the body of the projected mineralization at Cortez Hills. These fans are drilled approximately every 60 ft to 75 ft on the vertical axis of the body. Additional Cubex RC fan drilling using a four inch bit is carried out on working levels at a nominal 25 ft to 50 ft spacing. Down hole surveys for Cubex are conducted by the drill contractor, Connors Drilling LLC, which uses Reflex instrumentation run within PVC tubing placed in the hole.

Subsequent core drilling has been from drill platforms that drill perpendicular (shower heads) to mineralization. Breccia zone holes were drilled from the hangingwall side of the deposit. Middle and Lower Zones holes are drilled from development drifts located directly above the mineralization. Cubex (underground RC drills) drilling is used for grade control and can be drilled from active mining levels or dedicated drill bays

MINERAL RESOURCE DELINEATION DRILLING

Surface drilling is initially carried out on a 400 ft square pattern, closing in the next stage to a 200 ft grid. In-fill drilling is done on a five-spot pattern, resulting in an average hole spacing of 141 ft. At Pipeline, “X-shaped” patterns of more closely spaced holes have been drilled to provide information for gold grade variography; this may locally decrease the hole spacing to approximately 70 ft.

Underground mineralization is drilled to a nominal 200 ft spacing from surface, then underground drilling is conducted to reduce spacing to 100 ft or less for Mineral Resource to

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-6    


LOGO    www.rpacan.com

 

 

Mineral Reserve transition. Prior to production additional underground drilling is completed to close up the spacing to between 25 ft and 50 ft for final mine design.

Drill holes are generally vertical. Inclined core holes were drilled at Cortez Hills to confirm the orientation of relatively high-grade gold-mineralized zones and to obtain geotechnical information for the planned Cortez Hills pit. Several angle core holes were drilled at the Cortez Pits (NW Deep) and Pipeline to provide geotechnical data and further delineate areas of mineralization.

PIPELINE COMPLEX AND GOLD ACRES

Drilling in the area of the Pipeline Complex including the Pipeline, Crossroads, Gap and Gold Acres deposits comprises 5,419 drill holes for approximately five million feet. Drilling dates from the 1960s to 2014, and comprises conventional, RC and core drilling. Almost all of the conventional drilling was in upper portions of the deposits, and has subsequently been mined out. Approximately 20 conventional holes were drilled after 2006, for approximately 60,000 ft. The resource estimation database contains 3,266 holes totalling 2,908,456.8 ft of which 2,973 are core holes for 2,704,949 ft and 293 are RC holes for 203,508 ft, including pre-drilling for core holes. Additional metallurgical and ore characterization drilling was done in 2014 in the Pipeline Complex. The resource drilling database for Gold Acres consists of 1,725 surface drill holes for 461,363 ft and includes over 68,700 assays.

Figure 10-2 illustrates a drill hole location plan for the Pipeline Complex including the Pipeline, Crossroads, and Gap deposits.

Figures 10-3 and 10-4 show representative cross sections through the Pipeline and Crossroads deposits, respectively.

Figure 10-5 shows a surface plan with drill hole locations for the Gold Acres deposit and Figure 10-6 provides a representative cross section through the deposit.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-7    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-8    


LOGO    www.rpacan.com

 

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-9    


LOGO    www.rpacan.com

 

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-10    


LOGO    www.rpacan.com

 

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-11    


LOGO    www.rpacan.com

 

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-12    


LOGO    www.rpacan.com

 

 

CORTEZ HILLS AND PEDIMENT

The 2015 resource extraction showed that the surface and underground drilling in the area of the Pediment and Cortez Hills deposits totals over two million feet in 3,542 holes completed from 1964 to 2015. This includes RC, core, dewatering, piezometer, and various other drilling types. The drill data for Cortez Hills was culled and data with various quality assurance/quality control quality assurance and quality control (QA/QC) issues (i.e. downhole contamination, poor assay sampling, missing collars and surveys, etc.) was later excluded from the resource estimations.

Drill holes at the Pediment and Cortez Hills deposits are nominally spaced at 100 ft by 100 ft. Underground drilling of the Breccia Zone varies from 50 ft by 50 ft or less in areas of active underground mining to 150 ft by 150 ft within the “open-pit only” portions of the Mineral Resources. Underground drill hole spacing in the Middle Zone of Cortez Hills varies from 50 ft by 50 ft to 25 ft by 25 ft or less. Drill spacing in the Lower Zone of Cortez Hills varies from 50 ft by 50 ft to 100 ft by 100 ft depending on the level delineation across the deposit.

Figure 10-7 shows a location plan for the Cortez Hills Complex including the Breccia, Middle, and Lower Zones of Cortez Hills and the Pediment deposit. Figures 10-8 to 10-10 show cross and longitudinal sections illustrating the geology, gold mineralization limits, and typical drill hole density for the various Cortez Hills zones.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-13    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-14    


LOGO    www.rpacan.com

 

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-15    


LOGO    www.rpacan.com

 

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-16    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-17    


LOGO    www.rpacan.com

 

 

CORTEZ PITS (NW DEEP)

Drilling in the Cortez Pits area dates back to before 1967, but only validated holes from 1986 to 2015 are included in the drill database used for resource work. The Mineral Resource estimate is supported by approximately 280,860 ft of drilling in 450 holes and 37,415 assays. This includes 245,951 ft of RC drilling in 396 holes and 34,952 ft of core drilling in 54 holes.

Figure 10-11 presents the drilling for the Cortez Pits area and Figure 10-12 is a typical cross section.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-18    


LOGO    www.rpacan.com

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-19    


LOGO    www.rpacan.com

 

 

 

LOGO

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-20    


LOGO    www.rpacan.com

 

 

COMMENTS ON DRILLING

In RPA’s opinion, the quantity and quality of the lithological, geotechnical, collar, and down hole survey data collected in the exploration, delineation, and grade control drill programs are sufficient to support Mineral Resource and Mineral Reserve estimation. RPA also notes that:

 

   

Drill hole orientations are appropriate with respect to the orientation of the mineralization.

 

   

Drilling is normally perpendicular to the strike of the mineralization, but depending on the dip of the drill hole and the dip of the mineralization drill intercept widths are typically greater than true widths.

 

   

Drill hole intercepts adequately reflect the nature of the gold mineralization. Down hole composite data indicate areas of higher-grade and lower-grade mineralization, and waste material within the deposits.

 

   

The deposits have been well drilled.

 

   

Through interpretation and aggregation of the drill hole data, the sections provide a representative estimation of the true thickness of the mineralization for the various deposits in relation to planned pit and underground mining boundaries that are used to constrain the Mineral Resources and Mineral Reserves.

 

   

Collar surveys have been performed using industry-standard instrumentation.

 

   

Down hole surveys have been performed using industry-standard instrumentation.

SAMPLING METHOD AND APPROACH

RC SAMPLING

Drillers carry out the sampling on the RC drill rig. After material discharges from the hydraulic, revolving wet sample splitter on the cyclone, the fraction to be sampled was subdivided by a Y-shaped joint in a 5 in. sample discharge pipe and each split collected in a five-gallon plastic bucket lined with 19 in. by 22 in. Micro-Pore sample bags. Bags are pre-numbered and tagged by Cortez. Recently, collection has been modified to Micro-Pore bags placed in one-gallon metal sleeves hung beneath each arm of the Y pipe splitter. Samples are allowed to air dry in the field and are then picked up at the drill sites by geological technicians. Where areas are relatively open to the public, this loss of chain of command may compromise sample security.

RC chip samples (typically -1/2 in.) were collected by drillers in 5 ft intervals for Gold Acres drilling and in the initial 1991 drilling at Pipeline. By late 1991, RC samples at Pipeline were collected on 10 ft intervals per the Cortez Hills protocol. The 10 ft samples weigh from 10 lb

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-21    


LOGO    www.rpacan.com

 

 

to 15 lb and represent a mass reduction to a small percent of the original. The sample reduction is summarized in Table 10-2.

TABLE 10-2 RC SAMPLE REDUCTION

Barrick Gold Corporation – Cortez Operations

 

RC Hole    10 ft Length

Diameter

  

10 lb

  

15 lb

7”

   2%    4%

4.5”

   6%    9%

7”

   41x    27x

4.5”

   17x    11x

RC sampling procedures were modified for drilling at the Pediment deposit in accordance with recommendations by consultant Francis Pitard in 1999. Samples weighing from 35 lb to 40 lb are now collected from development RC holes at Pediment.

Footage intervals were recorded by a technician on a separate shipment record from the corresponding sample numbers. Commercially prepared standards and blank samples of landscaping marble are inserted by the drillers randomly into the numbering sequence prior to sample pickup.

Chip samples of each RC interval are collected and stored in plastic chip trays for geologic logging. Each chip tray represents about 200 ft of drilling. Chips are logged by project geologists or geological contractors. The logging form is set up to record stratigraphic formation, rock type, rock textural characteristics, veining, significant minerals, alteration, and estimated sulphide, carbonate and carbon content. Completed logs are entered into a master database. Chip trays are stored in a central warehouse facility on site. Until the 1970s, representative RC chips were glued to boards as hole records; however, none have survived. Digital backup copies of the geologic logs are stored offsite. All hardcopy logs that were used prior to the inception of digital logging are archived in files, labelled, and stored in the exploration or mine geology offices.

Drilling is almost always carried out with water injection. Drilling below elevations ranging from 5,000 ft to 5,700 ft at Cortez Hills is below the water table. Total sample weight cannot be measured because of wet drilling conditions; therefore RC recovery cannot be calculated.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-22    


LOGO    www.rpacan.com

 

 

CORE LOGGING AND SAMPLING

Drill core is washed and photographed prior to logging. Core is digitally photographed wet, except in cases of exceptionally poor rock quality. Older film photographs have been scanned and electronically archived. Step-out exploratory drill holes are summary-logged and representative chip samples are collected at one foot intervals, making up a composite sample over 20 ft. The chip samples are analyzed for gold as well as multi-element geochemistry. Chip samples are excluded from grade estimations. If the core was later cut, the cut core values are used for grade estimation, if the core was not cut, because of low grade assay results than the chip grades are set 0.0001 oz/st Au and treated as waste during grade estimation. Retained core character samples are stored on site at the Pipeline and Cortez core storage facilities.

When the assays are returned for the exploratory hole, detailed geologic logging is carried over the mineralized interval, bracketed by 100 ft of core above and below. The interval is then cut and resubmitted for gold assay. In-fill and development drill holes are subjected to detailed geologic and geotechnical logging.

The core is logged by a geologist for geological and geotechnical elements. Prior to 2004, logging was either done on paper and then entered into a computer or entered directly into a computer and was verified by Placer Dome software with text and graphics capability. After review by geologists, corrected logs were reprinted and electronically merged into the master database by a computer administrator. After the implementation of an acQuire SQL Server database in 2004, logging was changed to an acQuire data input form. This requires selection of attributes from a prescribed list, avoiding entry of non-standard symbols or qualifiers. The computerized geological logging format allows for recording mineralogy, structure, texture, alteration, rock type, colour, brightness, lightness, grain size, sorting, sphericity, shape, degree of decalcification, and carbon content.

Point load tests of selected intervals and other geotechnical data were collected by staff technicians and the geology department. After mid-2006, Golder Associates Ltd. (Golder) carried out this task, but only on core drilled for geotechnical purposes or upon request.

Most drill-core from Pipeline and Cortez Hills was sampled and assayed at 10 ft intervals, though several holes were assayed at 5 ft or variable geological intervals early in the drilling programs. Since 2004, exploration core holes have been sampled on 10 ft intervals in barren

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-23    


LOGO    www.rpacan.com

 

 

rock and on geologically defined intervals up to five feet in mineralization. Underground core is sampled on 5 ft intervals, however, samples could be a minimum of 2 ft to a maximum of 6 ft to facilitate respecting lithological or mineralization contacts.

Almost all core was sawn in half by a Cortez technician except for underground core where whole core is sampled. A hydraulic splitter has been used for extremely hard rock to maintain acceptable production rates. Any fragmented core less than one inch diameter was split through a riffle splitter. One-half of the core or a riffle split was placed back in the original core box and the other half in 10 in. by 22 in. Micro-Pore cloth sample bags with a numbered paper sample tag. Sample numbers are assigned using sample ticket books. The sample number was also handwritten on the exterior of the bag with a permanent marking pen, along with the drill hole number. Including drill hole numbers with sample labels is not considered best practice. A technician recorded footage intervals on a separate shipment record form with the corresponding sample number. Metallurgical core was quartered, with one quarter retained as a character sample and the remaining assayed and consumed for metallurgical testing.

The retained core is stored on site. Barrick exploration has a core storage facility, which contains drilling for the site, located near the Pipeline administration office. Other sample storage areas include the East Pit at Cortez Pits and the Gold Acres Pit.

CONVENTIONAL AIR-ROTARY AND MUD-ROTARY SAMPLING

Sampling was carried out at 5 ft to 10 ft intervals. Early (mid-1980s) rotary air sampling may have been accomplished in dry conditions using non-porous plastic bags. Sample numbers were assigned using sample ticket books.

BLAST HOLE SAMPLING

The practice is to double sample the 40 ft blast holes on mineralized horizons. One sample represents the bottom 20 ft, while the other represents the upper 20ft of the hole. Any 40 ft trim shots are single sampled as are 20 ft holes on a 20 ft bench. A representative sample of blast-hole drill cuttings is collected by placing a 6 in. diameter, 12 in. tall vertical cylinder near the drill hole and inside the rig dust rubber curtain. Approximately 7 lb to 8 lb of material is collected. The sample number records the location and uses a bar-coded tag. Samples are assayed at the Cortez Mine assay laboratory. Analytical data are incorporated electronically into the blast-hole database. The blast hole sample reduction is summarized in Table 10-3.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-24    


LOGO    www.rpacan.com

 

 

TABLE 10-3 BLAST HOLE SAMPLE REDUCTION

Barrick Gold Corporation – Cortez Operations

 

Diameter    Sample Reduction to:   Including Sub-Drill

(in.)

  

7 lb

 

8 lb

 

7 lb

 

8 lb

9.875

   0.22%   0.25%   0.20%   0.22%

8.875

   0.53%   0.61%   0.44%   0.51%

9.875

   465x   407x   511x   447x

8.875

   188x   164x   225x   197x

Blast-hole sample results are used for open-pit mine grade control, but are not used for Mineral Resource and Reserve estimates.

UNDERGROUND MUCK SAMPLING (CORTEZ HILLS)

Muck sampling is the only means of grade control currently used at Cortez Hills underground. Grab samples are collected by shovel from the bucket of the 6-yard scoop tram load-haul-dump (LHD). At the truck bay, the LHD operator takes a sample of every 1st, 5th, 10th, and 15th LHD load from the muck pile of a given round.

The muck sample is placed in 12 in. by 18 in. bar coded bags and represents approximately 20 lb of material. Analysis developed by Pierre Gy and screen tests determined that samples of one inch to two inch fragments plus fines are representative. Samples are assayed at the Cortez Mine assay laboratory. Analytical data are incorporated electronically into a muck database within the acQuire database and there is a plan to use the muck sample results and the exploration drilling results in a Vulcan software grade control module to create mini-block models.

Underground muck sample results are used for mine grade control, i.e., material routing on a round by round basis, but are not used for Mineral Resource and Mineral Reserve estimates.

BULK DENSITY DETERMINATION

Whole core sampling for bulk density measurement was initiated in April 1992 at the Pipeline deposit and density was determined for a total of 467 ore and waste samples. Standard practice since 1999 has been to collect samples at 35 ft to 40 ft intervals in mineralized rock and one sample within 50 ft. in the hanging wall and footwall. Generally, density samples are

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-25    


LOGO    www.rpacan.com

 

 

taken 0 ft to 50 ft above the mineralization, in mineralization, and 0 ft to 50 ft below the mineralization.

Core is prepared by the Cortez geology staff and the mine metallurgical laboratory carries out the density measurements. The primary method of measuring core density is by wax immersion. Competent core is coated in wax and then immersed in water. There are five other methods, which have been used in the past and may be used on occasion depending on the situation. Those other methods are:

 

  1.

Fragment displacement (lacquer coated fragments are immersed in water)

 

  2.

Core displacement (lacquer coated core is immersed in water)

 

  3.

Core axis length and diameter is measured and applied to dry weight of sample

 

  4.

Plastic sleeve (poor quality core in PVC pipe is wrapped and immersed in water)

 

  5.

Buoyancy (competent core is wrapped in cellophane and immersed in water)

Cortez has compiled bulk densities for the various rocks and overburden for each deposit. Values range from 11.7 ft3/st to 16.6 ft3/st for rocks and 16.2 ft3/st to 19.1 ft3/st for alluvium and the Pediment deposit.

LOGGING, SAMPLING, AND SAMPLE STORAGE FACILITIES

Cortez has permanent facilities for core logging and sampling, as well as storage warehouses. RPA visited the exploration core facility located near the Pipeline Mill and found the layout to be clean, organized and in line with industry standards for layout, facilities and procedures. Drill core, RC chips, retained character core, pulp, and pulp duplicate samples are stored onsite in the Cortez and Pipeline storage warehouses. Older core for mined-out portions of the deposits has been skeletonized to reduce storage. Samples rejects are retained, but stored outside where they degrade after two to three years at which time they are no longer useful. Prior to 2006, core could be stored in open air core yards, but this practice has been discontinued.

RPA COMMENTS ON SAMPLING METHOD AND APPROACH

In RPA’s opinion, the core handling, logging, and sampling protocols conform to industry-standard practice, are being carried out to a reasonable standard, and are acceptable for Mineral Resource and Mineral Reserve estimation.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-26    


LOGO    www.rpacan.com

 

 

QUALITY ASSURANCE AND QUALITY CONTROL

Since 2006, Barrick corporate geochemists have visited the laboratories that undertake analysis and sample preparation for the Cortez Mine. QA/QC for sampling, sample preparation, and assaying has evolved at Cortez since 1991. Current procedures include insertion of blanks and certified standard samples into sample streams to the mine and commercial laboratories, check assays of pulp duplicates by commercial laboratories, and assaying of coarse reject duplicates.

Barrick’s QA/QC practices at Cortez exploration comprise a minimum of one standard, one blank and one duplicate introduced per batch of 30 samples to the sample stream resulting in 10% quality control samples. Underground grade control drilling involves insertion of one standard and one control blank for every 30 samples, however, because whole core is often sampled there is no opportunity for duplicate samples.

The acQuire database is maintained by the Database Administrator at Barrick Gold Exploration Inc. office in Elko. The assay laboratories report results to the central office as well as the project geologist. Monthly QA/QC reports are prepared by the Database Administrator. The report evaluates the performance of the QA/QC samples, identifies any QA/QC failures, and tracks their investigation and resolution including any assay re-runs. Failures are reported to the project geologist who decides on a course of action. Issues that cannot be resolved by the project geologist result in a re-run of an entire batch or in some cases an entire hole. Assays are maintained on temporary status until signed off by the central office and the project geologist.

The QA/QC program for 2015 included standards, blanks, and duplicates, which accounted for greater than 6% of the total, an insertion rate of approximately 1:14. The failure rate was 1.8% and all of the issues were resolved.

STANDARD SAMPLES

Certified Reference Standard (CRM) samples are materials of known values used to check and quantify the analytical accuracy of laboratories.

At Cortez standards were originally made from stockpile materials at the mine. Since 2006, commercially available standards have been used. Certified Reference Standard (CRM)

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-27    


LOGO    www.rpacan.com

 

 

samples were purchased from Rocklabs as pulps that were assayed in a round robin of 28 laboratories or made from bulk samples sent from Barrick’s Nevada operations to CDN Resource Laboratories Ltd. to make reference material after a 14 laboratory round robin. The average value and its standard deviation (SD) for the round robins are certified. The variation from the standard’s mean value in standard deviations defines the QA/QC variance and is used to determine acceptability of the standard sample assay. Approximately 150 g of sample material is submitted per QA/QC sample.

There are currently fourteen standard samples being used with expected samples ranging from 0.00825 oz/st Au to 0.45442 oz/st Au. Standard samples are inserted into the sample stream at a ratio of 1:30 for surface exploration and approximately 1:15 for open pit production samples and underground diamond drill samples.

The criteria for pass or failure are as follows.

 

   

Assay value < certified mean ±2 SD g Pass

 

   

Assay value ³ mean ±2 SD and £ mean ±3 SD g Warning or Failure

 

   

Assay value > mean ±3 SD g Failure

A failure is declared when the same standard exceeds two consecutive ±2 SD warnings or when an individual result exceeds ±3 SD from the expected result.

The geologist in charge is notified when a standard failure occurs. The geologist then determines if the failure can be accepted or if the laboratory needs to re-run the failing batch.

BLANK SAMPLES

A blank control sample is material with a zero gold value. Blanks are inserted to assess sample preparation, specifically to identify “grade smearing” or sample carryover in subsequent samples caused by improper sample preparation and contamination, and to evaluate analytical “background noise”. Prior to 2006, blank material was made from:

 

   

Un-mineralized drill core from Gold Acres

 

   

Waste rock from the Cortez Pits

 

   

Alluvial gravel taken from a pit near the Gold Acres haul road

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-28    


LOGO    www.rpacan.com

 

 

Since 2006 landscape marble has been the material used to make blank samples for QA/QC at Cortez.

The following criteria are used to evaluate analytical results received for blank samples.

 

   

Assay result less than 0.002 oz/st Au - Pass

 

   

Pass limit is extended by 1% carry-over from surrounding samples

 

   

Assay result equal to or greater than 0.002 oz/st Au - Failure

The geologist in charge is notified when a blank failure occurs. The geologist then determines if the failure can be ignored or if the laboratory needs to re-run the failing batch.

Laboratory procedures include cleaning of the sample preparation circuit after sample batches, however, the 1% allowance of carry-over grade from surrounding samples makes some allowance for potential contamination from high grade samples processed within a sample batch.

DUPLICATE SAMPLES

Duplicate samples of coarse rejects provide information on sample preparation and assay precision, while duplicate pulp samples may be used to quantify analytical precision. The assay results of the duplicates are analyzed by preparing scatter plots and relative difference plots that compare the difference of grade of the pairs to the mean grade of the pairs. The pass/fail criteria used by Barrick for duplicate pulp samples is nominally +/- 20%.

OUTSIDE CHECK SAMPLES

American Assay Laboratories were sent 2% of the Cortez original sample pulps for independent check assays during 2015. Using the original assay results from the primary laboratory as a guide, the geologist selects the pulps to be submitted for check assay. The chosen suite of pulps are representative of the ore types present in the samples, and include high grade, low grade, and waste material. Requirements for this protocol include:

 

  1.

The original pulp splits must be submitted, not a duplicate split taken from pulp rejects.

 

  2.

The pulps are submitted to the secondary laboratory in one batch and should be assayed together.

 

  3.

At least one standard sample (SRM) pulp is included with each lot of check assay pulps.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-29    


LOGO    www.rpacan.com

 

 

Recent practices at Cortez for independent check assays are to have the primary laboratory, ALS Chemex, randomly select every 20th pulp and forward these to American Assay Laboratory for a second check assay. This represents a 5% check ratio. Pass/fail criteria used is ±20% of the original value.

In the past, results of check assaying on pulps and coarse rejects were not routinely evaluated. Check assays, however, were used intermittently to evaluate biases between the mine laboratories and commercial laboratories.

For the period 1992 to 1996, a large number of commercial laboratories were used to check assays by Laboratory No. 1. No record was kept of the source laboratories for each check in all cases; therefore, some of the data cannot be differentiated by laboratory. A detailed review of check and duplicate assay records in 2003 reduced the number of unidentified laboratory assays to approximately 4%. No significant bias was detected between the mine and the commercial laboratories.

Check assay plots show a relatively high variability between the mine laboratory and commercial laboratories for 1997 through 1999 assaying. For grades greater than 0.01 oz/st Au, a majority of check assays are within ±20% to ±30% of the original value, which is somewhat higher than the expected ±10%.

Check assays on samples primarily from the Pediment and Cortez Hills deposits by Rocky Mountain Geochemical and American Analytical laboratories in 2000 to 2003 show less variability, with most checks within ±10% of the original value. In 2003, Cortez investigated these biases in detail and adjusted historical assays for the Pipeline, South Pipeline, Crossroads, and Gap deposits for laboratory biases and sampling biases. The practice of adjusting assays has been discontinued.

Checks of the mine laboratory (Laboratory No. 1) assays were made for the 1995 FS. A pulp duplicate was prepared for one in every five Pipeline core sample and one in every ten South Pipeline core sample. A pulp duplicate was prepared for one in every ten RC sample for Pipeline and one every twenty RC sample for South Pipeline. These were assayed by Monitor Geochemical Laboratory and the Placer Dome Research Centre. Since 1995, this procedure of checking the mine laboratory assays has continued using Rocky Mountain Geochemical

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-30    


LOGO    www.rpacan.com

 

 

Laboratory, American Assay Laboratory, Barringer Laboratories (now Inspectorate), and Monitor Geochemical Laboratory.

SCREEN CHECKS

Screen check assaying is not done at Cortez. Previous test work determined that coarse gold has not been an analytical issue to date, given the disseminated distribution and very fine grained character of the gold mineralization.

CORTEZ LABORATORY

The on-site Cortez laboratory runs its own internal QA/QC program. They use commercial prepared and purchased standards of various grades. Current frequency of control samples is as follows:

 

   

Production samples (FA-GRAV and CNL-AA)

   

21 samples per set

   

1 standard, 1 blank, and 1 duplicate per set

 

   

Mill shift samples (solutions and solids)

   

1 standard for each solution set of 23 samples and each solid set of 12 samples

 

   

XRF – Carbon analysis

   

1 standard for each set of 20 samples

 

   

Leco – Carbon and sulfur analyses

   

1 standard and 1 blank for each set of 22 samples

 

   

Exploration samples (FA-GRAV and CNL-AA)

   

21 samples per set

   

1 standard, 1 blank, and 1 duplicate per set

The laboratory is organized such that quality control samples are inserted automatically. Different grades of standards are used and run with underground, open pit and mill process samples.

A monthly QA/QC compliance report details investigative findings regarding samples that fail the control criteria. With respect to gold analysis by both fire assay with a gravity finish (FA-GRAV) and cyanide leach and AA finish (CNL-AA) the following pass/fail criteria are applied by the Cortez laboratory. The pass criterion for standards is two standard deviations; standard

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-31    


LOGO    www.rpacan.com

 

 

variance between two and three standard deviations is taken as a warning; action is required when variance exceeds three standard deviations. The pass criterion for blanks is gold values less than 0.002 oz/st Au.

RPA’S COMMENTS ON QA/QC

In RPA’s opinion, the QA/QC protocols and reports meet industry-standard practice and provide the necessary control to identify potential analytical problems and allow for corrective follow-up and re-analysis when required.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 10-32    


LOGO    www.rpacan.com

 

 

11 SAMPLE PREPARATION, ANALYSES AND SECURITY

Analytical procedures that support Mineral Resource estimation, including sample preparation and sample analysis, were performed by independent analytical laboratories without company involvement from 2005 to the present. Samples prior to that date were primarily prepared and analyzed by the Cortez laboratory.

ANALYTICAL LABORATORIES

Prior to 2000, the mine laboratories at Mill No. 1 (Laboratory No. 1) and Mill No. 2 (Laboratory No. 2) assayed a majority of exploration samples, principally those for Pipeline, Crossroads, Gap, and Cortez NW Deep (Cortez Pits). Laboratory No. 1 was located at the old Cortez Mine facility and closed in 1997. Laboratory No. 2 was constructed in 1997 and currently is operating at the Pipeline process facility.

A number of commercial laboratories were used for assaying or check assaying since 1991, including Rocky Mountain Geochemical Laboratory, American Assay Laboratory, ALS Chemex, Barringer Laboratories (now Inspectorate), the Placer Dome Research Centre, and Monitor Geochemical Laboratory.

ALS Chemex has been the primary independent commercial laboratory. A majority of core and RC samples for Cortez Hills and Pediment deposits were prepared by the ALS Chemex sample preparation facility in Reno, Nevada, and assayed in Vancouver, B.C.

From 2005, all exploration assaying as well as underground assaying for development drilling at Cortez Hills and supplementary drilling at Pipeline, Gap, and Crossroads, has been performed by ALS Chemex. The mine laboratory has been principally used for mine related grade control samples and processing analysis.

The mineral laboratories used are ISO registered except for the Inspectorate (Barringer), Rocky Mountain Geochemical Laboratory, Monitor Geochemical Laboratory, and the Cortez Mine laboratories.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 11-1    


LOGO    www.rpacan.com

 

 

SAMPLE PREPARATION

Sample preparation protocols for the commercial and mine laboratories were similar. The initial sample preparation for Pipeline drilling in 1991 to 1992 was:

 

   

Sample bags were dried at 350°F for six to 12 hours.

 

   

Samples were weighed on a triple beam balance to an accuracy of 0.1 kg.

 

   

Samples were fed through a TM Engineering Ltd.’s (TM) Rhino Jaw Crusher set at 1/8”.

 

   

Entire sample was screened to minus 10 mesh. Oversize was run through a Bico disc pulverizer to reduce the oversize to minus 10 mesh.

 

   

Entire samples were split to 500 g with a Jones-type splitter. The 500 g split was dried a second time.

 

   

A 500 g aliquot was pulverized to 100% passing 150 mesh in a TM vibratory ring pulverizer. Pulverized sample was homogenized on a roll mat. Ring pulverizer was cleaned by pulverizing a crushed crucible between each sample.

 

   

Reject was retained and stored.

The coarse-crush protocol was changed to 80% passing 10 mesh in late 1992, and between 1992 and 1997 it was changed to 95% passing 6 mesh. By 1998, the crushing protocol was changed to:

 

   

Entire sample crushed to minus  14 in. using a jaw crusher.

 

   

Entire sample crushed to 95% passing 8 mesh in a rolls crusher.

 

   

500 g aliquot split for pulverizing to minus 200 mesh in an automated pulverizer.

This protocol was maintained until 2000 when new crushing and grinding equipment was acquired by mine Laboratory No. 2. The mine laboratory now uses a RockLabs crusher and rotary splitter and a TM automated ring-and-puck pulverizer for exploration samples. The RockLabs splitter uses a two-stage process to crush the entire exploration sample to 95% passing 10 mesh and produce a 500 g sample aliquot. The 500 g is pulverized for 75 seconds in the automated pulverizer, producing a product of 95% passing 175 mesh. Gravel is pulverized between each run of the 24-compartment pulverizer to clean the unit. Crush and pulverizer specifications are checked once weekly. Balances are calibrated every six months.

Blast-hole samples from 3 lb to 20 lb are crushed to 95% passing 6 mesh in a TM Rhino jaw crusher. A 250 g to 300 g aliquot is split with a Jones-type riffle splitter. No reject is retained.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 11-2    


LOGO    www.rpacan.com

 

 

The 250 g to 300 g aliquot is then pulverized for 150 seconds in a manual ring-and-puck pulverizer or for 75 seconds in the TM automated pulverizer.

ALS Chemex uses the following sample preparation procedures for Cortez samples:

 

   

High temperature drying of samples (DRY-21 procedure).

 

   

Weigh, dry, fine crush entire sample to better than 70% minus 2 mm, split off up to 250 g and pulverize split to greater than 85% passing 75 µm (PREP-31 procedure).

 

   

Compositing procedure, homogenize the composite pulp, gravimetric procedure (CMP-22).

ANALYSIS

A standard fire assay with gravimetric finish is performed on one-assay ton (29.18 g) pulp aliquots for all core and RC samples analyzed by the mine laboratory. If the initial fire assay is greater than 0.1 oz/st Au, an additional fire assay is performed. If the initial fire assay is greater than 0.2 oz/st Au, two additional fire assays are performed. The mean value of the two or three assays was used for resource estimation in the Pipeline FS resource model.

In 2004, ALS Chemex assayed Cortez Hills and Pediment samples by fire assay and AA finish, using a 30 g pulp aliquot. All samples reporting greater than 0.1 oz/st Au on the initial assay were re-assayed by fire assay with gravimetric finish. Cyanide leach gold assays were performed for initial FA assays higher than 0.008 oz/st Au. A cold cyanide shake leach, analyzed by AA, is performed if the initial fire assay is higher than 0.015 oz/st Au. If the initial fire assay is higher than 0.040 oz/st Au and lower than 0.15 oz/st Au, a “preg-rob” test is performed. This is performed by combining 10 g of pulp with 20 mL of a 0.050 oz/st Au cyanide solution and agitating for eight to ten minutes, then analyzing by AA. Samples with a cyanide AA/fire assay ratio of less than 0.3 are routinely assayed for sulphur and total carbon in a LECO furnace.

The current practice is to fire assay, AA, and preg rob on all intervals within pre-selected zones. More selective triggers apply in unmineralized zones. The following general protocol is used for gold and multi-element analyses:

 

   

Gold analyses: Gold assay (0.005 ppm to 10 ppm) by 30 g fire assay – atomic absorption (AA) analysis (Au-AA23 procedure).

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 11-3    


LOGO    www.rpacan.com

 

 

   

Au (0.03 ppm to 50 ppm by cyanide leach – AAS, 30 g nominal weight (Au-AA13 procedure).

 

   

Au by fire assay and gravimetric finish, 30 g nominal weight, range 0.05 ppm to 1,000 ppm Au (Au-GRA21 procedure).

 

   

Multi-element analyses by aqua regia digestion/ICP-AES/ICP-MS, 51 elements or 48 element analyses by four acid and ICP-AES/ICP-MS (ME-MS41 procedure or ME-MS61m procedure, respectively).

A Laboratory Information Management System (LIMS) was implemented at mine Laboratory No. 2 in 1998. Laboratory No. 2 uses a sample bar code system and transfers all information to the mine database electronically via the LIMS. ALS Chemex assay certificates are downloaded from the ALS Chemex website and loaded directly into the mine database using acQuire®.

Twenty foot composites made from core and RC samples are routinely analyzed for a 49 element suite by ALS Chemex. For the underground development holes, multi-element analysis is performed on every sample (~5 ft intervals). The trace-element suite is obtained by inductively coupled plasma–arc atomic absorption spectroscopy (ICP) following an aqua regia digestion of the sample pulp. Trace elements include As, Sb, Hg, Tl, Fe, and Ca, which in association with Au, show positive or negative correlations with mineralized areas. High Hg analyses from the partial-digestion ICP data have been checked against cold-vapour hydride analyses, also run at ALS Chemex, and have shown generally close correlation (±5%) with the cold-vapour values. The multi-element ICP suite has changed in composition and detection limits several times in the last 15 to 20 years as analytical techniques have improved.

Additional assay methods, as recorded in the database of the 1960s, were typically used for exploration or other specialized purposes such as gas sampling, and were not consistently carried out. They include gravimetric, sulphuric acid digest, total copper, neutron activation analysis, X-ray diffraction, and X-ray fluorescence methods.

SAMPLE SECURITY

Grade control samples from operations are managed by employees of the Cortez mining operation and its drill contractors, while exploration samples are managed by Barrick exploration personnel and its contractors. Prior to 2008 the chain-of-custody was managed by CJV staff and their contractors.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 11-4    


LOGO    www.rpacan.com

 

 

Blast hole samples are delivered directly from the pits to the Cortez laboratory. Underground muck samples are delivered initially to the Portal and then to the sample room at the F-Canyon Office block. Underground RC samples are taken directly to the F-Canyon sample room. Underground drill core boxes are taken directly to F-Canyon lay-down area. Exploration samples, after leaving the drill rigs, are taken by Company personnel to the secure Exploration Complex.

Sample security relies on the samples being either always attended to by Company personnel or stored in the locked on-site preparation facility or stored in a secure area prior to pick-up by ALS Laboratory personnel or delivery to the on-site Cortez laboratory. For the most part, a unique and independent sample number is used for each sample with dispatch-submittal sheets and database entries used to track the progress of samples and to ensure that all samples are received by the laboratory.

Unique and independent sample numbers and sample tags are used in all cases except underground muck samples that are identified by location, e.g., heading and footage. Sample dispatch and submittal sheets are used to check and track samples through the system. Sample information is entered into the computer database to help tracking and for receipt of results.

Table 11-1 summarizes the chain-of-custody of the samples from the collection point to the analytical laboratory.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 11-5    


LOGO    www.rpacan.com

 

 

TABLE 11-1    CHAIN OF CUSTODY SUMMARY

Barrick Gold Corporation – Cortez Operations

 

Grade Control         Exploration Drilling

Blast-holes (OP)

  

Muck (UG)

   Core (UG)    RC (UG)         RC        Core
Material Collection at Source            
 
Cortez drillers    Cortez loader operator    Cortez Geotechnician    Drill Contractor        Drill Contractor      Barrick employees
 
Transportation from Source, Handling, Sample Delivery to Lab            
 
Cortez drill & blast personnel    Cortez Supervisor    Drill Contractor    Drill Contractor        Barrick employees      Barrick employees
 
   Cortez employees    Cortez employees    Cortez employees        Barrick
Geotechnician
    
 
      ALS employees    ALS employees        ALS employees      ALS employees
 
Sample Preparation and Analysis            
 
Cortez lab    Cortez lab    ALS lab    ALS lab        ALS lab      ALS lab

RPA’S COMMENTS ON SAMPLE PREPARATION, ANALYSIS, AND SECURITY

In RPA’s opinion, the sample preparation, analytical procedures, and sample security used at Cortez for mining operations and exploration projects are adequate for use in the estimation of Mineral Resources.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 11-6    


LOGO    www.rpacan.com

 

 

12 DATA VERIFICATION

RPA checked previous Cortez and external data reviews and has conducted independent reviews in 2010, 2012, and again in the preparation of this Technical Report. RPA did not collect independent samples as the historical production of 19 million ounces of gold clearly demonstrates the presence of economic mineralization.

DATABASES

The Cortez technical database is being managed by the acQuire system implemented in 2004 replacing an earlier database system. Exploration data from a variety of sources are imported into acQuire using a variety of techniques and procedures to check the integrity of the data entered. Data that were collected prior to the introduction of digital logging have been subject to validation, using built-in program triggers that automatically checked data upon upload to the database. Since the mid-1990s, geological data have been validated by software routines and uploaded directly into the database. Analytical data are uploaded from digital sources. Survey data is uploaded by the project geologist from digital survey files. Verification is performed on all digitally collected data upon upload to the main database, and includes checks on surveys, collar co-ordinates, lithology data, and assay data. Since 2009, Cortez Hills and Pipeline Complex blast-hole data and Cortez Hills underground Cubex drilling data are also imported into acQuire.

Database security and integrity is accomplished by restricting access and user level permissions that are set by the Database Manager. Once data entry and validation are completed for a drill hole, access is locked. There are procedures for updates that retain all the original information and prioritize use of the updates.

BARRICK REVIEWS

REVIEW OF ASSAY BIASES

In 2003, an in-house study was carried out to determine the causes of historical biases between resource estimates based on exploration drilling, mine production based on blast-hole models, and mill production. Results indicated that:

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 12-1    


LOGO    www.rpacan.com

 

 

   

Blast hole assays performed by atomic absorption were biased low.

 

   

Blast hole and exploration hole fire assays performed by the mine laboratories were biased low relative to fire assays by commercial laboratories.

 

   

There are sampling losses in exploration holes, which result in an occasional low bias, even though core recovery is very high.

 

   

There are smoothing effects in resource estimation procedures that result in lower average grades in RC holes.

 

   

Small scale higher grade zones may exist between holes and are missed by drilling.

Bias adjustment factors were developed, however, by 2006 most of the affected areas had been mined out. Remaining data were evaluated on a hole by hole basis and where a down-hole contamination or bias issue occurred it was noted. The drill hole in question was flagged and was not used to support Mineral Resource or Mineral Reserve estimates. No bias adjustment factors for assay data have been used since 2007.

CORE VERSUS RC DRILL COMPARISON, CORTEZ HILLS

An in-house study, triggered by down-hole contamination noted in at least three RC drill holes, was undertaken in July 2004 to compare results from RC and core holes used in the Cortez Hills resource estimate. Core versus RC twin data were reviewed and resources were estimated separately based on only RC data and on only core data for comparison. Preliminary results suggested that core holes on average were of higher grade than RC holes, depending on the grade range. The core averages were considered to be biased high because core holes were more common in the high-grade centre of the deposit. Individual RC/core twin holes compared reasonably well, showing less of a high bias in the core holes. Additional core drilling at Cortez Hills since 2004 has replaced the contaminated RC holes.

BLAST HOLE SAMPLING REVIEW

Cortez reviewed the use of a pie sampler versus the cylinder sampler and found no significant difference in assays between the methods for 1,900 blast holes. The cylinder sampler has been retained.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 12-2    


LOGO    www.rpacan.com

 

 

EXTERNAL REVIEWS

Sampling reviews were undertaken in 1992 and 1999 by Francis Pitard, checking elements of the sample preparation procedures. Modifications were made to RC sample collection for the Pediment deposit drilling.

AMEC reviewed the Cortez Hills and Pediment drill database in 2004 and 2005, checking lithological and analytical data and database integrity. Data were found to be suitable to support Mineral Resource estimation.

RPA DATABASE REVIEW

RPA undertook reviews of the database as part of an audit review report in July 2010, as part of a Technical Report in 2012, and again in the preparation of this Technical Report.

JULY 2010 REVIEW

RPA received drill hole and block model databases in Vulcan/ISIS formats. Files were reformatted to ASCII and imported into Gemcom GEMS 6.2.2 software for review. GEMS was employed to validate the drill hole database using software routines that trap errors and potential problems.

GEMS validation routines found some down-hole survey records lacking collar zeros (fourth bullet above) and several cases of zero intervals, most at the end of lithology files/tables. None of these minor errors impact on resource estimation. Otherwise the drill hole databases were clean and readily imported.

JANUARY 2012 REVIEW

Drill hole and block model databases for each of the resources reported by Cortez for mid-2011 were received from Barrick in Vulcan/ISIS formats. The validation review focused on the databases supporting the June 30, 2011 Mineral Resource and Reserve estimates for the Cortez Hills Complex open pit, underground, and Lower Zone models that represented 76% of the contained gold in the Mineral Reserves.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 12-3    


LOGO    www.rpacan.com

 

 

The resource databases were imported into Vulcan 3D Version 8.0.3 software for review. Vulcan database validity routines found no errors with out of range values, or from-to intervals, and that sample lengths and assays values were within reasonable limits. With a few minor exceptions drill hole collars were found to be within the area limits of the model.

All the data was consistently presented and organized and all units within the database were consistent.

RPA also carried out a spot check comparison of the supplied resource databases against original documents for collar surveys, down-hole surveys, and laboratory assay certificates. The 35 holes checked for collar surveys were all found to be correctly entered. Two of the 16 holes reviewed for down hole surveys had minor errors that were corrected.

The azimuth and inclination measurements for the remainder of the database entries were found to correspond with the original down hole survey measurements.

The gold fire assay (“fa1”) and cyanide leach assay (“aa1”) values for 16 holes were checked against the original laboratory assay certificates. The fire assay values corresponded to the original certificates for all 16 holes. Two of the 16 holes had cyanide leach values that did not correspond to the laboratory reports and were corrected.

MAY 2015 REVIEW

RPA undertook the following validation checks as part of the database validation routine:

 

  1.

Overlapping sample intervals

 

  2.

Empty database tables

 

  3.

Visually anomalous survey records

RPA also undertook a spot check comparison of the supplied resource databases against original documents for laboratory assay certificates. The gold fire assay values for 12 underground drill holes and five surface drill holes were checked against the original laboratory assay certificates. All 1,004 fire assay values corresponded to the original certificates.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 12-4    


LOGO    www.rpacan.com

 

 

RPA OPINION

It is RPA’s opinion that the Cortez database is well prepared, as well as adequate and suitable for Mineral Resource estimation.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 12-2    


LOGO    www.rpacan.com

 

 

13 MINERAL PROCESSING AND METALLURGICAL TESTING

INTRODUCTION

During the nearly 40 year history of the Cortez Mine, a significant number of metallurgical studies including laboratory scale and/or pilot plant test work have been completed and historical operating data is available. The Cortez Mine has utilized numerous processes including carbon-in-leach (CIL) for higher grade oxide ore, heap leaching for lower grade oxide ore, roasting for carbonaceous refractory ore and pressure oxidation for higher grade sulphidic ore. Mill No. 1, which included CIL and a roaster, was placed on care and maintenance at the end of October 1999. The roaster has been inactive since 1995, and it is currently being demolished.

METALLURGICAL TESTING

Metallurgical testing of new ore types has confirmed the choices for processing unit operations and provided data to estimate capital and operating costs and gold recovery for the various ore types. Test data has also been generated to determine the expected performance in Mill No. 2 as new reserves have been identified and included in the LOM plans.

Recent metallurgical testing was or is being conducted to confirm the metallurgical performance of Pediment heap leach ore, Gap, Pipeline Phases 10C and 10D, Gold Acres, Cortez Pits, Cortez Hills Underground high grade oxide ore, and Minex samples from East Pediment, among others. Additional work is on-going to predict the metallurgical characteristics of the ore from Deep South (Olson, 2014a, 2014b, 2014c, 2014d, 2015e, Barrick Cortez, Inc., 2015a).

Cortez has extensive metallurgical testing facilities so much of the work is done on site, however, they make use of outside labs when specific expertise is needed or when timing dictates that the data is needed sooner than the in-house lab can provide it. Testing is conducted by McClelland Laboratories Inc., Hazen Research Inc., at the Barrick Goldstrike lab, and by AuTec in Vancouver, British Columbia, among others.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-1    


LOGO    www.rpacan.com

 

 

ORE ROUTING

Ore routing is conducted based on cyanide leaching amenability to fire assay ratio (CNAA to FA ratio). If the AA to FA ratio is greater than 50%, the ore is designated as oxide ore. If the AA to FA ratio is less than 50%, the ore is designated as refractory. The oxide ore will be routed to the Pipeline Mill or a heap leach pad depending on the gold grade. The refractory ore is routed to the Goldstrike roaster.

GOLD RECOVERY ESTIMATES

The recovery of gold is a function of the processing method (CIL, heap leaching, roasting, and arsenic concentration for refractory ore) and the lithology of the mineralization being processed. The recoveries used to support Mineral Resource and Mineral Reserve estimations are based on recovery equations that are derived from feasibility studies, metallurgical laboratory test work and historic production data, as summarized in Tables 13-1 to 13-3. These figures are incorporated in the Lerchs–Grossman pit shells that constrain the Mineral Resources and Mineral Reserves to be extracted by open pit mining methods.

Test work reports and plant operating results were reviewed to verify the reported recoveries used in the Mineral Resources and Mineral Reserves estimates.

For leach ore, the estimated recovery figure for Pipeline oxide is based on actual heap performance values.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-2    


LOGO    www.rpacan.com

 

 

TABLE 13-1 CORTEZ OXIDE MILL GOLD RECOVERY EQUATIONS

Barrick Gold Corporation – Cortez Operations

 

Ore Pit

 

Head Grade

(oz/st Au)

  

Recovery Equations

Cortez Hills Underground

  >0.800   

% Recovery = 94.0 – 57.1 x Sulphide Sulphur (%)

  £ 0.800   

% Recovery = 25.7 x CNAA/HG + 9.7 x CNAA + 59.3

Cortez Hills Open Pit

  >0.920   

% Recovery = 95.66 – 2.44

  >0.150   

% Recovery = [100 x HG – 1.3 x Ln(HG) – 4.1] / HG -2.4

  £0.150   

% Recovery = (18 x HG) + 86.4 – 5.9

Cortez Pits1

  Option 1   

% Recovery = 89.0

  Option 2   

% Recovery = 8.36 x HG – 9.78 x AAFA + 96.4

Pipeline/ South Pipeline/South Gap

  > 0.207   

% Recovery = 88.1 – 8.3

  £ 0.207   

% Recovery = 85.11 x EXP(0.36 x HG) – 11.9

Crossroads

    

% Recovery = 88.0

Notes:

 

1

Prefer Option 2 if there is confidence in the AAFA ratio in the block model

HG = gold head grade in oz/st

Ln = natural log function

EXP = Exponential Function

CNAA = cyanide shake in oz/st

AAFA = CNAA/HG (ratio)

TABLE 13-2 CORTEZ HEAP LEACH ULTIMATE GOLD RECOVERY EQUATIONS

Barrick Gold Corporation – Cortez Operations

 

Open Pit

  

Recovery Estimate

Cortez Hills

   % Recovery = 80%

Pediment

   % Recovery = 70%

Cortez Hills Underground (crushed leach)

  

Breccia and Middle Zone % Recovery = 84

Lower Zone and Deep South % Recovery = 70

Cortez Pits

   % Recovery = 75

Pipeline (Phase 10)

   % Recovery = 62%

Crossroads

   % Recovery = 62%

South Gap

   % Recovery = 55%

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-3    


LOGO    www.rpacan.com

 

 

TABLE 13-3 REFRACTORY ORE GOLD RECOVERY EQUATIONS

Barrick Gold Corporation – Cortez Operations

 

Process

 

Head Grade

(oz/st Au)

  

Gold Recovery Equations

Roaster1

  > 1.150   

% Recovery = 93.07

  0.250 < HG £ 1.150   

% Recovery = 3.1719 x Ln(HG) + 92.612

  0.125 < HG £ 0.250   

% Recovery = 71.836 + 40.456 x (HG) - 0.009 x 730 + 0.151 x 85

  £ 0.125   

% Recovery = -1017.2 x (HG)2 + 377.14 x (HG) + 51.909

RF1 Discount

    

Recovery Discount of 1.5% for Arsenic Discounts

Notes:

 

1

Roaster recovery estimates assume 730 tons-per-operating-hour and 85% sulfide oxidation. The estimates for autoclave recovery are not dependent on throughput or efficiency.

HG = Gold Head Grade in oz/st

Ln = Natural Log Function

TCM = Calcium Thiosulfate Leach

Table 13-4 summarizes the results of the budgeted versus actual data taken from the Cortez Flash Reports, which was evaluated to verify the recovery estimates. For an operating mine, RPA considers this data to be more reliable for determining if the recovery estimates are accurate than reporting on metallurgical test data and samples.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-4    


LOGO    www.rpacan.com

 

 

TABLE 13-4 PRODUCTION DATA 2013-2015

Barrick Gold Corporation – Cortez Operations

 

     2013         2014         2015
     Actual    Budget    Actual
vs.
Budget
        Actual    Budget    Actual
vs.
Budget
        Actual    Budget    Actual
vs.
Budget

OPEN PIT

                                  

Pit Mill

                                  

Grade Processed (oz/st)

   0.166    0.163    102%        0.064    0.063    102%        0.110    0.076    145%

Recovery Rate (%)

   89    90    99%        77    83    93%        89    85    105%

Average Tons per Day

   10,797    11,154    105%        10,057    10,864    93%        9,573    11,253    85%

Leach

                                  

Grade Processed (oz/st)

   0.018    0.018    105%        0.013    0.013    105%        0.013    0.010    135%

Recovery Rate (%)

   40    48    84%        72    86    83%        53    101    53%

Average Tons per Day

   46,655    49,825    94%        64,406    61,477    105%        54,443    37,400    146%

Autoclave

                                  

Grade Processed (oz/st)

   0.265    0.242    109%                     0.138    NA

Recovery Rate (%)

   94    91    103%                     68    NA

Average Tons per Day

   309    327    94%                     133    NA

Roaster

                                  

Grade Processed (oz/st)

   0.174    0.174    100%        0.149    0.149    100%        0.143    0.120    120%

Recovery Rate (%)

   94    91    103%        83    84    99%        85    82    103%

Average Tons per Day

   655    680    96%        2,196    2,278    96%        1,341    2,392    56%

Open Pit Total

                                  

Grade Processed (oz/st)

   0.049    0.047    105%        0.024    0.024    99%        0.031    0.030    103%

Recovery Rate (%)

   74    77    97%        76    85    89%        75    88    85%

Average Tons per Day

   58,416    61,986    94%        76,658    74,620    103%        65,490    51,044    128%
   

UNDERGROUND

                                  

Mill

                                  

Grade Processed (oz/st)

   0.928    0.934    99%        0.729    0.721    101%        0.662    0.608    109%

Recovery Rate (%)

   91    91    100%        89    92    97%        84    88    95%

Average Tons per Day

   1,611    1,509    107%        1,201    1,073    112%        924    925    100%

Autoclave

                                  

Grade Processed (oz/st)

   0.610    0.608    100%        0.711    0.804    88%        0.832    0.871    96%

Recovery Rate (%)

   85    86    99%        84    88    96%        77    87    88%

Average Tons per Day

   371    377    98%        449    482    93%        124    724    17%

Roaster

                                  

Grade Processed (oz/st)

                0.457    0.371    123%        0.618    0.311    198%

Recovery Rate (%)

                81    89    90%        92    89    104%

Average Tons per Day

                84    35    241%        1,130    255    444%

Underground Total

                                  

Grade Processed (oz/st)

   0.869    0.869    100%        0.711    0.738    96%        0.648    0.668    97%

Recovery Rate (%)

   90    90    100%        88    91    97%        88    88    100%

Average Tons per Day

   1,982    1,886    105%        1,734    1,589    109%        2,178    1,904    114%

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-5    


LOGO    www.rpacan.com

 

 

The estimated and actual gold recoveries correlate well which indicates that the recovery estimates are accurate.

Table 13-5 compares the contained, estimated recoverable, and actual recovered gold ounces for the life of the Cortez heap leach pads (i.e. Areas 28, 30, and 34). Figure 13-1 provides the same data graphically.

TABLE 13-5 HEAP LEACH GOLD PRODUCTION

Barrick Gold Corporation – Cortez Operations

 

Year

   Contained
(000 oz)
     Estimated
Recoverable

(000 oz)
     Actual
Produced

(000 oz)
 
1997      55         38         28   
1998      228         155         124   
1999      327         223         211   
2000      570         387         283   
2001      1,080         735         526   
2002      1,434         966         805   
2003      1,978         1,295         1,133   
2004      2,773         1,780         1,626   
2005      3,206         2,051         2,004   
2006      3,509         2,240         2,207   
2007      4,020         2,540         2,491   
2008      4,477         2,768         2,706   
2009      4,651         2,867         2,866   
2010      4,725         2,920         2,925   
2011      4,763         2,948         3,009   
2012      4,859         3,031         3,105   
2013      5,173         3,256         3,245   
2014      5,376         3,371         3,401   
2015      5,752         3,620         3,611   

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-6    


LOGO    www.rpacan.com

 

 

FIGURE 13-1 HISTORICAL HEAP LEACH DATA

 

LOGO

The data clearly shows that the estimated gold production from the heap leach pads and the actual gold production correlate well. This is also true for each individual heap leach pad.

DEEP SOUTH ZONE METALLURGICAL TESTING

AuTec completed optimization and variability testing using samples from the Deep South Zone. McClelland Laboratory, Inc. also completed column leach tests using the oxide samples from Deep South Zone. The results of the testing program were used to support a PFS of the Cortez Underground Expansion Project (AuTec, 2015). Eighty samples were used to create eight composite samples that were used for the optimization testing. Variability testing was also conducted using the 80 samples.

Comminution testing for 60 samples estimated that the majority of the samples are moderately hard (A x b < 40), but a few samples were exceptionally soft (A x b > 300) with respect to SAG milling. Bond work index (BWi) tests were conducted on seven of the composite samples at a closing size of 105 µm. The average BWi is 11.3 kWh/st. The comminution test results indicate

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-7    


LOGO    www.rpacan.com

 

 

that the grinding characteristics of Deep South samples are similar to the ore mined at Cortez Hills.

A series of tests were conducted using the optimization samples to complete the following tests:

 

   

Column leach tests

 

   

Direct cyanide leach (DCN)

 

   

CIL tests

 

   

Bench top roaster followed by CIL (BTR-CIL)

 

   

Bench top alkaline pressure leach tests followed by CIL (BTALK-CIL)

 

   

Bench top alkaline pressure leach tests followed by thiosulfate resin in leach (TCM) (BTALK-TCM)

The results are summarized in Table 13-6.

TABLE 13-6 DEEP SOUTH ZONE TEST RESULTS (AU RECOVERY)

Barrick Gold Corporation – Cortez Operations

 

Sample

 

Ore Type

 

Au

(oz/st)

 

DCN

 

CIL

 

BTR-

CIL

 

BTALK-

CIL

 

BTALK-

TCM

 

Column

Tests

V1

 

Oxide

  0.238   67.2%   87.4%   84.9%   81.5%   68.4%   76.5

V2

 

Oxide

  0.598   82.6%   88.1%   88,7%   88.2%   42.2%   71.5

V3

 

Oxide

  0.683   83.3%   91.2%   91,2%   89.1%   26.8%   77.6

V4

 

Oxide

  0.680   63.6%   88.1%   88.1%   76.0%   30.2%   47.0

V5

 

Oxide

  0.187   82.4%   89.1%   89.1%   89.3%   28.7%   84.4

V6

 

Oxide

  0.225   77.8%   89.9%   89.9%   88.1%   36.9%   74.4

V7

 

Refractory

  0.436   12.3%   15.7%   91.2%   83.2%   82.6%   —  

V8

 

Refractory

  0.256   32.3%   85.9%   85.9%   89.9%   89.5%   —  

Minimum

    0.683   12.4%   15.7%   84.9%   76.0%   26.8%   47.0

Maximum

    0.187   84.0%   91.8%   91.2%   89.9%   89.5%   84.4

Average

    0.418   63.1%   72.6%   88.6%   85.6%   50.7%   76.9

The key assays for the samples are summarized in Table 13-7.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-8    


LOGO    www.rpacan.com

 

 

TABLE 13-7 DEEP SOUTH ZONE OPTIMIZATION SAMPLES ANALYTICAL RESULTS

Barrick Gold Corporation – Cortez Operations

 

Sample

   Au
(oz/st)
   CNAA/HG   S=   Corg

V1

   0.238    65.7%   0.10%   1.17%

V2

   0.598    92.5%   0.05%   0.02%

V3

   0.683    91.4%   £ 0.01%   0.02%

V4

   0.680    87.8%   £ 0.01%   0.04%

V5

   0.187    97.6%   £ 0.01%   0.02%

V6

   0.225    89.1%   £ 0.01%   0.03%

V7

   0.436    15.8%   1.38%   £ 0.01%

V8

   0.256    34.3%   0.34%   0.17%

The Deep South Zone PFS recommends that the heap leach recovery can be estimated using the relationship between the CNAA and HG ratio and the direct cyanidation test results plus the relationship between DCN and column leaching. The resulting equation is:

HL %Au Recovery = 1.315 x CNAA/HG) – 40.481

The CIL recovery can be estimated accurately by applying the relationship between the CNAA/HG ratio and the CIL recovery using this equation:

CIL % Au Recovery = 0.942 x CNAA/HG

The recovery for refractory ore processed in the Goldstrike roaster followed by CIL were estimated using the current roaster recovery curves and grades from the Deep South Zone PFS production schedule. The average recovery for refractory ore sent to the roaster/CIL plant is estimated to be 88.7%.

SUMMARY AND CONCLUSIONS

Metallurgical test work completed for the Mine has been appropriate to establish optimal processing routes for the different ore types encountered at Cortez. Historical process data demonstrates that the metallurgical recovery models have been reliable. The metallurgical testing data available for ore scheduled to be processed in the LOM plan indicates that the models and methods used for estimating metallurgical performance will continue to be

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-9    


LOGO    www.rpacan.com

 

 

successful. Based on these observations, RPA concurs that the samples used to generate the metallurgical data and the historical operating data have been representative. Therefore, the estimates used to estimate future performance appear to be accurate.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 13-2    


LOGO    www.rpacan.com

 

 

14 MINERAL RESOURCE ESTIMATE

SUMMARY

A summary of the Mineral Resources, excluding Mineral Reserves, for Cortez as of December 31, 2015, is shown in Table 14-1. The Mineral Resources are presented by the most likely mine extraction method and gold recovery process. Cut-off grades for the Mineral Resources were established using a gold price of US$1,300 per ounce.

TABLE 14-1 MINERAL RESOURCE SUMMARY – DECEMBER 31, 2015

Barrick Gold Corporation – Cortez Operations

 

     Total Measured and Indicated      Total Inferred  
   Tons      Grade      Contained
Gold
     Tons      Grade      Contained
Gold
 

Mine & Process Type

   (000 st)      (oz/st Au)      (000 oz)      (000 st)      (oz/st Au)      (000 oz)  

Open Pit

                 

Mill

     6,001         0.058         345         2,031         0.09         175   

Heap Leach

     34,998         0.011         390         16,833         0.01         159   

Refractory

     4,010         0.117         471         494         0.12         61   

 

  

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

 

Open Pit Total

     45,009         0.027         1,206         19,359         0.02         395   

Underground

                 

Mill

     1,574         0.293         462         131         0.28         37   

Refractory

     1,598         0.301         481         1,210         0.36         429   

 

  

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

 

Underground Total

     3,172         0.297         943         1,341         0.35         466   

 

  

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

 

Total Open Pit & Underground

     48,180         0.045         2,149         20,700         0.04         861   

Notes:

 

1.

CIM definitions were followed for Mineral Resources.

2.

Mineral Resources are reported at the cut-off grades given in Tables 14-4, 14-14, 14-22 and 14-25.

3.

Mineral Resources are reported using a gold price of US$1,300 per ounce.

4.

A minimum mining width of 10 ft was used.

5.

Mineral Resources are additional to and exclusive of Mineral Reserves.

6.

Numbers may not add due to rounding.

RPA is not aware of any known environmental, permitting, legal, title, taxation, socio-economic, marketing, political, or other relevant factors that could materially affect the Mineral Resource estimate.

Mineral Resources decreased relative to EOY 2014 due to mining depletion as well as the completion of a PFS at Deep South Zone, Cortez Hills as material was reclassified as Mineral

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 14-1    


LOGO    www.rpacan.com

 

 

Reserve. Changes in cut-off grades and associated optimized pit shells following lower operating costs increased the Mineral Resources at Pipeline and Gold Acres. New model interpretation and new drilling in the underground portion of Cortez Hills added or upgraded Inferred ounces.

Cortez is currently reporting Mineral Resource estimates for four principal areas in the district. These include the Pipeline Complex and the Gold Acres deposit on the west side of Crescent Valley and the Cortez Hills Complex and Cortez Pits areas on the east side of the valley. Each of the mentioned areas include several gold deposits or zones. Table 14-2 identifies the principal areas, their included deposits or zones, when the Mineral Resources were most recently updated, and which group is responsible for the reported Mineral Resource estimate.

TABLE 14-2 CORTEZ MINERAL RESOURCE MODELS

Barrick Gold Corporation – Cortez Operations

 

Area   

Deposits or Zones

included

   Last Update    Responsible Group
   Pipeline    MID 2014   
Pipeline Complex    Gap    MID 2014    Tucson Technical Group
     Crossroads    MID 2014     
   Pediment    MID 2015    Mine Technical Group
   Breccia (open pit)    MID 2015    Mine Technical Group
Cortez Hills Complex    Breccia (underground)    MID 2015    Mine Technical Group
   Middle    MID 2015    Mine Technical Group
     Lower    MID 2015    Mine Technical Group
Cortez Pits    NW Deeps    EOY 2012    Mine Technical Group
Gold Acres       2008    Mine Technical Group

Details of the Mineral Resource estimation for each area are described in the sections below.

PIPELINE COMPLEX

Mineral Resources, exclusive of Mineral Reserves are listed in Table 14-3. Cut-off grades for the reported Mineral Resources were established using a gold price of US$1,300 per ounce and are shown in Table 14-4.

 

 

    Barrick Gold Corporation – Cortez Operations, Project 2471

    Technical Report NI 43-101 – March 21, 2016

   Page 14-2    


LOGO    www.rpacan.com

 

 

TABLE 14-3 PIPELINE COMPLEX MINERAL RESOURCE SUMMARY – DECEMBER 31, 2015

Barrick Gold Corporation – Cortez Operations

 

     Mill Material      Leach Material      Refractory Material      Total  
     Tons
(000 st)
     Grade
(oz/st
Au)
     Ounces
(000 oz)
     Tons
(000 st)
     Grade
(oz/st
Au)
     Ounces
(000 oz)
     Tons
(000 st)
     Grade
(oz/st
Au)
     Ounces
(000 oz)
     Tons
(000 st)
     Grade
(oz/st
Au)
     Ounces
(000 oz)
 

Measured Resources

  

Pipeline

     278         0.059         16         953         0.011         11         —           —           —           1,231         0.022         27   

Gap

     51         0.056         3         116         0.012         1         —              —           167         0.025         4   

Crossroads

     165         0.044         7         1,364         0.011         15         —           —           —           1,530         0.014         22   

 

  

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

 

Total Measured

     494         0.053         26         2,434         0.011         27         —           —           —           2,928         0.018         53   

Indicated Resources

  

Pipeline

     2,293         0.057         130         12,242         0.011         138         82         0.085         7         14,617         0.019         275   

Gap

     491