EX-99.1 2 d325661dex991.htm EX-99.1 EX-99.1

Exhibit 99.1

 

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TECHNICAL REPORT ON THE PUEBLO

VIEJO PROJECT, SANCHEZ RAMIREZ

PROVINCE, DOMINICAN REPUBLIC

PREPARED FOR BARRICK GOLD

CORPORATION

Report for NI 43-101

Rev. 0

Qualified Persons:

Robbert Borst, C.Eng.

Chester Moore, P.Eng.

Andre Villeneuve, P.Eng.

March 16, 2012


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Document Title

   Technical Report on the Pueblo Viejo Project, Sanchez Ramirez Province, Dominican Republic   

Client Name & Address

  

Mr. Rick Sims

Senior Director Reserves and Resources

Barrick Gold Corporation

10371 N. Oracle Road, Suite 201

Tucson, AZ

85737

  

  

  

  

  

  

Document Reference

   Project # 1659    Status &
Issue No.
    

 

Final    

Version

  

  

     Rev 0   

Issue Date

   March 16, 2012   

Lead Author

  

Robbert Borst, C.Eng.

Chester M. Moore, P.Eng.

André Villeneuve, P.Eng.

       

 

 

(Signed)

(Signed)

(Signed)

  

  

  

  

Peer Reviewer

   Graham G. Clow         (Signed)      

Project Manager Approval

   Chester M. Moore         (Signed)      

Project Director Approval

   Richard J. Lambert         (Signed)      

Report Distribution

   Name    No. of Copies   
   Client   
   RPA Filing         1 (project box)      

 

Roscoe Postle Associates Inc.

55 University Avenue, Suite 501

Toronto, Ontario M5J 2H7

Canada

Tel: +1 416 947 0907

Fax: +1 416 947 0395

mining@rpacan.com


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TABLE OF CONTENTS

PAGE

 

1 SUMMARY

     1-1   

Executive Summary

     1-1   

Technical Summary

     1-10   

2 INTRODUCTION

     2-1   

3 RELIANCE ON OTHER EXPERTS

     3-1   

4 PROPERTY DESCRIPTION AND LOCATION

     4-1   

Land Tenure

     4-4   

Permits

     4-5   

5 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY

     5-1   

Accessibility

     5-1   

Climate and Physiography

     5-1   

Infrastructure

     5-2   

6 HISTORY

     6-1   

Pre-1969

     6-1   

Rosario/AMAX (1969-1992)

     6-1   

Privatization (1996)

     6-3   

Previous Reserve Estimates

     6-4   

7 GEOLOGICAL SETTING AND MINERALIZATION

     7-1   

Regional Geology

     7-1   

Property Geology

     7-3   

Mineralization

     7-12   

8 DEPOSIT TYPES

     8-1   

9 EXPLORATION

     9-1   

PVDC Exploration Programs

     9-1   

10 DRILLING

     10-1   

Pre-PVDC Drilling

     10-5   

Evaluation of Drilling Programs

     10-8   

PVDC Drilling

     10-9   

11 SAMPLE PREPARATION, ANALYSES AND SECURITY

     11-1   

Sampling Strategy

     11-1   

Sample Preparation, Analyses, and Security

     11-2   

Quality Assurance and Quality Control

     11-8   

RPA Summary and Comments

     11-4   

12 DATA VERIFICATION

     12-1   

Pre-Placer Data

     12-1   

Verification of Pre-PVDC Data

     12-9   

 

 

Barrick Gold Corporation – Pueblo Viejo Project, Project # 1659    Rev. 0 Page i
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Drill Hole Database Validation

     12-13   

Summary

     12-13   

13 MINERAL PROCESSING AND METALLURGICAL TESTING

     13-1   

Introduction

     13-1   

Gold Deportment

     13-2   

Variation in Sulphur Grade

     13-3   

Relationship between Gold and Sulphur Grades

     13-3   

Metallurgical Studies Pre-Placer (before 2003)

     13-5   

14 MINERAL RESOURCE ESTIMATE

     14-1   

Introduction

     14-1   

Resource Database and Validation

     14-2   

Geological Interpretation and Domains

     14-3   

Data Analysis

     14-8   

Grade Capping

     14-10   

Compositing

     14-12   

Variography

     14-12   

Bulk Density

     14-13   

Cut-off Grade

     14-14   

Block Model

     14-14   

Use of Indicators for Grade Shells

     14-15   

Grade Interpolation

     14-15   

Resource Classification

     14-20   

Block Model Validation

     14-21   

Mineral Resource Summary

     14-25   

Mineral Resource Reconciliation

     14-27   

Conclusions

     14-27   

15 MINERAL RESERVE ESTIMATE

     15-1   

16 MINING METHODS

     16-1   

Summary

     16-1   

Open Pit Optimization

     16-3   

Mine Design Factors

     16-11   

Mine Production and Total Materials Handling Schedule

     16-15   

Mine Life and Material Movement

     16-21   

Mine Equipment

     16-26   

17 RECOVERY METHODS

     17-1   

Process Plant Description

     17-1   

Limestone and Lime Plant Description

     17-13   

18 PROJECT INFRASTRUCTURE

     18-1   

19 MARKET STUDIES AND CONTRACTS

     19-1   

Markets

     19-1   

Contracts

     19-1   

20 ENVIRONMENTAL STUDIES, PERMITTING, AND SOCIAL OR COMMUNITY IMPACT

     20-1   

 

 

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Environmental Legacy

     20-1   

Environmental Studies

     20-2   

Project Permitting

     20-5   

Social or Community Requirements

     20-7   

Water and Waste Management

     20-7   

Mine Closure Requirements

     20-10   

21 CAPITAL AND OPERATING COSTS

     21-1   

22 ECONOMIC ANALYSIS

     22-1   

23 ADJACENT PROPERTIES

     23-1   

24 OTHER RELEVANT DATA AND INFORMATION

     24-1   

25 INTERPRETATION AND CONCLUSIONS

     25-1   

Geology and Mineral Resources

     25-1   

Mining and Mineral Reserves

     25-1   

Mineral Processing and Metallurical Testing

     25-2   

26 RECOMMENDATIONS

     26-1   

Geology and Mineral Resources

     26-1   

Mining and Mineral Reserves

     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 Summary of Mineral Resources – December 31, 2011

     1-2   

Table 1-2 Pueblo Viejo Mineral Reserves – December 31, 2011

     1-2   

Table 1-3 Pueblo Viejo Cash Flow Summary

     1-6   

Table 1-4 Sensitivity Analysis

     1-9   

Table 1-5 NPI Sensitivity to Gold, Silver and Copper Prices

     1-10   

Table 1-6 Construction Capital Forecast at Completion

     1-27   

Table 1-7 LOM Capital Cost Estimate

     1-27   

Table 1-8 Operating Cost Summary

     1-28   

Table 6-1 Previous Mineral Reserve Estimates

     6-5   

Table 7-1 Mineralogically Determined Deportment of Gold

     7-15   

Table 10-1 Pre-PVDC Drilling

     10-2   

Table 11-1 Sample Interval Data for Rosario, GENEL JV and MIM Drill Holes

     11-2   

Table 11-2 ALS Analytical Protocols for Placer Samples

     11-5   

Table 12-1 Twin Hole Data in AMEC (2005)

     12-4   

Table 12-2 Types of Drill Hole “Twins”

     12-6   

Table 12-3 Placer 2005 “Twin” Holes

     12-7   

Table 12-4 Twin Hole Results

     12-8   

Table 13-1 Metallurgical Block Model Codes

     13-2   

Table 13-2 Summary of Metallurgical Test Programs

     13-6   

 

 

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Table 13-3 Comminution Testwork

     13-8   

Table 14-1 Summary of Mineral Resources – December 31, 2011

     14-1   

Table 14-2 Lithostructural Domains

     14-4   

Table 14-3 Raw Assay Statistics

     14-9   

Table 14-4 RPA Assay Statistics

     14-10   

Table 14-5 Assay Capping Statistics

     14-11   

Table 14-6 Bulk Density

     14-13   

Table 14-7 Block Model Geometry

     14-14   

Table 14-8 Estimation Parameters for Gold Indicators

     14-17   

Table 14-9 Parameters for Gold Grade Estimates

     14-18   

Table 14-10 Block Model Comparison

     14-21   

Table 14-11 Summary of Mineral Resources – EOY2011

     14-25   

Table 14-12 Zinc Mineral Resources – EOY2011

     14-26   

Table 15-1 Pueblo Viejo Mineral Reserves – December 31, 2011

     15-1   

Table 16-1 Metal and Commodity Prices Used for Pit Optimization

     16-4   

Table 16-2 Mining and Processing Costs Used for Pit Optimization

     16-5   

Table 16-3 Smelting and Refining Costs and Payable Metals Used for Pit Optimization

     16-5   

Table 16-4 Pueblo Viejo Pit Optimization – Total Tonnages per Pit Shell

     16-7   

Table 16-5 Pueblo Viejo Base Case and Sensitivities

     16-8   

Table 16-6 Pueblo Viejo Pit Optimization – Comparison between the Final Pit Design and Pit Shell 19

     16-11   

Table 16-7 IRA and BFA for Sediments, Pyroclastic Rocks and Lavas

     16-14   

Table 16-8 Project Limestone Requirements

     16-25   

Table 16-9 Open Pit Mobile Equipment

     16-27   

Table 16-10 Total Mine Labour per Period

     16-28   

Table 17-1 Limestone and Lime Plant Design Basis

     17-13   

Table 21-1 Construction Capital Cost Estimate

     21-2   

Table 21-2 2012 Life of Mine Capital Cost Estimate by Year

     21-2   

Table 21-3 Actual Operating Costs – for 2011

     21-4   

Table 21-4 Average LOM Operating Cost

     21-4   

Table 22-1 Pueblo Viejo Cash Flow Summary

     22-2   

Table 22-2 Sensitivity Analysis

     22-8   

Table 22-3 NPI Sensitivity to Gold, Silver and Copper Prices

     22-9   

LIST OF FIGURES

 

     PAGE  

Figure 1-1 Pueblo Viejo Sensitivity Analysis

     1-8   

Figure 1-2 NPI Sensitivity to Gold Price

     1-10   

Figure 4-1 Location Map

     4-2   

Figure 4-2 Montenegro Fiscal Reserve

     4-3   

Figure 7-1 Regional Geology

     7-2   

Figure 7-2 Property Geology

     7-4   

Figure 7-3 Stratgraphic Column

     7-5   

Figure 7-4 Local Structures and Lithology

     7-6   

Figure 7-5 Plan View of Main Structures

     7-9   

Figure 7-6 Plan View of Alteration Assemblages

     7-11   

Figure 10-1 Drill Hole Locations – Moore Deposit

     10-3   

 

 

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Figure 10-2 Drill Hole Locations – Monte Negro Deposit

     10-4   

Figure 11-1 PVDC Sample Preparation Procedure

     11-7   

Figure 11-2 Standard Reference Material Charts

     11-12   

Figure 11-3 Field Duplicate Charts

     11-2   

Figure 11-4 Blank Sample Charts

     11-3   

Figure 12-1 AMEC Drill Hole Comparison

     12-2   

Figure 12-2 Frequency Distribution of Gold by Drilling Campaign: All Drill Holes vs. PVDC Drill Holes

     12-11   

Figure 12-3 Frequency Distribution of Gold by Drilling Campaign: All Drill Holes vs. Placer Rotary Holes

     12-12   

Figure 13-1 Relationship between Sulphur and Gold Grades

     13-4   

Figure 13-2 Relationship between Gold to Sulphur Ratio and Gold Grade

     13-5   

Figure 13-3 Effect of Gold Head Grade on Gold Recovery

     13-10   

Figure 13-4 Effect of Temperature on CIL Silver Extraction from Lime Boil Plant Operation

     13-12   

Figure 13-5 Relationship between Gold Recovery and Organic Carbon Content

     13-13   

Figure 14-1 Main Geological Areas

     14-6   

Figure 14-2 Isometric View of Block Models

     14-7   

Figure 14-3 Omni-directional Correlogram for Gold

     14-13   

Figure 14-4 Cross Section – Monte Negro Deposit

     14-22   

Figure 14-5 Cross Section – Moore Deposit

     14-23   

Figure 14-6 Composite and Block Grade Distribution

     14-24   

Figure 16-1 Sensitivity of Recovered Gold to Various Parameters

     16-8   

Figure 16-2 Final Pit Design Based on Pit Shell 19

     16-10   

Figure 16-3 Plant Daily Ore Treatment Capacity as Function of S Content

     16-12   

Figure 16-4 Sulphur Grade Decay Model for Ore in Stockpiles

     16-13   

Figure 16-5 Ore Stockpile Locations

     16-18   

Figure 16-6 Mine Yearly ROM

     16-21   

Figure 16-7 Mine Annual Movement

     16-22   

Figure 16-8 Proportion of Ore to Crusher Direct from Mine and from Stockpiles

     16-24   

Figure 17-1 Process Flow Sheet

     17-3   

Figure 22-1 Pueblo Viejo Sensitivity Analysis

     22-7   

Figure 22-2 NPI Sensitivity to Gold Price

     22-9   

 

 

Barrick Gold Corporation – Pueblo Viejo Project, Project # 1659    Rev. 0 Page v
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1 SUMMARY

EXECUTIVE SUMMARY

Roscoe Postle Associates Inc. (RPA) was retained by Barrick Gold Corporation (Barrick) to prepare an independent Technical Report on the Pueblo Viejo Project (the Project) located in the Dominican Republic. The purpose of this report is to support disclosure of the Mineral Resources and Mineral Reserves for the Project as of December 31, 2011. This Technical Report conforms to NI 43-101 Standards of Disclosure for Mineral Projects. RPA visited the Project on March 14 to 17, 2011.

Barrick is a Canadian publicly traded mining company with a portfolio of operating mines and projects across five continents. Pueblo Viejo, a precious and base metal deposit, is located in the central part of the Dominican Republic on the Caribbean island of Hispaniola in the province of Sanchez Ramirez. The Project is 15 km west of the provincial capital of Cotuí and approximately 100 km northwest of the national capital of Santo Domingo. Barrick controls 60% of the mineral rights to the Pueblo Viejo deposit and Goldcorp Inc. (Goldcorp) holds the remaining 40%. Pueblo Viejo Dominicana Corporation (PVDC) is the operating company for the joint venture partners.

The Pueblo Viejo Project comprises development of a 24,000 tpd mining and processing facility. The mine will consist of two open pits, Moore and Monte Negro, and will be mined by conventional truck and shovel method. The mine life will be 18 years, with total material movement of approximately 47 Mtpa. Lower grade ore will be stockpiled for later processing, resulting in a forecasted processing life of the Project of 36 years.

Table 1-1 summarizes the Pueblo Viejo Mineral Resources exclusive of Mineral Reserves as of December 31, 2011.

 

 

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TABLE 1-1 SUMMARY OF MINERAL RESOURCES – DECEMBER 31, 2011

Barrick Gold Corporation – Pueblo Viejo Project

 

     Tonnage
(Mt)
            Grade
(g/t  Ag)
            Contained Metal  

Category

      (g/t Au)         (% Cu)      Gold
(Moz Au)
     Silver
(Moz Ag)
     Copper
(Mlb)
 

Measured

     3.47            12.53         0.12         0.24         1.40         9.17   

Indicated

     178.26         1.88         10.39         0.08         10.76         59.54         330.52   
  

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

    

 

 

 

Total M + I

     181.73         1.88         10.43         0.08         10.99         60.94         339.70   

Barrick (60%)

     109.04         1.88         10.43         0.08         6.60         36.56         203.82   

Goldcorp (40%)

     72.69         1.88         10.43         0.08         4.40         24.37         135.88   

Inferred

     22.6         1.6         12.8         0.08         1.17         9.3         38.4   

Barrick (60%)

     13.6         1.6         12.8         0.08         0.70         5.6         23.0   

Goldcorp (40%)

     9.1         1.6         12.8         0.08         0.47         3.7         15.4   

Notes:

 

  1. CIM definitions were followed for Mineral Resources.

 

  2. Mineral Resources are estimated at a break-even cut-off grade that equates to between 1.3 g/t Au and 1.4 g/t Au.

 

  3. Mineral Resources are estimated using a long-term price of US$1,400/oz Au, US$28.00/oz Ag, and US$3.25/lb copper.

 

  4. There are also zinc resources that have not been converted to Mineral Reserves.

 

  5. A minimum mining width (block size) of 10 m was used.

 

  6. Mineral Resources are exclusive of resources converted to Mineral Reserves.

 

  7. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

 

  8. Numbers may not add due to rounding.

Proven and Probable Mineral Reserves for the Project, contained in the Moore and Monte Negro pits, are listed in Table 1-2.

TABLE 1-2 PUEBLO VIEJO MINERAL RESERVES – DECEMBER 31, 2011

Barrick Gold Corporation – Pueblo Viejo Project

 

Area/Category    Tonnage
(Mt)
            Grade
(g/t  Ag)
            Contained Metal  
      (g/t Au)         (% Cu)      Gold
(M oz)
     Silver
(M oz)
     Copper
(M lb)
 

Monte Negro Pit

                    

Proven

     13.8         3.3         22.4         0.07         1.5         9.9         20.5   

Probable

     91.3         2.6         16.1         0.07         7.5         47.1         144.3   

Sub-total Monte Negro

     105.1         2.7         16.9         0.07         9.0         57.1         164.8   

Moore Pit

                    

Proven

     10.6         3.1         24.0         0.14         1.1         8.2         31.5   

Probable

     157.9         2.7         16.3         0.11         13.8         82.8         382.4   

Sub-total Moore

     168.4         2.8         16.8         0.11         14.9         91.0         413.9   

Sub-total Stockpiles

     11.8         3.6         32.0         0.05         1.4         12.1         11.8   

 

 

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Area/Category    Tonnage
(Mt)
            Grade
(g/t  Ag)
            Contained Metal  
      (g/t Au)         (% Cu)      Gold
(M oz)
     Silver
(M oz)
     Copper
(M lb)
 

Totals

                    

Proven

     36.2         3.4         26.0         0.08         3.9         30.2         63.8   

Probable

     249.2         2.7         16.2         0.10         21.4         129.9         526.7   

Proven + Probable

     285.4         2.8         17.5         0.09         25.3         160.2         590.5   

Barrick (60%)

     171.2         2.8         17.5         0.09         15.2         96.1         354.3   

Goldcorp (40%)

     114.2         2.8         17.5         0.09         10.1         64.1         236.2   

Notes:

 

  1. CIM definitions were followed for Mineral Reserves.

 

  2. No cut-off grade is applied. Instead, the profit of each block in the Mineral Resource is calculated and included in the reserve if the value is positive.

 

  3. Mineral Reserves are estimated using an average long-term gold price of US$1,200 per ounce.

 

  4. Totals may not add due to rounding.

CONCLUSIONS

Based on RPA’s site visit, interviews with Pueblo Viejo personnel, and subsequent review of gathered information, RPA offers the following conclusions:

GEOLOGY AND MINERAL RESOURCES

 

   

The Pueblo Viejo deposits are high sulphidation, quartz-alunite epithermal gold and silver deposits.

 

   

The sampling, sample preparation, analyses, and sample security are appropriate for the style of mineralization and Mineral Resource estimation.

 

   

The end of year (EOY2011) Mineral Resource estimates are competently completed to industry standards using reasonable and appropriate parameters and are acceptable for use in Mineral Reserve estimation. The resource estimates conform to NI 43-101.

 

   

Mineral Resources are reported exclusive of Mineral Reserves and are estimated effective December 31, 2011.

 

   

On a 100% basis, Measured plus Indicated Mineral Resources total 181.73 Mt, grading 1.88 g/t Au, 10.43 g/t Ag, and 0.08% Cu, containing 11.0 Moz Au, 60.9 Moz Ag, and 340 Mlbs Cu.

 

   

On a 100% basis, Inferred Mineral Resources total 22.6 Mt, grading 1.6 g/t Au, 12.8 g/t Ag, and 0.08% Cu, containing 1.2 Moz Au, 9.3 Moz Ag, and 38.4 Mlb Cu.

MINING AND MINERAL RESERVES

   

On a 100% basis, open pit Proven and Probable Mineral Reserves total 285.4 million tons grading 2.8 g/t Au, 17.5 g/t Ag, and 0.09% Cu containing 25.3 million oz Au, 160.2 million oz Ag, and 590.5 million pounds Cu.

 

 

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The Pueblo Viejo Mineral Reserves stated for the EOY2011 meet Canadian NI 43-101 requirements to be classified as Mineral Reserves.

 

   

Mining planning for the Pueblo Viejo open pit mine follows industry standards.

 

   

In RPA’s opinion, the methodology used by PVDC for pit limit determination, cut-off grade optimization, production sequence and scheduling, and estimation of equipment/manpower requirements is in line with good industry practice.

MINERAL PROCESSING AND METALLURICAL TESTING

 

   

RPA is of the opinion that the metallurgical testwork is adequate to support the Project and that the recovery models are reasonable.

RECOMMENDATIONS

RPA recommends that:

GEOLOGY AND MINERAL RESOURCES

 

   

The Measured classification be defined by 40% to 50% of the variogram sill and requires at least one composite from two drill holes.

MINING AND MINERAL RESERVES

 

   

Sulphur grades be reported in the LOM and sulphur received in the processing plant be reconciled with reserve sulphur grades. Monitor the effectiveness of the sulphur decay in the stockpiles and adjust stockpile design if the required rate of decay is not achieved.

ECONOMIC ANALYSIS

RPA was provided with the December 2011 updated individual production plans, capital forecasts, manpower forecasts, and operating cost forecasts for the Pueblo Viejo open pit. The LOM plan for the open pit provides for mining and processing through to 2047.

The Net Present Value (NPV) for Pueblo Viejo is based on revenue and costs from the open pit between 2012 and 2047. A discount rate of 5% has been used by Barrick. In RPA’s opinion, this is a low rate for a developing project.

From the information provided RPA prepared a pre-tax cash flow analysis, which is presented in Table 1-3. A summary of the key criteria is provided below.

ECONOMIC CRITERIA

REVENUE

   

Average 15.4 M tpa mined from 2012 to 2029 in Monte Negro and Moore pits sent to process plant and stockpiles.

 

 

Barrick Gold Corporation – Pueblo Viejo Project, Project # 1659    Rev. 0 Page 1-4
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8.8 M tpa process plant feed from 2012 to 2047.

 

   

All ore to plant supplied from stockpiles after 2029.

 

   

Average gold head grade of 2.64 g/t and recovery of 92.1% for LOM.

 

   

Average gold head grade of 4.30 g/t between 2012 and 2019.

 

   

Average silver head grade of 16.6 g/t and recovery of 87.6%.

 

   

Average head grade of 0.10% Cu and recovery of 79.4%.

 

   

For the LOM, the gold price is $1,200 per ounce, silver is $20 per ounce, and copper is $2.75/lb.

 

   

Revenue is recognized at the time of production.

COSTS

   

Mine life from 2012 through to 2047, including closure.

 

   

Capital cost totals $5,730 million for the period 2012 to 2047, including $457 million to be committed before completion of construction and $1,367 million for sustaining capital.

 

   

Average operating cost over the mine life of $50.18 per tonne milled.

 

   

Royalty of 3.2% is payable to the Government of the Dominican Republic over revenues minus freight and refining charges.

 

   

Net Profit Interest (NPI) is 28.75% of net profits payable to the Government of the Dominican Republic, which is charged after the Project, including full construction capital, has achieved a 10% Internal Rate of Return (IRR). The NPI is discounted to 2008 dollars at a 10% discount rate.

 

   

Average cash cost (minus Ag and Cu revenue) of $467 per ounce Au.

 

   

Average capital cost of $246 per ounce.

 

   

Total production cost of $713 per ounce Au sold.

 

 

 

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TABLE 1-3 PUEBLO VIEJO CASH FLOW SUMMARY

 

 

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CASH FLOW AND PROJECT ECONOMICS

Considering the Pueblo Viejo Mine on a stand-alone basis, excluding sunk cost of $3.17 billion, the undiscounted pre-tax cash flow totals $10.1 billion over the mine life. The annual cash flow is positive in all years through the end of the mine production in 2041. The pre-tax NPV at a 5% discount rate starting in 2012 and excluding sunk cost is $4.2 billion and the IRR is 39%. Simple payback occurs in the second quarter of 2015, or 34 months from the start of production.

If full capital expenditure of $3.63 billion for construction is included, the cash flow drops to $7.3 billion, the pre-tax NPV at a 5% discount rate to $1.7 billion, the IRR to 9.1% and payback occurs near the midpoint of 2022.

The Total Cash Cost is $467 per ounce of gold, calculated by subtracting silver and copper revenue from the cash cost. The mine life capital unit cost is $246 per ounce of gold, for a Total Production Cost of $713 per ounce of gold. Average annual gold production during operation is 666,200 ounces per year.

RPA notes that the economic analysis confirms that the material classified as Mineral Reserves is supported by a positive economic analysis.

SENSITIVITY ANALYSIS

Project risks can be identified in both economic and non-economic terms. Key economic risks were examined by running cash flow sensitivities:

 

   

Metal prices, metallurgical recovery, and head grade

 

   

Operating costs (Total Direct Operating Cost)

 

   

Capital costs

The sensitivity of the NPV at 5% over the base case has been calculated for -20% to +20% variations. The revenue for gold is proportional to the product of price times head grade times metallurgical recovery. Therefore, the metal sensitivity is shown as a single item where the change in the variable is the combination of the changes to the price, metallurgical recovery, and head grade. The sensitivities for the base case are shown in Figure 1-1 and Table 1-4. The NPV is most sensitive to changes in gold, silver, and copper price/recovery followed by the operating costs and capital costs. The total cost of construction is not included in the sensitivity analysis, which explains the lack of sensitivity to capital costs.

 

 

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The 28.75% NPI is highly sensitive to revenue and therefore the metal prices. Below $1,300/oz of gold, no NPI is payable. The effect of increasing metal prices on the NPI can be seen in Figure 1-2 and Table 1-5.

FIGURE 1-1 PUEBLO VIEJO SENSITIVITY ANALYSIS

 

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TABLE 1-4 SENSITIVITY ANALYSIS

Barrick Gold Corporation – Pueblo Viejo Project

 

Sensitivity to Gold, Silver and Cu prices

     Gold Price    Cashflow    NPV at 5%
     US$/Oz    US$ M    US$ M

-20%

   960    3,900    972

-10%

   1,080    7,006    2,574

0%

   1,200    10,111    4,175

10%

   1,320    12,556    5,643

20%

   1,440    13,929    6,655

Sensitivity to Operating Cost

     Cost/tonne    Cashflow    NPV at 5%
     US$    US$ M    US$ M

-20%

   40.14    13,109    5,662

-10%

   45.16    11,610    4,919

0%

   50.18    10,111    4,175

10%

   55.19    8,613    3,432

20%

   60.21    7,114    2,689
Sensitivity to Capital Cost
     Capex    Cashflow    NPV at 5%
     US$M    US$ M    US$ M

-20%

   3,667    11,257    5,035

-10%

   4,641    10,684    4,605

0%

   5,730    10,111    4,175

10%

   6,933    9,538    3,745

20%

   8,251    8,965    3,315
  

 

  

 

  

 

 

 

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FIGURE 1-2 NPI SENSITIVITY TO GOLD PRICE

 

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TABLE 1-5 NPI SENSITIVITY TO GOLD, SILVER AND COPPER PRICES

Barrick Gold Corporation – Pueblo Viejo Project

 

000000 000000 000000 000000
     Gold Price    NPI    Cashflow    NPV at 5%
     US$/oz    US$ M    US$ M    US$ M

-20%

   960       3,900    972

-10%

   1,080       7,006    2,574

0%

   1,200       10,111    4,175

10%

   1,320    661    12,556    5,643

20%

   1,440    2,394    13,929    6,655

30%

   1,560    3,326    16,102    7,816

40%

   1,680    4,170    18,363    8,985

50%

   1,800    4,916    20,723    10,208

TECHNICAL SUMMARY

PROPERTY LOCATION AND LAND TENURE

The Pueblo Viejo site is located in the central part of the Dominican Republic on the Caribbean island of Hispaniola in the province of Sanchez Ramirez. The Project is 15 km west of the provincial capital of Cotuí and approximately 100 km northwest of the national capital of Santo Domingo.

The Pueblo Viejo property, situated on the Montenegro Fiscal Reserve (MFR), is centred at 19°02' N, 70°08' W in an area of moderately hilly topography. The MFR covers an area of 4,880 ha and encompasses all of the areas previously included in the Pueblo Viejo and Pueblo Viejo II concession areas, which were owned by Rosario Dominicana S.A. (Rosario) until March 7, 2002, as well as the El Llagal area.

 

 

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Placer Dome Inc. (Placer), through PVDC, acquired the Project in July 2001. PVDC is the holder of a lease right to the MFR by virtue of a Special Lease Agreement of Mining Rights (SLA). In March     , 2002, the Dominican state created the MFR with an area of 3,200 ha. The SLA was ratified by the Dominican National Congress and became effective in 2003. On August 3, 2004, the Dominican state modified the MFR to include El Llagal. In February 2006, Barrick acquired Placer and subsequently sold 40% of the Project to Goldcorp.

The SLA governs the development and operation of the Project and includes the right to exploit the Las Lagunas and Mejita Tailings impoundment facilities and the Hatillo limestone deposit. The SLA will extend for 25 years following PVDC’s decision to develop a mine, with one extension by right for 25 years and a second 25 year extension at the mutual agreement of PVDC and the Dominican state, allowing a possible total term of 75 years.

PVDC shall make Net Smelter Royalty (NSR) payments to the Dominican state of 3.2% of net receipts of sales, make an NPI payment (with a rate that varies with the price of gold) after PVDC has recaptured its initial and ongoing investments, and pay income tax under a stabilized tax regime.

In November 2009, amendments to the Project SLA were ratified which set out revised fiscal terms and clarified various administrative and operational matters to the mutual benefit of the state and PVDC. Barrick issued a statement on November 16, 2010, confirming amendments had been approved on the Project, including fiscal adjustments.

EXISTING INFRASTRUCTURE

The Project is located approximately 100 km northwest of Santo Domingo, the capital of the Dominican Republic, which is the principal source of supply for the mine. It is a port city with a population of over three million with daily air service to the USA and other countries.

 

 

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The main road from Santo Domingo to within about 22 km of the mine site is a surfaced, four-lane, divided highway, which is generally in good condition. Access from the divided highway to the site is via a two-lane, surfaced road. Gravel surfaced, internal access roads provide access to the mine site facilities.

In order to transport the autoclaves, which weigh over 700 tonnes each, upgrades to a north coast road were completed so that this road could be used instead of the route from Santo Domingo. Upgrading included road and bridge improvements, clearing of overhead obstructions, erosion control, bypass route construction, clearing utility interferences, and work permitting.

As well as the existing access roads, current site infrastructure includes accommodation, offices, truck shop, medical clinic and other buildings, water supply, and old tailings impoundments with some water treatment facilities. Upgrades and renovations will be performed on some of these facilities.

A tailings storage facility (TSF) is under construction in the El Llagal valley approximately 3.5 km south of the plant site and consists of two rockfill dams with saprolite cores.

PVDC will supply power for permanent operations from a new power plant that it is building near San Pedro de Macoris on the south shore of the Dominican Republic. The output will be 215 MW. The plant will operate on heavy fuel oil (HFO) and will be connected to the mine by 110 km of private transmission line that is being constructed by PVDC. The power supply for permanent operations will be completed in 2013. Currently, on-site generation supplies 13 MW, sufficient for pre-commissioning, which has been supplemented by an additional 30 MW of power generated on-site for commissioning.

HISTORY

The earliest records of Spanish mine workings at Pueblo Viejo are from 1505. The Spanish mined the deposit until 1525, when the mine was abandoned in favour of newly discovered deposits on the American mainland. There are few records of activity at Pueblo Viejo from 1525 to 1950, when the Dominican government sponsored geological mapping in the region.

 

 

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Rosario Resources Corporation of New York (Rosario) optioned the property in 1969 and completed drilling, which resulted in an oxide deposit of significant tonnage. Open pit mining of the oxide resources commenced on the Moore deposit in 1975, and in 1980 Rosario merged into AMAX Inc. (Amax).

Rosario continued exploration throughout the 1970s and early 1980s, and the Monte Negro, Mejita, and Cumba deposits were identified by soil sampling and percussion drilling and were put into production in the 1980s.

With the oxide resources diminishing, Rosario initiated studies on the underlying refractory sulphide resource in an effort to continue the operation. Feasibility level studies were conducted by Fluor Engineers Inc. in 1986 and Stone & Webster Engineering/American Mine Services in 1992.

Rosario continued to mine the oxide material until approximately 1991, when the oxide resource was essentially exhausted. Mining in the Moore deposit stopped early in the 1990s owing to high copper content (which resulted in high cyanide consumption) and ore hardness. Mining in the Monte Negro deposit ceased in 1998, and stockpile mining continued until July 1999, when the operation was shut down. In 24 years of production, the Pueblo Viejo Mine produced a total of 5.5 million ounces of gold and 25.2 million ounces of silver.

Lacking funds and technology to process the sulphide ore, Rosario attempted to joint venture the property in 1992 and again in 1996. Three companies were involved in the privatization process: GENEL JV, Mount Isa Mines Ltd. (MIM), and Newmont Mining Corporation (Newmont). This privatization was not achieved, but each of the three companies conducted work on the property during their evaluations.

In 1996 and 1999, the GENEL JV completed diamond drilling, developing a new geological model, mining studies, evaluation of refractory ore milling technologies, socio-economic evaluation, and financial analysis. In 1997, MIM conducted a 31 hole, 4,600 m diamond drilling program, collected a metallurgical sample from drill core, carried out detailed pit mapping, completed induced polarization (IP) geophysical surveys over the known deposits, and organized aerial photography over the mining concessions to create a surface topography. MIM also proposed to carry out a pilot plant and feasibility

 

 

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study using ultra-fine grinding/ferric sulphate leaching. In 1992 and 1996, Newmont proposed to carry out a pilot plant and feasibility study for ore roasting/bio-oxidation. Samples were collected for analysis, but no results are available.

Between 2002 and mid-2005, Placer Dome Dominicana Corporation, a subsidiary of Placer Dome Inc. (together Placer), completed extensive work on Pueblo Viejo including drilling, geological studies, and mineral resource/reserve estimation. This work was compiled in a Feasibility Study completed in July 2005.

In addition to drilling programs in 2002 and 2004, Placer conducted structural pit mapping of the Moore and Monte Negro open pits in 2002. Placer also mapped and sampled a 105 km2 area around the concessions as part of an ongoing environmental baseline study to identify acid rock drainage (ARD) sources outside the main deposit areas. Part of the regional mapping and sampling program focused on evaluating the potential for mineralization in the proposed El Llagal tailings storage area.

GEOLOGY AND MINERALIZATION

Pueblo Viejo is hosted by the Lower Cretaceous Los Ranchos Formation, a series of volcanic and volcaniclastic rocks that extend across the eastern half of the Dominican Republic. The Los Ranchos Formation consists of a lower complex of pillowed basalt, basaltic andesite flows, dacitic flows, tuffs and intrusions, overlain by volcaniclastic sedimentary rocks and interpreted to be a Lower Cretaceous intra-oceanic island arc. The unit has undergone extensive seawater metamorphism (spilitization) and lithologies have been referred to as spilite (basaltic-andesite) and keratophyre (dacite).

The Pueblo Viejo Member of the Los Ranchos Formation is confined to a restricted, sedimentary basin measuring approximately three kilometres north-south by two kilometres east-west. The basin is interpreted to be either due to volcanic dome collapse forming a lake, or a maar-diatreme complex that cut through lower members of the Los Ranchos Formation. The basin is filled with lacustrine deposits that range from coarse conglomerate deposited at the edge of the basin to thinly bedded carbonaceous sandstone, siltstone, and mudstone deposited further from the paleo-shoreline.

The Moore deposit is located at the eastern margin of the Pueblo Viejo Member sedimentary basin. Stratigraphy consists of finely bedded carbonaceous siltstone and

 

 

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mudstone (Puerto Viejo sediments) overlying horizons of spilite (basaltic-andesite flows), volcanic sandstone, and fragmental volcaniclastic rocks. The entire sequence in the Moore deposit area has a shallow dip to the west. The numerous north-northeast and north-northwest faults in the area are associated with an intense cleavage and bedding-parallel quartz veins with gold mineralization.

The Monte Negro deposit is located at the northwestern margin of the sedimentary basin. Stratigraphy consists of interbedded carbonaceous sediments ranging from siltstone to conglomerate, interlayered with volcaniclastic flows. These volcaniclastic flows become thicker and more abundant towards the west. This entire sequence has been grouped as the Monte Negro Sediments. In the eastern part of the Monte Negro deposit area, the bedding dip is shallow to the southwest; in the west, the dip is shallow to the northwest. Numerous dikes barren of mineralization intrude the Monte Negro stratigraphy. A steep north-northwest trending fault (Monte Negro Fault) with a west-side-up sense of movement is interpreted to separate the sediments in the east from the volcanic rocks in the west and has been a focus for silicification, breccia dyke emplacement, and mineralization.

The Pueblo Viejo deposits have undergone typical high sulphidation, zoned alteration characterized by silica, pyrophyllite, pyrite, kaolinite, and alunite. Silica is predominant in the core of the alteration envelope and occurs with kaolinite in the upper zones where a silica cap is often formed. Unlike typical high sulphidation deposits where silicic alteration is residual and a result of acid leaching, silicification at Pueblo Viejo represents silica introduction and replacement. Silica enriched zones are surrounded by a halo of quartz-pyrophyllite and pyrophyllite alteration.

The Pueblo Viejo mineralization is predominantly pyrite, with lesser amounts of sphalerite and enargite. Pyrite mineralization occurs as disseminations, layers, replacements, and veins. Sphalerite and enargite mineralization is primarily in veins, but disseminated sphalerite has been noted in core.

Gold is intimately associated with pyrite veins, disseminations, replacements, and layers within the zones of advanced argillic alteration. Gold occurs as native gold, sylvanite (AuAgTe4), and aurostibnite (AuSb2). The principal carrier of gold is pyrite where the sub-microscopic gold occurs in colloidal-size micro inclusions (less than 0.5 µm) and as a solid solution within the crystal structure of the pyrite.

 

 

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Assay results for silver demonstrate that it has the strongest correlation with gold. In particular, silver has a strong association with Stage III sulphide veins where it occurs as native silver and in pyrargyrite (antimony sulphide), hessite (silver telluride), sylvanite and petzite (gold tellurides), and tetrahedrite.

The majority of the zinc occurs as sphalerite, primarily in Stage III sulphide veins, and to a lesser extent as disseminations. The sphalerite is beige to orange coloured and is relatively iron-free. Sphalerite commonly contains inclusions and intergrowths of pyrite, sulphosalts, galena, and silicate gangue. The encapsulated pyrite is often host to sub-microscopic gold mineralization.

Most of the copper occurs as enargite hosted in Stage III sulphide veins. Only trace amounts of chalcocite and chalcopyrite have been documented. Enargite-rich vein zones typically are confined laterally and vertically within the larger sphalerite-rich vein zones.

EXPLORATION STATUS

In 2006, PVDC began to review the entire geological potential of the Project, using works performed by previous owners to develop an understanding of the geology of the deposit and its potential. The 2006 program included data compilation, rock sampling and pit mapping, alteration studies, geophysical and geochemical surveys, two-phase diamond drilling program (53 holes totalling approximately 14,000 m), and preparation of an updated mineral resource estimate. The 2006 program allowed better definition of deposit geology and significantly increased the amount of ounces in both the Moore and Monte Negro deposits.

A total of 67,127 m were drilled in 2007, primarily for definition drilling, condemnation, and limestone purposes. During 2008, PVDC completed 121 diamond drill holes for 28,067 m.

 

 

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In 2009, PVDC undertook a major relogging program of all historical drill core, carried out detailed geological mapping of pits and construction excavations, and reinterpreted the geological models underpinning resource and reserve estimates.

In 2010, PVDC continued the detailed in-pit and construction excavation geological mapping and also undertook a close-spaced, reverse circulation (RC) grade control drilling program for Phase 1 pit shells in the Moore and Monte Negro open pits. This drilling comprised 1,120 holes for 38,485 m in Monte Negro and 593 holes for 22,026 m in Moore. In-fill RC drilling of 33 holes for 5,306 m was also carried out within the limestone resource areas.

PVDC continued close-spaced RC grade control drilling program for Phase 1 pit shells in the Moore and Monte Negro pits. A total of 22,876 m were completed in 2011.

MINERAL RESOURCES

The EOY2011 Mineral Resources were estimated by conventional 3D computer block modelling based on surface drilling and assaying. Geologic interpretation of the drilling data was carried out and wireframes were constructed for resource estimation based on major geological areas, lithology, alteration, oxidation boundary, and a grade indicator to define broad grade shells. The three main geological areas are Monte Negro, Moore, and Cumba. Statistical analysis of assay data was carried out to determine grade capping levels and metal losses for each domain. Variography using 10 m composites was completed to determine search parameters and inverse distance to the third power was employed for gold, silver, and sulphur grade interpolation in the block model. Copper grades were interpolated using ordinary kriging and inverse distance to the second power. The resource model was classified using a combination of estimation pass number, number of composites used to assign the block grade, and the distance to nearest composite. PVDC visually validates the block model gold grades against drill holes and composites in section and plan view. Grades are also compared against the nearest neighbour (composite) gold grades and a histogram of the original composite distribution is compared to the block gold grade estimate.

RPA examined the EOY2011 Mineral Resources as reported in Table 1-1 in detail and found them to meet or exceed industry standards. The EOY2011 Mineral Resources are based on the same block models but have been estimated using higher metal prices.

 

 

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The Mineral Resources are exclusive of Mineral Reserves and could not be converted to Mineral Reserves due to operational constraints or economics (i.e., Measured and Indicated Mineral Resources), or an insufficient level of confidence (i.e., Inferred Mineral Resources).

In RPA’s opinion, the EOY2011 Mineral Resource estimates are competently completed to industry standards using reasonable and appropriate parameters and are acceptable for reserve work. The resource estimates conform to NI 43-101.

RPA is not aware of any environmental, permitting, legal, title, taxation, socio-economic, marketing, political, or other relevant factors which could materially affect the open pit mineral resource estimates.

MINERAL RESERVES

Mineral Reserves were estimated based on the value, or profit, calculated for each Mineral Resource block, which takes into account metal grade, sulphur content, time required for processing (higher sulphur means longer processing time and reduced daily plant capacity), processing plant recoveries, and costs in determining the value of a given block.

To further optimize the block value, a Ranking Index (profit/hr) was applied to each block of the Mineral Resource model. Measured and Indicated Resource blocks were treated as potential mill feed, while Inferred Resource and unclassified blocks were treated as waste and were assigned a Ranking Index of zero.

RPA reviewed the reported Mineral Reserves, production schedules, and cash flow analysis to determine if the Mineral Reserves met the CIM Definition Standards for Mineral Resources and Mineral Reserves. Based on this review, it is RPA’s opinion that the Measured and Indicated Mineral Resource within the final pit design at Pueblo Viejo can be classified as Proven and Probable Mineral Reserves.

MINING

Pueblo Viejo will be a conventional truck and shovel operation. The Mineral Reserves are contained in two pits, Monte Negro and Moore. The operation is designed for processing 24,000 tpd and mining approximately 100,000 tpd ROM total material (excluding rehandle).

 

 

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Until first ore is processed, all run-of-mine (ROM) ore will be stockpiled in three locations, for high grade, medium grade, and low grade material. By the start of the plant feed in July 2012, the total ore on stockpile is scheduled to be 21 Mt. Total ore on stockpiles will reach a maximum of approximately 152 Mt in 2029.

The initial pre-stripping requirement is very low as previous mining has left ore outcropping on surface. The waste to ore ratio is 1:0.98 but increases to 1.19:1, i.e., by 21%, in the final pit design. This indicates that the final pit design is sub-optimal and there is scope to further optimize the pit design and improve the economics of the Project.

The pit stages have been chosen to facilitate the early extraction of the higher grade ore. Elevated initial cut-off grades have been used for this purpose. Notwithstanding, the driver of the mine schedule will be the sulphur blending requirement. This variable is as important as the gold grade, because the metallurgical aspects of the processing operation, the recoveries achieved, and the processing costs all strongly depend on a very stable, low-variability sulphur content in the plant feed.

All waste rock from the Moore and Monte Negro pits will be hauled to the El Llagal tailings area, with potential acid generating waste being submerged in the tailings facility. An eight kilometre haul road has been constructed to link the pit area to the TSF.

The processing method requires a significant amount of limestone slurry and lime derived from high quality limestone. Limestone quarries, located approximately two kilometres from the Project, have been in production since 2009.

Processing higher grade ore in the early years, while stockpiling lower grade ore for later processing, results in a mine life of 18 years and a processing life of 36 years. In years 2012 to 2029, total material movement, including limestone, averages approximately 47 Mtpa, and about 84%% of ROM ore is stockpiled for later processing.

 

 

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MINERAL PROCESSING

METALLURGY

The Pueblo Viejo ore is refractory and consists primarily of gold and silver intimately associated with pyrite that occurs as encapsulated sub-micron particles and in solid solution. As a result, there is a requirement to chemically break down the pyrite to recover the precious metals. In addition, there are cyanide consuming minerals and preg-robbing carbonaceous material in some of the ores. Pyrite and sphalerite are the two main sulphide minerals, both occurring in veins and disseminated within the host rock.

Using lithological and mineralization criteria, five metallurgical ore types have been defined, including two for the Moore deposit and three for the Monte Negro deposit. The main criterion used to define metallurgical domains was carbon content, i.e., separating carbonaceous rocks from lower carbon-content rocks in each deposit.

In addition to the mineralogical examinations used to identify gold association in the various ore types, diagnostic leach procedures were also used. Test results showed that approximately 55% to 70% of the gold is encapsulated in sulphide minerals and is not recoverable by cyanide leaching without prior destruction of the sulphide matrix. For the two black sedimentary ore types, 19% to 29% of the gold in the ore was preg-robbed by gold adsorption onto organic carbon.

Metallurgical testwork indicated that pressure oxidation (POX) of the whole ore followed by CIL cyanidation of the autoclave product will recover 88% to 95% (average 91.6%) of the gold and 86% to 89% (average 87%) of the silver.

RPA is of the opinion that the metallurgical testwork is adequate to support the Project and that the recovery models are reasonable.

The efficient and trouble-free operation of the POX circuit relies heavily on maintaining relatively constant sulphur content in the autoclave feed. Studies showed that there are wide variations in the sulphur content of the ore as the blocks are mined sequentially. The variation in sulphur grade ranges from 3% to 20% sulphur and generally between 5% and 10%. Blending will be practiced by the mine through mine planning and blending of ores prior to crushing.

 

 

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PROCESSING PLANT

PDVC is currently building the processing plant as described in its December 2007 FSU. The process plant is designed to process 24,000 tpd of ore and will consist of the following unit operations:

 

   

Crushing

 

   

Semi-autogenous grinding (SAG) and ball milling

 

   

Pebble crushing

 

   

POX

 

   

Hot curing

 

   

Counter-current decantation (CCD) washing

 

   

Ferric precipitation

 

   

Copper recovery

 

   

Neutralization

 

   

Solution cooling

 

   

Lime boiling for silver enhancement

 

   

Slurry dilution and cooling

 

   

CIL circuit

 

   

Carbon acid washing, stripping and regeneration

 

   

Electrowinning

 

   

Refining

 

   

Cyanide destruction

 

   

Tailings disposal

 

   

Tailings effluent and ARD treatment

LIMESTONE AND LIME PLANT

Ground limestone and lime are required to neutralize acidic liquors and to control the pH in the CIL circuit. Lime is also used to adjust the pH of the effluent after water treatment. Satisfying the 24,000 tpd ore process requirement includes grinding 9,070 tpd of limestone to 80% passing 60 µm and calcining 2,785 tpd of limestone in vertical kilns to produce 1,484 tpd of lime. The proposed limestone plant will include primary crushing and screening, grinding, calcining, and lime slaking.

PROJECT INFRASTRUCTURE

Gravel surfaced, internal access roads provide access to the mine site facilities. A network of haul roads are being built to supplement existing roads so that mine trucks can haul ore, mine overburden, and limestone from the various quarries. As well as the existing access roads, current site infrastructure includes accommodation, offices, truck shop, medical clinic and other buildings, water supply, and old tailings impoundments with some water treatment facilities. Some of these facilities are being upgraded or renovated.

 

 

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The new process plant site will be protected by double and single fence systems. Within the plant site area, the freshwater system, potable water system, fire water system, sanitary sewage system, storm drains, and fuel lines will be buried underground. Process piping will typically be left above ground on pipe racks or in pipe corridors.

POWER SUPPLY

Power supply for the Project can be broken into two time periods: 1) start-up and initial operations; and 2) permanent operations. For start-up and initial operations, power will be supplied by 43 MW of onsite diesel generators with the balance being supplied from the national grid pursuant to a power purchase agreement from EGE Haina S.A., a major power generator in the Dominican Republic. PVDC owns the Monte Rio power plant, which has a rated output of 100 MW. The output of Monte Rio will be sold to EGE Haina to “firm” Haina’s deliveries to PVDC, with EGE Haina providing the balance of PVDC’s demand from other generators. The Project is connected to the national grid at a new substation built by PVDC near the town of Piedra Blanca. Power then is delivered to the Project though 26 km of private transmission line owned by PVDC.

Due to a deficit of power supply and reliability issues in the national system, PVDC will supply power for permanent operations from a new power plant that it is building near San Pedro de Macoris on the south shore of the Dominican Republic. The plant is a dual-fueled reciprocating engine plant that will operate in combined cycle. The output will be 215 MW. The plant will operate on HFO and will be connected to the mine by 110 km of private transmission line that is being constructed by PVDC. The power supply for permanent operations will be completed in 2013. Upon completion, the Project will be able to access power from its own plant as well as the national grid.

It is the opinion of RPA that the permanent plan and back-up plans for supplying power to the site are adequate, although successful implementation remains contingent on a number of factors, including granting all the necessary permits and also resolving current land claims and issues from local residents.

PROCESS CONTROL FACILITIES

The plant wide distributed control system (DCS) will use Ethernet communication links, fibre optics, Foundation Fieldbus for analogue devices, conventional controls for discrete devices, and radio-links for remote sites. Three main control rooms, 13 satellite control rooms, and three maintenance workstations will be located throughout the site.

 

 

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WATER SUPPLY

The Hatillo and Hondo reservoirs will supply fresh water to the site. Reclaimed water from the TSF sites will only be used as a supplementary water supply under drought and flood situations. Barge-mounted pumps at the larger Hatillo Reservoir will pump fresh water to the Hondo Reservoir for make-up purposes. Fresh water will then be pumped to a fresh water/fire water tank at the 400 m level and a freshwater pond, and from there will be distributed throughout the site for process, fire protection and potable needs. The potable water will be a treated system.

CONSTRUCTION

In order to build the Project, PVDC retained major Engineering, Procurement, and Construction Management (EPCM) organizations to oversee the detailed design, the procurement, and the construction management functions for the Project. Fluor Corporation (Fluor) is responsible for the execution of the whole plan, while Hatch Ltd. (Hatch) has been retained to look after the POX and oxygen plants. BGC Engineering has been directed to perform the detailed design of the TSF as well as to provide geotechnical engineering support for the Project. SNC-Lavalin was awarded the EPCM contract for the power plant and transmission line.

Most notably, PDVC made the initial decision to use a combined self-perform construction (direct hire) and construction management (CM) approach to build the Project, using a mix of local subcontractors and specialty contractors. A key consideration in this process was helping PDVC build strong relationships with the local community, authorities, and labour organizations.

In the opinion of RPA, PDVC has used an adequate construction execution strategy. The completion of the 230 kV transmission line is on the critical path and efforts must be devoted to ensure completion in a timely fashion.

 

 

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ENVIRONMENTAL, PERMITTING AND SOCIAL CONSIDERATIONS

ENVIRONMENTAL LEGACY

When the Rosario mine shut down in 1999, proper closure and reclamation was not undertaken. The result was a legacy of polluted soil and water and contaminated infrastructure.

Acid Rock Drainage (ARD) studies confirm that historic mining (prior to Placer Dome Inc.’s acquisition of the Project) and consequential ARD generation have severely impacted the surrounding area. ARD has developed from exposure of sulphides occurring in the existing pit walls, waste rock dumps, and stockpiles to air, water, and bacteria. Untreated and uncontrolled ARD has contaminated local streams and rivers and has led to deterioration of water quality and aquatic resources both on the mine site and offsite.

Under the SLA, environmental remediation within the mine site and its area of influence is the responsibility of PVDC, while the Dominican government is responsible for historic impacts outside the Project development area. However, agreement was reached in 2009 that PVDC would donate up to $37.5 million, or half of the government’s total estimated cost of $75 million, for its clean-up responsibilities. In December 2010, PVDC agreed to contribute the remaining $37.5 million on behalf of the government towards these clean-up activities.

ENVIRONMENTAL STUDIES

Background data and baseline information were collected on the existing biophysical and human environments from 2002 through 2007. The baseline studies covered the immediate project areas and also areas beyond the mine site. The studies included ARD, air quality, archaeology sites, aquatic biology, flora and fauna, bedrock geology, soil geochemistry, and surface drainage.

ARD studies confirm that historic mining (prior to Placer’s acquisition of the Project) and consequential ARD generation have severely impacted the surrounding area. Test results indicate that most of the exposed rock at the mine site is acidic and contains significant sulphide levels providing a source for additional acidity.

 

 

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PROJECT PERMITTING

As of January 2011, PVDC had obtained 62 permits required to operate a mine in the Dominican Republic and 53 remained outstanding. The full list of obligations arising from the various permits, licences, and agreements total some 4,600, of which 80% relate to the mine site and the remaining 20% relate mainly to the power transmission line and other aspects of power supply.

TAILINGS AND WASTE ROCK STORAGE FACILITY

Tailings and waste rock from mine development will be deposited in the El Llagal valley, a tributary of the Rio Maguaca. The El Llagal valley is being constructed to store tailings from the CIL circuit blended with sludge from the neutralization circuit and also waste rock from the open pits. Storage of tailings and waste rock under a permanent water cover will prevent the onset of ARD. The rock fill dams are being constructed with a compacted saprolite core to provide an impermeable barrier to seepage, and appropriate filter zones are being provided.

Design criteria for static and seismic stability meet the minimum safety factors for the high to very high consequence of failure classification as recommended by the Canadian Dam Association, Dam Safety Guidelines. Flood storage and spillway design have been developed based on extreme precipitation events.

Currently, the El Llagal TSF is the only one permitted and approved for construction. With respect to Mineral Reserve estimates, the current mine life is constrained by the TSF availability. Other potential TSF sites have been identified and negotiations are underway to obtain relevant permits.

MINE CLOSURE REQUIREMENTS

PVDC’s intent is to leave the site at closure with better water quality in the Margajita drainage system downstream than existed when the Project commenced. Freshwater diversions, ARD collection ditches, ARD collection ponds, and ARD pump stations will be required to remain in service during the post closure phase. These facilities will have to be maintained in good operating condition until water quality meets acceptable discharge criteria.

There is potential to submerge waste rock, tailings, and/or sludge in the pits after completion of mining.

 

 

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Seepage from the TSF will be required to be collected and pumped back to the impoundment until such time as the seepage meets acceptable standards for release to the environment. The water level in the TSF will be allowed to increase and the water will be allowed to flow over the emergency spillways once the water quality meets the discharge criteria.

BOND

The Environmental Licence requires a compliance bond of RD$635,250,000 (approximately US$16,400,000), corresponding to 10% of the cost of the Environmental Adjustment and Management Plan (PMAA) of the construction phase. Once the construction phase is completed, PVDC will provide a bond that corresponds to 10% of the amount of the updated PMAA defined for the operational phase. At the end of the operational phase, PVDC will provide the corresponding bond at 10% of the total amount of the PMAA for the closure and post closure phases.

As part of the SLA agreement, PVDC is required to create an Environmental Reserve Fund in an offshore escrow account funded at a rate equal to 5% of all operational costs, other than costs of concurrent rehabilitation, until the funds are adequate to discharge the closure reclamation obligations.

CAPITAL AND OPERATING COST ESTIMATES

Current Forecast to Completion capital costs for the Project are estimated to be $3.63 billion as shown in Table 1-6, of which $3.14 billion was committed at the end of December 2011.

 

 

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TABLE 1-6 CONSTRUCTION CAPITAL FORECAST AT COMPLETION

Barrick Gold Corporation – Pueblo Viejo Project

 

Capital Cost Category

   US$ million

Open Pit Mine

       222  

Ore Handling

       33  

Processing

       927  

Tailings & Water treatment facilities

       163  

On-Site Infrastructure

       427  

Off-Site Infrastructure

       357  

Owner’s Indirect Costs

       426  

Other Indirect Costs

       1,037  

Transfer to Operations

       (39 )

Forecast Update

       73  

Grand Total

       3,626  

The capital expenditure budget over the LOM amounts to $3.09 billion (Table 1-7).

TABLE 1-7 LOM CAPITAL COST ESTIMATE

Barrick Gold Corporation – Pueblo Viejo Project

 

Description

   US$ million

Construction Cost to Completion

       457  

Site Services – Power

       440  

Capitalized Waste Stripping

       344  

Sustaining Capital

       1,367  

Capitalized Interest

       212  

Closure Costs

       269  

Total

       3,089  

The total operating cost for mining, processing, and general and administrative expenses (G&A) is estimated to be approximately $14.5 billion over the mine life. Over the same time period, the average operating cost per tonne milled for Mining, Processing, and G&A is estimated to be $48.41 and cash cost is estimated to be $467 per ounce of gold (Table 1-8).

 

 

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TABLE 1-8 OPERATING COST SUMMARY

Barrick Gold Corporation – Pueblo Viejo Project

 

Area

   Value
(US$)

Mining Cost Per Tonne Milled

   5.92

Process Cost Per Tonne Milled

   36.82

G & A Cost Per Tonne Milled

   5.63

Total Operating Cost Per Tonne Milled

   48.41

Total Cash Cost Per Oz Au Sold

   467

RPA finds the currently projected Forecast to Completion costs, sustaining capital, and operating costs for the LOM to be reasonable.

 

 

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2 INTRODUCTION

Roscoe Postle Associates Inc. (RPA) was retained by Barrick Gold Corporation (Barrick) to prepare an independent Technical Report on the Pueblo Viejo Project (the Project) located in the Dominican Republic. The purpose of this report is to support disclosure of the Mineral Resources and Mineral Reserves for Project as of December 31, 2011. 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. Pueblo Viejo, a precious and base metal deposit, is located in the central part of the Dominican Republic on the Caribbean island of Hispaniola in the province of Sanchez Ramirez. The Project is 15 km west of the provincial capital of Cotuí and approximately 100 km northwest of the national capital of Santo Domingo. Barrick controls 60% of the mineral rights to the Pueblo Viejo deposit and Goldcorp Inc. (Goldcorp) holds the remaining 40%. Pueblo Viejo Dominicana Corporation (PVDC) is the operating company for the joint venture partners.

The primary source of information for this Technical Report is the existing Feasibility Study prepared by Barrick in 2007 (2007 Feasibility Study Update, or FSU) on the Project, the 2011 Pueblo Viejo Gold Project Technical Report by AMC Mining Consultants (Canada) Ltd. (AMC), the PVDC 2011 Year End Resources and Reserves update, and the RPA site visit in March 2011.

Prior RPA involvement in the Project dates back to 2008 when RPA conducted a detailed audit of the December 2007 Mineral Resource and Mineral Reserve estimates for the Pueblo Viejo gold deposit.

SOURCES OF INFORMATION

This report was prepared by the following Qualified Persons (QPs):

 

   

Robbert Borst, C.Eng., Associate Principal Mining Engineer

 

   

Chester Moore, P.Eng., Principal Geologist

 

   

André Villeneuve, P.Eng., Associate Metallurgist

Messrs. Borst and Moore visited the Pueblo Viejo site from March 14 to 17, 2011. Mining and stockpiling ore was taking place during the visit, as well as construction of the metallurgical plants and tailings storage facility. During the visit, discussions were held with the following people:

 

 

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Kendall Cole-Rae, Geology Manager, Capital Projects & Evaluations, Barrick

 

   

Ettiene Smuts, Mining Manager, PVDC

 

   

Michael Goers, Chief Mine Geologist, PVDC

 

   

Benjamin Sanfurgo C., Resources and Reserves Modelling Superintendent, Barrick Sudamérica

 

   

José Gonzales Borja, Senior Long Term Planning Engineer, PVDC

 

   

Peter Nahan, Senior Evaluation Engineer, Goldcorp

Robbert Borst is responsible for Sections 15, 18, 19, 21, and 22, and contributed to Sections 1, 2, 25, and 26. Chester Moore is responsible for Sections 3 to 12, 14, and 23, for compiling the report and contributed to Sections 1, 2, 25, and 26. André Villeneuve is responsible for Sections 13, 17, and 20.

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

 

 

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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.

 

µ

   micron    km2    square kilometre

°C

   degree Celsius    kPa    kilopascal

°F

   degree Fahrenheit    kVA    kilovolt-amperes

µg

   microgram    kW    kilowatt

µm

   micrometre    kWh    kilowatt-hour

A

   ampere    L    litre

a

   annum    L/s    litres per second

bbl

   barrels    m    metre

Btu

   British thermal units    M    mega (million)

C$

   Canadian dollars    m2    square metre

cal

   calorie    m3    cubic metre

cfm

   cubic feet per minute    min    minute

cm

   centimetre    MASL    metres above sea level

cm2

   square centimetre    mm    millimetre

d

   day    mph    miles per hour

dia.

   diameter    MVA    megavolt-amperes

dmt

   dry metric tonne    MW    megawatt

dwt

   dead-weight ton    MWh    megawatt-hour

ft

   foot    m3/h    cubic metres per hour

ft/s

   feet per second    opt, oz/st    ounces per short ton

ft2

   square foot    oz    Troy ounce (31.1035g)

ft3

   cubic foot    ppm    parts per million

g

   gram    psia    pounds per square inch absolute

G

   giga (billion)    psig    pounds per square inch gauge

Gal

   Imperial gallon    RD$    Dominican peso

g/L

   grams per litre    RL    relative elevation

g/t

   grams per tonne    s    second

gpm

   Imperial gallons per minute    st    short ton

gr/ft3

   grains per cubic foot    stpa    short tons per year

gr/m3

   grains per cubic metre    stpd    short tons per day

hr

   hour    t    metric tonne

ha

   hectare    tpa    metric tonnes per year

hp

   horsepower    tpd    metric tonnes per day

in

   inch    US$    United States dollar

in2

   square inch    USg    United States gallon

J

   joule    USgpm    US gallons per minute

k

   kilo (thousand)    V    volt

kcal

   kilocalorie    W    watt

kg

   kilogram    wmt    wet metric tonne

km

   kilometre    yd3    cubic yard

km/h

   kilometres per hour    yr    year

 

 

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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. Although the ownership has been granted by presidential decree, Barrick has obtained a favourable opinion by De Marchena Kaluche & Asociados dated December 3, 2009, entitled “Special Lease Agreement for Mining Rights of August 4, 2001 entered into by and between the Dominican State, the Central Bank of Dominican Republic, Rosario Dominicana S.A., and Pueblo Viejo Dominicana Corporation (the Special Leasing Agreement)” referring to property and legal status of lots located in the Montenegro Fiscal Reserve. RPA has not researched property title or mineral rights for the Project 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 the Project.

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.

 

 

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4 PROPERTY DESCRIPTION AND LOCATION

Pueblo Viejo is located in the central part of the Dominican Republic on the Caribbean island of Hispaniola in the province of Sanchez Ramirez (Figure 4-1). The Project is 15 km west of the provincial capital of Cotuí and approximately 100 km northwest of the national capital of Santo Domingo.

The Pueblo Viejo property, situated on the Montenegro Fiscal Reserve (MFR), is centred at 19°02' N, 70°08' W in an area of moderately hilly topography (Figure 4-2). The MFR covers an area of 4,880 ha and encompasses all of the areas previously included in the Pueblo Viejo and Pueblo Viejo II concession areas, which were owned by Rosario Dominicana S.A. (Rosario) until March 7, 2002, as well as the El Llagal area.

 

 

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FIGURE 4-1 LOCATION MAP

 

LOGO

 

 

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FIGURE 4-2 MONTENEGRO FISCAL RESERVE

 

LOGO

 

 

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LAND TENURE

PVDC is the holder of a lease right to the MFR by virtue of a Special Lease Agreement of Mining Rights (SLA). On March 2002, Rosario renounced the Pueblo Viejo and Pueblo Viejo II concessions and the Dominican state terminated such concessions. On March 7, 2002, the Dominican state, by virtue of Presidential Decree No. 169-02, created the MFR with an area of 3,200 ha. The SLA was ratified by the Dominican National Congress and published in the Official Gazette of the Dominican Republic on May 21, 2003, and became effective shortly thereafter. On August 3, 2004, the Dominican state, by virtue of Presidential Decree No. 722-04, modified the MFR to include El Llagal resulting in a current area of 4,880 ha. The SLA governs the development and operation of the Project and includes the right to exploit the Las Lagunas and Mejita Tailings impoundment facilities and the Hatillo limestone deposit. In August 2003 PVDC, informed the Dominican Government that it was not going to include the Las Lagunas tailings impoundment facilities as part of its development areas.

Pertinent terms of the SLA are:

 

  1. The SLA will extend for 25 years following notice by PVDC to the Dominican state that PVDC will develop a mine at the Pueblo Viejo site (Project Notice), with one extension by right for 25 years and a second 25 year extension at the mutual agreement of PVDC and the Dominican state, allowing a possible total term of 75 years.

 

  2. PVDC may exploit the Hatillo limestone deposit and all other limestone deposits within the MFR at no additional charge.

 

  3. The Dominican state will acquire and lease to PVDC the lands and mineral rights necessary for the permanent disposal of tailings and waste.

 

  4. The Dominican state will mitigate all historical environmental matters, except those conditions within areas designated for development by PVDC in the Project Notice.

 

  5. The Dominican state will relocate, at its sole cost and in accordance with World Bank Standards, those persons dwelling in the Los Cacaos section of the site.

 

  6. The Dominican state will provide a permanent and reliable source of water necessary to conduct the operations, at no additional charge to PVDC.

 

  7. PVDC shall make Net Smelter Royalty (NSR) payments to the Dominican state of 3.2% of net receipts of sales, make a Net Profits Interest (NPI) payment (with a rate that varies with the price of gold) after PVDC has recaptured its initial and ongoing investments, and pay income tax under a stabilized tax regime.

 

 

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In November 2009, following approval by the Dominican Republic National Congress, President Leonel Fernandez ratified amendments to the Project SLA. Amendments to the SLA included revised fiscal terms and clarified various administrative and operational matters to the mutual benefit of the state and PVDC, the Project operator. Barrick issued a statement on November 16, 2010, confirming amendments had been approved on the Project, including fiscal adjustments. The most notable modifications included:

 

  1. Adjustment of the NPI sliding scale to ensure a minimum Internal Rate of Return (IRR) of 10%. The NPI rate will be 0% until the Project reaches an IRR of 10%. Once this rate is reached, the NPI percentage that corresponds to the Dominican state shall be 28.75%.

 

  2. PVDC agreed to cover 50% of the capital costs required for the environmental remediation of the historic environmental matters that are the responsibility of the Dominican state under the SLA, up to US$37.5 million. It is noted that in a separate agreement executed in 2010, PVDC agreed to cover up to US$75.0 million towards historic environmental liabilities.

 

  3. In addition to relocating the persons residing in the Los Cacaos Basin, the Dominican state will also relocate, at its sole cost, those persons from El Llagal Basin, an area necessary for Project operations. Relocation will be in accordance with World Bank Standards as set forth in the SLA.

PERMITS

General Environmental and Natural Resources Law No. 64-00 (Law 64-00) of August 18, 2000 and its complementary regulations, governs all environmental related issues, including those applicable to mining, in the Dominican Republic. Law 64-00 sets out the general rules of conservation, protection, improvement, and restoration of the environment and natural resources by unifying segregated rules concerning environmental protection and creating a governmental body (the Ministry of Environment and Natural Resources) with wide authority to oversee and regulate its application. The Ministry of Environment and Natural Resources enforces Law 64-00 and establishes the process of obtaining environmental permits.

PVDC completed a Feasibility Study on the Project in September 2005 and presented an Environmental Impact Assessment (EIA) to the Dominican state in November of the same year. The terms of reference for the Project were approved by the Environmental Authority on May 30, 2005, and the Ministry of Environment approved the EIA in December 2006 and granted the Environmental License 101-06. Requirements of the

 

 

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Environmental License included submission of detailed design of tailings dams, installation of monitoring stations, and submission for review of the waste management plan and incineration plant.

An environmental evaluation report was submitted in 2008 to address an increase in the planned processing rate to 24,000 tpd and in September 2010 the Ministry of Environment and Natural Resources issued the Environmental License 101-06 Modified.

When the former Rosario mine shut down its operations in 1999, proper closure and reclamation was not undertaken. The result has been a legacy of polluted soil and water and contaminated infrastructure. Responsibility for the clean-up is now shared jointly between PVDC and the Dominican government. Terms have been set for both parties in the SLA that governs the development and operation of the Project.

In November 2009, following approval by the Dominican Republic National Congress, President Leonel Fernandez ratified amendments to the SLA for the Project. The amendments better reflected the scope and scale of the Project since its acquisition by Barrick in 2006 and the amendments set out revised fiscal terms and clarified various administrative and operational matters to the mutual benefit of PVDC and the Dominican state. In particular, the agreement stipulates that environmental remediation within the development area is the responsibility of the company with the exception of the hazardous substances; the Dominican government is responsible for historic impacts outside the Project development area and hazardous substances at the plant site. However, PVDC may manage the cleanup effort on the government’s behalf, subject to the execution of management agreement with the Dominican Government.

The Pueblo Viejo mine site requires 146 permit approvals from 16 governmental agencies. At the time of writing, approval had been granted for 86 permits, 18 have been submitted to the government, and 42 have been identified to be prepared.

In addition to mine site permit approvals, in March 2011 PVDC obtained an environmental license for a power transmission line (TL) of approximately 122 km in length from Azua to the mine site. PVDC has decided to resort to a new power solution which includes a 215 MW combined circle power plant to be installed in Quisqueya, San Pedro de Macoris and a power transmission line approximately 110 km in length from

 

 

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Quisqueya to the Pueblo Viejo Mine. The length of the original power line was reduced to 26 km and was completed from Piedra Blanca, Monseñor Nouel to the Mine. In January 2012, PVDC submitted to the Ministry of Environment and Natural Resources the EIA for the new power solution and is currently awaiting approval. Ten authorizations for the new power project have been obtained and 11 have been identified to be obtained in the future.

The principal agencies from which permits, licenses, and agreements are required for mine operation in the Dominican Republic include:

 

   

Ministry of Environment and Natural Resources – MIMARENA (Ministerio de Medio Ambiente y Recursos Naturales)

 

   

Dominican Institute of Water Resources – INDRHI (Instituto Dominicano de Recursos Hidráulicos)

 

   

Various Municipalities (Cotuí, for example)

 

   

Ministry of Public Works and Communications – MOPC (Ministerio de Obras Públicas y Comunicaciones)

 

   

National Institute of Potable Water and Sewage – INAPA (Instituto Nacional de Aguas Potables y Alcantarillados)

 

   

General Mining Agency – DGM (Dirección General de Minería)

 

   

Dominican Telecommunications Institute – INDOTEL (Instituto Dominicano de las Telecomunicaciones)

 

   

Ministry of Industry and Commerce – MIC (Ministerio de Industria y Comercio)

 

   

Ministry of Public Health and Social Assistance – MISPAS (Ministerio de SaludPública y Asistencia Social)

 

   

National Energy Comission – CNE (Comisión Nacional de Energía)

 

 

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5 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY

ACCESSIBILITY

Access from Santo Domingo is by a four lane, paved highway (Autopista Duarte, Highway #1) that is the main route between Santo Domingo and the second largest city, Santiago. This highway connects to a secondary highway, #17, at the town of Piedra Blanca, approximately 78 km from Santo Domingo. This secondary highway is a two lane, paved highway that passes through the towns of Maimon, Palo de Cuaba, and La Cabirma on the way to Cotuí. The gatehouse for the Pueblo Viejo Mine is 22 km from Piedra Blanca or approximately 6.5 km from Palo de Cuaba.

The main port facility in the Dominican Republic is Haina in Santo Domingo. Other port facilities are located at Puerto Plata, Boca Chica, and San Pedro de Macoris.

CLIMATE AND PHYSIOGRAPHY

The central region of the Dominican Republic is dominated by the Cordillera Central mountain range, which runs from the Haitian border to the Caribbean Sea. The highest point in the Cordillera Central is Pico Duarte at 3,175 m. Pueblo Viejo is located in the eastern portion of the Cordillera Central where local topography ranges from 565 m at Loma Cuaba to approximately 65 m at the Hatillo Reservoir.

Two rivers run through the concession, the Margajita and the Maguaca. The Margajita drains into the Yuna River upstream from the Hatillo Reservoir while the Maguaca joins the Yuna below the Hatillo Reservoir. The flows of both rivers vary substantially during rainstorms.

The Dominican Republic has a tropical climate with little fluctuation in seasonal temperatures, although August is generally the hottest month and January and February are the coolest. The average annual temperatures in the Project area are approximately 25ºC, ranging from daytime highs of 32°C to night time lows of 18°C. Annual rainfall is approximately 1,800 mm, with May through October typically being the wettest months.

 

 

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The Dominican Republic is located in an area where hurricanes occur, with the hurricane season typically from August to November.

Earthquakes are a real risk. Major earthquakes occur on average every 50 years because the island of Hispaniola sits on top of small crustal blocks sandwiched between the North American and Caribbean plates.

As a result of previous mining and agriculture, there is little primary vegetation on the Pueblo Viejo Mine site and surrounding concessions. Secondary vegetation is abundant outside of the excavated areas and can be quite dense. Rosario, the previous owner of the concessions, also aided the growth of secondary vegetation by planting trees throughout the property for soil stabilization.

The economic base of the Project area is mainly agriculture and cattle ranching. Vegetation mainly consists of crops and grasses. South of Cuance, submontane rain forest occurs in uncultivated areas. Crops include sugarcane, coffee, cocoa, tobacco, bananas, rice coconuts, cassava, tomatoes, pulses, dry beans, eggplants, and peanuts. Mining is an increasingly important economic activity and the Pueblo Viejo Mine currently employs nearly 6,500 workers.

INFRASTRUCTURE

The Pueblo Viejo Project is located approximately 100 km northwest of Santo Domingo, the capital of the Dominican Republic. The main road from Santo Domingo to within about 22 km of the mine site is a surfaced, four-lane, divided highway that is generally in good condition. Access from the divided highway to the site is via a two-lane, surfaced road. Gravel surfaced, internal access roads provide access to the mine site facilities.

In order to transport the autoclaves, which weigh over 700 tonnes each, upgrades to a north coast road were completed instead of the route from Santo Domingo. Upgrading included road and bridge improvements, clearing of overhead obstructions, erosion control, bypass route construction, clearing utility interferences, and work permitting.

A network of haul roads within the Project limits will supplement existing roads so that mine trucks can haul ore, mine overburden, and limestone from the various quarries.

 

 

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As well as the existing access roads, current site infrastructure includes accommodation, offices, truck shop, medical clinic and other buildings, water supply, and old tailings impoundments with some water treatment facilities. Upgrades and renovations will be performed on some of these facilities.

A double and single fence system will protect the new process plant site. Within the plant site area, the freshwater system, potable water system, fire water system, sanitary sewage system, storm drains, and fuel lines will be buried underground. Process piping will typically be left above ground on pipe racks or in pipe corridors.

A tailings storage facility is under construction in the El Llagal valley approximately 3.5 km south of the plant site and consists of two rock fill dams with saprolite cores.

POWER PLANTS

Power supply for the Project can be broken into two time periods: 1) start-up and initial operations; and 2) permanent operations. For start-up and initial operations, power will be supplied by 43 MW of onsite diesel generators with the balance being supplied from the national grid pursuant to a power purchase agreement from EGE Haina S.A., a major power generator in the Dominican Republic. PVDC owns the Monte Rio power plant, which has a rated output of 100 MW. The output of Monte Rio will be sold to EGE Haina to “firm” Haina’s deliveries to PVDC, with EGE Haina providing the balance of PVDC’s demand from other generators. The Project is connected to the national grid at a new substation built by PVDC near the town of Piedra Blanca. Power then is delivered to the Project though 26km of private transmission line owned by PVDC.

Due to a deficit of power supply and reliability issues in the national system, PVDC will supply power for permanent operations from a new power plant that it is building near San Pedro de Macoris on the south shore of the Dominican Republic. The plant is a dual-fueled reciprocating engine plant that will operate in combined cycle. The output will be 215 MW. The plant will operate on HFO and will be connected to the mine by 110 km of private transmission line that is being constructed by PVDC. The power supply for permanent operations will be completed in 2013. Upon completion, the Project will be able to access power from its own plant as well as the national grid.

 

 

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Currently, on-site generation supplies 13 MW, sufficient for pre-commissioning, which has been supplemented by an additional 30 MW of power generated on-site for commissioning. A temporary connection to the national grid, supplying an additional 80 MW will allow operation of the processing plant at 6,000 tpd (76 MW), then eventually to 12,000 tpd (105 MW).

Infrastructure issues and requirements are discussed in detail in Section 18.

LOCAL RESOURCES

The city of Santo Domingo is the principal source of supply for the mine. It is a port city with a population of over three million with daily air service to the USA and other countries. Most non-technical staff positions and labour requirements are filled from local communities.

 

 

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6 HISTORY

The following exploration and mining history summary is mainly taken from Barrick’s 2007 FSU (Volume 1—Geology).

PRE-1969

The earliest records of Spanish mine workings at Pueblo Viejo are from 1505, although Spanish explorers sent into the interior of the island during the second visit of Columbus in 1495 probably found the deposit being actively mined by the native population. The Spanish mined the deposit until 1525, when the mine was abandoned in favour of newly discovered deposits on the American mainland.

There are few records of activity at Pueblo Viejo from 1525 to 1950, when the Dominican government sponsored geological mapping in the region. Exploration at Pueblo Viejo focused on sulphide veins hosted in unoxidized sediments in streambed outcrops. A small pilot plant was built, but economic quantities of gold and silver could not be recovered.

ROSARIO/AMAX (1969-1992)

During the 1960s, several companies inspected the property but no serious exploration was conducted until Rosario Resources Corporation of New York (Rosario) optioned the property in 1969. As before, exploration was directed first at the unoxidized rock where sulphide veins outcropped in the stream valley and the oxide cap was only a few metres thick. As drilling moved out of the valley and on to higher ground, the thickness of the oxide cap increased to a maximum of 80 m, revealing an oxide ore deposit of significant tonnage.

In 1972, Rosario Dominicana S.A. was incorporated (40% Rosario, 40% Simplot Industries and 20% Dominican Republic Central Bank). Open pit mining of the oxide resource commenced on the Moore deposit in 1975. In 1979, the Dominican Central Bank purchased all foreign held shares in the mine. Management of the operation continued under contract to Rosario until 1987. Rosario was merged into AMAX Inc. (Amax) in 1980.

 

 

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Rosario continued exploration throughout the 1970s and early 1980s, looking for additional oxide resources to extend the life of the mine. The Monte Negro, Mejita, and Cumba deposits were identified by soil sampling and percussion drilling and were put into production in the 1980s. Rosario also performed regional exploration, evaluating much of the ground adjacent to the Pueblo Viejo concessions, with soil geochemistry surveys and percussion drilling. An airborne electromagnetic (EM) survey was flown over much of the Maimon Formation to the south and west of Pueblo Viejo.

With the oxide resources diminishing, Rosario initiated studies on the underlying refractory sulphide resource in an effort to continue the operation. Feasibility level studies were conducted by Fluor Engineers Inc. (Fluor) in 1986 and Stone & Webster Engineering/American Mine Services (SW/AMS) in 1992.

Fluor concluded that developing a sulphide project would be feasible if based on roasting technology, with sulphuric acid as a by-product. Rosario rejected this option due to environmental concerns related to acid production.

SW/AMS concluded that a roasting circuit would be profitable at 15,000 tpd using limestone slurry for gas scrubbing and a new kiln to produce lime for gas cleaning and process neutralization.

Rosario continued to mine the oxide material until approximately 1991, when the oxide resource was essentially exhausted. A carbon-in-leach (CIL) plant circuit and new tailings facility at Las Lagunas were commissioned to process transitional sulphide ore at a maximum of 9,000 tpd. Results were poor, with gold recoveries varying from 30% to 50%. Selective mining continued in the 1990s on high-grade ore with higher estimated recoveries. Mining in the Moore deposit stopped early in the 1990s owing to high copper content (which resulted in high cyanide consumption) and ore hardness. Mining ceased in the Monte Negro deposit in 1998, and stockpile mining continued until July 1999, when the operation was shut down.

In 24 years of production, the Pueblo Viejo Mine produced a total of 5.5 million ounces of gold and 25.2 million ounces of silver.

 

 

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PRIVATIZATION (1996)

Lacking funds and technology to process the sulphide ore, Rosario attempted two bidding processes to joint venture the property, one around 1992 and the other in 1996. In November 1996, Rosario selected Salomon Brothers (Salomon Smith Barney) to coordinate a process to find a strategic partner to rehabilitate the operation and to determine the best technology to economically exploit the sulphide resource. Three companies were involved in the privatization process: GENEL JV, Mount Isa Mines Ltd. (MIM), and Newmont Mining Corporation (Newmont). This privatization was not achieved, but each of the three companies conducted work on the property during their evaluations.

GENEL JV

The GENEL JV was formed in 1996 as a 50:50 joint venture between Eldorado Gold Corporation and Gencor Inc. (later Gold Fields Inc.) to pursue their common interest in Pueblo Viejo. The GENEL JV expended $6 million between 1996 and 1999 in studying the Project and advancing the privatization process. Studies included diamond drilling, developing a new geological model, mining studies, evaluation of refractory ore milling technologies, socio-economic evaluation, and financial analysis.

MOUNT ISA MINES

In 1997, MIM conducted a due diligence program as part of its effort to win Pueblo Viejo in the privatization process. It conducted a 31 hole, 4,600 m diamond drilling program, collected a metallurgical sample from drill core, carried out detailed pit mapping, completed induced polarization (IP) geophysical surveys over the known deposits, and organized aerial photography over the mining concessions to create a surface topography. MIM also proposed to carry out a pilot plant and feasibility study using ultra-fine grinding/ferric sulphate leaching.

NEWMONT

In 1992 and again in 1996, Newmont proposed to carry out a pilot plant and feasibility study for ore roasting/bioheap oxidation. Samples were collected for analysis, but no results are available. Both of Newmont’s attempts to privatize or joint venture the property failed.

 

 

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PLACER DOME INC.

Placer Dome Inc., through PVDC, acquired the Project in July 2001. Between 2002 and mid-2005, Placer Dome Dominicana Corporation, a subsidiary of Placer Dome Inc. (together Placer), completed extensive work on Pueblo Viejo including drilling, geological studies, and mineral resource/reserve estimation. This work was compiled in a Feasibility Study completed in July 2005. In February 2006, Barrick Gold acquired Placer and subsequently sold 40% of the Project to Goldcorp.

In addition to drilling programs in 2002 and 2004, Placer conducted structural pit mapping of the Moore and Monte Negro open pits in 2002. Placer also mapped and sampled a 105 km2 area around the concessions as part of an ongoing environmental baseline study to identify acid rock drainage (ARD) sources outside the main deposit areas. Part of the regional mapping and sampling program focused on evaluating the potential for mineralization in the proposed El Llagal tailings storage area. Mapping and stream sediment sampling were conducted in the El Llagal valley and adjacent Maguaca and Naranjo river valleys. Further geotechnical evaluation of the El Llagal valley resulted in BGC Engineering Inc. (BGC) of Vancouver drilling 20 core holes and collecting numerous outcrop samples. Select samples identified with the most favourable mineralization were sent for gold and trace element analysis.

PREVIOUS RESERVE ESTIMATES

Previous reserve estimates for the Project are presented in Table 6-1. Barrick has revised the Mineral Reserve estimates for Pueblo Viejo each year reflecting a number of factors that changed as the Project progressed.

The reserve totals are presented on a 100% basis. Where applicable, data was converted to metric units. The reserve estimates are compliant with the requirements of NI 43-101.

 

 

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TABLE 6-1 PREVIOUS MINERAL RESERVE ESTIMATES

Barrick Gold Corporation – Pueblo Viejo Project

 

2009 Mineral Reserve Estimate (US$ 825 Au/oz; US$ 14.00 Ag/oz; US$ 2.00/lb Cu)

 
     Tonnage
(Mt)
            Grade
(g/t  Ag)
            Contained Metal  
         (g/t Au)         (% Cu)      (Moz Au)      (Moz Ag)      (Mlb Cu)  

Proven

     5.14         3.33         21.6         0.11         0.55         3.6         13   

Probable

     95.64         2.91         17.3         0.09         8.95         53.1         189   

Total

     100.78         2.93         17.5         0.09         9.50         56.7         202   

2008 Mineral Reserve Estimate (US$ 725 Au/oz; US$ 13.50 Ag/oz; US$ 2.00/lb Cu)

 
     Tonnage      Grade      Contained Metal  
      (Mt)      (g/t Au)      (g/t Ag)      (% Cu)      (Moz Au)      (Moz Ag)      (Mlb Cu)  

Proven

     4.63         3.52         22.6         0.12         0.52         3.4         12   

Probable

     84.85         3.09         18.0         0.09         8.44         49.2         170   

Total

     89.48         3.11         18.3         0.09         8.96         52.5         182   

2007 FSU Mineral Reserve Estimate (US$650 Au/oz; US$11.50 Ag/oz; US$2.25/lb Cu)

 
     Tonnage
(Mt)
            Grade
(g/t  Ag)
            Contained Metal  
         (g/t Au)         (% Cu)      (Moz Au)      (Moz Ag)      (Mlb Cu)  

Proven

     11.24         3.39         18.93         0.100         1.22         6.84         25   

Probable

     194.48         2.91         14.56         0.085         18.19         91.05         363   

Total

     205.72         2.94         14.80         0.086         19.41         97.89         388   

 

 

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7 GEOLOGICAL SETTING AND MINERALIZATION

The following regional geology description is taken largely from Barrick’s 2007 FSU.

REGIONAL GEOLOGY

Pueblo Viejo is hosted by the Lower Cretaceous Los Ranchos Formation, a series of volcanic and volcaniclastic rocks that extend across the eastern half of the Dominican Republic, generally striking northwest and dipping southwest (Figure 7-1). The Los Ranchos Formation consists of a lower complex of pillowed basalt, basaltic andesite flows, dacitic flows, tuffs and intrusions, overlain by volcaniclastic sedimentary rocks and interpreted to be a Lower Cretaceous intra-oceanic island arc, one of several bimodal volcanic piles that form the base of the Greater Antilles Caribbean islands. The unit has undergone extensive seawater metamorphism (spilitization) and lithologies have been referred to as spilite (basaltic-andesite) and keratophyre (dacite).

The Pueblo Viejo Member of the Los Ranchos Formation is confined to a restricted, sedimentary basin measuring approximately three kilometres north-south by two kilometres east-west. The basin is interpreted to be either due to volcanic dome collapse forming a lake, or a maar-diatreme complex that cut through lower members of the Los Ranchos Formation. The basin is filled with lacustrine deposits that range from coarse conglomerate deposited at the edge of the basin to thinly bedded carbonaceous sandstone, siltstone, and mudstone deposited further from the paleo-shoreline. In addition, there are pyroclastic rocks, dacitic domes, and diorite dykes within the basin. The sedimentary basin and volcanic debris flows are considered to be of Neocomian age (121 Ma to 144 Ma). The Pueblo Viejo Member is bounded to the east by volcaniclastic rocks and to the north and west by Platanal Member basaltic-andesite (spilite) flows and dacitic domes.

To the south, the Pueblo Viejo Member is overthrust by the Hatillo Limestone Formation, thought to be Cenomanian (93 Ma to 99 Ma), or possibly Albian (99 Ma to 112 Ma), in age.

 

 

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FIGURE 7-1 REGIONAL GEOLOGY

 

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PROPERTY GEOLOGY

Pueblo Viejo hosts the Moore and Monte Negro deposits (Figure 7-2). A revised stratigraphic column as prepared by Barrick in 2009 is shown in Figure 7-3. Cross sections with interpreted structures and the lithology are shown in Figure 7-4. The following property geology description is mostly taken from Placer (2005) and Barrick (2007).

MOORE DEPOSIT

The Moore deposit is located at the eastern margin of the Pueblo Viejo Member sedimentary basin. Stratigraphy consists of finely bedded carbonaceous siltstone and mudstone (Puerto Viejo sediments) overlying horizons of spilite (basaltic-andesite flows), volcanic sandstone, and fragmental volcaniclastic rocks. The entire sequence in the Moore deposit area has a shallow dip to the west.

Fragmental Dacite Porphyry (FDP) that outcrops north of the plant site intrudes the stratigraphic sequence. FDP is best described as a vent breccia with a volcaniclastic appearance with quartz eyes and lithic fragments, intrusive phases such as local breccia dikes, and intrusive contacts. Propylitically altered porphyry has been intersected in core with intrusive textures and appears to form a north-northeast striking root zone to the FDP. The FDP appears to have been emplaced prior to mineralization with local zones of disseminated pyrite and anomalous gold mineralization. The eastern margin of the sedimentary basin hosting the Moore deposit, is defined by fragmental volcaniclastic rocks (Zambrana Member) and non-carbonaceous sedimentary rocks (Mejita Sediments).

There are indications that an internal sub-basin exists at Moore below the Puerto Viejo Sediments. The sub-basin is partially filled with a mixed sedimentary sequence consisting of inter-fingering Puerto Viejo Sediments and fragmental volcaniclastic rocks. Graded bedding and slump folding textures are often observed in core. The south and west margins of the sub-basin are defined by pinching of the spilite and volcanic sandstone horizons.

 

 

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FIGURE 7-2 PROPERTY GEOLOGY

 

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FIGURE 7-3 STRATGRAPHIC COLUMN

 

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FIGURE 7-4 LOCAL STRUCTURES AND LITHOLOGY

 

 

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Bedding generally dips shallowly westwards (less than 25°), but locally steep faults with north-northeast and north-northwest strikes have rotated bedding into steep orientations. The north-northeast faults preserve evidence for an east-side-up and left-lateral sense of movement subsequent to mineralization. The north-northeast faults appear to link with a north-northwest trending fault that controls the eastern margin of the Moore dacite porphyry and is a boundary to a gold-bearing pyrite vein zone at North Hill. The westward-dipping thrust and bedding plane faults offset pyrite veins with only minor displacement evident. The faults are associated with an intense cleavage and bedding-parallel quartz veins with gold mineralization.

MONTE NEGRO DEPOSIT

The Monte Negro deposit is located at the northwestern margin of the sedimentary basin. Stratigraphy consists of interbedded carbonaceous sediments ranging from siltstone to conglomerate, interlayered with volcaniclastic flows. These volcaniclastic flows become thicker and more abundant towards the west. This entire sequence has been grouped as the Monte Negro Sediments. In the eastern part of the Monte Negro deposit area, the bedding dip is shallow to the southwest; in the west, the dip is shallow to the northwest.

The Monte Negro Sediments overlie a horizon of spilite and spilite-derived conglomerate. The conglomerate consists of pebble to boulder size clasts of spilite that are often silicified and a light pink colour. Silicification is likely volcanogenic, occurring prior to the sedimentation of the basin. The conglomerate horizon represents either a basal conglomerate channelled into the margin of the basin or a reworked, brecciated flow top of the spilite below. The horizon ranges in thickness from tens of metres to non-existent and is likely filling channels in the uneven spilite surface below.

Spilite that forms the basement of the Monte Negro deposit is the Platanal Member of the Los Ranchos Formation. Porphyritic textures and massive andesitic flows, often separated by brecciated flow tops are in the west part of the deposit. The brecciated textures become more abundant towards the east.

Thin section work on the porphyritic spilite indicates a composition of either a high-silica andesite or a low-silica dacite. Primary textures observed are consistent with an intrusion indicating that either a dome or a near surface plug may exist under the west

 

 

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hill of Monte Negro. The dimensions of this possible intrusion have not been determined because core drilling is limited. Dikes that intrude the Monte Negro stratigraphy include a steeply dipping north-northwest striking mafic (diorite/andesite) dike approximately 10 m wide. The dike typically follows the F5 fault through the deposit area but occasionally splays to the north. The dike is propylitically altered and is barren of gold mineralization. Similar dikes have been intersected in core in the west part of the deposit, but they are much thinner. Thin breccia dikes (pebble dikes) have also been mapped in the pit walls.

Interbedded carbonaceous siltstones, sandstones, and volcanic rocks in the Monte Negro Central Zone generally dip shallowly towards the southwest. In the Monte Negro South Zone andesitic volcanic and volcaniclastic rocks generally dip shallowly (13°) towards the northwest. A steep north-northwest trending fault (Monte Negro Fault) with a west-side-up sense of movement is interpreted to separate the sediments in the east from the volcanic rocks in the west. The fault is interpreted to have been a focus for silicification, breccia dyke emplacement, and mineralization.

Bedding in the hanging and footwalls of the Monte Negro Fault has been folded into upright, open folds in close proximity to the fault. The axial trace of the folds trends north-northwest sub-parallel to the strike of the north-northwest conjugate vein set.

Thrust faults displace veins and have brought sedimentary rocks into contact with andesitic volcanic and volcaniclastic rocks. A disconformable thrust contact is well exposed at the southern end of Monte Negro West.

STRUCTURE

Surface mapping and core logging have identified two main structural trends (Figure 7-5). The first trend is northeast bearing with vertical dips. The second, later trend is north-northwest bearing with vertical dips, and cuts the northeast structures. This second trend is more economically important because many feeders in the hydrothermal system used these structures for mineralization.

 

 

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FIGURE 7-5 PLAN VIEW OF MAIN STRUCTURES

 

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Both structural trends have contributed to basin formation, as many of these faults were growth faults during basin development.

Low angle faults are recognized in surface mapping. These faults were the last deformation event in the basin because they cut the previous systems and mainly affect the carbonaceous sedimentary package. They have an average dip of 8º to 10º and no mineralization is related to these low angle faults.

HYDROTHERMAL ALTERATION

The Pueblo Viejo deposit has undergone typical high sulphidation, zoned alteration characterized by silica, pyrophyllite, pyrite, kaolinite, and alunite. Silica is predominant in the core of the alteration envelope and occurs with kaolinite in the upper zones where a silica cap is often formed. Unlike typical high sulphidation deposits where silicic alteration is residual and a result of acid leaching, silicification at Pueblo Viejo represents silica introduction and replacement. Silica enriched zones are surrounded by a halo of quartz-pyrophyllite and pyrophyllite alteration.

Ongoing studies by Barrick have determined four main alteration assemblages at the Pueblo Viejo deposit (Figure 7-6). These assemblages are:

 

   

Quartz – Alunite ± Dickite (qtz – al ± dk)

 

   

Quartz – Pyrophyllite ± Dickite (qtz – py ± dk)

 

   

Pyrophyllite – Illite – Kaolin (py – ill – kao)

 

   

Illite – Chlorite – Smectite (ill – chl – sm)

Advanced argillic alteration is easily distinguished from the assemblage typical of the seawater metamorphosed (spilitized) Los Ranchos Formation. Limits of the alteration zones are marked by a rapid change (over a few metres) in mineralogy. Outside of alteration zones, finer grained sedimentary rocks are pyritic (framboids) or sideritic with diagenetic conditions suggesting an anoxic, restricted basin. Within mineralization, siderite is completely replaced by pyrite.

 

 

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FIGURE 7-6 PLAN VIEW OF ALTERATION ASSEMBLAGES

 

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In the Moore deposit, silica and kaolinite are more common in the upper parts of the system. In the now depleted oxide mineralization, silicification was closely associated with gold mineralization and caused mineralized zones to form hills with relief of about 200 m. In areas of intense silicification, jasperoid masses were produced, original sedimentary textures destroyed, and carbonaceous material removed. Locally, veins and masses of pyrophyllite cut the jasperoid bodies.

In the Monte Negro deposit, silica and kaolinite are again more abundant in the upper portions of the system and a silica cap is present. Silicification is more widespread at Monte Negro and not as closely associated with gold mineralization. Regardless, gold content is typically higher in silicified or partially silicified (quartz-pyrophyllite) rock.

WEATHERING

Past mining operations have stripped the deposit areas of almost all surface oxidation and the oxide mineralization is now virtually depleted. The oxide was formed where surface oxidation removed sulphide minerals and carbon from the host sediments, leaving silicified host rock and massive jasperoid with jarosite, goethite, and local hematite mineralization. The thickness of the oxide mineralization ranged from 80 m at North Hill in the Moore deposit to 50 m in the South Hill and East Mejita deposits to nothing in the stream valleys. The thickest oxide mineralization was developed in intensely silicified, thinly bedded, and well fractured sedimentary rocks. In contrast, areas underlain by intensely pyrophyllitized sedimentary rocks only had a few metres of oxidation. Soil cover and saprolite were negligible over the oxide mineralized zones.

Gold mineralization was largely immobile in the oxide mineralization. No gold enrichment occurred, but free gold existed. Fine specks of gold (less than 100 µm) could be panned from only the highest grade zones. Silver was depleted in the near-surface parts of the oxide mineralization and enriched at the oxide-sulphide interface. Zinc and copper were leached from the oxide with the destruction of the sulphides.

MINERALIZATION

The following summary is sourced from Barrick’s 2007 FSU and a 2009 Barrick report summarizing an updated geological interpretation on the deposit.

 

 

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GENERAL DESCRIPTION

Metallic mineralization in the deposit areas is predominantly pyrite, with lesser amounts of sphalerite and enargite. Pyrite mineralization occurs as disseminations, layers, replacements, and veins. Sphalerite and enargite mineralization is primarily in veins, but disseminated sphalerite has been noted in core.

Studies have determined that there were three stages of advanced argillic alteration associated with precious metal mineralization:

 

  1. Stage I alteration produced alunite, silica, pyrite, and deposited gold in association with disseminated pyrite.

 

  2. Stage II overprinted Stage I and produced pyrophyllite and an overlying silica cap.

 

  3. Stage III of mineralization occurred when hydro-fracturing of the silica cap produced pyrite-sphalerite-enargite veins with silicified haloes. Syntaxial vein growth preserves evidence for pyrite-enargite-sphalerite-grey-silica paragenesis.

Individual Stage III veins have a mean width of four centimetres and are typically less than 10 cm wide. Exposed at surface, individual veins can be traced vertically over three pit benches (30 m). Veins are typically concentrated in zones that are elongated north-northwest and can be 250 m long, 100 m wide, and 100 m vertical. Stage III veins contain the highest precious and base metal values and are more widely distributed in the upper portions of the deposits.

Veins tend to be parallel to follow a number of local structures that crosscut the deposit. Those structures have a northerly trend at Monte Negro and Moore, with a northwest-southeast trend also present at Moore.

The most common vein minerals are pyrite, sphalerite, and quartz, with lesser amounts of enargite, barite, and pyrophyllite. Trace amounts of electrum, argentite, colusite, tetrahedrite-tennantite, geocronite, galena, siderite, and tellurides are also found in veins.

The abundance of pyrite and sphalerite within veins varies across the deposit areas. Veins in the southwest corner of the Monte Negro pit are relatively sphalerite-rich and pyrite-poor when compared to veins elsewhere in the Moore and the Monte Negro

 

 

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deposits. The sphalerite in these veins is darker red in colour, possibly indicating that it is richer in iron. The abundance of dark red sphalerite in these veins may also be indicative of the outer margins of a system of hydrothermal-magmatic mineralized fluids.

Late massive pyrophyllite veins that probably represent the last stage of veining and alteration cut the Stage III veins. All stages of veining are cut by thin, white quartz veins associated with low angle thrusts that post-date mineralization.

The Moore resource pit will have final dimensions of approximately 1,200 m by 850 m and a depth of 280 m. The Monte Negro pit will have final dimensions of approximately 1,500 m by 800 m and a depth of 360 m.

METAL OCCURRENCE AND DISTRIBUTION

The following summary is taken from Barrick’s 2007 FSU.

GOLD

Gold is intimately associated with pyrite veins, disseminations, replacements, and layers within the zones of advanced argillic alteration. Gold values are generally the highest in zones of silicification or strong quartz-pyrophyllite alteration. These gold-bearing alteration zones are widely distributed in the upper parts of the deposits and tend to funnel into narrow feeder zones.

In the Moore deposit, a high-grade structural feeder zone within an alteration funnel was intersected by a GENEL JV core hole GEN_MDD6. The hole intersected an intensely silicified shear zone that returned gold values of 9.1 g/t Au over 40 m (30 m true width). The shear is steeply dipping and appears to strike either north or northwest. While the shear is open to depth, it possibly has a strike length of less than 100 m. This style of mineralization differs from the upper zones of the deposit, where high grade gold is associated with sulphide veins. This feeder zone also contains a higher concentration of lead in the form of lead sulphosalts and galena.

In the Monte Negro deposit, a high-grade feeder zone has not been identified. A potential target is the Monte Negro Fault that is intensely silicified and bounds high-grade mineralization at the surface. A second possibility is a deeper zone of mineralization that has been intersected by a vertical core hole testing an IP-chargeability anomaly approximately 100 m east of the main deposit.

 

 

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AMTEL Laboratories of London, Ontario, conducted a study to establish the deportment of gold in four separate composites from Pueblo Viejo. These composites represented four of the five metallurgical rock types established for the deposit: sedimentary rocks (MN-BSD) and volcanic rocks (MN-VCL) at Monte Negro and sedimentary rocks (MO-BSD) and volcanic rocks (MO-VCL) at Moore. Spilites at Monte Negro (MN-SP) were not sampled (see Section 13 for further discussion on the metallurgy of the deposit).

Gold occurs as native gold, sylvanite (AuAgTe4), and aurostibnite (AuSb2). The principal carrier of gold is pyrite where the sub-microscopic gold occurs in colloidal-size micro inclusions (less than 0.5 µm) and as a solid solution within the crystal structure of the pyrite. The abundance of the gold minerals varied significantly between the different composites (Table 7-1).

TABLE 7-1 MINERALOGICALLY DETERMINED DEPORTMENT OF GOLD

Barrick Gold Corporation – Pueblo Viejo Project

 

Form and Carrier Gold Minerals

   MN-BSD
(%)
   Form and Carrier
Gold Minerals
   MN-BSD
(%)
   Form and Carrier
Gold Minerals

Free gold

       1.8          25.3          22.4          68.6  

Free sylvanite

       20.6          0.8          5.1          —    

Free aurostibnite

       —            —            —            0.2  

Rock-sulphide binaries

       8.3          13.1          8.5          0.9  

“Clean” rock

       4.0          6.1          9.6          0.2  

Sub-microscopic Gold

  

Micro inclusions

       51.7          33.4          28.0          19.8  

Solid solution

       13.6          21.5          26.4          10.3  

Studies have shown that there are four major forms of pyrite: microcrystalline, disseminated, porous, and coarse grained. The microcrystalline pyrite tends to have the highest gold concentration. This type of pyrite is also the most arsenic-rich, which renders it the most prone to oxidation and the most difficult to liberate, as it forms complex intergrowths within the rock and with sphalerite. Coarse-grained pyrite has the lowest gold concentration and has a well-developed crystal habit making it less susceptible to oxidation.

 

 

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There are less common forms of gold, gold minerals such as native gold, electrum, tellurides (sylvanite, calaverite, petzite), and locally, aurostibnite. Most grains are less than 10 µm in diameter and are largely associated with growth zones of pyrites. To a lesser extent, gold minerals occur as inclusions in enargite, quartz, and lead-sulphosalts (primarily geocronite). Gold may also exist in the crystal structure of sulphosalts, such as enargite and geocronite, but additional research is required.

While there is a strong correlation between gold and zinc (zones with sphalerite veins tend to have the highest gold grades), sphalerite carries gold only as intergrowths of gold-bearing pyrite. The quantity of gold carried by the sphalerite depends on the percentage of gold-bearing pyrite encapsulated and the amount of sub-microscopic gold within the pyrite.

SILVER

Assay results for silver demonstrate that it has the strongest correlation with gold. In particular, silver has a strong association with Stage III sulphide veins where it occurs as native silver and in pyrargyrite (antimony sulphide), hessite (silver telluride), sylvanite and petzite (gold tellurides), and tetrahedrite.

ZINC

The majority of the zinc occurs as sphalerite, primarily in Stage III sulphide veins and to a lesser extent as disseminations. The sphalerite is beige to orange coloured and is relatively iron-free. An exception is the dark red veins found in the southwest corner of the Monte Negro deposit that may represent a discontinuous halo surrounding the alteration zone.

Sphalerite commonly contains inclusions and intergrowths of pyrite, sulphosalts, galena, and silicate gangue. The encapsulated pyrite is often host to sub-microscopic gold mineralization.

Trace amounts of zinc can be found in tetrahedrite and enargite.

COPPER

Most of the copper occurs as enargite hosted in Stage III sulphide veins. Only trace amounts of chalcocite and chalcopyrite have been documented. Enargite-rich vein

 

 

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zones typically are confined laterally and vertically within the larger sphalerite-rich vein zones. Enargite is difficult to identify in hand specimen and is easily confused with tennantite-tetrahedrite.

LEAD

Lead minerals include galena, geocronite, boulangerite, and bournonite, most of which are present as fine inclusions or within fractures in pyrite, sphalerite, and enargite. Geocronite and boulangerite are the most prevalent.

There are a limited number of lead assays in the Project database. Assaying completed by GENEL JV shows a strong correlation between gold and lead. Elevated lead values were found in the structural feeder zone in the Moore deposit and lead may provide clues on where to search for other feeder zones.

MOORE DEPOSIT MINERALIZATION

Pyrite-rich, gold-bearing veins at the deposit have a mean width of four centimetres and are steeply dipping with a trend commonly north-northwest. Secondary pyrite vein sets trend north-south and north-northeast. The orientation of pyrite veins and steep faults is similar, albeit with different dominant sets (north-northwest for veins and north-northeast for faults). This suggests a probable link between steep faulting and vein development.

WEST FLANK ZONE

Thinly bedded carbonaceous siltstones and andesitic sandstones in the West Flank dip shallowly westwards. Dips increase towards the west where north trending thrusts displace bedding.

Pyrite and limonite-rich veins with gold mineralization are subvertical and trend commonly north-northwest. The veins are oblique to the general north-northeast strike of bedding and do not appear to have been rotated. Quartz veins with gold trend northwest oblique to the pyrite veins have a similar strike to the interpreted contact with the overlying Hatillo limestone. They also occur as tension gash arrays in centimetre-scale dextral shear zones that trend north-northwest.

Faults create centimetre-scale displacement of bedding and pyrite-sphalerite veins occur along steep north-northeast trending faults and westerly dipping thrusts. Two main north-northeast faults were mapped across the West Flank, sub-parallel with the Moore dacite porphyry contact. Displacement of veins preserves evidence for a lateral, sinistral component of movement.

 

 

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NORTH AND SOUTH HILLS ZONES

Bedding to the north of the Moore dacite porphyry dips shallowly westwards. Bedding has been rotated about both north-northwest and north-northeast axes. The change in bedding orientation reflects movement associated with north-northwest and north-northeast trending faults.

There are three steep-dipping, gold-bearing, pyrite-rich vein sets: northwest, northeast, and north-south. Northwest trending veins generally contain enargite and sphalerite, while northeast trending veins are more pyrite ± pyrophyllite rich. The average vein width is 3.5 cm.

The fault pattern is dominated by steep north-northeast trending faults that appear to link with north-northwest trending faults. A north-northeast trending steep fault along the western margin of the Moore dacite breccia has rotated bedding from shallow to steep dips, indicating an east-side-up sense of movement. The sense of movement along north-northwest faults could not be determined. Thrusting parallel to bedding is common and is evidenced by intense cleavage and quartz veins parallel to bedding. Bedding plane displacement is minor, generally less than 20 cm.

MONTE NEGRO DEPOSIT MINERALIZATION

MONTE NEGRO CENTRAL ZONE

Pyrite-rich veins with gold mineralization are sub-vertical and have bimodal trends, which are interpreted to form conjugate sets. The mean width is two centimetres. The north-northwest trending set is sub-parallel to the strike of bedding and fold axes, indicating a possible genetic relationship between folding and mineralization. Enargite and sphalerite-bearing veins with gold dominantly trend north-northeast and have a mean width of three centimetres. The combination of vein trends forms a high grade gold zone (Vein Zone 1) which extends 500 m north-northwest, is 150 m wide, and up to 100 m thick between the F5 Fault to the east and the Main Monte Negro Fault to the west.

The fault pattern is dominated by steep north-northwest trending faults sub-parallel to the dominant pyrite vein set. The main Monte Negro Fault is a 25 m x 500 m zone of silicification, brecciation, mineralization, folding, and faulting. It is interpreted as a major fault that was active during and subsequent to mineralization.

 

 

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MONTE NEGRO SOUTH ZONE

Andesitic volcanic and volcaniclastic rocks with minor intercalations of carbonaceous sediments dip shallowly northwards. Close to the interpreted Monte Negro Fault, bedding dips more westerly and strikes north-northwest.

North-northwest trending steep faults displace bedding and dip towards the southwest. Displacement of marker agglomerate beds indicates a metre scale west-side-up sense of movement. The faults are sub-parallel to the interpreted Monte Negro Fault, which also has an apparent west-side-up sense of movement.

Mineralized veins at the Monte Negro South Zone are relatively pyrite-poor, sphalerite-rich, and wider (five centimetres to six centimetres). The veins are sub-vertical and trend northwest. The episodic vein fill demonstrates a clear paragenesis (massive pyrite-enargite-sphalerite-grey silica).

Shallow-dipping bedding and sub-vertical sphalerite-silica veins on the southern margin of Monte Negro South are cut by a westerly-dipping thrust. The thrust has brought thinly bedded pyritic sedimentary rocks into contact with andesitic volcanic and volcaniclastic rocks. The fault dips 35° and was mapped across the top of the Monte Negro South hill. The overthrust sedimentary rock package contains asymmetric folds and bedding cleavage relationships that indicate a reverse (west-side-up) sense of movement. An upper thrust has brought a massive volcanic unit into contact with the underlying folded sediments.

The main zone of gold mineralization that results from this combination of structures extends for approximately 150 m along the West Thrust Fault.

MINERALIZATION CONTROLS USED IN RESOURCE ESTIMATES

Lithology does not constraint mineralization at Pueblo Viejo. The primary controls on the geometry of the gold deposits are strong quartz-pyrophyllite alteration and quartz-pyrite veining along sub-vertical structures and stratigraphic zones. The stratigraphic shape of some zones may be controlled by sub-horizontal structures that contain pyrite veins.

 

 

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The veins are tens of centimetres wide but are most commonly less than two centimetres wide. Narrow veinlets occur along bedding planes and along fracture surfaces. These veins are commonly highly discordant to bedding but locally branch out along shallow-dipping bedding planes, linking high angle veins in ladder-like fashion without obvious preferred orientations. These veins served as feeders to the layered and disseminated mineralization that occurs in shallower levels in the deposit. The result is composite zones of mineralization within fracture systems and stratigraphic horizons adjacent to major faults that served as conduits for hydrothermal fluids.

In summary, gold is intimately associated with the pyrite veins, disseminations, replacements, and layers within the zones of advanced argillic alteration. Gold values generally are the highest in zones of silicification or strong quartz-pyrophyllite alteration. Sphalerite is largely restricted to the veins, with pyrite lining the vein walls and sphalerite occurring as botryoidal aggregates. Galena, enargite, and boulangerite occur in small quantities in the centre of the veins.

These gold-bearing alteration zones are widely distributed in the upper parts of the deposits and tend to funnel into narrow feeder zones at depth. Mineralization is generally contained within the boundaries of advanced argillic alteration. The outer boundary of advanced argillic alteration, combined with lithological and veining zones were used to generate domains for resource estimation.

 

 

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8 DEPOSIT TYPES

Pueblo Viejo is a high sulphidation, quartz-alunite epithermal gold and silver deposit. High sulphidation deposits are typically derived from fluids enriched in magmatic volatiles, which have migrated from a deep intrusive body to an epithermal crustal setting, with only limited dilution by groundwater or interaction with host rocks. Major dilatant structures or phreatomagmatic breccia pipes provide conduits for rapid fluid ascent and so facilitate evolution of the characteristic high sulphidation fluid.

Similar deposits occur at Summitville, Colorado; El Indio, Chile; Lepanto, Philippines; and Goldfield, Nevada. They are characterized by veins, vuggy breccias and sulphide replacements ranging from pods to massive lenses, occurring generally in volcanic sequences and associated with high-level hydrothermal systems. Acid leaching, advanced argillic alteration and silicification are characteristic alteration styles. Grade and tonnage varies widely. Pyrite, gold, electrum and enargite/luzonite are typical minerals and minor minerals include chalcopyrite, sphalerite, tetrahedrite/tennantite, galena, marcasite, arsenopyrite, silver sulphosalts and tellurides (Panteleyev 1996).

The geological setting of the deposit is not certain at this time. Sillitoe and Bonham (1984), Muntean et al. (1990), and Kesler et al. (2005) have described the setting as a maar diatreme complex with the various deposits around the margins of the diatreme. These studies concluded that coarse-grained fragmental rocks that occur at depth are the product of an explosive volcanic eruption that partially filled the crater with fragmented rock. The crater was subsequently filled with shallow, marine sedimentary rocks with variable amounts of fragmental rocks from nearby volcanoes. This sequence was cross-cut by younger dykes and small dacite and andesite lava domes.

Alternatively, Nelson (2000) describes the setting as a volcanic dome complex emplaced in a shallow marine environment and attributes the coarse fragmental rocks to collapsing carapaces on those domes. The author concludes that sedimentary rocks were deposited in depressions between the domes.

More recently, Sillitoe et al. (2006) provide evidence from the Pueblo Viejo district that an extensive advanced argillic lithocap and the contained giant high sulphidation epithermal gold-silver deposits were emplaced beneath a thick limestone cover. The

 

 

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authors imply that alteration and mineralization cannot be synchronous with the host volcano-sedimentary sequence and are substantially younger. Hence, there is no genetic relationship between the Moore and Monte Negro deposits and either a maar-diatreme system or volcanic dome complex. Whereas other interpretations imply that mineralization pre-dated deposition of the Hatillo Limestone, Sillitoe et al. (2006) suggest that the impermeable limestone acted as a barrier inhibiting upward fluid flow, groundwater recharge, and heat dissipation. This resulted in high gold and zinc tenors, the dominance of quartz-pyrophyllite over vuggy quartz alteration, prograde overprinting of alunite by higher temperature pyrophyllite, and the almost exclusively magmatic character of the mineralized fluid. The authors present a model of blind high sulphidation deposits, based on a regional rather than detailed analysis of the mineralized zone within the open pits that could be applied to exploration in calc-alkaline magmatic arc elsewhere, especially in limestone terranes or potentially beneath other low permeability rock units.

In 2009, PVDC undertook a major relogging campaign of historical drill core and carried out detailed mapping of pits and construction excavations. The work has led to an updated geological model underpinning the resource and reserve estimations and a maar-diatreme deposit formation interpretation in which extensive and compressive deformation resulted in the present-day lithostructural domains. The conduits provided by maar-diatreme formation controlled mineralization. Structural control predominates, particularly at depth, and passes into lithological control near surface. Mineralization is present in pyroclastic rocks and sediments and occurs along bedding planes in upper sedimentary units and within narrow, local structures in the lower volcanic package.

The PVDC interpretation is based on geological evidence observed within the Pueblo Viejo deposit and is not a regional interpretation as presented by Sillitoe et al. (2006). However, PVDC believes uncertainty with respect to the deposits origin has no practical impact on exploration at the levels that may be mined by open pit methods. The areal extent of the deposits has been constrained by drilling and the vertical extents are reasonably well known, although additional drilling is required to define the deepest parts of the deposit.

 

 

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9 EXPLORATION

Section 9 provides a general overview of pre-PVDC exploration conducted on the Project. Reviews of drilling and sampling from this era are included in subsequent sections of this report. Much of the following exploration description is taken from Barrick’s 2007 FSU.

PVDC EXPLORATION PROGRAMS

In 2006, PVDC began to review the entire geological potential of the Pueblo Viejo Project, using works performed by previous owners to develop an understanding of the geology of the deposit and its potential.

The main components of PVDC’s 2006 exploration program, which provided data for input to the 2007 FSU were:

 

   

Data compilation and integration

 

   

Rock sampling (300 samples) and pit mapping

 

   

Alteration studies on 1,427 soil samples, 3,591 rock samples and 5,249 core samples

 

   

Geophysical surveys.

 

   

41 km of IP Pole—Dipole

 

   

132 km of ground magnetic readings on a 200 m grid

 

   

Geochemical Survey

 

   

1,482 samples collected for gold and inductively coupled plasma (ICP) assaying

 

   

Two-phase diamond drilling program:

 

   

Phase 1, 13 diamond drill holes, 3,772m

 

   

Phase 2, 40 diamond drill holes, 6,334m

 

   

Updated Mineral Resource estimate

The 2006 program allowed better definition of deposit geology and significantly increased the amount of ounces in both Moore and Monte Negro deposits.

No significant drilling was undertaken in 2009, but PVDC undertook a major relogging program of all historical drill core, carried out detailed geological mapping of pits and construction excavations, and reinterpreted the geological models underpinning resource and reserve estimates.

 

 

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In 2010, PVDC continued the detailed geological mapping of the pits and construction excavations, and also undertook a close-spaced reverse circulation (RC) grade control drilling program for Phase 1 pit shells in the Moore and Monte Negro open pits.

 

 

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10 DRILLING

Much of the following drilling description is taken from Barrick’s 2007 FSU.

Drilling campaigns have been conducted by most of the participating companies during the history of the Pueblo Viejo Project including Rosario, GENEL JV, MIM, and Placer. In 2006, PVDC began its first core drilling campaign to evaluate the Project. The time periods of drilling on the Project are summarized below:

 

   

Rosario—1970s to the early 1990s

 

   

GENEL JV—1996

 

   

MIM—late 1996 to 1997

 

   

BGC—2002 to 2004

 

   

Placer—2002 to 2004

 

   

PVDC—2006 to present

All pre-PVDC drill campaigns plus the drilling used in the Feasibility Study Mineral Resource estimate are listed in Table 10-1. Figures 10-1 and 10-2 show the drill hole locations on the Moore and Monte Negro deposits including the holes drilled by Barrick.

 

 

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TABLE 10-1 PRE-PVDC DRILLING

Barrick Gold Corporation—Pueblo Viejo Project

 

DH Prefix

   Company    Drill
Type
   Total
Holes

Included
     Total  Metres
Included
     Total  Holes
Excluded
     Total  Metres
Excluded
 

AH

   Rosario    Rotary      0         0         534         14,368   

CU

   Rosario    Rotary      0         0         357         9,721   

DDH

   Rosario    DDH      181         22,966         0         0   

DPV06

   PVDC    DDH      60         14,710         0         0   

GEN_MDD

   Genel JV    DDH      11         2,098         0         0   

GEN_MNDD

   Genel JV    DDH      9         1,053         0         0   

GT04

   Rosario    DDH      13         1,939         0         0   

HA

   Rosario    Rotary      0         0         111         2,966   

MIM_MN

   MIM    DDH      16         2,065         0         0   

MIM_MO

   MIM    DDH      15         2,535         0         0   

MN

   Placer    Rotary      2         44         0         0   

MO

   Placer    Rotary      48         672         0         0   

P

   Rosario    RC      343         8,706         0         0   

PD02

   Placer    DDH      19         3,039         0         0   

PD04

   Placer    DDH      102         13,485         0         0   

R

   Rosario    Rotary      115         6,571         0         0   

RC

   Rosario    RC      64         10,002         0         0   

RS

   Rosario    Rotary      175         24,258         1         138   

ST

   Rosario    Rotary      551         22,951         79         1,833   

SX

   Rosario    Rotary      90         1,254         59         769   
  

 

  

 

  

 

 

    

 

 

    

 

 

    

 

 

 
   Rotary      981         55,750         1,141         29,795   

Total

      RC      407         18,708         0         0   
      DDH      426         63,891         0         0   
      Total      1,814         138,349         1,141         29,795   

 

 

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FIGURE 10-1 DRILL HOLE LOCATIONS—MOORE DEPOSIT

 

 

LOGO

 

 

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FIGURE 10-2 DRILL HOLE LOCATIONS—MONTE NEGRO DEPOSIT

 

 

LOGO

 

 

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PRE-PVDC DRILLING

ROSARIO DRILLING

Rosario employed several drilling methods as summarized in Table 10-1. Geological information was recorded on paper logs or graphic logs for all core, RC, and rotary percussion drill holes.

Geology was recorded for deeper holes and for some of the shallow holes. Very few of the shallow holes are relevant to the 2007 Mineral Resource estimate. No photographs of the core were taken, a common practice in the 1970s and 1980s. The majority of holes were vertical with a drill hole spacing ranging from 20 m to 80 m. Downhole surveys were not performed and the type of instrumentation used for surveying collar locations is not documented.

Core recoveries were reported to be approximately 50% in areas of mineralization and within silicified material. This was evaluated by Fluor in 1986 with the following observations:

 

   

Gold grades varied with different recovery classes. In zones of 80% to 100% recovery, gold values decreased with decreasing core recovery. In zones of 60% to 80% recovery, gold values increased with decreasing recovery. For recoveries less than 60%, gold values were generally low.

 

   

Silver values were not affected by recovery.

 

   

Zinc grades exceeding 1.5% decreased with decreasing core recovery. Zinc grades below 1.5% appeared to be unaffected by core recovery.

Fluor concluded that poor core recovery affected gold grades but in both positive and negative ways. It also concluded that in the context of the whole deposit, statistical noise was apparent but the data were not biased.

With respect to rotary and RC drill holes, Fluor concluded that, with the exception of the P-series RC holes and the RS series of holes below the 250 m elevation in the West Flank of the Moore deposit, there was no systematic high bias in RC gold values versus core gold values. Zinc values appeared to be affected by “placering” in overflowing RC sampling devices, resulting in a low bias in RC holes. In any case, most of the shallow Rosario holes were drilled in oxide areas now mined out and have only limited, if any, influence on sulphide mineral resource estimates.

 

 

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GENEL JV DRILLING

In 1996, the GENEL JV drilled 20 holes at Pueblo Viejo, eleven in the Moore deposit and nine in the Monte Negro deposit (Table 10-1). Swiss-Boring was contracted to do the drilling using HQ core size. All holes were drilled at an angle. Downhole surveys were performed, but there is no record of the type of instruments used for the surveys. GENEL JV used a GPS system to locate drill holes and to survey the existing pits.

AMEC verified 5% of the assay data from these holes 2005 and found no errors in the database.

MIM DRILLING

In late 1996 and into 1997, MIM drilled 31 holes at Pueblo Viejo, 15 in the Moore deposit and 16 in the Monte Negro deposit (Table 10-1). Geocivil was contracted to do the drilling. Core size was HQ with occasional reductions to NQ as necessary to complete the holes. Five holes were vertical and 26 were drilled at an angle. There was apparently no downhole surveys performed on these holes. There is no record of instrumentation used to survey collar locations.

Original data documentation is not available from this drilling campaign for database confirmation and so the laboratory that analyzed the samples or the methodology used cannot be confirmed. Source certificates for confirmation of the database results are not available. Drill logs were entered into MS Excel and assays presented as printouts.

Placer personnel found some of the core, but because of its very poor condition, it could not be relogged or reassayed.

HISTORICAL DRILL HOLE SURVEYING

It has been concluded that the accuracy of the surveying methods used for GENEL JV holes are suitable to support resource estimates. The accuracy of collar and downhole surveys for Rosario and MIM drill holes cannot be confirmed. However, review of comparisons made between the results of these holes and results from more recent proximal holes of good quality, it has been taken to be sufficiently accurate to support resource estimates.

 

 

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PLACER DRILLING

Placer completed 3,039 m of core drilling in 18 holes during 2002 and 15,424 m of core drilling in 111 holes during 2004 (Table 10-1). The drilling used thin-walled NQ rods that produce NTW (57 mm) core. All but one of the holes was angled, allowing the vertical sulphide veining to be better represented in the drill hole intercepts. Placer drilled with oriented core to calculate the true orientations of bedding, veining, and faulting in the deposit areas.

Drill pads were located using GPS or surface plans where the GPS signal was weak. After completion, the drill hole locations were surveyed in UTM coordinates by a professional surveyor, translated into the mine coordinate system, and entered into the drill hole database.

Two or three downhole surveys were completed in all drill holes using a Sperry-Sun single-shot survey camera. Surveys were spaced every 60 m to 75 m and deviation of the drill holes was minimal. Azimuth readings were corrected to true north by subtracting 10°.

Drill holes were logged on paper forms using codes, graphic logs, and geologists’ remarks. Geological information related to assay intervals was recorded on a geology log. A second log was used to record structural information and a third log used to record geotechnical information. Coded data and remarks were typed into MS Excel spreadsheets and edited on site by geology technicians. Coded data were later imported into Gemcom to generate sections for resource modelling.

The following data were recorded on the geological log:

 

   

Lithology—type, interval in metres

 

   

Assay—interval, sample number (interval normally 2 m but intervals were also cut at lithology changes or major structures)

 

   

Oxidation—oxide, transitional, or sulphide facies

 

   

Alteration—type, intensity

 

   

Veining—type, estimated percentage

 

   

Disseminated sulphides—type, percentage

 

 

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The following data were recorded on the structural log:

 

   

Oriented Interval—core interval oriented by crayon mark

 

   

Structure Interval—downhole depth of structure

 

   

Structure description—type, true thickness (mm), oxidized (Y/N)

 

   

Structure angle—alpha angle to core axis (0-90°), beta angle from bottom of the core to the downhole apex of the structure (0-360°)

 

   

Vein composition/dominance—minerals in vein listed in order of abundance

The following data were recorded on the geotechnical log (by technicians under the supervision of a geologist):

 

   

Drill interval—From-To and length in metres of block-to-block intervals; 1.5 m under normal drilling conditions

 

   

Core recovery—measured in block-to-block intervals

 

   

Sum of core pieces greater than 10 cm (rock quality designation, or RQD), measured from block-to-block intervals

 

   

Fracture count—number of natural fractures per interval

 

   

Oriented—whether or not drill interval was successfully marked with orienting crayon

Prior to making geotechnical measurements, the entire core interval was removed from the core box and placed in a long trough made of angle-iron. The fractures in the core were lined up and artificial fractures were identified. This process allowed the technician to mark the orienting line on the core for a better estimate of core recovery and RQD.

EVALUATION OF DRILLING PROGRAMS

Validation of the historical drilling information was addressed as part of AMEC’s 2005 Pueblo Viejo Technical Report. To evaluate the possible biases between drill types and to validate the historical Rosario and MIM drilling information, Placer and AMEC performed two tests prior to the 2006 Barrick drilling. The first test compared assays from Placer and previous drilling programs. The second test was a cross section review.

 

 

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The following conclusions were drawn by Barrick in the 2007 FSU:

 

   

Approximately 2.5% of the Rosario data have been verified against original documents. Extensive evaluations of the possible bias introduced by various drilling procedures have been undertaken by Fluor, PAH, Placer, and AMEC. After reviewing the drill data, AMEC was of the opinion that the Rosario core, RC, and some Rosario conventional rotary data (pre-1975 and some Rosario RS-series) are generally reliable. There may be some bias in the RC data but those holes have been individually evaluated and obvious problems have been eliminated. The risk involved in using those data is judged to be acceptable. Drilling types that have produced questionable results, such as the P-series percussion holes, ST-series rotary holes and select RC holes, have been excluded from the database and are not used in the resource estimate.

 

   

GENEL JV data have been verified against original documents and are believed to be reliable.

 

   

MIM data have not been verified against original documents and there is some risk involved with using those data. AMEC compared those data to nearby Placer data and found that the MIM holes indicated mineralized zones with very similar tenors and thicknesses as the Placer and Rosario data. The risk involved with using the MIM data is considered acceptable.

 

   

Placer data have been verified against original documents and are believed to be reliable.

PVDC further reviewed the historical drill hole data prior to updating the 2007 resource estimate (see Section 12).

PVDC DRILLING

2006

PVDC completed 10,015 m of core drilling in 53 holes during 2006. The drilling was a part of the resource confirmation program conducted by the Barrick Geological Team. Six holes totalling 1,506 m were drilled to identify mineralization along high grade trends and potential mineralization with high priority targets near the pits. Forty-two holes (7,293 m) tested open mineralization along pit edges to define inferred resources along the pit edges, and five holes totalling 1,216 m were drilled to test the pit bottom.

The drilling was completed using thin-walled NQ rods that produce NTW (57 mm) core. Some holes were started on PQ and some holes were reduced to 42 mm. All the core holes drilled by Barrick were angle holes, allowing for a better representation of the vertical sulphide veining.

 

 

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Drill pads were marked with wooden pegs after using GPS to find the pre-selected locations. In areas where the GPS signal was weak, the Rosario bench map and IKONOS satellite images were used. Holes were aligned using foresight and backsight pegs.

Two or three downhole surveys were completed in all drill holes using a Sperry-Sun single-shot survey camera. Surveys were spaced every 60 m to 75 m and deviation of the drill holes was minimal. Azimuth readings were corrected to true north by subtracting 10o. After completion, a wooden post marked with the drill hole number was placed in the collar of every hole. Final drill hole locations were then surveyed in UTM coordinates by a professional surveyor, translated into the mine coordinate system (truncated UTM), and entered into the drill hole database.

2007

Exploration drilling undertaken during 2007, post-dating the Barrick FSU exploration programs, concentrated on exploration drilling near the pits, condemnation drilling in the proposed plant area, and exploration drilling in outer targets. A total of 67,127 m of drilling was completed resulting in the discovery of new deeper mineralization on the east side of Monte Negro and additional mineralization in the west part of the Moore pit.

2008

During 2008, PVDC completed 121 diamond drill holes for 28,067 m. The programs included definition drilling on open mineralization at Monte Negro North, definition drilling between the Moore and Monte Negro pits, and geotechnical drilling to define pit slope parameters. In addition, 19 diamond drill holes for 3,366 m were drilled into the limestone areas to assist in the definition of limestone quality for construction and processing purposes.

2009

No PVDC drilling was undertaken in 2009.

2010

In 2010, PVDC undertook a close-spaced RC grade control drilling program for Phase 1 pit shells in the Moore and Monte Negro pits. This drilling comprised 1,120 holes for 38,485 m in the Monte Negro pit and 593 holes for 22,026 m in the Moore pit. In-fill RC drilling of 33 holes for 5,306 m was also carried out within the limestone resource areas.

 

 

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2011

PVDC continued close-spaced RC grade control drilling program for Phase 1 pit shells in the Moore and Monte Negro pits. A total of 22,876 m were completed in 2011.

 

 

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11 SAMPLE PREPARATION, ANALYSES AND SECURITY

Much of the following description of sample preparation, analyses, and security is taken from Barrick’s 2007 FSU.

SAMPLING STRATEGY

PRE-PLACER DRILLING PROGRAMS

No information is available concerning the sampling strategies used by Rosario during its drilling programs. The record indicates that Rosario generally sampled core on two metre intervals with some samples based on lithology. RC holes were generally sampled on two metre intervals.

The GENEL JV sampled on two metre intervals. The core was split into thirds and one-third was used for the analytical sample. The remainder could be archived or split again for metallurgical testwork.

From the records, it appears that MIM samples were collected on two metre intervals with adjustments for lithological boundaries. There is no documentation of the approach.

Averaged sample intervals for the different drilling campaigns are summarized in Table 11-1.

 

 

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TABLE 11-1 SAMPLE INTERVAL DATA FOR ROSARIO, GENEL JV

AND MIM DRILL HOLES

Barrick Gold Corporation—Pueblo Viejo Project

 

Drill

Hole

Series

   Company    Avg.
Sample
Interval
(m)
     Min
Sample
Interval
(m)
     Max
Sample
Interval
(m)
     No.
Samples
Taken
     Avg. Au
Grade
(g/t)
 

R

   Rosario      2.18         0.20         4.60         1,489         2.49   

RS

   Rosario      1.99         1.00         6.00         9,959         1.79   

RC

   Rosario      2.00         1.00         2.00         5,003         1.77   

DDH

   Rosario      2.20         0.08         14.41         8,910         2.02   

GEN

   GENEL JV      2.00         1.40         2.30         520         2.51   

MIM

   MIM      1.97         0.20         8.00         2,309         2.21   

PLACER DIAMOND DRILLING

Placer sample intervals were normally two metres, but were shortened at lithological, structural, or major alteration contacts. Prior to marking the sample intervals, geotechnicians photographed and geotechnically logged the core, then a geologist quick-logged the core, marking all the geological contacts. Geotechnicians then marked the sample intervals and assigned sample numbers. After the sample intervals were marked, the geologist logged the core in detail and the core was sent for sampling where it was cut into halves using a core saw.

PVDC DIAMOND DRILLING

PVDC adopted Placer’s core sampling procedures as described above, with the exception that three metre samples are used in non-mineralized zones.

SAMPLE PREPARATION, ANALYSES, AND SECURITY

ROSARIO

Samples were analyzed by fire assay for gold and silver, by LECO combustion furnace for carbon, and sulphur and by atomic absorption (AAS) for copper and zinc. No details are available on crush sizes, sub-sample sizes, or final pulp sample weights used during sample preparation. It was reported in a feasibility study undertaken for Rosario by Stone & Webster International Projects Corporation in 1992 (Stone & Webster, 1992) that the analytical procedures used up to that time were of industry standard.

 

 

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For the sulphide drilling program that started in 1984, two assay laboratories were present at site, a mainline laboratory responsible for gold, silver, copper, zinc, and iron analyses and a sulphide laboratory responsible for carbon and sulphur analyses. Sample preparation methods are not documented for this period.

Security of the samples after removal from the hole is not documented.

GENEL JV

It is inferred from discussions in GENEL JV documents, that samples were prepared on site by GENEL JV personnel. A one-third split of the core was crushed to minus 10 mesh, homogenized by passing through a Gilson splitter three times and sub-sampled to about 400 g using a Gilson splitter. The sub-sample was packaged and sent to Chemex Laboratories Ltd. in Vancouver, BC, Canada (Chemex) where presumably the final pulverization was undertaken. In GENEL JV documents, the final pulp grain size is not stated.

Samples were assayed at Chemex for gold, silver, zinc, copper, sulphur, and carbon. The procedures are not stated in GENEL JV documentation. A 32-element ICP analysis (G-32 ICP) was performed on each sample.

Security measures utilized by the GENEL JV are not documented.

MIM

No details are available on the sample preparation, analytical procedures, or security measures for the MIM samples.

Core from Rosario, MIM, and GENEL JV drilling was previously stored in inadequate storage facilities, which led to severe oxidation of the remaining core rendering it of limited value.

PLACER

During the 2002 and 2004 programs, drill core was cut in half with a diamond blade saw at site. The second half of the 2002 core was consumed in metallurgical testwork. The

 

 

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archived half of 2004 core was stored on site for future reference in suitable storage conditions. The other half was placed in plastic sample bags marked with the appropriate sample number and sealed with a numbered security tag (zap-strap). The manager of the drilling company drove the samples from the site to the airport unaccompanied by a Placer employee. The core samples were sent to Vancouver using airfreight and were received by ALS Chemex Labs Ltd. (ALS). No record was kept of the state of the security tags when logged into ALS.

The samples were prepared by marking all bags with a bar code, drying and weighing the sample, crushing the entire sample to greater than 70% passing 2 mm (10 mesh), and splitting off 250 g. The split was pulverized to better than 85% passing 75 µm (200 mesh) and was used for analysis. The remaining sample was stored at ALS in Aldergrove, BC, Canada.

Samples were assayed for gold, silver, copper, zinc, carbon, sulphur, and iron using the analytical techniques listed in Table 11-2. In addition to these elements, multi-element analysis was performed on 80 samples from drill hole PD02-003 using ALS’s ME-MS61 procedure. In 2004, every other sample from all drill holes was also analyzed using the ME-MS41 procedure.

All drill core samples from the Placer drilling programs were analyzed for total carbon by ALS’s C IR07 LECO furnace procedure. To ensure that the total carbon values represented organic carbon, a suite of 114 samples were reanalyzed by the C-IR6 procedure which removes all inorganic carbonate by leaching the sample prior to LECO analysis. The sample suite represented all of the lithologies found in the deposit area. All exhibited advanced argillic alteration or silicification of varying intensities. The results showed that the total carbon analysis was representative of organic carbon in samples with advanced argillic alteration or silicification.

 

 

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TABLE 11-2 ALS ANALYTICAL PROTOCOLS FOR PLACER

SAMPLES

Barrick Gold Corporation – Pueblo Viejo Project

 

Element

  

ALS Chemex

Method Code

  

Description

  Range

Au

   Au-GRA21    30 g fire-assay, gravimetric finish   0.05-1,000 ppm

Ag

   Ag-GRA21    30 g fire-assay, gravimetric finish   5-3,500 ppm

Cu

   AA46    Ore grade assay, aqua regia digestion, AA finish   0.01-30%

Zn

   AA46    Ore grade assay, aqua regia digestion, AA finish   0.01-30%

C

   C-IR07    Total Carbon, LECO furnace   0.01-50%

S

   S-IR07    Total Sulphur, LECO furnace   0.01-50%

Fe

   AA46    Ore grade assay, aqua regia digestion, AA finish   0.01-30%

PVDC

PVDC drill core is cut in half with a diamond blade saw at site. The entire second half of core is kept for records and future metallurgical testwork. The archived half of the core is stored on site for future reference in suitable storage conditions. The sampled half is placed in plastic sample bags marked with the appropriate sample number and sealed with a numbered security tag.

Core samples from 2006 and early 2007 were shipped directly to ALS (ISO 9001, ISO/IEC 17025). PVDC requested fire assay (FA) with atomic absorption (AA) finish for gold and silver on 30 g aliquots and gravimetric finishes (GR) for all assays exceeding 10 g/t Au. A 32-element ICP analysis was done on all samples. All of the LECO furnace assays for 2006 and 2007 were done at Acme Analytical Laboratories Ltd., Vancouver (ACME) (ISO 9001). PVDC switched to ACME in February 2007. In 2007, PVDC changed the crushing specification from at least 70% passing 10 mesh to 80% passing 10 mesh and also modified the analytical protocols. The gold fire assay aliquot was increased to 50 g and ICP was used for silver, copper, and zinc. Silver values over 50 ppm were reanalyzed using FA-GR and copper and zinc values over 10,000 ppm were reanalyzed using a total digestion method.

 

 

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ACME set up a sample preparation facility at the Pueblo Viejo site in 2007. RPA previously visited the ACME facility while at the site and found it was clean, organized, and professionally operated. Since mid-2010, PVDC has been preparing the sub-samples on-site and sending the pulverized samples to commercial laboratories: ACME in Santiago, Chile, and ALS in Lima, Peru. Construction of the on-site laboratory is expected to be completed in late 2011.

Figure 11-1 shows PVDC’s on-site sample preparation flow sheet. In RPA’s opinion, sampling by Placer and PVDC has been performed appropriately for the style of mineralization present at Pueblo Viejo. Sampling of the pre-Placer samples may have been adequate, but there is little in the way of documentation to confirm this. Sample preparation for the Rosario and MIM samples has not been documented.

PVDC currently requests gold assays by FA with AA on 30 g aliquots and gravimetric finishes for all assays exceeding 10 g/t Au. Silver and zinc values are analyzed using aqua regia digestion method and AA finish. A 35-element inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis is done on all samples. Sulphur and carbon are assayed by LECO furnace.

 

 

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FIGURE 11-1 PVDC SAMPLE PREPARATION PROCEDURE

 

LOGO

 

 

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QUALITY ASSURANCE AND QUALITY CONTROL

Quality assurance and quality control (QA/QC) procedures have varied significantly during the work history at Pueblo Viejo. AMEC (2005) found the QA/QC data pertaining to all the historical (pre-2005) drilling programs, except GENEL JV, to be inadequate for proper validation of the assay results. Placer data from 2002 to 2004 was found to be adequate, but improved QA/QC protocols would benefit future drill programs.

ROSARIO

The number of check assays completed for the Rosario drill holes is limited but provides a level of confidence for specific drill holes. In general, Rosario did not insert duplicates, blanks and standards, however, they did send replicates in 1978 and 1985 to outside laboratories.

In 1978, Rosario sent 1,586 replicate samples from ten drill holes to Union Assay Laboratory in Salt Lake City, Utah. The gold check assays exhibited substantial scatter, including several obvious outliers. Some of the scatter may have been due to sample swaps, but most of it was unexplained. There was a small bias just outside a reasonable acceptance limit of 5%. Overall, excluding obvious outliers, the data corresponded reasonably well. The silver data was similar to the gold data in the significant amount of scatter and the large number of outliers. There was a small (5%) bias between the laboratories. Copper exhibited a small amount of scatter and no appreciable bias between the laboratories. Zinc exhibited more scatter than copper but less than gold and silver, although some of the outliers appeared to be sample swaps. There was about a 7% bias between the laboratories (direction of bias not stated).

In 1985, Rosario sent samples to three laboratories for gold, silver, carbon, and sulphur assay validation including:

 

   

392 samples sent to the Colorado School of Mines Research Institute (CSMRI) for check assaying of the Au and Ag values in three batches.

 

   

236 samples sent to Hazen Laboratories.

 

   

154 samples sent to AMAX Research and Development Laboratory for sulphur and carbon analysis. Results for these checks have not been located.

 

 

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AMEC (2005) reviewed the CSMRI check and reported that gold results generally corresponded well, but there were a number of outliers, possibly caused by sample swaps. The same conclusions were drawn for silver. AMEC also noted that there was a small bias between the two laboratories of about 7% (direction of bias not stated).

GENEL

The GENEL JV used a combination of duplicate and Standard Reference Materials (SRMs) to monitor the quality of its assays and a detailed review of the results found that the relative error of the 171 duplicates at the 90th percentile was 14%, which is very good precision for gold mineralization, and that the standard results were generally within acceptable limits (AMEC, 2005). However, the standard dataset includes many results that exceed the accepted limits and it is not known if these samples were reassayed.

MIM

The MIM samples have no known QA/QC data.

PLACER

In 2002, Placer inserted SRMs as every 20th sample to the primary laboratory, ALS. The SRMs where commercially purchased for gold only and corresponded to the average grade and cut-off grade at the time. Plots of gold versus batch number showed that the majority of the SRMs returned values within two standard deviations of their established means.

In 2004, Placer began inserting one blank (barren limestone) in addition to one SRM with every batch of 20 samples. All of these standards and the blank were assayed for Au, Ag, C, S, Cu, Fe, and Zn and provide a basis to evaluate the performance of those elements. AMEC calculated best values for all of the elements in each sample based on the results from ALS. Gold was the only certified value, and the best values calculated from the ALS data were indistinguishable from the certified values indicating that ALS generally performed well. The blank data (380 analyses) generally showed blank values except for ten anomalous of these samples which were inadvertently switched for SRMs.

 

 

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Placer also monitored the ALS internal quality control results for its blanks, duplicates, and SRMs. As well, Placer sent approximately ten sample pulps from every drill hole, resulting in 187 samples, or 13% of the total samples, from the 2002 drill program, to ACME. An additional 247 sample pulps were shipped during the 2004 drilling program and were analyzed for gold only. SRMs were not inserted into the external check pulp shipments. Results for gold, copper, and zinc indicated no significant biases between the two laboratories. The ALS Chemex silver assays, however, averaged approximately 12% lower than ACME.

ALS QUALITY CONTROL

ALS conducted analytical quality control in its laboratory by inserting blanks, standards, and duplicates into every sample run, results being reviewed by laboratory staff.

PVDC

PVDC inserted two blanks, two standards (commercial and custom), and two core duplicates into each batch of 75 samples sent to ALS. From February 2007 onwards, PVDC inserted two blanks, two to three standards (commercial and custom), two core duplicates, two coarse duplicates, and seven cleaning blanks into each batch of 76 samples prepared on the site and sent to ACME. Since August 1, 2007, PVDC began sending 5% of the pulps to a secondary laboratory (SGS in Peru) and, as of January 2008, was still working towards getting external check assays for 5% of all of its samples. The ACME on-site preparation facility carried out regular granulometric control tests on approximately three percent of the crushed and pulverized material. The results were monitored by ACME and PVDC personnel.

From July 2006 to August 2007, PVDC sent 29,977 samples and 2,997 control samples, or 10%, to ALS and ACME. The control samples included 958 blanks, 960 core duplicates, and 1,079 SRMs. The blank results show a significant reduction in failures in February 2007, coincident with the changeover to ACME. The scatter plots compiled by PVDC indicate fairly poor precision for core duplicates, probably in the ±30% to ±40% range for assays in the 2 g/t Au to 4 g/t Au range. Scatter plots for the duplicates were also compiled on a monthly basis and some months exhibit significantly more scatter than others, suggesting that some parts of the deposit, such as the Stage III veined areas, have much higher nugget effects than other parts.

 

 

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PVDC made five custom SRMs, averaging approximately 1 g/t Au to 10 g/t Au, from Pueblo Viejo mineralization. PVDC also inserted five commercial SRMs in 2006. Surprisingly, the commercial SRMs had much higher failure rates, in the 5% to 10% range, compared with the in-house standards with failure rates of generally less than 1% to 2%. No gold assaying bias is evident from any of the standard quality control charts.

Monitoring is completed on a batch by batch basis. For check samples that fell outside of the established control limits, PVDC examined the cause and, if found not to be the result of a sample number switch, the relevant batch was re-assayed. Corrective actions taken by PVDC are detailed in its in-house resource database and reports.

A PDVC internal quarterly report details the QA/QC results of the check samples for January to August 2010 on the RC grade control drilling currently underway. A total of 32,437 samples were dispatched in 560 shipments including 2,161 SRMs (6.7%), 2,161 blanks (6.7%), and 2,166 field duplicates (6.7%). Samples were sent to ACME from January to May and to ALS from June to August. Nine SRMs were available for insertion into the sample stream. Monitoring of the results required reanalysis of 136 groups of samples. Selected control charts for the SRMs are shown in Figure 11-2. Control Charts for the blanks and field duplicates are shown in Figures 11-3 and 11-4.

 

 

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FIGURE 11-2 STANDARD REFERENCE MATERIAL CHARTS

 

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FIGURE 11-3 FIELD DUPLICATE CHARTS

ACME

 

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ALS

 

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FIGURE 11-4 BLANK SAMPLE CHARTS

ACME

 

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ALS

 

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RPA SUMMARY AND COMMENTS

QA/QC procedures have varied significantly during the history of work at Pueblo Viejo. During the time of Rosario’s operation, QA/QC consisted of two batches of check assays sent to a second laboratory without duplicate, blank, or standard samples. Although the QA/QC was sub-standard relative to current industry practice, it must be viewed in its historical context and check assaying was the industry standard for QA/QC at that time.

MIM sample data lack any QA/QC validation. The quality of those data is indeterminate. There is no reason to believe that there are any problems with those data, but the quality cannot be directly evaluated. Comparison of the tenor and thickness of mineralized zones defined by the MIM data with tenor and thickness of mineralized zones defined by the Placer and GENEL JV indicate that the grades are similar.

Placer relied on two standards and check assaying for QA/QC. No duplicate samples were analyzed and the check analysis program included no certified reference materials or blank samples. RPA considers Placer assay data to meet a minimum standard to include in resource model and estimates.

In RPA’s opinion, the QA/QC results from PVDC are acceptable and have shown that sample preparation carried out by PVDC and assaying completed by the commercial laboratories are suitable for resource estimate purposes. RPA is also of the opinion that sample security is adequate and meets industry standards.

 

 

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12 DATA VERIFICATION

Much of the following description of data verification is taken from Barrick’s 2007 FSU with additional material from AMC’s 2011 Technical Report.

PRE-PLACER DATA

American Mine Services (AMS), as part of the 1992 Stone & Webster (1992) study, developed a computer database consisting of drill hole collar locations, assays and assay intervals, and geological data. The AMS database formed the foundation of the database provided to GENEL JV and MIM in 1995 and subsequently acquired by Placer. Placer compared the GENEL JV database with that provided by Rosario and confirmed that only minor changes had been made since AMS’s validation exercise. The changes were corrected based on original Rosario assay sheets and drill logs at the Pueblo Viejo site.

Placer compared drill locations and assay grades to original paper plans and sections at the mine site. Drill hole collar maps were plotted using the computer database and compared against hand-drawn maps and typewritten drill hole collar reports. A complete description of the validation work is contained in Placer (2003).

For the MIM drill holes, original drill logs or assay certificates are not available for validation. Assay data for MIM drill holes was received electronically. For the GENEL JV drill holes, the original assay certificates, which were used to validate the assay database and copies of drill logs, were printed from an MS Excel database. These were entered from the original logs, which have been lost. Survey notes are not available to validate the GENEL JV collar data. Placer checked 8% of the Rosario samples, 64% of the GENEL JV samples, none of the MIM samples, and 0.8% of its own samples and found very few data entry errors.

DRILL HOLE PSEUDO PAIRINGS

Rosario “pseudo” twin assay pair testing was completed by AMEC (2005). The test compared results of nearby holes by searching for Rosario samples near Placer drill holes (2002 and 2004 drilling programs) and also using earlier drilling by GENEL JV. Assays from Placer and GENEL JV drilling were paired with assays from Rosario drilling

 

 

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using different search radii and AMEC constructed declustered QQ plots and confirmed conclusions by Placer. The work generally showed that Rosario drilling was reliable, although biases where noted at grades higher than 6 g/t Au and below 2 g/t Au (Figure 12-1).

FIGURE 12-1 AMEC DRILL HOLE COMPARISON

Placer Dome Drilling Versus Rosario Drilling

10m Search Criteria

Moore Deposit

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HISTORICAL TWINNED HOLE COMPARISONS

As part of the 1986 Feasibility Study, Fluor (1986) undertook “twinned” hole comparison, looking at closely spaced drill holes applying a metal accumulation (grade x interval thickness) approach. Fluor concluded that there was no significant gold, silver, and zinc biases and that “carbon assays were consistently lower by 7% and zinc assays were lower on average by 36% than the original hole”. One hole, RS-40, was removed from the resource estimation database because it appeared to have been drilled down a near-vertical mineralized structure.

AMEC (2005) compiled a list of “twinned” holes (Table 12-1) and found that the wide divergence in “twinned” hole behaviour allowed no simple conclusions to be drawn. AMEC also observed that there was a tendency for RC holes to return somewhat higher

 

 

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grades and metal contents than core holes, due possibly in part to localized, downhole contamination in the RC holes; and that there appeared to be zones within the Pueblo Viejo deposits where the grades were extremely erratic and holes separated by only a few metres returned very different results. AMEC concluded that this probably explained many of the differences observed between twin holes. RPA notes that the 39 “twinned” holes in Table 12-1 represent pairs of holes with collars that are located within approximately one metre to ten metres. Normally, twinned holes are drilled to compare the reliability of different sample media and diamond drill holes are used to validate RC holes.

The types of “twin” hole pairs are summarized in Table 12-2. There are 26 pairs of holes that are of the same type, including eighteen rotary air blast (RAB) pairs, five diamond drill hole pairs, and three RC pairs. These 26 pairs are useful for investigating short-range variability, which is reported to be high locally (AMEC, 2005). Some of these same type drill hole pairs may have been a second test of holes with unusually high or low values. These 26 pairs cannot be used to validate the results from specific historical drilling programs.

 

 

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TABLE 12-1 TWIN HOLE DATA IN AMEC (2005)

Barrick Gold Corporation – Pueblo Viejo Project

 

Hole-ID

   Easting      Northing      Elevation      Length  

AH367

     73626.00         96332.70         472.40         34   

AH533

     75615.30         95618.90         311.70         16   

DDH131

     75756         94552         214.5         38.2   

DDH161

     76159.75         94600.34         348.61         232.5   

DDH162

     76000.00         95302.20         338.39         242   

DDH218

     74992.03         95750.3         381.28         108   

DDH219

     74881.52         95808.29         363.06         116.1   

DDH258

     74312.19         95613.00         303.35         89.6   

DDH259

     75836.23         95092.43         310.96         187.85   

GEN_MDD2

     75871.76         94400.91         219.52         132.2   

GEN_MNDD1

     75210.71         95175.38         262.67         27.4   

GEN_MNDD4

     75151.64         95600.18         318.77         140.2   

GT04-10

     76251.35         94657.25         344.92         126.49   

MIM_MN007

     75175.61         95713.38         351.77         50.3   

MIM_MO007

     76006.03         94476.26         245.14         200.15   

MIM_MO015

     75903.42         94702.51         258.41         150   

R117

     76674.50         94570.10         328.70         18   

R17

     75992         94298         243.5         98.3   

R29

     75860.00         94455.60         226.60         18.3   

R42

     76233         95003         332.8         77.7   

R60

     75856.00         94782.00         258.00         75.4   

R70

     75852         94832         264.6         91.4   

RC14

     75043.02         95746.28         380.13         204   

RC15

     75115.12         95394.38         309.67         114   

RC16

     75985.15         94802.1         281.68         84   

RC16

     75985.15         94802.1         281.68         84   

RC9

     75115.18         95397.14         309.79         208   

RS111

     74904.55         95592.19         344.56         56   

RS131

     75290.86         95100.48         251.04         116   

RS142

     75195.50         95362.30         291.90         150   

RS2

     76165.87         94596.29         348.84         152   

RS3

     76169.54         94604.54         349.04         202   

RS4

     76175.83         94609.45         349.41         72   

ST257

     75947.72         94360.58         220.18         30   

ST329

     76252.18         94759.21         337.08         30   

ST445

     75073.19         95630.21         341.21         10   

ST543

     74882.45         95652.65         344.62         12   

ST569

     75633.84         95850.93         338.29         11   

ST630

     76252.18         94759.21         337.08         60   

AH369

     73626.10         96332.80         472.40         26   

DDH233

     75615.32         95618.90         311.73         128.6   

RS83

     75751.2         94546.53         215.65         174   

 

 

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Hole-ID

   Easting      Northing      Elevation      Length  

RS2

     76165.87         94596.29         348.84         152   

RS11

     76000.14         95301.24         329.35         130   

RC3

     74992.97         95747.84         381.18         210   

RS108

     74882.88         95808.97         362.81         184   

AH395

     74314.00         95608.40         304.20         40   

RC47

     75834.01         95097.23         311.25         112   

GEN_MDD2A

     75871.76         94400.91         219.52         40   

GEN_MNDD1A

     75209.46         95175.25         262.41         74.1   

GEN_MNDD4A

     75151.64         95600.18         318.77         18.3   

RC21

     76251.48         94647.66         347.44         177   

MIM_MN008

     75175.61         95713.38         351.77         122   

MIM_MO009

     76005         94476.3         245.1         200   

RC23

     75899.97         94700.09         261.05         178   

R117B

     76675.72         94571.16         329.03         44   

RS135

     75997.24         94302.59         247.42         200   

R30

     75860.90         94451.10         226.60         59.4   

RS90

     76232.8         95005.17         329.34         194   

ST562

     75856.42         94787.88         258.30         60   

RC51

     75845.41         94837.84         265.8         164   

RS94

     75051.03         95752.06         379.84         237.58   

RC9

     75115.18         95397.14         309.79         208   

RC18

     75981.53         94808.59         281.36         146   

RS40

     75984.9         94800.8         288.9         180   

RC15

     75115.12         95394.38         309.67         114   

RS111A

     74901.39         95583.09         343.61         140   

ST455

     75291.20         95104.90         250.00         60   

ST183

     75196.20         95370.70         291.90         50   

RS3

     76169.54         94604.54         349.04         202   

RS4

     76175.83         94609.45         349.41         72   

RS5

     76184.67         94605.36         349.38         142   

ST236

     75947.78         94361.00         220.00         30   

ST630

     76252.18         94759.21         337.08         60   

ST445A

     75073.19         95630.22         341.21         50   

ST543A

     74882.45         95652.65         344.62         32   

ST578

     75633.84         95850.93         338.29         16   

ST631

     76252.18         94759.21         337.08         50   

 

 

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TABLE 12-2 TYPES OF DRILL HOLE “TWINS”

Barrick Gold Corporation – Pueblo Viejo Project

 

Description

   Count  

DDH versus RAB

     6   

DDH versus RC

     4   

RC versus RAB

     3   

DDH versus DDH

     5   

RAB versus RAB

     18   

RC VS RC

     3   
  

 

 

 

Total Number of “Twins”

     39   

Placer (2005) used the average of 17 “twin” holes (Table 12-3), including four pairs that are spaced more than 10 m apart and that are not included in Table 12-3, to conclude that:

the average grades of the twinned hole results compare well, within 10% of each other. There does not appear to be any obvious trends between drilling methods, as many of the different drilling methods compare well.

Placer (2005) excluded two additional twin pairs (RC16-RS40 and DDH259-RC47) because of poor results and did not use RS-40 in its resource estimate. Placer excluded all of the ST series holes due to concerns related to poor sampling techniques and all of the SX holes because they were outside the resource area. Some 58 R-series, 38 RS-series, and 18 DDH-series holes were also excluded due to contamination concerns or because the holes were situated outside the resource area.

 

 

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TABLE 12-3 PLACER 2005 “TWIN” HOLES

Barrick Gold Corporation – Pueblo Viejo Project

 

Hole 1

   Hole 2    Distance
(m)
     Nb Data      Mean 1      Mean 2      Difference     Correlation  

DDH 162

   RS I I      9.1         21         5.054         5.464         8.1     -0.003   

DDH218

   RC3      2.6         46         5.355         7.143         33.4     0.492   

DDH219

   RS 108      1.5         28         1.827         1.675         -8.3     -0.203   

RC14

   RS94      9.9         79         3.393         3.545         4.5     0.493   

RC9

   RC15      2.8         46         2.435         2.163         -11.2     0.040   

RS27

   RC20      14.9         22         5.932         6.411         8.1     0.443   

RS62

   DDH220      11.3         63         0.780         0.725         -7.1     0.397   

RS75

   RC17      17.6         77         4.773         5.288         10.8     -0.094   

RS93

   RC13      13.7         62         2.529         3.096         22.4     0.045   

DM-1,161

   RS2      7.3         66         1.779         1.854         4.2     0.553   

MIMMN007

   M1MMN008      0.0         24         1.149         2.140         86.2     0.405   

MIMM0007

   MIMM0009      1.0         100         2.319         2.454         5.8     0.437   

MIMM0015

   RC23      5.0         74         3.360         3.061         -8.9     0.134   

R70

   RC:51      8.9         33         2.026         1.909         -5.8     0.139   

RC16

   RC18      7.4         41         3.212         3.333         3.8