EX-96.1 17 vgz-20211231xex96d1.htm EX-96.1

Exhibit 96.1

P1C1T1#yIS1

S-K 1300 Technical Report Summary

Mt Todd Gold Project | 50,000 tpd Feasibility Study

Northern Territory, Australia

Graphic

Effective Date: December 31, 2021

Issue Date: February 9, 2022

Amended Date: February 7, 2023

Project No. 117-8348002

P14#y1


Suite 5

-1185

Suite 500

+1 (303) 217-5700
tetratech.com

S-K 1300 Technical Report Summary

Mt Todd Gold Project | 50,000 tpd Feasibility Study

Northern Territory, Australia

Project No. 117-8348002

Effective Date:December 31, 2021

Issue Date:February 9, 2022

Amended Date:February 7, 2023

PRESENTED TO

PRESENTED BY

Vista Gold Corp.

7961 Shaffer Parkway, Suite 5

Littleton, CO 80127

P +1 (720) 981-1185

Tetra Tech

350 Indiana Street, Suite 500

Golden, CO 80401

P: +1 (303) 217-5700
tetratech.com

Prepared by:

Sabry Abdel Hafez, Ph.D., P.Eng.

Rex Clair Bryan, Ph.D., SME RM

Thomas L. Dyer, P.E., SME RM

Amy L. Hudson, Ph.D., CPG, REM

April Hussey, P.E.

Chris Johns, M.Sc., P.Eng

Max Johnson, P.E.

Deepak Malhotra, Ph.D., SME RM

Zvonimir Ponos, BE, MIEAust, CPeng, NER

Vicki J. Scharnhorst, P.E., LEED AP

Keith Thompson, CPG, member AIPG

P65#y1


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

FORWARD-LOOKING STATEMENTS

This Technical Report contains forward-looking statements within the meaning of the U.S. Securities Act of 1933, as amended, and U.S. Securities Exchange Act of 1934, as amended, and forward-looking information within the meaning of Canadian securities laws. All statements, other than statements of historical facts, included in this Technical Report that address activities, events or developments that Vista expects or anticipates will or may occur in the future, including such things as, the Company’s continued work on the Mt Todd gold project; that process improvements will result in lower operating costs, reduced power consumption, increased gold recovery and higher gold production; estimates of mineral reserves and resources; projected project economics, including anticipated production, average cash costs, before and after-tax NPV, IRR, capital requirements and expenditures, gold recovery after-tax payback, operating costs, average tonnes per day milling, mining methods procedures, estimated gold recovery, project design, and life of mine; that the Project is an advanced stage development project; average annual production over time; commencement of commercial production; timing for construction and commissioning; exploration of new deposits at Mt Todd and the surrounding exploration areas; size of final product through the high pressure grinding roll crusher; potential costs or savings related to gas price; ability to convert Quigleys estimated mineral resources to proven or probable mineral reserves; grade of minerals at the Quigleys deposit; ability to add higher grade feed from the Quigleys deposit to the Project in its mid years; timing for and completion of the S-K 1300 technical report for the FS; and other such matters are forward-looking statements and forward-looking information. The material factors and assumptions used to develop the forward-looking statements and forward-looking information contained in this Technical Report include the following: the accuracy of the results of the FS, mineral resource and reserve estimates, and exploration and assay results; the terms and conditions of the Company’s agreements with contractors and Vista’s approved business plan; the anticipated timing and completion of a feasibility study on the Project and permissions including approval of the MMP; the potential occurrence of certain threatened species of flora, vegetation, and fauna within the mine site; the anticipated receipt of required permits; no change in laws that materially impact mining development or operations of a mining business; the potential occurrence and timing of a production decision; the anticipated gold production at the Project; the life of any mine at the Project; all economic projections relating to the Project, including estimated cash cost, NPV, IRR, and initial capital requirements; and Vista’s goal of becoming a gold producer. When used in this Technical Report, the words “optimistic,” “potential,” “indicate,” “expect,” “intend,” “plans,” “hopes,” “believe,” “may,” “will,” “if,” “anticipate,” and similar expressions are intended to identify forward-looking statements and forward-looking information. These statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of Vista to be materially different from any future results, performance or achievements expressed or implied by such statements. Such factors include, among others, uncertainty of mineral resource estimates, estimates of results based on such mineral resource estimates; risks relating to cost increases for capital and operating costs;  risks related to the timing and the ability to obtain the necessary permits, risks of shortages and fluctuating costs of equipment or supplies; risks relating to fluctuations in the price of gold; the inherently hazardous nature of mining-related activities; potential effects on Vista’s operations of environmental regulations in the countries in which it operates; risks due to legal proceedings; risks relating to political and economic instability in certain countries in which it operates; as well as those factors discussed under the headings “Note Regarding Forward-Looking Statements” and “Risk Factors” in Vista’s Annual Report Form 10-K as filed on February 26, 2021 and other documents filed with the U.S. Securities and Exchange Commission and Canadian securities regulatory authorities. Although Vista has attempted to identify important factors that could cause actual results to differ materially from those described in forward-looking statements and forward-looking information, there may be other factors that cause results not to be as anticipated, estimated or intended. Except as required by law, Vista assumes no obligation to publicly update any forward-looking statements or forward-looking information; whether as a result of new information, future events or otherwise.

TETRA TECH

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

NOTE

All references to the term “ore” contained in this Technical Report refer to mineral reserves, not mineral resources.

TETRA TECH

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

TABLE OF CONTENTS

1. EXECUTIVE SUMMARY

1

1.1

Introduction

1

1.2

Location

1

1.3

Property Description

1

1.4

Geology and Mineralization

6

1.5

Mineral Resource Estimate

6

1.6

Mineral Reserve Estimates

8

1.6.1

Heap Leach Reserve Estimate

8

1.7

Mining Methods

8

1.8

Metallurgy

10

1.9

Mineral Processing

12

1.10

Project Infrastructure

12

1.11

Market Studies and Contracts

13

1.11.1

Markets

13

1.11.2

Contracts

13

1.12

Social and Environmental Aspects

14

1.12.1

Existing Environmental and Social Information

14

1.12.2

Social or Community Requirements

14

1.12.3

Approvals, Permits and Licenses

14

1.13

Capital and Cost Estimates

15

1.13.1

Capital Cost Estimates

15

1.13.2

Operating Cost Estimates

17

1.14

Financial Analysis

17

1.15

Conclusions and Recommendations

18

2. INTRODUCTION

19

2.1

Background Information

19

2.2

Terms of Reference and Purpose of the Report

20

2.3

Sources of Information

20

2.4

Units of Measure

20

2.5

Detailed Personal Inspections

20

3. PROPERTY DESCRIPTION

22

3.1

Property Description

22

3.2

Lease and Royalty Structure

22

3.3

Risks

27

4. ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY

28

4.1

Accessibility

28

4.2

Climate and Physiography

28

4.3

Local Resources and Infrastructure

28

4.4

Topography, Elevation and Vegetation

28

5. HISTORY

29

5.1

History of Previous Exploration

30

5.2

Historic Drilling

32

5.2.1

Batman Deposit

32

5.2.2

Drillhole Density and Orientation

32

5.2.3

Quigleys

33

5.3

Historic Sampling Method and Approach

35

5.4

Historic Sample Preparation, Analysis and Security

35

5.4.1

Sample Analysis

35

TETRA TECH

i

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

5.4.2

Check Assays

36

5.4.3

Security

36

5.5

Historic Process Description

36

5.6

Technical Problems with Historical Process Flowsheet

37

5.6.1

Crushing

37

5.6.2

Flotation Circuit

40

5.6.3

CIL of Flotation Concentrate and Tailings

40

6. GEOLOGICAL SETTING, MINERALIZATION, AND DEPOSIT

41

6.1

Geological and Structural Setting

41

6.2

Local Geology

41

6.3

Mineralization

44

6.3.1

Batman Deposit

44

6.3.2

Quigleys Deposit

45

7. EXPLORATION

46

7.1

Deposit Types

46

7.2

Exploration

46

7.2.1

Golden Eye Target

48

7.2.2

RKD Target

49

7.2.3

Silver Spray Target

49

7.2.4

Snowdrop Target

49

7.2.5

Sample Preparation Methods and Quality Control (QC) Measures

50

7.2.6

Relevant Information Regarding Sample Preparation, Assaying, and Analytical Procedures

50

7.3

Drilling

51

7.3.1

Summary of Batman Drilling 1988-2017

51

7.3.2

Vista Drilling Detail 2012-2021

51

7.3.3

Summary of Quigleys Drilling 1975-2011

75

7.3.4

Drilling Procedures

88

7.3.5

Sampling

89

7.3.6

Summary and Interpretation of Relevant Results

89

8. SAMPLE PREPARATION, ANALYSES, AND SECURITY

91

8.1

Sample Preparation

91

8.2

Sample Analyses

92

8.3

Sample Security

97

9. DATA VERIFICATION

98

9.1

Drill Core and Geologic Logs

98

9.2

Topography

98

9.3

Verification of Analytical Data

98

9.3.1

Latest Drilling Data Verification

101

10. MINERAL PROCESSING AND METALLURGICAL TESTING

106

10.1

Summary

106

10.2

Historic Metallurgical Test Programs

106

10.3

2017 Metallurgical Test work

108

10.3.1

HPGR Testing at Thyssen-Krupp Industries (TKI)

108

10.3.2

Tomra/Outotec Ore Sorting Testwork

109

10.3.3

Preparation of Composites for Metallurgical Testwork

112

10.3.4

Mineralogical Study

112

10.3.5

Head Analyses

112

10.3.6

Abrasion Indices

113

10.3.7

Bond Ball Mill Work Indices

114

10.3.8

Leach Tests

115

TETRA TECH

ii

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

10.3.9

Cyanide Destruction

118

10.3.10

Thickening Tests

118

10.4

2018/2019 Metallurgical Test Work

118

10.4.1

HPGR Testing at Thyssen-Krupp Industries (TKI)

122

10.4.2

HPGR Testing at WEIR Minerals

122

10.4.3

Tomra/Outotec Ore Sorting Test Work

122

10.4.4

Steinert Ore Sorting Test Work

124

10.4.5

Preparation of Composites for Metallurgical Test Work and Head Analyses

126

10.4.6

Bond's Ball Mill Work Indices

126

10.4.7

Primary Grind

126

10.4.8

Fine Grind

127

10.4.9

Leach Feed Thickener

127

10.4.10

Leach Agitator Design and Power Requirements

127

10.4.11

Leach Tests

127

10.4.12

Thickening Tests on Leach Residue

131

10.4.13

Cyanide Destruction

131

10.5

Process Flowsheet

132

11. MINERAL RESOURCE ESTIMATES

134

11.1

Introduction

134

11.2

Geologic Modeling of the Batman Deposit

137

11.2.1

Batman Deposit Density Data

141

11.2.2

Grade Capping

141

11.3

Batman Block Model Parameters

141

11.3.1

Geostatistics of the Batman Deposit

141

11.4

Batman Estimation Quality

155

11.5

Quigleys Deposit

158

11.5.1

Quigleys Exploration Database

159

11.5.2

Quigleys Block Model Parameters

148

11.6

Existing Heap Leach Gold Resource

163

11.7

Batman Resource Estimate Over Time

164

11.8

Risk and Relevant Factors Affecting Resource Estimates

165

12. MINERAL RESERVES

167

12.1

Pit Optimization

1767

12.1.1

Economic Parameters

168

12.1.2

Slope Parameters

170

12.1.3

Pit-Optimization Results

172

12.2

Pit Designs

175

12.2.1

Bench Height

175

12.2.2

Pit Design Slopes

175

12.2.3

Haulage Roads

176

12.2.4

Ultimate Pit

177

12.2.5

Pit Phasing

179

12.3

Cutoff Grade

183

12.4

Dilution

183

12.5

Reserves

183

12.6

Heap Leach Reserve Estimate

184

13. MINING METHODS

185

13.1

Methods

185

13.2

Site Landforms and Impoundments

185

13.3

Waste Material Type Characterization

185

13.4

WRD Construction

186

TETRA TECH

iii

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

13.5

Operational Controls

186

13.6

Mine-Waste Construction and Reclamation Requirements

187

13.7

Mine Production Schedule

189

13.8

Equipment Selection and Productivities

193

13.9

Mine Personnel

196

14. PROCESSING AND RECOVERY METHODS

201

14.1

Process Design Criteria

201

14.2

Flow Sheet Development

202

14.2.1

Crushing Modeling

203

14.2.2

Primary Crusher

203

14.2.3

Secondary Crushers

203

14.2.4

HPGR

203

14.2.5

Grinding Modeling

203

14.2.6

Thickener/Leach/CIP Design

203

14.3

Description of Process Areas

204

14.3.1

Area 3100 – Crushing Circuit Availabilities

204

14.3.2

Area 3200 – Coarse Ore Stockpile, Reclaim, HPGR and Ore Sorting

205

14.3.3

Area 3300 – Grinding and Classification

205

14.3.4

Area 3400 – Pre-Leach Thickening, Leach Conditioning, Leach, and CIP

205

14.3.5

Area 3500 – Desorption, Goldroom, and Carbon Regeneration

206

14.3.6

Area 3600 – Detoxification and Tailings

206

14.3.7

Area 3700 – Reagents

206

14.3.8

Area 3800 – Process Plant Services

207

14.4

Plant Mobile Equipment

209

15. INFRASTRUCTURE

210

15.1

Facility 2000 – Mine

211

15.1.1

Area 2300 – Mine Support Facilities

211

15.1.2

Area 2400 – Mine Support Services

213

15.1.3

FACILITY 3000 – PROCESS PLANT

214

15.2

Facility 4000 – Project Services

224

15.2.1

Area 4100 – Water Supply

224

15.2.2

Area 4200 – Power Supply

225

15.2.3

Area 4300 – Communications

228

15.2.4

Area 4400 – Tailings Dam

229

15.2.5

Area 4500 – Waste Disposal

230

15.2.6

Area 4600 – Plant Mobile Equipment

230

15.3

Facility 5000 – Project Infrastructure

230

15.3.1

Area 5100 – Site Preparation

230

15.3.2

Area 5200 – Support Buildings

231

15.3.3

Area 5400 – Heavy Lift Cranage

233

15.3.4

Area 5600 – Bulk Transport

233

15.3.5

Area 5800 – Communications

233

15.4

Facility 6000 – Permanent Accommodation

234

15.4.1

Area 6100 – Personnel Transport

234

15.5

Facility 7000 – Site Establishment and Early Works

234

15.5.1

Area 7300 – Construction Camp

234

15.6

Facility 8000 – Management, Engineering, EPCM Services

235

15.6.1

Area 8100 – EPCM Services

235

15.6.2

Area 8200 – External Consultants/Testing

235

15.6.3

Area 8300 – Commissioning

235

15.6.4

Area 8400 – Owners Engineering/Management

235

TETRA TECH

iv

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

15.6.5

Area 8800 – License, Fees, and Legal Costs

235

15.6.6

Area 8900 – Project Insurances

236

15.7

Facility 9000 – Preproduction Costs

236

15.7.1

Area 9100 – Preproduction Labor

236

15.7.2

Area 9200 – Commissioning Expenses

236

15.7.3

Area 9300 – Capital Spares

236

15.7.4

Area 9400 – Stores and Inventories

236

15.7.5

Area 9600 – Working Capital and Finance

236

15.7.6

Area 9700 – Escalation and Foreign Currency Exchange

237

15.7.7

Area 9800 – Contingency Provision

237

15.7.8

Area 9900 – Management Reserve Provision

237

15.8

Electric Power

237

16. MARKET STUDIES

238

16.1

Markets

238

16.2

Contracts

238

17. ENVIRONMENTAL STUDIES, PERMITTING, AND PLANS, NEGOTIATIONS, OR AGREEMENTS WITH LOCAL INDIVIDUALS OR GROUPS

239

17.1

Environmental Studies

239

17.1.1

Flora and Vegetation

240

17.1.2

Nationally Threatened Fauna

240

17.1.3

Migratory and/or Marine Species

240

17.1.4

National Heritage Places

240

17.2

Waste and Tailings Disposal, Site Monitoring and Water Management

241

17.2.1

Waste Rock Disposal

241

17.2.2

Tailings Disposal

241

17.2.3

Site Monitoring

241

17.2.4

Water Management

241

17.3

Permitting and Authorizations

243

17.4

Social or Community Requirements

245

17.5

Mine Reclamation and Closure

245

17.5.1

Batman Pit

246

17.5.2

Waste Rock Dump

246

17.5.3

Tailings Disposal Facility

246

17.5.4

Processing Plant and Pad Area

247

17.5.5

Heap Leach Pad and Pond

247

17.5.6

Low Grade Ore Stockpile

247

17.5.7

Mine Roads

247

17.5.8

Water Storage Ponds

248

17.5.9

Low Permeability Borrow Area

248

17.5.10

Closure Cost Estimate

248

18. CAPITAL AND OPERATING COSTS

249

18.1

Capital Cost

249

18.1.1

Mining

250

18.1.2

CIP Process and Infrastructure

255

18.1.3

Mine Dewatering

267

18.1.4

Reclamation and Closure

267

18.1.5

Water Treatment Plant

268

18.1.6

Raw Water Dam

268

18.1.7

Tailings Storage Facilities

269

18.2

Operating Costs

270

18.3

Mining

270

TETRA TECH

v

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

18.3.2

Mine Dewatering

273

18.3.3

CIP Process and G&A

273

18.3.4

Water Treatment Plant

277

18.3.5

Tailings Storage Facilities

277

18.3.6

General & Administrative

278

19. ECONOMIC ANALYSIS

278

19.1

Principal Assumptions

278

19.2

LoM Production

279

19.3

Capital Costs

280

19.3.1

2000 Mining

280

19.3.2

3000 Process Plant

280

19.3.3

4000 Project Services

281

19.3.4

5000 Project Infrastructure

281

19.3.5

6000 Permanent Accommodation

281

19.3.6

7000 Site Establishment & Early Works

281

19.3.7

8000 Management, Engineering, EPCM Services

282

19.3.8

9000 Pre-Production Costs

282

19.3.9

10000 Asset Sale

282

19.4

Operating Costs

283

19.4.1

Open Pit Mining

283

19.4.2

CIP Process Plant

284

19.4.3

Water Treatment Plant

285

19.4.4

Tailings

285

19.4.5

General & Administrative

285

19.4.6

JAAC Royalty

286

19.4.7

Refining Costs

286

19.4.8

Operating Cost Inputs

287

19.5

Economic Results

294

19.5.1

Taxes, Royalties

298

19.5.2

Sensitivity

299

20. ADJACENT PROPERTIES

301

21. OTHER RELEVANT DATA AND INFORMATION

301

21.1

Process Plant Geotechnical

301

21.2

Water Management

301

21.2.1

Site-wide Water Balance

301

21.2.2

Wet Infrastructure

305

21.3

Geochemistry

312

21.4

Surface Water Hydrology

314

21.5

Regional Groundwater Model and Mine Dewatering

314

21.5.1

Regional and Site Hydrogeology

315

21.5.2

Regional Numerical Groundwater Flow Model

315

21.5.3

Inflow Estimates

317

21.5.4

Mine Dewatering

317

21.6

Project Implementation

320

21.6.1

Project Implementation Strategy

320

21.6.2

EPCM Organization

323

21.6.3

EPCM Management

323

21.6.4

Engineering

323

21.6.5

EPCM Controls

324

21.6.6

Procurement

325

21.6.7

Construction Management

330

TETRA TECH

vi

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

21.6.8

Commissioning

330

21.6.9

Temporary Construction Facilities

332

21.6.10

Industrial Relations

332

21.6.11

Health and Safety

332

21.6.12

Environment

333

21.6.13

Schedule

333

22. INTERPRETATION AND CONCLUSIONS

337

22.1

Project Risks

337

22.2

Geology and Resources

338

22.3

Mineral Reserve and Mine Planning

339

22.4

Mineral Processing

339

22.5

Infrastructure

339

22.5.1

Site Preparation

339

22.5.2

Support Buildings

340

22.5.3

Access Roads Parking and Laydown

340

22.5.4

Heavy Lifts

340

22.5.5

Bulk Transport

340

22.5.6

Communications

340

22.6

Project Services

340

22.7

Process Risks

340

22.7.1

Equipment Performance

340

22.7.2

Leach / Adsorption / Desorption Performance

341

22.7.3

Operations

341

22.7.4

Capital Cost and Operating Cost Risks

341

22.7.5

Schedule Risks

342

22.7.6

Hazard Identification Study

342

22.7.7

Health, Safety, Environment and Community

342

22.8

Environmental and Social Conclusions

342

22.8.1

Existing Body of Work

342

22.8.2

Environmental Impact Study and Approvals

343

22.8.3

Social or Community Impacts

343

22.9

Results of the Site-wide Water Balance Model

345

22.10

Water Treatment Plant

345

23. RECOMMENDATIONS

346

24. REFERENCES

346

25. RELIANCE ON INFORMATION PROVIDED BY THE REGISTRANT

350

26. CERTIFICATE OF QUALIFIED PERSON

351

26.1

Qualifications of Consultants

351

26.2

Table of Responsibility

352

TETRA TECH

vii

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

LIST OF TABLES

Table 1-1:

Description of Landforms and Impoundments

3

Table 1-2:

Statement of Mineral Resources Estimates

7

Table 1-3:

Statement of Mineral Reserve Estimate

8

Table 1-4:

Initial Economic Parameters

9

Table 1-5:

WhittleTM Pit Optimization Results – Using 0.35 g Au/t Cutoff

10

Table 1-6:

Headline Design Criteria

12

Table 1-7:

Mt Todd Permit Status

14

Table 1-8:

Estimated Capital Cost Summary (US$000s)

16

Table 1-9:

Estimated LoM Operating Costs (US$)

17

Table 1-10:

Estimated Technical-Economic Results (US$000s)

18

Table 5-1:

Heap Leach – Historic Actual Production

29

Table 5-2:

Property History

31

Table 5-3:

Summary of Quigleys Exploration Database

33

Table 6-1:

Geologic Codes and Lithologic Units

42

Table 7-1:

Exploration Sampling Before 2018

47

Table 7-2:

Exploration Sampling Between 2018 and 2019 by Target Area

47

Table 7-3:

Exploration Prospects

48

Table 7-4:

Batman Deposit Drilling History

51

Table 7-5:

Batman Deposit Drillholes Added for Resource Update

52

Table 7-6:

Batman Drillhole Details

53

Table 7-7:

Quigleys Deposit Drilling History

75

Table 7-8:

Quigleys Drillhole Details

75

Table 8-1:

Assay and Preparation Laboratories

92

Table 8-2:

Comparison of Assay Values between the Database and Source Documents (MDA, 2011)

93

Table 8-3:

Summary of Comparisons of Historical Assays (MDA, 2011)

94

Table 8-4:

Summary of Comparisons of Vista Assays (MDA, 2011)

94

Table 10-1:

Material Balance for HPGR Tests

109

Table 10-2:

Tomra Sorting Test Results

111

Table 10-3:

Head Analyses of Composite Samples

113

Table 10-4:

Whole Rock Analyses of Composite Samples

113

Table 10-5:

Assayed vs. Projected Head Analyses

113

Table 10-6:

Abrasion Indices for the Various Composite Samples

114

Table 10-7:

Bond Ball Mill Work Indices for Composite Samples

114

Table 10-8:

Bond Ball Mill Work Indices for Ore Sorting Products and Wastes

114

Table 10-9:

Gold Extraction vs. Grind Size for the Four Composites

116

Table 10-10:

Gold Extraction at P80 of 270 mesh (53µm) with Two-stage Grind for the Four Composites

116

Table 10-11:

Effect of Pulp Density and NaCN Concentration on Gold Extraction for Composite No. 1 at P80 of 270 mesh (53µm) with Two-stage Grinding

117

Table 10-12:

Effect of Pulp Density and NaCN Concentration on Gold Extraction for Composite No. 3 at P80 of 270 mesh (53µm) with Two-stage Grinding

117

Table 10-13:

Effect of Pulp Density and NaCN Concentration on Gold Extraction for Composite No. 4 at P80 of 270 mesh (53µm) with Two-stage Grinding

117

Table 10-14:

Cyanide Destruction Test Results

118

Table 10-15:

Unit Area Requirements for Thickener for Composite Samples

118

Table 10-16:

Metallurgical Drilling Intercept Angle to Mineralized Vein

119

Table 10-17:

Vista Drillholes and their Metallurgical Twins

119

Table 10-18:

Material Balance for HPGR Tests at TKI

122

TETRA TECH

viii

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Table 10-19:

Tomra Ore Sorting Test Results Tomra Ore Sorting Test Results

123

Table 10-20:

Steinert Sorting Results for Composites 1, 3, and 4

125

Table 10-21:

Head Analyses of Composite Samples

126

Table 10-22:

Bond's Ball Mill Work Indices for Composite Samples

126

Table 10-23:

Leach Results for Feed Grade >1.5 g/t Au

128

Table 10-24:

Leach Results for Feed Grade of 1.0 to 1.5 g/t Au

129

Table 10-25:

Leach Results for Feed Grade of 0.8 to 1.0 g/t Au

129

Table 10-26:

Leach Results for Feed Grade of 0.6 to 0.8 g/t Au

130

Table 10-27:

Leach Results for Feed Grade of 0.4 to 0.6 g/t Au

130

Table 10-28:

Leach Results for Feed Grade of <0.4 g/t Au

130

Table 10-29:

Leach Residue Assay Versus Ore Feed Grade

131

Table 10-30:

Cyanide Destruction Test Results

131

Table 11-1:

Statement of Mineral Resource Estimates

140

Table 11-2:

Summary of Batman Bulk Density Data by Oxidation State

141

Table 11-3:

Block Model* Physical Parameters – Batman Deposit

141

Table 11-4:

Batman Resource Classification Criteria and Variogram

144

Table 11-5:

Global Reconciliation of Batman Pit historical production with Vista model

158

Table 11-6:

Quigleys Deposit Specific Gravity Data

159

Table 11-7:

Summary of Quigleys Exploration Database

159

Table 11-8:

Block Model Physical Parameters – Quigleys Deposit

159

Table 11-9:

Search Parameters for each Domain

162

Table 11-10:

Search Parameters and Sample Restrictions

162

Table 11-11:

WhittleTM Pit Shell Parameters for the Quigleys Deposit

163

Table 11-12:

Existing Heap Leach Indicated Gold Resource Estimate (September 2019)

164

Table 11-13:

Progression of Resource Estimates – Batman Deposit

165

Table 12-1:

Initial Economic Parameters

168

Table 12-2:

Slope Angles for Pit Optimization

170

Table 12-3:

WhittleTM Pit Optimization Results – using 0.35 g g Au/t Cutoff

173

Table 12-4:

$1,400 Au Price Pit by Pit Results

174

Table 12-5:

Pit Slope Design Parameters

176

Table 12-6:

Interim Pit Slope Parameters (Sectors 1 & 2)

176

Table 12-7:

Proven and Probable Reserves by Pit Phase

184

Table 12-8:

Total Batman Project Reserves (plus Heap Leach)

184

Table 13-1:

Description of Landforms and Impoundments

185

Table 13-2:

Feasibility Waste Tonnages by Waste Type

186

Table 13-3:

Construction and Reclamation Requirements

188

Table 13-4:

Annual Mine Production Schedule

190

Table 13-5:

Annual Stockpile Balance

191

Table 13-6:

Annual Ore Delivery to the Mill Crusher

192

Table 13-7:

Maximum Loader Productivity Estimate

194

Table 13-8:

Annual Load and Haul Equipment Requirements

195

Table 13-9:

Mt Todd Personnel Salaries

197

Table 13-10:

Mine Personnel Requirements

199

Table 13-11:

Mine Annual Personnel Costs ($000’s USD)

200

Table 14-1:

Headline Design Criteria

201

Table 14-2:

Mobile Equipment for Process Plant

209

Table 15-1:

Predicted Power Requirements

226

Table 15-2:

50 ktpd TSF 1 and TSF 2 Parameters

229

Table 15-3:

Mobile Equipment for Process Plant

230

Table 15-4:

Heavy Lift Cranage Requirements

233

Table 17-1:

Mt Todd Permit Status

243

TETRA TECH

ix

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Table 17-2:

Reclamation Approach

245

Table 18-1:

Operating Periods

249

Table 18-2:

Estimated Capital Cost Summary (US$000s)

250

Table 18-3:

Mine Annual Capital Costs (US$000s)

250

Table 18-4:

Haulage Truck Costs

253

Table 18-5:

Mine Light Vehicle Capital (US$)

254

Table 18-6:

Estimated Capital Cost Summary (AUD000s)

255

Table 18-7:

Process Plant Capital Cost Summary

256

Table 18-8:

Quantity of Bulk Commodities for the Process Plant

256

Table 18-9:

Indirects Capital Cost Summary

257

Table 18-10:

CCE Methodology for Facility 3000 – Process Plant

258

Table 18-11:

Methodology for Other Areas of the Capital Cost Estimate

259

Table 18-12:

Construction Gang Rate Development

261

Table 18-13:

Estimated Mine Dewatering Capital Cost Summary (US$000s)

267

Table 18-14:

Estimated Reclamation Capital Cost Summary (US$000s)

267

Table 18-15:

Estimated Water Treatment Plant Capital Cost Summary (US$000s)

268

Table 18-16:

Estimated Raw Water Dam Capital Cost Summary (US$000s)

268

Table 18-17:

Estimated Tailings Storage Facility Capital Cost Summary (US$000s)

269

Table 18-18:

Estimated LoM Operating Costs (US$)

270

Table 18-19:

Annual Mine Operating Costs (US$)

272

Table 18-20:

Estimated Plant Operating Costs (@ Steady State) (AUD)

274

Table 19-1:

TEM Principal Assumptions

278

Table 19-2:

Estimated Refining Costs (US$)

279

Table 19-3:

LoM Ore Production

279

Table 19-4:

Estimated LoM Capital Costs (US$000s)

280

Table 19-5:

Estimated Mining Costs (US$000s)

280

Table 19-6:

Estimated CIP Process Plant Capital Costs (US$000s)

280

Table 19-7:

Estimated Project Services Capital Costs (US$000s)

281

Table 19-8:

Estimated Project Infrastructure Capital Costs (US$000s)

281

Table 19-9:

Estimated Permanent Accommodation Costs (US$000s)

281

Table 19-10:

Estimated Site Establishment & Early Works (US$000s)

281

Table 19-11:

Estimated Management, Engineering, EPCM Services (US$000s)

282

Table 19-12:

Estimated Pre-Production Costs (US$000s)

282

Table 19-13:

Estimated Asset Sale (US$000s)

284

Table 19-14:

Estimated LoM Operating Costs (US$)

284

Table 19-15:

Estimated Open Pit Operating Costs (US$)

284

Table 19-16:

Estimated CIP Process Plant Operating Costs (US$)

284

Table 19-17:

Estimated Water Treatment Plant Operating Costs (US$)

285

Table 19-18:

Estimated Tailings Operating Costs (US$)

285

Table 19-19:

Estimated G&A Operating Costs (US$)

285

Table 19-20:

Estimated JAAC Royalty Costs (US$)

286

Table 19-21:

Estimated Refining Costs (US$)

286

Table 19-22:

Estimated Labor Rates & Costs (AUD)

287

Table 19-23:

Position & Salary Matrix (AUD)

291

Table 19-24:

Process Reagents (AUD)

293

Table 19-25:

Process Consumables (AUD)

293

Table 19-26:

Technical-Economic Results (US$000s)

295

Table 19-27:

Cash Costs and All-In Sustaining Costs (US$/oz)

295

Table 19-28:

Annual Cash Flow

296

Table 19-29:

Project Sensitivity

299

Table 19-30:

Sensitivities of NPV (US$M) to Gold Price versus NPV Discount Rate

300

TETRA TECH

x

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Table 19-31:

Sensitivities of NPV @5% Discount Rate (US$M) and IRR to Gold Price versus Foreign Exchange Rate (US$:AUD)

300

Table 21-1:

Mean Monthly Precipitation

304

Table 21-2:

Site-specific Trigger Values, Edith River Downstream of WTP Discharge

308

Table 21-3:

Edith River Flow at SW4 (m3/h), February 2013 – September 2017

307

Table 21-4:

Water Quality Data at Sampling Site SW2, Edith River Upstream of WTP Discharge, January 2015 – April 2017

308

Table 21-5:

Mt Todd WTP Effluent Goals

308

Table 21-6:

Anticipated Influent Water Quality at the WTP

309

Table 21-7:

Opinion of Probable Capital Costs

310

Table 21-8:

Opinion of Probable Annual Chemical Consumption

311

Table 21-9:

Seasonal Inflow Volumes and Dewatering Pump Operating Times for Mine Dewatering Design

317

Table 21-10:

Construction Packages

326

Table 21-11:

Supply Packages

326

Table 21-12:

Supply Packages with Significant Lead Times

334

Table 22-1:

Project Risks

337

TETRA TECH

xi

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

LIST OF FIGURES

Figure 1-1:

General Project Location Map

2

Figure 1-2:

Concessions

4

Figure 1-3:

General Arrangement

5

Figure 1-4:

Mt Todd Flowsheet

11

Figure 3-1:

General Project Location Map

24

Figure 3-2:

Concessions

25

Figure 3-3:

General Arrangement

26

Figure 5-1:

Drillhole Location Map – Batman and Quigleys Deposits

34

Figure 5-2:

Plant Process Flowsheet for Project as Designed

38

Figure 5-3:

Modified Plant Process Flowsheet for Project

39

Figure 6-1:

General Geologic Map

43

Figure 7-1:

Drillhole Location Map Batman Deposit to VB17-003

69

Figure 7-2:

Batman Cross-section 1 (see Figure 7-1 for location)

70

Figure 7-3:

Batman Cross-section 2

71

Figure 7-4:

Batman Cross-section 3

72

Figure 7-5:

Batman Cross-section 4

73

Figure 7-6:

Batman Cross-section 5

74

Figure 7-7:

Isometric View of the Quigleys Drilling Pattern

87

Figure 7-8:

Quigleys Cross-section A-A’ (8,438,200 North +/- 10m window)

88

Figure 8-1:

NAL Pulp Repeats

95

Figure 8-2:

Original Pulp Cross Lab Checks

96

Figure 9-1:

NAL Resplit Analyses

100

Figure 9-2:

Scatterplot of Relative Au Value to Certified Standard Reference Material Value

102

Figure 9-3:

Scatterplots (Log Scale) of Replicates by Drillhole

103

Figure 9-4:

Location of Metallurgical Drillholes

104

Figure 9-5:

Two Views of VB07-013, VB18-002 and VB08-036 in Cross-sections

105

Figure 10-1:

Protocol for HPGR/Ore Sorting

109

Figure 10-2:

Drillhole Trace of VB08-030, VB17-001 and VB08-012

120

Figure 10-3:

Drill hole trace of drillholes VB08-030, VB17-001 and VB08-012

121

Figure 10-4:

Conceptual Process Flowsheet for Mt Todd Ore (1 of 2)

132

Figure 10-5:

Conceptual Process Flowsheet for Mt Todd Ore (2 of 2)

133

Figure 11-1:

Drillhole Location Map Batman & Quigleys Deposits and Heap Leach Pad

136

Figure 11-2:

Schematic of Codes and Surface Designations (Looking North)

139

Figure 11-3:

Sectional View of Drillhole Data 8,434,803 mN (Looking North)

140

Figure 11-4:

Example Log Variograms of Gold within the Core Complex

143

Figure 11-5:

Blocks Kriged Au – Cross-section 8,434,900 mN looking North, Batman Deposit

146

Figure 11-6:

Classified Blocks Measured, Indicated, and Inferred – Cross-section 8,434,900 mN looking North, Batman Deposit

147

Figure 11-7:

Blocks Kriged Au – Level Plan -100m msl Batman Deposit

148

Figure 11-8:

Classified Blocks Measured, Indicated, and Inferred – Level Plan -100m msl Batman Deposit

149

Figure 11-9:

Blocks Kriged Au – Long Section of the Core Complex looking West

150

Figure 11-10:

Classified Blocks Measured, Indicated, and Inferred – Long Section of the Core Complex looking West

151

Figure 11-11:

Plan Map of Mineral Reserve Pit Rim and location of sections through block model

152

Figure 11-12:

Section 600 of mineral reserves above ultimate pit

153

Figure 11-13:

Section 650 of mineral reserves above ultimate pit

153

Figure 11-14:

Section 700 of mineral reserves above ultimate pit

154

Figure 11-15:

Section 750 of mineral reseves above ultimate pit

154

TETRA TECH

xii

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Figure 11-16:

Jackknife Correlation Plot for Measured Blocks

156

Figure 11-17:

Jackknife Correlation Plot for Inferred Blocks

157

Figure 11-18:

3-D Visualization of the Quigleys Deposit Mineralized Zone Positions with Wireframe Codes

160

Figure 11-19:

Quigleys Median Indicator Variogram

161

Figure 12-1:

Mt Todd Geotechnical Sectors

171

Figure 12-2:

Graph of Whittle Results

175

Figure 12-3:

Mt Todd Ultimate Pit Design

178

Figure 12-4:

Phase 1 Design

180

Figure 12-5:

Phase 2 Design

181

Figure 12-6:

Phase 3 Design

182

Figure 13-1:

Mine Organizational Chart

198

Figure 14-1:

Simplified Process Flow Diagram

202

Figure 15-1:

Site Plan

210

Figure 19-1:

Project NPV (at 5% discount rate) Sensitivity

300

Figure 21-1:

Open Pit Dewatering System Conceptual Design

318

Figure 21-2:

Conceptual Layout of Dewatering System

319

Figure 21-3:

EPCM Stage 1 – Design & Procurement. Refer Diagram 1

321

Figure 21-4:

EPCM Stage 2 – Construct & Commission. Refer Diagram 2

322

Figure 21-5:

Commissioning Phases

331

TETRA TECH

xiii

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

ACRONYMS, ABBREVIATIONS AND SYMBOLS

"

second (plane angle)

%

percent

minute (plane angle)

<

less than

>

greater than

°

degree

°C

degrees Celsius

°F

degrees Fahrenheit

µg

micrograms

µg/L

micrograms per liter or parts per billion

µm

microns

µS/cm

microsiemens percentimeter

3D

three-dimensional

2020 PFS

NI 43-101 Technical Report – Mt Todd Gold Project 50,000 tpd Preliminary Feasibility Study – Northern Territory, Australia [Effective Date September 10, 2019; Issued October 7, 2019; Amended September 22, 2020

A

ampere

a

annum (year)

AA

Atomic adsorption

ABA

acid base accounting

AD

annual deduction

ADWG

Australian Drinking Water Guidelines

AGR

Australian Gold Reagents Pty. Ltd.

AHD

Australian Height Datum

ALS

Australian Laboratory Services

AN

Ammonium nitrate

ANE

Ammonium nitrate emulsion

ANFO

Ammonium nitrate fuel oil

ANZECC

Australian and New Zealand Environment Conservation Council

ANZMARC

Australian and New Zealand Marketing Academy

AOM

Australian Ores and Minerals Limited

AP

aeration/settling ponds

APW

Aerobic Polishing Wetlands

ARD/ML

acid rock drainage and metal laden leachates

ARMCANZ

Agriculture and Resource Management Council of Australia and New Zealand

AStrk

Along Strike

Au

gold

AUD

dollar (Australian)

Ausenco

Ausenco Limited

B

billion

BCR

biochemical reactor

BFA

Bench face angle

bgs

below ground surface

BH

Bench height

BKK

Bateman Kinhill and Kilborne

BP

Batman pit

Bt

billion tonnes

TETRA TECH

xiv

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

BWi

Bond Ball Mill work index

CAPEX

capital expenditure or capital expense

CCE

Capital Cost Estimate

CCI

Chamber of Commerce and Industry

CCTV

closed circuit television

CDN

Canadian dollar

CIL

carbon-in-leach

CIM

Canadian Institute of Mining, Metallurgy and Petroleum

CIM Standards

Canadian Institute of Mining, Metallurgy and Petroleum Definition Standards

CIP

carbon-in-pulp

cm

centimeters

cm2

square centimeter

cm3

cubic centimeter

CoA

chart of accounts

CRD

capital recognition deduction

CV

Construction Verification

CWi

Crusher work index

d

day

d/a

days per year (annum)

D&C

Design and Construct

d/wk

days per week

DC

Dry Commissioning

DDH

Diamond drillhole core

DH

drillhole

DITT

Department of Industry, Tourism and Trade

dmt

dry metric ton

DO

Dissolved oxygen

DoR

Department of Resources

DRDPIFR

Department of Regional Development, Primary Industry, Fisheries and Resources

DUST

dust suppression

DWi

Drop Weight index

E&I

Electrical and Instrumentation

EEE

eligible exploration expenditure

EFCE

Enhanced Factored Cost Estimate

EHS

Environment, Health and Safety

EIS

Environmental Impact Statement

EL

exploration licenses

EMP

Environmental Management Plan

EPBC

Australian Environmental Protection and Biodiversity Conservation Act of 1999

EPCM

Engineering procurement construction management

EQP

equalization pond

F80

80% feed passing size

FIS

Free In Store

FLS

FLSmidth

FS Case

50,000 tpd Case

ft

foot

ft2

square foot

ft3

cubic foot

ft3/s

cubic feet per second

TETRA TECH

xv

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

g

gram

g/L

grams per liter

g/m3

gram per cubic meter

g Au/t

grams gold per tonne

g/t

grams per tonne

G&A

general and administrative

Ga

billion years ago

GCL

geosynthetic clay liner

General Gold

General Gold Resources Pty. Ltd.

GHD

GHD Pty Ltd.

GJ

Gigajoule

gpm

gallons per minute (US)

GPR

Gross Proceeds Royalty

GR

gross realization

GW

gigawatt

h/a

hours per year

h/d

hours per day

h/wk

hours per week

ha

hectare (10,000 m2)

HAZOP

Hazard and Operability

HCL

Hydrochloric Acid

HHV

Higher Heating Value

HLP

heap leach pad

HNO3

nitric acid

HPGR

high pressure grinding rolls

HQ

88.9 mm drill rod (outer diameter)

hr

hour

HSEC

Health, Safety, Environment and Community

HV

Heavy vehicles

HW

hanging wall

Hz

hertz

IBC

Intermediate bulk containers

ICP

Inductively Coupled Plasma Atomic Emission Spectroscopy

ICP-MS

Inductively Coupled Plasma-Mass Spectometry

ICP-OES

Inductively Coupled Plasma Optical Emission Spectroscopy

in

inch

in2

square inch

in3

cubic inch

IP

Internet Protocol

IRA

Inner-ramp angles

IRR

Internal Rate of Return

IR

Industrial Relations

IT

Information Technology

ITV

interim trigger values

JAAC

Jawoyn Association Aboriginal Corporation

k

kilo (thousand)

kg

kilogram

kg/h

kilograms per hour

kg/m2

kilograms per square meter

TETRA TECH

xvi

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

kg/m3

kilograms per cubic meter

km

kilometer

km/h

kilometers per hour

km2

square kilometer

koz

kilo-ounce

kPa

kilopascal

kt

kilotonne

KV

Kriging variance

kV

kilovolts

kVA

kilovolt-ampere

kW

kilowatt

kWh

kilowatt hour

kWh/a

kilowatt hours per year

kWh/t

kilowatt hours per tonne

kW/sec

Kilowatts per second

L

liter

L/m

liters per minute

lb

pound(s)

LGOS

low grade ore stockpile

LGRP

Low grade ore stockpile retention pond

LIMS

Laboratory information system

LLDPE

linear low-density polyethylene

LoM

life of mine

LPM

low-permeability material

m

meter(s)

M

million

m bgs

meters below ground surface

m/min

meters per minute

m/s

meters per second

m2

square meter

m3

cubic meter

m3/hr

cubic meter(s) per hour

MARC

maintenance and repair contract

masl

meters above mean sea level

Mb/s

megabytes per second

Mbm3

million bank cubic meters

Mbm3/a

million bank cubic meters per annum

mbsl

meters below sea level

MCC

Motor Control Center

MDA

Mine Development Associates

µg/L

micrograms per liter

MGA

Map Grid of Australia

mg

milligram

mg/L

milligrams per liter or parts per million

mg/L

milligrams per liter

MIF

Measured, Indicated, inferred

min

minute (time)

mL

milliliter

ML

Mineral License

TETRA TECH

xvii

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

MLN

Mineral License Number

mm

millimeter

MMP

Mine Management Plan

mo

month

Moz

million ounces

Mpa

megapascal

mPa∙s

centipoise

MPU

Mobile processing unit

MRT

Mining & Resource Technology Pty Ltd

Mt

million tonnes

Mt/a

million tonnes per annum

MTO

material take-off

Mtpy

million tonnes per year

MVA

megavolt-ampere

MW

megawatt

MWH

Montgomery Watson Harza (now Stantec)

N/mm2

Newtons per square millimeter

NAF

non-acid forming

NAL

Northern Australian Laboratories

NaOH

sodium hydroxide

NaSH

sodium hydrosulfide

NAPP

net acid production potential

NHMRC

National Health and Medical Research Council

NI

National Instrument

Nm3/h

Normal meters cubed per hour

NOI

Notice of Intent

NP

neutralization potential

NPI

Non Process Infrastructure

NPR

neutralizing potential ratio

NPV

Net Present Value

NQ

69.9 mm drill rod (outer diameter)

NRETAS

Natural Resources, Environment, the Arts and Sport

NRMMC

Natural Resource Management Ministerial Council

NSR

Net Smelter Return

NT

Northern Territory

NTEL

NT Environmental Laboratories

NTEPA

Northern Territory Environmental Protection Authority

ø

diameter

OC

operating costs

OH&S

Occupational Health and Safety

OP

open rotary holes

OPEX

operating expenditure or operating expense

OPGW

optical ground wire

oz

ounce

oz/a

ounces/annum

oz/d

ounces/day

P80

80% product passing size, in microns or µm

P&ID

piping and instrumentation diagram

Pa

Pascal

TETRA TECH

xviii

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Pacific Gold Mines

Pacific Gold Mines NL

PAF

potentially acid forming

PAH

Pincock Allen and Holt

PbS

galena

PC

Prime Cost

PCG

Pine Creek Geosyncline

pcg

Porphyry copper gold

PER

Public Environmental Report

PFS

Preliminary Feasibility Study

PGM

plant growth medium

PP

Process Plant

ppb

parts per billion

ppm

parts per million

Project

Mt Todd Gold Project

PRP

Process Plant Retention Pond

PSR

Procurement Status Report

PWC

Power and Water Corporation

PWP

Process Water Pond

QA/QP

Quality Assurance/Quality Control

QP

Qualified Person

R&R

Rest and recreation

RDi

Resource Development Inc.

RESPEC

Mine Development Associates (MDA)

RKD

RKD (Company Name)

RL

Sample name

RO

runoff pond

RoM

Run of Mine

RP

retention pond

RP1

Waste rock dump retention pond

RP3

Batman Pit

rpm

revolutions per minute

RVC

reverse circulation drilling method

RWD

raw water dam

s

second (time)

SAPS

Successive alkalinity producing systems

SG

specific gravity

SMBS

sodium meta bi-sulfite

SMC

SAG mill comminution

SME

Society for Mining, Metallurgy, and Exploration, Inc.

SMP

Structural, Mechanical and Piping

SOCS

Site of Conservation Significance

SoW

Scope of Work

SPX

SPX company name

SRE

Soil and Rock Engineering

SRM

Standard reference materials

st

short ton (2,000 lb)

st/d

short tons per day

st/y

short tons per year

S.U.

Standard unit

TETRA TECH

xix

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

SWWB

Site-wide water balance

t

tonne (1,000 kg) (metric ton)

t/a

tonnes per year

t/d

tonnes per day

t/m3

tonnes per cubic meter

Technical Report

this Feasibility Study

TEM

technical economic model

Tetra Tech

Tetra Tech, Inc.

TKI

Thyssen-Krupp Industries

tpd

tonnes per day

tph

tonnes per hour

ts/hm3

ton-sec/hour-cubic meter

TSF

tailings storage facility

TTP

Coffey Services Australia Pty Ltd (trading as Tetra Tech Proteus)

TUNRA

The University of Newcastle Research Associates

TV

Trigger value

TWC

The Winters Company

UCS

Unconfined compressive strength

US$

U.S. dollar

V

volt

Vista

Vista Gold Corp.

Vista Australia

Vista Gold Australia Pty Ltd

VoIP

voice over Internet protocol

w/v

weight/volume

w/w

weight/weight

WA

Western Australia

WAD

weak acid dissociable

WC

Wet Commissioning

WDL

Waste Discharge License

WGC

World Gold Counsel

wk

week

WRD

waste rock dump

WTP

water treatment plant

WWTP

waste water treatment plant

XRD

x-ray diffraction

yd3

cubic yard

XRT

x-ray transmission

ZnS

Sphalerite

TETRA TECH

xx

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

UNITS OF MEASURE

All dollars are presented in U.S. dollars (US$) unless otherwise noted. Common units of measure and conversion factors used in this report include:

Weight:

1 oz (troy)

= 31.1035 g

1 tonne

= 1,000 kg

Analytical Values:

percent

grams per
metric tonne

1%

1%

10,000

1 g/t

0.0001%

1.0

10 ppb

100 ppm

Linear Measure:

1 inch (in)

= 2.54 centimeters (cm)

1 foot (ft)

= 0.3048 meters (m)

1 yard (yd)

= 0.9144 meters (m)

1 mile (mi)

= 1.6093 kilometers (km)

Area Measure:

1 acre

= 0.4047 hectare

1 square mile

= 640 acres

= 259 hectares

TETRA TECH

xxi

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

ABBREVIATIONS OF THE PERIODIC TABLE

actinium = Ac

aluminum = Al

americium = Am

antimony = Sb

argon = Ar

arsenic = As

astatine = At

barium = Ba

berkelium = Bk

beryllium = Be

bismuth = Bi

bohrium = Bh

boron = B

bromine = Br

cadmium = Cd

calcium = Ca

californium = Cf

carbon = C

cerium = Ce

cesium = Cs

chlorine = Cl

chromium = Cr

cobalt = Co

copper = Cu

curium = Cm

dubnium = Db

dysprosium = Dy

einsteinium = Es

erbium = Er

europium = Eu

fermium = Fm

fluorine = F

francium = Fr

gadolinium = Gd

gallium = Ga

germanium = Ge

gold = Au

hafnium = Hf

hassium = Hs

helium = He

holmium = Ho

hydrogen = H

indium = In

iodine = I

iridium = Ir

iron = Fe

krypton = Kr

lanthanum = La

lawrencium = Lr

lead = Pb

lithium = Li

lutetium = Lu

magnesium = Mg

manganese = Mn

meitnerium = Mt

mendelevium = Md

mercury = Hg

molybdenum = Mo

neodymium = Nd

neon = Ne

neptunium = Np

nickel = Ni

niobium = Nb

nitrogen = N

nobelium = No

osmium = Os

oxygen = O

palladium = Pd

phosphorus = P

platinum = Pt

plutonium = Pu

polonium = Po

potassium = K

praseodymium = Pr

promethium = Pm

protactinium = Pa

radium = Ra

radon = Rn

rhodium = Rh

rubidium = Rb

ruthenium = Ru

rutherfordium = Rf

rhenium = Re

samarium = Sm

scandium = Sc

selenium = Se

silicon = Si

silver = Ag

sodium = Na

strontium = Sr

sulfur = S

technetium = Tc

tantalum = Ta

tellurium = Te

terbium = Tb

thallium = Tl

thorium = Th

thulium = Tm

tin = Sn

titanium = Ti

tungsten = W

uranium = U

vanadium = V

xenon = Xe

ytterbium = Yb

yttrium = Y

zinc = Zn

zirconium = Zr

TETRA TECH

xxii

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

1.EXECUTIVE SUMMARY

1.1Introduction

Vista Gold Corp. (Vista) retained Tetra Tech, along with RESPEC (formerly Mine Development Associates (MDA)), Resource Development Inc. (RDi), Pro Solv Consulting, LLC (Pro Solv), and Tetra Tech Proteus (TTP) to prepare this Technical Report for its Mt Todd Gold Project (the Project) in Northern Territory (NT), Australia. The Technical Report evaluates a development scenario of a 50,000 tonne per day (tpd) processing facility.

This Technical Report Summary provides results of the current mineral resource estimate for the Project, including operating parameters and financial metrics. The report has been prepared in accordance with the disclosure and reporting requirements of the United States Securities and Exchange Commission’s (“SEC”) new mining rules under subpart 1300 and item 601 (96)(iii) of Regulation S-K (the ‘New Mining Rules’). The authors of this Technical Report Summary are independent of Vista and all their subsidiaries and have only a client/consultant relationship with these companies.

Vista and its subsidiary, Vista Gold Australia Pty Ltd (Vista Australia) entered into an agreement to acquire an interest in the Project located in NT, Australia on March 1, 2006. The acquisition was completed on June 16, 2006 when the mineral leases comprising the Project were transferred to Vista Australia and funds held in escrow were released. Vista Australia is the operator of the Mt Todd property.

The Mt Todd property contains a number of known occurrences of gold, which have been explored and/or exploited to various degrees. The largest and best-known deposits are the Batman and Quigleys deposits, both of which have had historic mining by prior operators. The Batman deposit has produced and been explored more extensively than the Quigley deposit. Vista has reported mineral resource estimates in accordance with S-K 1300 Standards.

This information is intended to assist stakeholders and other readers of this Technical Report in their understanding of the Mt Todd Gold Project and in forming judgements regarding the quality of the data collected, reported, and used in the Technical Report.

1.2Location

The Project is located 56 kilometers (km) by road northwest of Katherine, and approximately 290 km southeast of Darwin in NT, Australia (Figure 1-1). Access to the property is via high quality, two-lane paved roads from the Stuart Highway, the main arterial within the territory.

1.3Property Description

Vista Australia is the holder of four mineral licenses (ML) MLN 1070, MLN 1071, MLN 1127, and MLN 31525 comprising approximately 5,544 hectares (ha).  In addition, Vista Australia controls exploration licenses (EL) EL 29882, EL 29886, EL 30898, EL 32004, and ELA 32005 comprising approximately 160,000 ha.  Figure 1-1 illustrates the general location of the tenements and the position of the Batman deposit.

TETRA TECH

1

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

The general arrangement for the Project is shown on Figure 1-3, and landforms and impoundments are described in Table 1-2.

Graphic

Figure 1-1: General Project Location Map

TETRA TECH

2

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Table 1-1: Description of Landforms and Impoundments

Landform/Impoundment

Abbreviated Name

Tailings Storage Facility 1

TSF1

Tailings Storage Facility 2

TSF2

Tailings Storage Facility 1

TSF 1

Tailings Storage Facility 2

TSF 2

Raw Water Dam

RWD

Low Grade Ore Stockpile

LGOS

Low Grade Ore Stockpile Retention Pond

LGRP

Heap Leach Pad

HLP

Batman Pit

RP3

Process Plant Retention Pond

PRP

Waste Rock Dump

WRD

Waste Rock Dump Retention Pond

RP1

Process Water Pond

PWP

Water Treatment Plant

WTP

Process Plant

PP

TETRA TECH

3

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Graphic

NOTE: Prepared by Vista Gold Corp.; updated January 2022

Figure 1-2: Concessions

TETRA TECH

4

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Graphic

Figure 1-3: General Arrangement

TETRA TECH

5

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

1.4Geology and Mineralization

The Project is situated within the southeastern portion of the Early Proterozoic Pine Creek Geosyncline (PCG). Meta-sediments, granitoids, basic intrusives, acid and intermediate volcanic rocks occur within this geological province.

The Batman deposit geology consists of a sequence of hornfelsed interbedded greywackes, and shales with minor thin beds of felsic tuff. Bedding is striking consistently at 325°, dipping at 40° to 60° to the southwest. Minor lamprophyre dykes trending north-south pinch and swell, crosscutting the bedding.

The deposits are similar to other gold deposits of the PCG and are classified as orogenic gold deposits in the subdivision of thermal aureole gold style. The Batman deposit shares some characteristics with intrusion-related gold systems, especially in terms of the association of gold with bismuth and reduced ore mineralogies. This makes the Batman deposit unique in the PCG. The mineralization within the Batman deposit is directly related to the intensity of the north-south trending quartz sulfide veining. The lithological units impact on the orientation and intensity of mineralization.

Sulfide minerals associated with the gold mineralization are pyrite, pyrrhotite and lesser amounts of chalcopyrite, bismuthinite and arsenopyrite. Galena and sphalerite are also present but appear to be post-gold mineralization and are related to calcite veining, bedding and the east-west trending faults and joints.

A variety of mineralization styles occur within the Project area. Of greatest known economic significance are auriferous quartz-sulfide vein systems. These vein systems include the Batman, Jones Brothers, Golf-Tollis, Quigleys and Horseshoe prospects, which occur within a north-northeast trending corridor, and are hosted by the Burrell Creek Formation. Tin occurs in a north-northwest trending corridor. The tin mineralization comprises cassiterite, quartz, tourmaline, kaolin, and hematite bearing assemblages, which occur as bedding parallel to breccia zones and pipes. Polymetallic Au, W, Mo, and Cu mineralization occurs in quartz-greisen veins within the Yinberrie Leucogranite; a late stage highly fractionated phase of the Cullen Batholith. The Batman deposit extends approximately 2,200 meters (m) along strike, 400 m across dip and drill tested to a depth of 800 m. Drilling indicates the Batman mineralization to be open along-strike and down-dip.

To date, with regard to the exploration licenses (ELs), they represent an early-stage exploration program which has not produced an announceable discovery. While the work is promising and will be ongoing, there are no quantifiable resources or reserves on the ELs. Once an announceable discovery is made, Vista will detail that discovery according to all applicable disclosure regulations.

1.5Mineral Resource Estimate

The following sections summarize the process, procedures, and results of Tetra Tech’s independent estimate of the contained gold resources of the:

1)Batman deposit;
2)Existing heap leach pad; and
3)Quigleys deposit.

This report includes an estimate of gold contained in a historic heap leach pad adjacent to the Batman deposit. Additionally, this report contains the resource estimation of the Batman and Quigleys deposits. The Project resource estimates are shown in Table 1-2. The resource estimates are S-K 1300 compliant.

TETRA TECH

6

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Table 1-2: Statement of Mineral Resources Estimates

BATMAN DEPOSIT

HEAP LEACH PAD

QUIGLEYS DEPOSIT

Tonnes
(000s)

Grade
(g/t)

Contained Ounces (000s)

Tonnes
(000s)

Grade
(g/t)

Contained Ounces (000s)

Tonnes
(000s)

Grade
(g/t)

Contained Ounces (000s)

Measured (M)

-

-

-

-

-

-

594

1.15

22

Indicated (I)

10,816

1.76

613

-

-

-

7,301

1.11

260

Measured & Indicated

10,816

1.76

613

-

-

-

7,895

1.11

282

Inferred (F)

61,323

0.72

1,421

-

-

-

3,981

1.46

187

NOTES:

(1)Measured & indicated resources exclude proven and probable reserves.
(2)The Point of Reference for the Batman and Quigleys mineral resource estimates is in-situ at the property. The Point of Reference for the Heap Leach mineral resource estimate is the physical Heap Leach pad at the property.
(3)Batman and Quigleys resources are quoted at a 0.40g Au/t cut-off grade. Heap Leach resources are the average grade of the heap, no cut-off applied.
(4)Batman:  Resources constrained within a US$1,300/oz gold WhittleTM pit shell. Pit parameters:  Mining Cost US$1.50/tonne, Milling Cost US$7.80/tonne processed, G&A Cost US$0.46/tonne processed, G&A/Year 8,201 K US4, Au Recovery, Sulfide 85%, Transition 80%, Oxide 80%, 0.2g Au/t minimum for resource shell.
(5)Quigleys:  Resources constrained within a US$1,300/oz gold WhittleTM pit shell. Pit parameters:  Mining cost US$1.90/tonne, Processing Cost US$9.779/tonne processed, Royalty 1% GPR, Gold Recovery Sulfide, 82.0% and Ox/Trans 78.0%, water treatment US$0.09/tonne, Tailings US$0.985/tonne
(6)Differences in the table due to rounding are not considered material. Differences between Batman and Quigleys mining and metallurgical parameters are due to their individual geologic and engineering characteristics.
(7)Rex Bryan of Tetra Tech is the QP responsible for the Statement of Mineral Resources for the Batman, Heap Leach Pad and Quigleys deposits.
(8)Thomas Dyer of RESPEC is the QP responsible for developing the resource WhittleTM pit shell for the Batman Deposit.
(9)The effective date of the Heap Leach, Batman and Quigleys resource estimate is December 31, 2021.
(10)Mineral resources that are not mineral reserves have no demonstrated economic viability and do not meet all relevant modifying factors.

TETRA TECH

7

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

1.6Mineral Reserve Estimates

The QP [Thomas L. Dyer, P.E.] has used measured and indicated resources provided by Tetra Tech to estimate mineral reserves. Pit optimization was done using Geovia’s WhittleTM software to define pit limits with input for economic and slope parameters.

Optimization used only measured and indicated resources for processing. All inferred resource was considered as waste.

Varying gold prices were used to evaluate the sensitivity of the deposit to the price of gold as well as to develop a strategy for optimizing Project cash flow. To achieve cash-flow optimization, mining phases or push backs were developed using the guidance of WhittleTM pit shells at lower gold prices.

Table 1-3: Statement of Mineral Reserve Estimate

Batman Deposit

Heap Leach Pad

Total P&P

K Tonnes

g Au/t

K Ozs Au

Tonnes (000s)

Grade (g/t)

Contained Ounces (000s)

Tonnes (000s)

Grade (g/t)

Contained Ounces (000s)

Proven

81,277

0.84

2,192

-

-

-

81,277

0.84

2,192

Probable

185,744

0.76

4,555

13,354

0.54

232

199,098

0.75

4,787

Proven &
Probable

267,021

0.79

6,747

13,354

0.54

232

280,375

0.77

6,979

NOTES:

1)Thomas L. Dyer, P.E., is the QP responsible for reporting the Batman Deposit Proven and Probable reserves.
2)Batman deposit reserves are reported using a 0.35 g Au/t cutoff grade.
3)Deepak Malhotra is the QP responsible for reporting the heap-leach pad reserves.
4)Because all the heap-leach pad reserves are to be fed through the mill, these reserves are reported without a cutoff grade applied.
5)The reserves point of reference is the point where material is fed into the mill.
6)The effective date of the mineral reserve estimates is December 31, 2021

1.6.1

Heap Leach Reserve Estimate

Existing heap leach pad (HLP) reserves are provided in Table 1-4, which are estimated to be 13.4 million tonnes (Mt). These reserves will be processed through the mill at the end of the mine life.

Previous test work indicated the following possible results:

Cyanidation leach tests on “as is” material on the heap will extract ± 30% of the gold.
CIP cyanidation tests at a grind size of P80 of 90 microns will extract on average 72% of gold (range: 64.14% to 80.37%) in 24 hours of leach time. The average lime and cyanide consumptions were 1.75 kg/t and 0.78 kg/t, respectively.

Vista will undertake additional metallurgical test work at the targeted P80 40 microns size at a later date, since this material will be processed in years 15 and 16 at the end of project life. However, for purposes of classifying the heap leach material as a reserve, the previous recovery values were used. The heap leach reserve constitutes approximately 3% of the total reserves quoted.

1.7Mining Methods

The Project is designed to be a conventional, owner-operated, large open-pit mining operation that will use large-scale mining equipment in a drill/blast/load/haul operation. All dollar values in Section 1.7 are reported in US$.

TETRA TECH

8

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

A base gold price of US$1,250 per ounce was used for scenario analysis. However, various gold prices from US$300 to US$2,000 per ounce, in increments of US$20 per ounce, were used to determine different optimized pit shells. Economic parameters used for the pit designs are provided in Table 1-4.

Table 1-4: Initial Economic Parameters

Parameter

Value Used

Gold Recovery

Grade dependent constant tail equation

Payable Gold

99.9%

Reference Mining Cost

US$1.65 per tonne

Incremental Mining Cost

US$0.010 per bench

Overall Mining Cost

US$1.95 per tonne

Processing Cost

US$8.04 per tonne processed

General & Administrative

$1.11 per tonne processed

Royalty1

1% GPR

The mining costs used were varied by bench. An incremental cost of US$0.010 was added for each six- meter bench below the 145-meter elevation. This represents the incremental increase in cost of haulage for both waste and ore for each bench that is to be mined below the 145-meter elevation. The incremental cost was determined based on truck operating costs, truck cycle time to haul and return through a six-meter gain in elevation, and truck capacity. The reference mining cost of US$1.65 was determined using first principles from previous studies. The overall mining cost (reference plus incremental) is US$1.95.

Processing, tailings construction, tailings reclamation, and water treatment costs were provided by Vista. Calculated cutoff grade based on the economic parameters is 0.33 g Au/t. At Vista’s request, the QP [Thomas L. Dyer, P.E.] used a minimum cutoff grade of 0.35 g Au/t. This was done to maintain higher grades with respect to material allowed to be processed. The elevated cutoff grade of 0.35 g Au/t is appropriate for the Project.

Several iterations of pit optimizations were reviewed to determine the final pit limits. A US$1,125/oz-Au pit shell was used to guide the ultimate pit design. Table 1-5 shows the WhittleTM optimization results. Note that the ultimate pit used for pit design is highlighted in green.


1  Prior royalty used for initial Lerch-Grossman cone runs.  Final designs use actual royalty data.

TETRA TECH

9

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Table 1-5: WhittleTM Pit Optimization Results – Using 0.35 g Au/t Cutoff

Pit

Gold Price
(US$)

MATERIAL PROCESSED

Waste

Tonnes

Total

Tonnes

Strip

Ratio

K Tonnes

g Au/t

K Ozs Au

1

$300

4,904

1.71

269

4,513

9,417

0.92

5

$400

10,679

1.48

510

10,445

21,124

0.98

9

$500

21,303

1.25

853

22,441

43,745

1.05

13

$600

68,789

1.04

2,297

127,555

196,344

1.85

17

$700

105,916

0.96

3,270

202,227

308,143

1.91

21

$800

142,059

0.89

4,068

271,346

413,406

1.91

25

$900

188,713

0.83

5,011

368,324

557,037

1.95

29

$1,000

225,125

0.80

5,782

486,075

711,200

2.16

33

$1,100

255,744

0.79

6,481

637,266

893,010

2.49

34

$1,125

258,911

0.79

6,551

654,092

913,003

2.53

37

$1,200

267,537

0.79

6,758

711,750

979,287

2.66

41

$1,300

277,680

0.78

6,996

788,389

1,066,068

2.84

45

$1,400

281,936

0.78

7,105

831,091

1,113,028

2.95

49

$1,500

282,846

0.78

7,124

838,454

1,121,301

2.96

53

$1,600

288,378

0.78

7,255

895,665

1,184,042

3.11

57

$1,700

290,024

0.78

7,294

915,109

1,205,132

3.16

61

$1,800

290,104

0.78

7,296

916,385

1,206,489

3.16

65

$1,900

293,971

0.78

7,382

964,544

1,258,515

3.28

69

$2,000

294,809

0.78

7,401

975,627

1,270,436

3.31

73

$2,100

297,762

0.78

7,461

1,013,887

1,311,649

3.41

77

$2,300

298,683

0.78

7,476

1,024,472

1,323,155

3.43

81

$2,400

299,793

0.78

7,507

1,050,018

1,349,811

3.50

Pit 34 was used for design purposes.

1.8Metallurgy

The flowsheet consists of primary crushing, closed circuit secondary crushing, closed circuit tertiary crushing using high pressure grinding rolls (HPGRs), ore sorting, two-stage grinding, cyclone classification, pre-leach thickening, leach and adsorption, elution electrowinning and smelting, carbon regeneration, tailings detoxification and disposal to conventional tailings storage facility (TSF).

TETRA TECH

10

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Figure 1-4 provides the schematic diagram of the flowsheet.

Diagram

Description automatically generated

Figure 1-4: Mt Todd Flowsheet

TETRA TECH

11

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

1.9Mineral Processing

Detailed design criteria have been developed for the process plant. The nominal headline design criteria are listed in Table 1-6 below.

Table 1-6: Headline Design Criteria

Unit

Value Used

Annual Ore Feed Rate

Mt/a

17.75

Operating Days per Year

d/a

355

Daily Ore Feed Rate

t/d

50,000

Crushing Rate (6,637 hours per year availability)

tph

2,674

HPGR Rate (7,838 hours per year)

tph

2,264

Ore Sorting Rate (7,838 hours per year)

tph

408

Milling Rate (7,838 hours per year)

tph

2,055

Gold Head Grade

g/t

0.82

Copper Head Grade

%

0.055

Cyanide Soluble Copper

%

0.0024

Ore Specific Gravity

t/m3

2.76

Primary Grind P80 to Secondary Grind

µm

250

Grind P80 to Leach

µm

40

Gold Recovery

%

91.9

Gold Production (average)

oz/d

1,211

Gold Production (average)

oz/a

430,050

1.10Project Infrastructure

Access to local resources and infrastructure is excellent. The Project is located sufficiently close to the city of Katherine to allow for an easy commute for workers. The area has both historic and current mining activity and therefore a portion of the skilled workforce will be sourced locally. In addition, Katherine offers the necessary support functions that are found in a medium-sized city with regard to supplies, accommodations, communications, etc.

The property has an existing high-pressure gas line and an electric power line that were used by previous operators. In addition, wells for potable water and a dam for process water are also located on or adjacent to the site. Finally, a side hill-type TSF is present on site.

Planned infrastructure for the site includes the following:

Ammonium Nitrate and Fuel Oil (ANFO) Facility;
Mine Support Facilities (Heavy Vehicle (HV) Workshop, Lube Farm, Washdown and Tire Change, Warehouse, Fuel Farm, Mining Offices, Core Storage Facility);
Heap Leach Pad (existing);
Accommodation Camp;
Water Treatment Plant (WTP);
Power Supply (supplied by a third-party supplier by contract);
Pit Dewatering;

TETRA TECH

12

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

Mine Services;
Communications;
Gatehouse;
Emergency Services Building;
Administration Building;
Process Plant Office;
Process Plant Workshop;
Process Plant Control Rooms;
Sample Preparation and Laboratory; and
Expanded existing and additional TSF.

1.11Market Studies and Contracts

1.11.1

Markets

Gold metal markets are mature, with many reputable refiners and brokers located throughout the world. The advantage of gold, like other precious metals, is that virtually all production can be sold in the market. As such, market studies, and entry strategies are not required.

Metallurgical process studies confirm that the Project will produce doré of a specification comparable with existing operating mines.

Demand is presently strong, with prices sustained in the range of $1,750–$1,850 per ounce. The gold price used in this Technical Report is US$1,600/oz. Detailed information used for the determination of the minable reserves can be found in Section 12.1Pit Optimization of this Feasibility Study.

1.11.2

Contracts

Currently there are no contracts in place for development and operations. However, Vista has obtained budgetary quotes, as is common for PFS level studies, for future materials and service needs. The following contracts are expected to be in place upon project commencement:

Secure doré transportation to refinery;
Doré refining;
Supplier and service contracts including;
­EPCM;
­Equipment supply;
­D&C;
­Diesel and fuel oil;
­Natural gas for the power plant;
­3rd Party Power Generation (build, own, operate)
­Process reagents;
­Equipment preventive maintenance and repair (MARC) services;
­Site security services; and
­Camp management, catering, and support services.

TETRA TECH

13

February 2023


Table of Contents

Vista Gold Corp.

Mt Todd Gold Project | 50,000 tpd Feasibility Study

S-K 1300 Technical Report Summary

1.12Social and Environmental Aspects

1.12.1

Existing Environmental and Social Information