Exhibit 99.2

 

S-K 1300 Technical Report Summary on the Mineral Resource Estimates for the Lone Tree Deposit, Nevada Prepared for i-80 Gold Corp. https://www.i-80gold.com Prepared by Abani R. Samal, RM-SME Brian Arthur, RM-SME Paul Gates, PE Effective Date: December 31, 2024 Publication date: March 24, 2025

Lone Tree Property Battle Mountain, Nevada, U.S.A. NI 43-101 Technical Report October 20, 2021

 

 

NOTES ON FORWARD-LOOKING INFORMATION

This Technical Report Summary (TRS) contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended (and the equivalent under Canadian securities laws), which are intended to be covered by the safe harbor created by such sections. Words such as “may”, “will”, “should”, “expects”, “intends”, “projects”, “believes”, “estimates”, “targets”, “anticipates” and similar expressions are used to identify these forward-looking statements. Such forward-looking statements include, without limitation, statements regarding i-80 ’s expectation for its mines and any related development or expansions, including estimated cash flows, production, revenue, costs, taxes, capital, rates of return, mine plans, material mined and processed, recoveries and grade, future mineralization, future adjustments and sensitivities and other statements that are not historical facts. Other forward-looking statements in this Report may involve, without limitation, the following

 

●

Assumed commodity prices and exchange rates

 

●

Proposed mining and process production plan

 

●

Projected mining and process recovery rates

 

●

Sustaining capital costs and proposed operating costs

 

●

Assumptions as to dewatering processes

 

●

Assumptions about environmental, permitting, and social risks

For a more detailed discussion of such risks and other factors, see the latest Annual Information Form and Consolidated Financial Statements, available on the i-80 website. i-80 does not undertake any obligation to release publicly, revisions to any “forward-looking statement,” including, without limitation, outlook, to reflect events or circumstances after the date of this presentation, or to reflect the occurrence of unanticipated events, except as may be required under applicable securities laws. Investors should not assume that any lack of update to a previously issued “forward-looking statement” constitutes a reaffirmation of that statement. Continued reliance on “forward-looking statements” is at investors’ own risk.

 

 

2

 

 

T A B L E O F C O N T E N T S

 

1.    SUMMARY			8
1.1   Mineral Resource Estimates			8
1.2   Location of the Lone Tree Mine			8
1.3   Site Infrastructure			9
1.4   Land Tenure and Ownership			10
1.5   Geology and Mineralization			11
1.6   On-site Verification of Data and Information			12
1.7   Historical Summary of the Deposit			12
2.    INTRODUCTION			13
2.1   Terms of Reference and Purpose of this Report			14
2.2   Qualified Persons and Firms Engaged in this Project			14
2.2.1  GeoGlobal LLC			14
2.2.2  Dr. Abani R. Samal – Project Manager & Principal Geologist			15
2.2.3  Mr. Brian Arthur – Principal Metallurgist			15
2.2.4  Mr. Paul Gates – Principal Mining Engineer			16
2.2.5  Responsibilities of the Qualified Persons			16
2.3   Scope of this Project			16
2.4   Units of Measure			18
2.4.1  Coordinate Reference System (CRS) Used in the Maps:			18
2.4.2  Conversion Factors Used			18
2.5   Definitions			18
3.    PROPERTY DESCRIPTION			19
3.1   Location of the Project			19
3.2   Land Status			19
4.    ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY			21
4.1   Climate			21
4.2   Physiography			22
4.3   Vegetation			22
4.4   Site Infrastructure			22
4.4.1  Water Wells:			22
4.4.2  Electric Power			23
4.4.3  Mineral Processing & Metallurgy Facilities			23
4.4.4  Laboratory Facilities:			25
5.    HISTORY			26
5.1   Historical Summary of the District			26
6.    GEOLOGICAL SETTING, MINERALIZATION & DEPOSIT			26
6.1   Regional Geology			26
6.2   Deposit Geology and Mineralization			29
6.3   Controls of Mineralization			32
6.4   Alteration			35
6.5   Gold Mineralogy			35
6.6   Deposit Type			35
7.    EXPLORATION			36
7.1   Exploration History			36
7.1.1  Drilling and Sampling			37
7.1.2  Recent Exploration Drilling			37
7.1.3  Rotary Drilling			39
7.1.4  Reverse Circulation Drilling			40
7.1.5  Core Drilling			41
7.2   Collar Surveys/Locations			43

 

 

3

 

 

7.3   Down-Hole Surveys			43
7.4   Opinion of the Qualified Person			44
8.    SAMPLE PREPARATION, SECURITY, AND ANALYSES			44
8.1   Sampling			44
8.2   Sample Preparation and Analysis			44
8.3   Data Security			45
8.4   QA/QC Procedures			45
8.4.1  Standards			46
8.4.2  Blanks			46
8.4.3  Check Samples			46
8.5   Opinion of the Qualified Person			46
9.    DATA VERIFICATION			46
9.1   On-site Verification of Data and Information			46
9.2   Review of the QA/QC procedure			51
9.2.1  Re-assay of pulps and drill cores			51
9.2.2  Database Review			53
9.3   Opinion of the Qualified Person			54
10.   MINERAL PROCESSING AND METALLURGICAL TESTING			54
10.1   Opinion of the Qualified Person			55
11.   MINERAL RESOURCE ESTIMATES			56
11.1   Datasets			56
11.1.1 Drill Holes			56
11.1.2 Other Data Sets			56
11.2   Geological Interpretation and Lithological Models			58
11.3   Lithology Model			60
11.4   Exploratory Data Analysis and Compositing			60
11.4.1 Compositing			61
11.4.2 Statistical Analyses of Composited Data			61
11.4.3 Contact Plots			64
11.5   Geological Domains			66
11.6   Variogram Analysis			66
11.7   Density /Tonnage Factor Model			68
11.8   Grade Interpolation			69
11.9   Resource Classification			71
11.10 Criteria for Reasonable Prospect for Economic Extraction			71
11.10.1  Inferred blocks			72
11.10.2  Indicated blocks			73
11.10.3  Inventory of Mineral Resources			73
11.11 Model Validation			75
11.11.1  Cross Sections			75
11.11.2  Statistical Validation			76
11.12 Tabulation of Estimated Resources			83
11.13 Opinion of the Qualified Person			83
12.   MINERAL RESERVE ESTIMATES			83
13.   MINING METHODS			84
14.   PROCESSING AND RECOVERY METHODS			84
14.1   Heap Leach			85
14.2   Oxide Milling			85
14.3   Flotation			86
14.4   Autoclaving			86
14.5   Process Operating Costs			87
14.5.1 Oxide Leach Cost Factors			88
14.5.2 Oxide Mill Cost			88

 

 

4

 

 

14.5.3 Flotation Cost updated with PPI factors			88
14.5.4 Acidic Autoclave			88
14.6   Model Estimate			89
14.7   Opinion of the Qualified Person			89
15.   PROJECT INFRASTRUCTURE			89
16.   MARKETING STUDIES AND CONTRACTS			89
17.   ENVIRONMENTAL STUDIES, PERMITTING, AND SOCIAL OR COMMUNITY IMPACT			89
17.1   Environmental Liabilities			89
17.2   Dewatering			90
17.3   Current Permits			90
18.   CAPITAL AND OPERATING COSTS			91
19.   ECONOMIC ANALYSIS			91
20.   ADJACENT PROPERTIES			91
21.   OTHER RELEVANT DATA AND INFORMATION			94
22.   TECHNICAL REPORT INTERPRETATION AND CONCLUSIONS			94
23.   RECOMMENDATIONS			94
23.1   Resource Model update			94
23.2   Risk Analyses in Resource Eestimates			94
23.3   Future Exploration			94
23.4   Geometallurgical Study			95
24.   REFERENCES			96
25.   RELIANCE ON INFORMATION PROVIDED BY THE REGISTRANT			99
26.   QUALIFIED PERSONS CERTIFICATES			100
27.   APPENDIX A:DETAILS OF THE LAND CLAIMS OF THE LONE TREE PROJECT			104
28.   APPENDIX B:VARIOGRAM MAPS			114
29.   APPENDIX C:VARIOGRAM MODELS			119

T A B L E S

 

Table 1-1:Estimated Mineral Resources at 0.62 g/t Au Cut-off Grade			8
Table 2-1:QPs and Responsibilities for the Contents of the Report			16
Table 3-1:The Area of the Lone Tree Claims			19
Table 7-1:Summary of Drilling by Hole Type			37
Table 9-1:Details of the Samples Selected for Re-assay			51
Table 9-2:Descriptions of the CRMs Used			52
Table 10-1:Recoveries and Material Types or Lone Tree			55
Table 11-1:Block Model Geometry			60
Table 11-2:The Lithology Codes Used in the Block Model			60
Table 11-3:General Statistical Characteristics of the Gold (AuFA, opt)			62
Table 11-4:Variogram Parameters of AuFA			68
Table 11-5:Tonnage Factor by Geologic Unit (ft3/ton)			68
Table 11-6:Interpolation Parameters Used for Estimation of Gold Grades			70
Table 11-7:Optimum Pit Criteria Applied to Resource Estimate			72
Table 11-8:Inventory of Mineral Resources Within $2,175 Pit Shell			74
Table 11-9:Comparison of Gold Grades for Composite Data by Lithologic Unit			80
Table 11-10: Estimated Mineral Resources at 0.62 g/T Cut-off Grade			83

 

 

5

 

 

Table 14-1:Suggested operating Costs for Lone Tree Ores			88
Table 20-1:Mineral Resources for Nearby Properties			92
Table 27-1:Lone Tree Unpatented Claims, Claimant: Goldcorp Dee LLC			104
Table 27-2:Claimant: VEK/ANDRUS ASSOCIATES & Goldcorp Dee LLC			108
Table 27-3:Claimant: Larie K. Richardson, Lessee: Goldcorp Dee LLC			109
Table 27-4:Lone Tree Brooks Project, Claimant: Goldcorp Dee LLC			111
Table 27-5:Lone Tree Buffalo Mountain Project, Claimant: Goldcorp Dee LLC			112
Table 27-6:Lone Tree Patented Lands			113

F I G U R E S

 

Figure 1-1:Location of the Lone Tree Gold Deposit			9
Figure 1-2:The Location of Lone Tree Deposit and Infrastructure			10
Figure 1-3:The Property Boundary for the Lone Tree Deposit Project			11
Figure 1-4:The Mineralized Zone of the Lone Tree Deposit.			12
Figure 2-1:The Property Boundary of the Lone Tree Project			13
Figure 3-1:Location of Lone Tree Property and Land Position			20
Figure 4-1:Location and Accessibility of the Lone Tree Mining Project			21
Figure 4-2:Autoclave Agitator Access Ports			24
Figure 4-3:Pulverizing and Preparation Stations			24
Figure 4-4:The LECO Facility			25
Figure 4-5:ICP Laboratory Facility at Lone Tree			25
Figure 6-1:Location of the Lone Tree Mine Relative to Major Mineral Trends in Nevada			27
Figure 6-2:Location of Lone Tree Deposit in the Battle Mountain Mining District			28
Figure 6-3:General Stratigraphic Sequence of Lone Tree			30
Figure 6-4:Local Geology of Lone Tree Deposit and Controls of MIneralizaton			31
Figure 6-5:Diagrammatic Model of Geology of Distal-Disseminated Ag-Au Deposit			36
Figure 7-1:Location of Selected 1840 Drill Holes for Resource Estimation			38
Figure 7-2:Exploration Drill Hole LTE-20001 (Source: NGM)			39
Figure 9-1:Location of LTE-20001 on the West Side of the Lone Tree Pit			47
Figure 9-2:Location Tag of an Exploration Drill Hole in Sequoia Zone			48
Figure 9-3:An Example of a Mineralized Core Stored in a Core Box			49
Figure 9-4:Half Core of LTE-20001 from 2544 ft to 2549 ft with 1.215 ppm Gold Grade			49
Figure 9-5:The Chip Samples from the Upper Portion of the Hole (LTE-20001)			50
Figure 9-6:The Pulps Preserved in a Storage Area of i-80			50
Figure 9-7:Comparison of the Re-assayed Analytical Results with the Original Data			52
Figure 9-8:The Relationship Between the % Differences Original Au Assay Data			53
Figure 11-1:Location of the Drill Holes at the Lone Tree Project			57
Figure 11-2:The Geological Codes Used In Creating Solid Model			58
Figure 11-3:A Vertical Cross Section at 28000N (Looking North)			59
Figure 11-4:A Vertical Cross Section with Rock-type Models (27300N)			59
Figure 11-5:The Lithology Block Model (28000 N, Looking North)			60
Figure 11-6:Histogram of Drill Hole Assay Lengths			61
Figure 11-7:Comparison of Data Statistics of All Lithology Types			62
Figure 11-8:Comparison of Sample Means and Confidence Intervals			63
Figure 11-9:Histograms of Gold Assay Values (AuFA) by Lithology			63
Figure 11-10:Cumulative Frequency Plots of Gold Composites (AuFA)			64
Figure 11-11:Contact Plot of AuFA for the Boundary Between Qal and Phv			65
Figure 11-12:Contact Plot of AuFA for the Boundary Between Phv and Pem			65
Figure 11-13:Contact Plot of AuFA for the Boundary Between Pem and Pb			65

 

 

6

 

 

Figure 11-14:Contact Plot of AuFA for the Boundary Between Pb and Ova			66
Figure 11-15:Steps Followed in Variogram Analysis			66
Figure 11-16:Blocks Below the Current Pit Used for the Optimized Pit shell			71
Figure 11-17:The Blocks Classified as Indicated and Inferred Category Resources			73
Figure 11-18:The Grade Tonnage Curve of Indicated Category Resources			74
Figure 11-19:The Grade Tonnage Curve of Inferred Category Resources			75
Figure 11-20:Estimate Blocks with Assay Data Within the $2,175 Pit Shell			75
Figure 11-21:Histogram of Holes Used for Estimating Indicated and Inferred Blocks			76
Figure 11-22:Histogram of the Holes Used for Estimating Indicated and Inferred Blocks			77
Figure 11-23:Number of Composites Used to Estimate Blocks with Gold Grade			77
Figure 11-24:Number of Composites Used to Estimate Blocks			78
Figure 11-25 Average Distance of Samples From Block Centers			78
Figure 11-26:Minimum Distance of Composites From Blocks			79
Figure 11-27:Comparison of Composites and Block Grade Estimates in the Ova			80
Figure 11-28:Comparison of Composites and Block Grade Estimates in the Pb			81
Figure 11-29:Comparison of Composites and Block Grade Estimates in the Pem			81
Figure 11-30:Comparison of Composites and Block Grade Estimates in the Phv			82
Figure 11-31:Comparison of Composites and Block Grade Estimates in the Qal			82
Figure 20-1:Mineral Deposits Adjacent to Lone Tree			93
Figure 23-1:A Vertical Cross Section (Looking East) Along East 83700 North-South			95
Figure 28-1:Variogram map of AuFA in Qal			114
Figure 28-2:Variogram Map of AuFA in Phv			115
Figure 28-3:Variogram Map of AuFA in Pem			116
Figure 28-4:Variogram Map of AuFA in Pb			117
Figure 28-5:Variogram Map of AuFA in Ova			118
Figure 29-1:Variogram Model of Lithology code 1 (Qal)			119
Figure 29-2:Variogram Model of Lithology Code 2 (Phv)			120
Figure 29-3:Variogram Model of Lithology Code 3 (Pem)			121
Figure 29-4:Variogram Model of Lithology Code 4 (Pb)			122
Figure 29-5:Variogram Modle of Lithology Code 5 (Ova)			123

 

 

7

 

 

1.

SUMMARY

The acquisition of the Lone Tree Property from Nevada Gold Mines (NGM) in 2021 provided i-80 access to processing infrastructure including an autoclave, CIL (carbon-in-leach) mill, a flotation plant, and a heap leach facility complete with an assay lab, and gold refinery. In addition to processing facilities, the land package includes the Lone Tree Mine, the Buffalo Mountain deposit, and the Brooks open pit mine, which are currently on care and maintenance. During this acquisition, independent verification of the quantity of mineral resources at Lone Tree was conducted by GeoGlobal using the available drill hole data and information shared by NGM at that time. A technical report was produced as per the NI 43-101 guidelines and published in October 2021. The acquisition of the Lone Tree mine (along with the processing facilities mentioned above) was completed after the publication of this report. Since then the market conditions have also changed, and there has been an increase in the percentage of shareholders in the United States and the requirement to file an S-K 1300 Technical Report.

GeoGlobal was engaged by i-80 to review the resource estimates and update them as required based on current market conditions and produce this report conforming to the United States Securities and Exchange Commission’s (SEC) Modernized Property Disclosure Requirements for Mining Registrants as described in Subpart 229.1300 of Regulation S-K, Disclosure by Registrants Engaged in Mining Operations (S-K 1300) and Item 601 (b)(96) Technical Report Summary (TRS).

The effective date of published mineral resources is December 31, 2024.

 

1.1	Mineral Resource Estimates

The in-situ Lone Tree mineral deposit hosts substantial gold mineral resources as shown below. The summary of estimated resources at the end of the fiscal year ended December 31, 2024, is shown in Table 1-1. These mineral resources are estimated using a gold price of $2,175/oz Au and an open-pit cut-off grade of 0.62 g/T Au. More details about the estimated mineral resources are presented in section 11.12. Mineral resources are not mineral reserves and do not have demonstrated economic viability.

Table 1-1: Estimated Mineral Resources at 0.62 g/t Au Cut-off Grade

 

		Million Tonnes (MT)		Au (g/T)		Au (K ozs)
Indicated Mineral Resources		7.69		1.73		428
Inferred Mineral Resources		52.94		1.64		2,789

Resource expansion potential exists down-plunge of the main Lone Tree deposit and in the unmined Sequoia zone where previous drilling returned multiple wide, high-grade, intercepts.

 

1.2	Location of the Lone Tree Mine

The Lone Tree mine project is approximately 30 miles east of Winnemucca, Nevada, and 20 miles northwest of Battle Mountain, Nevada at 40° 50’ 19” N, 117° 12’ 37” W. The land package includes the process area, the Lone Tree Pit, and the Buffalo

 

 

8

 

 

Mountain Property. The mine office is accessible from Interstate 80 by a paved highway (Figure 1-1).

Figure 1-1: Location of the Lone Tree Gold Deposit

 

 

1.3	Site Infrastructure

The Lone Tree site has an employee parking lot with secure access to the administration building and a security gate for vehicles entering the mine property. The site has many buildings on the property. Processing infrastructure at Lone Tree includes an autoclave, carbon-in-leach mill, flotation mill, and heap leach facility. The list of processing facilities includes the following:

 

 

9

 

 

●

Lone Tree Autoclave, which processes higher-grade refractory ore.

 

●

Lone Tree Flotation Plant, which processes lower-grade refractory ore.

 

●

Lone Tree Leach pad (Phases 1-4, Figure 1-2), which treats oxide ore in a cyanide heap-leach process.

 

●

Lone Tree Leach pad (Phase 5, Figure 1-2), which treats oxide ore in a cyanide heap-leach process.

 

●

Lone Tree Leach pad (Phase 6, Figure 1-2), which treats oxide ore in a cyanide heap-leach process.

The autoclave and flotation mill, which are currently in care and maintenance.

Details of the site infrastructure are provided in section 4.4.

Figure 1-2: The Location of Lone Tree Deposit and Infrastructure

 

 

1.4	Land Tenure and Ownership

Figure 1-3 shows the property boundary of the Lone Tree project. It is significant to note that the land package includes the process area, the Lone Tree Pit and Buffalo Mountain exploration project.

The Lone Tree Properties include interests in fee lands, mineral rights in fee lands, patented mining claims, and unpatented mining claims which are leased or owned by i-80 as of the effective date of this report. All interests were acquired from Nevada Gold Mines and a full description of land and interests is shown in Figure 3-1. Details of all claims are provided in Appendix A. These properties are identified as part of the Lone Tree Mine Plan

 

 

10

 

 

of Operations (PoO) in Sections 11, 12, 13 and 14. More details are available in Section 4.

Figure 1-3: The Property Boundary for the Lone Tree Deposit Project

 

 

1.5	Geology and Mineralization

Mineralization is structurally controlled within three Paleozoic rock sequences at the Lone Tree deposit. The oldest of these three is the Valmy Formation which is unconformably overlain by rocks of the Pennsylvanian Antler Sequence of the Battle and Edna Mountain Formations. The Pennsylvanian-Permian Havallah sequence rocks were thrust over the Antler Sequence rocks in the mine area. The Havallah Sequence is dominated by siltstones, chert and basalts with lesser sandstones and conglomerates. Amongst the three mineralized Paleozoic sequences, Antler Sequence rocks appear to have been preferentially mineralized within the structural zones.

Out of three principal mineralized zones, the Wayne Zone, the Sequoia Zone, and the Antler High Zone, the Wayne Zone is the most preferred zone with a higher amount of mineralized material. The main structural component of the Wayne zone (Figure 1-4) is the north-south trending Powerline Fault, shown in Figure 1-4. While the pit bottom is currently underwater, the footwall of the Powerline fault appears to be exposed on the east wall of the Lone Tree mine.

 

 

11

 

 

Figure 1-4: The Mineralized Zone of the Lone Tree Deposit.

 

 

1.6	On-site Verification of Data and Information

As part of the S-K 1300 report work, Mr. Brian Arthur and Dr. Abani Samal visited the site on Wednesday, August 28th, and Thursday, August 29th, 2024. Dr. Abani Samal also completed a site visit on July 7th and 8th, 2021, as part of the 2021 NI 43-101 report. During the site visit, the following tasks were completed.

 

●

Field review of the general geology of the deposit.

 

●

Physical verification of selected drill hole intercepts.

 

●

Verification of available core, logging, and cutting facilities at the new Lone Tree storage facility.

 

●

A visit to the leach pads and the mill facilities.

 

●

Detailed discussions with site personnel were held.

 

●

A visit to the on-site laboratory facilities.

The locations of selected holes were completed in 2021 and have not changed.

 

1.7	Historical Summary of the Deposit

In the early days, the Lone Tree Hill area was explored for copper. Cordex discovered the southern extension of the Lone Tree gold deposit in 1988, which was referred to as the Stonehouse deposit at the time. Santa Fe Pacific Gold discovered the main part of the Lone Tree deposit in the pediment on the west flank of the hill in 1989 and acquired the Stonehouse portion of the deposit. Santa Fe Pacific Gold began producing gold from the site in 1991. Newmont acquired the deposit from Santa Fe Pacific Gold through a merger and continued operations in 1997. Newmont completed mining operations in 2006.

 

 

12

 

 

Reclamation activities began in 2007 and residual leaching continues into the present. In July 2019, the non-operating Lone Tree project became part of Nevada Gold Mines, a joint venture between Barrick and Newmont.

In 2021, i-80 Gold acquired the Lone Tree mine along with the processing facilities including an autoclave, CIL (carbon-in-leach) mill, a flotation plant, an assay lab and a heap leach facility. Gold is still being recovered from the leach pad.

 

2.	INTRODUCTION

The Lone Tree Property was acquired on October 14, 2021, by i-80 Gold Corp (i-80) from Nevada Gold Mines (NGM). This acquisition provided i-80 with important processing infrastructure including an autoclave, a flotation mill, CIL (carbon-in-leach) mill, and a heap leach facility complete with an assay lab, carbon columns, and interim toll processing agreements for i-80 at NGM facilities. The property boundary contains the existing mine and the process facilities as shown in Figure 2-1.

Figure 2-1: The Property Boundary of the Lone Tree Project

 

In addition to the processing facilities, the land package also includes the Buffalo Mountain deposit and the Brooks open pit mine (Figure 2-1), which is currently on care and maintenance.

 

 

13

 

 

2.1	Terms of Reference and Purpose of this Report

During this acquisition, independent verification of the quantity of mineral resources at Lone Tree was conducted by GeoGlobal using the available drill hole data and information shared by NGM at that time. A technical report with the title ‘Technical Report on the Mineral Resource Estimates for the Lone Tree Deposit, Nevada’ was produced as per the NI 43-101 guidelines and published in October 2021 (henceforth referred to as the 2021 report).

The acquisition of the Lone Tree mine (along with the processing facilities mentioned above) was completed after the publication of the 2021 report. Additionally, the composition of the shareholders of i-80 has recently changed. Therefore, i-80 engaged GeoGlobal again to review the resource estimates and update as required based on current market conditions and produce this report conforming to the United States Securities and Exchange Commission’s (SEC) Modernized Property Disclosure Requirements for Mining Registrants as described in Subpart 229.1300¹ of Regulation S-K, Disclosure by Registrants Engaged in Mining Operations (S-K 1300) and Item 601 (b)(96)² Technical Report Summary (TRS).

The effective date of the published mineral resources is December 31, 2024.

 

2.2	Qualified Persons and Firms Engaged in this Project

This project was led and managed by Dr. Abani Samal, a geologist working for GeoGlobal LLC. The following serve as the qualified persons or qualified firms for this Report in compliance with 17 CFR § 229.1302 (b)(1)(i) and (ii) qualified person definition.

 

2.2.1

GeoGlobal LLC

GeoGlobal, LLC (GeoGlobal) is an international service-providing company to the mineral industry based in the Salt Lake City area in the state of Utah, USA. GeoGlobal provides services to mineral exploration and mining projects around the world. Website: https://geoglobal.co/

Dr. Abani R. Samal is the Principal and owner of the company. The GeoGlobal retains a team of highly experienced professionals as Principal Associates, who together have more than 20 years of experience. The company specializes in mineral deposit evaluation for various commodities globally.

Projects were conducted for various entities including Waterton Copper, First Majestic, i-80 Gold Corp, Equinox Gold Corp, Nevada Copper, World Bank / Government of Nigeria, Rio Tinto, Resource Capital Funds, Orion Mining Finance / Aquila Resources, and Forbes & Manhattan.

 

 

¹ Title 17—Commodity and Securities Exchanges, Chapter II—Securities and Exchange Commission, Part 229—Standard Instructions for Filing Forms Under Securities Act of 1933, Securities Exchange Act of 1934 and Energy Policy and Conservation Act of 1975—Regulation S-K

² https://www.ecfr.gov/current/title-17/chapter-II/part-229/subpart-229.600/section-229.601

 

 

14

 

 

The GeoGlobal team has provided support and services to many exploration and mining projects in the USA, Canada, Brazil, Mexico, Kazakhstan, and most recently in Namibia and Nigeria. The types of projects include strategic project development, resource estimation, mine-mill reconciliation, etc.

The following professionals from GeoGlobal conducted this project for i-80 Gold Corp.

 

2.2.2

Dr. Abani R. Samal – Project Manager & Principal Geologist

Dr. Abani Samal has extensive training (M.S. and Ph.D.) in economic geology, mineral resource estimation, and geostatistics. He is the owner of GeoGlobal LLC where he works as a Principal.

Prior to GeoGlobal, Dr. Samal worked as the lead resource geologist with Rio Tinto at their corporate regional HQ based in Salt Lake City, Utah, USA, where he led and contributed to various major projects. He also worked as the lead geologist and geostatistician at an international mining consulting firm, Pincock Allen and Holt (now RPM Global), based in Denver, USA.

Dr. Samal has more than 20 years of experience in the mineral industry. He has experience in various commodities including gold-silver, base metals such as Cu-Mo-Au, and ferrous deposits around the world. Dr. Samal’s gold-silver experience includes his contribution to various projects such as Jerritt Canyon, Lone Tree, Las Brisas Venezuela, Pascua-Lama (Chile), Chapada (Brazil), and Black-Fox (Canada). He has led/completed many other confidential projects for M&A, corporate assurance, and corporate financing.

Dr. Samal is a Registered Member of the Society for Mining Metallurgy & Exploration (RM-SME), a Certified Professional Geologist (CPG), and a Fellow of the Society for Economic Geologists (SEG).

Dr. Samal is the project manager for this project and a Qualified Person (QP) for the sections mentioned in Section 2.2.5. He is also the lead QP on behalf of GeoGlobal LLC.

 

2.2.3

Mr. Brian Arthur – Principal Metallurgist

Mr. Brian Arthur is an independent consulting metallurgist who gained more than 30 years of professional experience in precious metal process operations and development with Newmont before becoming independent. He designed hydrometallurgical flowsheets to recover copper, nickel, cobalt, chromium, and zinc from various bi-product streams before joining Newmont.

Brian managed metallurgical laboratories, production teams, process design initiatives, metallurgical test programs, metallurgical accounting activities, and long-range process planning activities. Brian has experience with whole ore roasting, SAG milling, rod milling, and flotation, gold leaching, heap leaching, gold refining, and bio-oxidation.

He holds B.S. and M.S. degrees in Metallurgical Engineering from Montana College of Mineral Science and Technology and an MBA from the University of Nevada – Reno. He is also a QP as a registered member of the Society for Mining Metallurgy & Exploration (SME). Mr. Brian Arthur is working as a Principal Associate with GeoGloball LLC for this project.

 

 

15

 

 

2.2.4

Mr. Paul Gates – Principal Mining Engineer

Mr. Paul Gates has more than 37 years of experience in the mining industry, including extensive experience in field exploration, long-term mine planning, project feasibility and business case analysis, mine development and operations, mine valuation, and mine optimization. He supervised loading and haulage fleets in large open-pit copper mines with crews in excess of 60 operators.

He is skilled at planning, coordinating, and supervising operations at gold, copper, and silver mines. Paul also has consulting experience at uranium, coal, platinum, and iron ore mines and has a solid understanding of permitting and environmental challenges facing today’s mining industry.

Paul holds a B.S. degree in Mining Engineering from Montana College of Mineral Science and Technology and an M.S. in Business Administration degree from Western New Mexico University.

Paul is a Registered Professional Engineer (PE). He is working as a Principal Associate with GeoGloball LLC for this project.

 

2.2.5

Responsibilities of the Qualified Persons

The QPs have supervised the preparation of this report and take responsibility for the contents of the Report as set out in Table 2-1. The QP Certificates can be found in Section 26.

Table 2-1: QPs and Responsibilities for the Contents of the Report

 

		Qualified Persons		Report Sections		Topics
		Abani Samal		1, 2, 3, 5, 6, 7, 8, 9, 11, 15, 22, 23, 24, 25, 26		Summary, Introduction, Geology, Resource Estimation etc.
		Paul Gates		1, 2, 11 and 13		Criteria for Reasonable Prospect for Economic Extraction (Optimum Pit shell and Economic Analyses), Resource Tabulation) and Mining Methods
		Brian Arthur		1.3, 4, 10, 14		Mineral Processing and Metallurgy, Site Infrastructures

Sections 12, 16, 18, and 19 are beyond the scope of this project.

The data and information used in sections 4, 17, 20, and 21 were provided by the registrant.

 

2.3	Scope of this Project

It is understood that no exploration or mining activity has happened at Lone Tree Deposit since the above-mentioned NI 43-101 report was published in October, 2021 (2021 report). However, since then three years have passed and i-80 remains as the 100% owner of the Lone Tree deposit. This project provides an opportunity to revisit the existing data and information and cross-check various aspects of existing resource models and

 

 

16

 

 

estimates including criteria to demonstrate that there are reasonable prospects for economic extraction which may affect mineral resource classification for the purposes of an S-K 1300 Report. The scope of this project is discussed below.

 

i.

Onsite Verifications: As per the requirement of the S-K 1300 guidelines, the qualified persons (QPs) comprising the lead geologist and process engineer completed the site visit to do the onsite investigation. The following tasks were completed during the site visit.

 

●

Verification of the geology of the deposit, examination of available drill cores, pulps, and rejects acquired by i-80 from NGM.

●

Verification of the drill hole logs and sampling methods.

●

Selection of pulps and drill cores for re-assay.

●

On-site verification of leach pads, and processing facilities.

●

Verification of processes followed in the on-site laboratory facilities.

●

Verification of the quality of data includes QA/QC procedures, checking original assay records, etc.

 

ii.

Metallurgical Recovery: The Principal Metallurgist & Process engineer completed the site visit and later reviewed various sets of data as listed below.

 

●

Datasets for determining the appropriate metallurgical processing suitable for the remaining mineralized materials.

●

Recovery factors for various material types and process methods.

●

Processing costs for autoclave and flotation options.

 

iii.

Geological Model Verification: The geological models are to be reviewed for correctness.

 

iv.

Mineral Resource Estimation: The mineral resource estimation exercise conducted to produce the above-mentioned NI 43-101 report (the effective date of July 31, 2021) was reviewed and updated as required. The following items were considered.

●

Exploration Data Analyses (EDA).

●

Variogram analyses.

●

The density (or tonnage factor).

●

Grade estimation for gold.

●

Resource classification.

●

Development of an optimized pit shell by a qualified mining engineer with updated criteria.

●

Model validation review and update if required.

 

v.

Resource Estimates and Tabulation: The resource estimates were updated with new pit-optimization parameters. The classifications of the mineral resources were updated accordingly and the mineral resources were tabulated with an effective date of December 31, 2024.

 

 

17

 

 

2.4	Units of Measure

 

2.4.1

Coordinate Reference System (CRS) Used in the Maps:

Universal Transverse Mercator Zone 11, North American Datum of 1983. EPSG: 26911. For this report, maps were generated using a combination of Google Earth Pro and QGIS version 3.16.0-Hannover mapping tools.

The block model and drill hole coordinates are in the local Lone Tree mine grid system as defined by Newmont/NGM.

 

2.4.2

Conversion Factors Used

 

i.

1 ounce (oz) per short ton (t) = 34.2857 parts per million (ppm) = 0.0034286 %

 

ii.

1 part per million (ppm) = 0.0291667 ounce (oz) per short ton (t)

 

iii.

1 g/T = Opt*31.1035*1.102 (Opt: 1 ounce per short ton)

 

iv.

Million Tonnes (MT) = short tons (t) /1.102/1000000

 

v.

K Ozs = Oz/ 1000

 

2.5	Definitions

 

 

 

18

 

 

 

3.	PROPERTY DESCRIPTION

 

3.1	Location of the Project

The Lone Tree gold deposit is in the Battle Mountain district in Humboldt County, Nevada. As shown in Figure 1-1, the nearest town with full services is Winnemucca, which is a historic mining town in northwestern Nevada. The Lone Tree Mine is located approximately 30 miles east of Winnemucca, Nevada, and 20 miles northwest of Battle Mountain, Nevada. The mine office is accessible from Interstate 80 by a paved highway (Figure 3-1). The reference coordinates of the mine are 40° 50’ 19” N, 117° 12’ 37” W. The Lone Tree facilities include an autoclave, carbon-in-leach (CIL) mill, flotation plant, and heap leach facility.

 

3.2	Land Status

The Lone Tree Properties include interests in fee lands, mineral rights in fee lands, patented mining claims, and unpatented mining claims which are leased or owned by i-80 as of the effective date of this report. All interests were acquired from Nevada Gold Mines and a full description of land and interests is shown in Figure 3-1. Details of all claims are provided in Appendix A. The information on the Lone Tree/Buffalo Mountain map was prepared by the Land Department of i-80 (refer to Figure 3-1). The areas of unpatented and patented claims are shown in Table 3-1.

Table 3-1: The Area of the Lone Tree Claims

 

It should be noted that The Brooks unpatented claims are encapsulated in the Lone Tree Unpatented acreage, as they are adjacent to the Lone Tree property.

 

 

19

 

 

Figure 3-1:Location of Lone Tree Property and Land Position

 

These properties are identified as part of the Lone Tree Mine Plan of Operations (PoO) in Sections 11, 12, 13 and 14.

This report focuses only on the Lone Tree Mine properties. i-80 has been informed by the Clerk of the Eleventh Judicial District Court, Humboldt County, Nevada that there are no

 

 

20

 

 

pending actions which relate to the Lone Tree Mine properties in which the Company or the Company’s subsidiaries are named as parties.

 

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

The Lone Tree Mine project is located immediately adjacent to Interstate Highway 80 (i-80), approximately 35 miles east of Winnemucca, and approximately 12 miles west of Battle Mountain, Nevada. The project office is easily accessible from Interstate 80 as shown in Figure 4-1. From the mine office, the mine and process facilities are accessible via paved roads. The nearest town with full services is Battle Mountain, Nevada.

Figure 4-1:Location and Accessibility of the Lone Tree Mining Project

 

 

4.1

Climate

The climate of the Lone Tree mine area is cold and semi-arid typical of eastern Nevada. The temperatures range from highs of upper 40°C in summer to lows of –7°C in winter. The area experiences low annual precipitation of 15 to 20 cm per year and 50% of the precipitation occurs as snowfall during winter. The climate condition presents no restrictions to the operation of the Lone Tree mine and facilities.

 

 

21

 

 

4.2	Physiography

Elevations at the Lone Tree property range from approximately 1,490 metres above mean sea level (AMSL) to 1,350 metres AMSL for total relief of approximately 140 metres. The historic open pit bottom is at approximately 1,080 metres AMSL. The terrain varies from a relatively flat alluvial plain to sloped foothills in the area.

 

4.3	Vegetation

Vegetation in this area mainly comprises sagebrush, rabbit brush, and a variety of grasses and forbs. Fauna is not abundant on the Property primarily due to the lack of surface water and limited forage. No threatened or endangered plant or animal species have been noted within the Property’s operating area.

 

4.4	Site Infrastructure

The Lone Tree site has an employee parking lot with secure access to the administration building and a security gate for vehicles entering the mine property. All active areas of the mine are accessed by well-maintained gravel and dirt roads. The access roads are engineered at 60-70 feet wide to accommodate haul trucks and mining equipment traffic.

The site has many buildings on the property, including the following facilities.

●

Administration building

 

●

Haul truck maintenance shop and warehouse

 

●

Dewatering shop

 

●

Potable and fire water pump house

 

●

Mill and autoclave building

 

●

Flotation building

 

●

Filter building

 

●

Maintenance shop

 

●

Geology building

 

●

Assay laboratory building

 

●

CIC process building

 

●

Oxygen plant

 

●

Gold refinery

 

●

Two warehouses in the process area

 

4.4.1

Water Wells:

There are three active water wells on site. Well # NWW1 supplies fresh water to the fire water pump house storage tank and the potable water storage tank at an average pumping rate of 5.3 gallons per minute. Well #SS13 supplies water to the truck shop area fire water pump house storage tank at a rate of 14 gallons per minute. Well #SS14 supplies water to the truck shop area fire water pump house storage tank at a rate of 10 gallons per minute.

 

 

22

 

 

4.4.2

Electric Power

Electrical power is supplied by Nevada Energy via a main transmission line that runs through the property and delivers 20KV to the main site substation. Transformers step the power down to 24.9KV and then to 4160V for further distribution. Additional transformers are in place to step down the power to the level needed in each area of the site.

The main source of heating comes from three propane tanks, each holding 12,000 gallons. Out of three, one is used in the administration building area and two in the mill processing area.

 

4.4.3

Mineral Processing & Metallurgy Facilities

The site has an autoclave and a flotation mill and a leach pad. The autoclave and flotation mill are in care and maintenance. The leach pad is still producing remaining significant amounts of gold and has a remaining capacity of 10,000,000 tons. The list of processing plants includes the facilities as discussed below.

 

4.4.3.1

Mill Facilities

The mill site was once used to process high grade oxide ore and refractory ores from the Lone Tree mine. The mill had two grinding lines, with one line that prepared feed for an autoclave and the other prepared feed for a flotation plant or oxide leach ores. The SAG and ball mills for both lines are intact.

 

i.

Lone Tree Autoclave (Figure 4-2), which processes high-grade refractory ore.

 

ii.

Lone Tree Flotation Plant, which processes low-grade refractory ore.

 

iii.

Oxygen Plant to supply oxygen to the autoclave and nitrogen to flotation.

 

4.4.3.2

Lone Tree Leach Pads:

The leach pads treat oxide ore in a cyanide heap-leach process. The leach pads (Phases 1-4 and Phases 5-7 as shown in Figure 1-2) are still in service and operation. i-80 has recently stacked some oxide ore from Granite Creek and it is now under leach. The carbon columns were located on the leach pad and looked to be in good condition.

 

4.4.3.3

Carbon Stripping Facilities

Carbon stripping facilities were used to recover the gold loaded on carbon from both the CIL and CIC circuits. Currently, i-80 sends loaded carbon from CIC off-site for stripping.

 

 

23

 

 

Figure 4-2:Autoclave Agitator Access Ports

 

Figure 4-3:Pulverizing and Preparation Stations

 

 

 

24

 

 

4.4.4

Laboratory Facilities:

The laboratory facilities are fully functional. The laboratory facility includes the areas for sample receiving, sample preparation area, weighing area, fire assay, wet chemistry area, LECO, and ICP areas. The sample pulverizing machine and preparation area are shown in Figure 4-3. The LECO and ICP labs are shown in the figures (Figure 4-4) and Figure 4-5 respectively.

Figure 4-4:The LECO Facility

 

Figure 4-5:ICP Laboratory Facility at Lone Tree

 

 

 

25

 

 

5.

HISTORY

 

5.1	Historical Summary of the District

In the early days, the Lone Tree area was explored for copper, but no significant resources were discovered. The initial discovery hole at Lone Tree was drilled in July 1989 by Cordex Exploration Co. on the southern extension of what was to become the Lone Tree gold deposit. This southern portion of the deposit was referred to as the Stonehouse deposit. Santa Fe Pacific Gold discovered the main part of the Lone Tree deposit in the pediment on the west flank of the hill in 1989 and acquired the Stonehouse portion of the deposit from Cordex. Sante Fe Gold began producing gold from the site in 1991. Newmont acquired the deposit from Santa Fe Pacific Gold through a merger and began operations in 1997. Newmont completed mining operations in 2006.

Operations were discontinued in 2006 due to increased production costs, largely resulting from the influx of groundwater into the deepening pit. The pit was allowed to flood and create a lake within the pit. Approximately 4.6 million ounces of gold were produced from the Lone Tree Mine and approximately 5.2 million ounces of gold were produced at the Lone Tree processing facilities during this time.

Mining on the Brooks deposit which lies to the southwest of the main Lone Tree pit was conducted from 2015 to 2019. Approximately 52,000 ounces were placed on the heap leach pad and residual leaching is continuing.

Residual leaching and ongoing reclamation activities from the Lone Tree Mine have continued since 2007. In July 2019, the non-operating Lone Tree project became part of Nevada Gold Mines, a joint venture between Barrick and Newmont.

i-80 Gold Corp acquired the Lone Tree property and processing facilities from NGM on October 14, 2021.

 

6.	GEOLOGICAL SETTING, MINERALIZATION & DEPOSIT

 

6.1	Regional Geology

The Lone Tree deposit occurs in Humboldt County, Nevada, within the Basin and Range physiographic province, in the northern part of the Battle Mountain mining district. The Battle Mountain mining district is dominated by Late Cretaceous and Eocene age magmatism with various ore deposit types including porphyry Cu-Au, porphyry Mo, skarn, and distal disseminated +/- Carlin-type deposits. Holley et al 2019, list several Cu-Mo porphyry along with sedimentary rock-hosted gold deposits, such as Lone Tree, Buffalo Valley, Marigold, North Peak, and Trenton Canyon, which have been classified as distal disseminated and Carlin-type deposits (Doebrich and Theodore, 1996, Theodore, 1998, 2000, Reid et al. 2010). The location of the Lone Tree Mine Relative to Major Mineral Trends in Nevada are shown in Figure 6-1 (modified from Wallace et al. 2004 and Fithian

 

 

26

 

 

et al. 2018). The location of the Lone Tree deposit is shown along with other deposits in the Battle Mountain trend in Figure 6-2 (Source: NGM); and Au-skarn deposits, such as those at Buckingham, Copper Canyon, Copper Basin, and Elder Creek.

Figure 6-1: Location of the Lone Tree Mine Relative to Major Mineral Trends in Nevada.

 

Ag:Au ratios are consistent with those in most other Carlin-type deposits, although the lower ratios of some ores are similar to the distal-disseminated Au-Ag deposits such as Lone Tree, Nevada. (Ressel, 2005).

The low Ag:Au ratios and lack of base metals have been used to differentiate Carlin-type Deposits from other sedimentary rock-hosted deposits in northern Nevada such as Lone Tree, which are classified as pluton-related or distal-disseminated Ag- Au (e.g., Cox, 1992; Mosier et al., 1992; Doebrich and Theodore, 1998, Wallace et al 2004).

 

 

27

 

 

Figure 6-2: Location of Lone Tree Deposit in the Battle Mountain Mining District

 

Wallace et al (2004) provide a detailed account of the regional tectonic activities in northern Nevada, occurring over a period of 2 billion years starting with Precambrian rocks occurring in the East Humboldt. Paleozoic rocks in this region generally comprise the four distinct tectonostratigraphic assemblages described below (Source: Holley, 2019).

 

●

Cambrian-Ordovician miogeoclinal carbonate shelf-slope rocks identified through deep drilling in the district but not exposed at the surface (Fithian et al., 2018).

 

 

28

 

 

●

Ordovician-Mississippian eugeoclinal siliciclastic rocks of the Roberts Mountain allochthon, including the Valmy Formation.

 

●

Autochthonous Pennsylvanian to Permian shallow-water facies of the Antler overlap sequence.

 

●

Mississippian to Permian deep-water siliciclastic rocks and basalts of the Golconda allochthon, which were thrust on top of the Antler overlap sequence by the Golconda thrust during the Permian-Triassic Sonoma orogeny (Theodore, 2000), constituting the Havallah sequence many of the clastic constituents of these rocks appear to be sourced from the Antler highlands (Whiteford, 1990).

Gold deposits are hosted in a variable stratigraphic package of Ordovician through lower Mississippian shallow-water rocks that have been overthrust by deep-water, siliciclastic allochthonous rocks along the Roberts Mountains Thrust during the late Devonian to Early Mississippian Antler orogeny (Roberts et al., 1958, Roberts 1960). Subsequent orogenic shortening during the Pennsylvanian and Permian (Humboldt disturbance) (Ketner, 1977), Early Triassic (Sonoma orogeny) (Silberling and Roberts, 1962), Middle Jurassic (Elko orogeny) (Thorman et al, 1990) and Early Cretaceous (Sevier orogeny) (Armstrong, 1968) have reactivated earlier basement and Antler-related faults. The sedimentary rocks are intruded or unconformably overlain by igneous rocks of three magmatic episodes: Cretaceous, Eocene, and Miocene age.

The current regional physiography is the result of extensional tectonics during the Tertiary. High angle faults formed during this period are interpreted as the main pathways for ore forming fluids. Economic concentrations of gold typically occur near the intersections of northeast and north-south faults, along the margins of intrusive bodies, or at contacts between siliceous and carbonate lithologies. Geochemical enrichment in trace elements such as silver, arsenic, antimony, mercury, and thallium are common to nearly all trend deposits.

 

6.2	Deposit Geology and Mineralization

Mineralization is hosted within structures which crosscut all three Paleozoic rock sequences present in the mine area. The oldest of these three sequences is the Ordovician Valmy Formation, which is a part of the Roberts Mountain Allochthon.

In the mine area, the Valmy consists primarily of quartzite, with lesser amounts of chert, argillite, and minor basalt. The Valmy rocks are unconformably overlain by rocks of the Pennsylvanian Antler Sequence, which belong to the Battle and Edna Mountain Formations. A geological map of the Lone Tree mine along with vertical Cross Section are presented in Figure 6-4. The Edna Mountain Formation at Lone Tree is typified by a sandy siltstone unit grading downward into a lithic sandstone unit. The Battle Formation is observed as a poorly sorted cobble conglomerate of varying thickness. A thin calcareous sandstone tentatively identified as a lateral equivalent of the Antler Formation rocks present at the Marigold Mine has been encountered in drill holes on the southeastern margin of the mine area. Rocks of the Pennsylvanian-Permian Havallah sequence were

 

 

29

 

 

thrust over the Antler Sequence rocks in the mine area during the Sonoma Orogeny. The Havallah Sequence at Lone Tree encompasses several rock types within at least three packages, but is dominated by siltstones, chert, and basalts with lesser sandstones and conglomerates.

Figure 6-3:General Stratigraphic Sequence of Lone Tree

 

 

 

30

 

 

Figure 6-4:Local Geology of Lone Tree Deposit and Controls of MIneralizaton

 

 

 

31

 

 

Although gold mineralization is present in all three Paleozoic sequences, Antler Sequence rocks appear to have been preferentially mineralized within the structural zones. Alluvial cover over the deposit ranges from a minimum of two feet to a maximum in excess of 400 feet. Bedrock has been sharply down-dropped to the north and to the southeast by post-mineral faulting, creating alluvium-filled basins in excess of 1,000 feet deep. See Figure 6-3 for the local stratigraphic interpretation Mine (K.C Raabe, 1995. The Lone Tree Extension Project, Humboldt County, Nevada).

 

6.3	Controls of Mineralization

Gold mineralization at Lone Tree is primarily controlled by structure as seen in Figure 6-4. This figure was developed by modifying the figures developed by NGM staff and the figures shown in Holley et al. (2019). Three principal mineralized structural zones and at least one lesser zone are currently recognized. The three principal structural zones are known as the Wayne Zone, the Sequoia Zone, and the Antler High Zone. The Wayne Zone is the most significant of the three major zones in terms of strike length, mineralized tons, and contained ounces. The Wayne Zone encompasses more than 50 percent of the contained tons and ounces within the overall deposit. The most widely recognized of the lesser zones is known as the Chaotic Zone, aptly named for the structural complexity associated with it.

The Wayne Zone has been described as a system of relatively narrow north-northwest and north-northeast trending faults forming an anastomosing complex of brittle shears enveloping rhomboid blocks of relatively competent but highly fractured domains of lesser strain (Bloomstein et al, 1992). With few exceptions, ore-grade mineralization does not extend along the north-northeast and north-northwest faults beyond the margins of the Wayne Zone. Detailed examination of blast hole data clearly demonstrates a “zig-zag” pattern of mineralization within the principal component structure of the Wayne Zone, known as the Powerline Fault. Higher gold grades within the Powerline Fault are commonly associated with the hanging wall and footwall margins of the fault, which averages 50 feet in width.

The Powerline fault zone is a North - South trending high angle fault zone, extending at least 2,500 m along strike. Mineralization is truncated to the north by the NE trending Poplar Fault. Mineralization in the Wayne Zone is hosted in all 3 rock packages (Valmy, Antler, Havallah) as breccia within the complex structure.

The southern zones of mineralization (Sequoia, Antler High zones) are primarily hosted in the Edna Mountain Formation of the Antler sequence. This mineralization is a combination of structural (Sequoia Fault) and stratiform control. Unlike the Carlin Trend where gold is primarily hosted in arsenian pyrite, at Lone Tree gold is primarily hosted in both arsenopyrite and arsenian pyrite. Lone Tree has always been considered a horst block cored by the Valmy Formation. Siliciclastic sediments with the Powerline Fault on the west side and Sequoia Fault on east side are the main controls to mineralization (Figure 6-4).

 

 

32

 

 

The Wayne Zone itself ranges in width from 150 to 300 feet. It trends north-south, dips to the west at an average of 65 degrees and has a drill-defined strike length in excess of 9,000 feet. The northern half of the zone essentially bounds Lone Tree Hill on the west. Drilling has encountered Wayne Zone mineralization down-dip nearly 1,000 feet from the original ground surface sub-economic mineralization remains open below this depth.

The Sequoia Zone is located to the southeast of Lone Tree Hill and essentially describes the southeastern margin of the deposit. The structural fabric of the Sequoia Zone is quite similar to that of the Wayne Zone, with some important differences. The known strike length of the Sequoia Zone is 2,000 feet, significantly less than that of the Wayne Zone.

The overall dip of the Sequoia Zone is 75 degrees, as opposed to the 65 degrees of the Wayne Zone. Post-mineral faulting has displaced or cut out mineralization within the Sequoia Zone and has had a significant effect on the continuity of mineralization, both down-dip and along strike.

The Antler High Zone is located within a horst block of Antler sequence rocks between the Wayne Zone and Sequoia Zone and is limited to the southern third of the deposit. The Antler High mineralization is primarily developed within rocks of the Edna Mountain, Battle, and underlying Valmy Formations, and commonly appears parallel or sub-parallel to bedding. Evidence suggests that the Antler High gold mineralization is hosted within a dense network of very narrow fractures similar to a stockwork. Several high-angle mineralized structures are known to cut through the Antler High and may have served as feeder structures. The trends and dip angles of these latter structures are sub-parallel to those of the Wayne Zone and Sequoia Zone. Along the northern margin of the Antler High, several of these structures trend upward through the Golconda thrust and into the overlying highly siliceous Havallah rocks. The combination of these specific high-angle structures and local, lower-angle mineralized structures is known as the Chaotic Zone. In addition to the high-angle structural control in the Antler High, a low-angle (45 degrees east) west-vergent compressional feature known as the Redwood Fault controls a substantial portion of the mineralization in that zone. The Redwood Fault effectively doubles the thickness of the Edna Mountain host rocks within the Antler High.

Mineralization is hosted both within the fault plane itself, and within the highly shattered rocks of the adjacent hanging wall block. The age of the Redwood Fault is not known, but certain evidence suggests that it pre-dates the Sonoma Orogeny.

Mineralized structures have been identified in the hanging wall of the Wayne Zone, and within the footwall of both the Wayne Zone and the Sequoia Zone. Many structures controlling gold mineralization are moderate to high angle, west- or east-dipping normal faults or fractures. Some lower-angle mineralized structures, which are thought to have been re-activated during extension, have been noted. As within the Wayne Zone, mineralization most often occurs at the intersection of NNW and NNE-trending faults of varying dip angles. Strike-slip or oblique-slip motion has been noted on some structures,

 

 

33

 

 

although kinematic indicators are essentially non-existent in the highly silicified, brittle rocks of the Edna Mountain Formation, or in the Valmy quartzite.

A principal characteristic of the Lone Tree deposit is the spatial coincidence of several structurally controlled episodes of mineralization. Hydrothermal breccias, with as much as 25% matrix expansion, host a significant portion of the gold mineralization. High-grade ore occurs at fault or fracture intersections, or at jogs in the faults, which form dilatant zones.

Silicified, multiple-phase breccias have been noted along the margins of the principal mineralized zones. These appear to be early, and in general, are lower in grade. Later tectonic breccias were superposed on the hydrothermal breccias. The most recent structures tend to be milled-breccia post-mineral faults and shears, which often possess >50% clay gouge, and display a crude lamination produced by streaks of iron oxide, pyrite, or angular clasts. Reactivation of high-angle faults is demonstrated by barren, vuggy silica-cemented structures overprinting similarly oriented mineralized zones.

Mineralization is also known to occur in crackle breccias within the more brittle rocks of the Edna Mountain and Valmy Formations, which are crosscut by the Wayne Zone. Zones of intense micro-fracturing noted in the highly silicified Edna Mountain rocks are the closest approximation to “classic” disseminated mineralization yet noted at Lone Tree.

Numerous cross-structures have been identified at Lone Tree. Significant gold mineralization has not been observed in association with any of these structures. The Wayne Zone is cut on the north by a major northeast-trending fault zone known as the Poplar Fault Zone. While the Wayne Zone as a structural zone does not appear to be terminated by the Poplar Fault zone, the down drop of the bedrock surface, thinning of the mineralized faults, and decreased grade all currently limit the economic potential of the Wayne Zone north of the Poplar. Other northeast-trending faults, such as the Willow Fault, have significant effects on the mineralization even though they do not offset the Wayne Zone.

A west-northwest-trending zone of southerly dipping normal faults known as the Pinon Fault zone truncates Lone Tree Hill to the south and is associated with a change in the strike direction of the Wayne Zone at that location. At the extreme southern end of the known mineralization, the Wayne Zone and Sequoia Fault converge. Drilling has identified at least one major northeast-trending structural zone in this area which appears to have some effect on mineralization.

As a result of the fact that the Lone Tree deposit occurs at the margin of a bedrock block essentially surrounded by alluvium, the relationship of the deposit to regional structure is not well understood. It has been speculated that the deposit may have formed in response to strike-slip and normal faulting related to regional wrench faulting. An alternate hypothesis suggests that the faults which control and host mineralization at Lone Tree may be dominantly extensional in nature, with little relationship to strike-slip and wrench faults. The age of the mineralization is constrained to the Eocene based on dating of

 

 

34

 

 

mineralized intrusive rocks (Holley et al., 2019). It’s clear many of the faults were active at the time of mineralization, although their age of first movement is uncertain.

 

6.4	Alteration

The principal alteration process associated with gold mineralization at Lone Tree is potassic alteration (Bloomstein et al., 1992). Other alteration types noted in the mine area are argillization, silicification, propylitization, and skarnification. A general progression from oxidized argillic alteration in the Havallah sediments down into unoxidized argillization, silicification and potassic alteration in the Antler and Valmy rocks has been noted. Alteration assemblages are commonly mixed within the fault zones as a result of the structural control of mineralization. Pervasive pre-mineral silicification is common in portions of the Havallah Sequence, and throughout most of the Antler Sequence rocks at Lone Tree Mine (K.C Raabe, 1995. The Lone Tree Extension Project, Humboldt County, Nevada).

 

6.5	Gold Mineralogy

Gold mineralization occurs as sub-micron sized inclusions within a distinct generation of very fine-grained pyrite and arsenopyrite in the sulfide zone. Evidence gathered to date suggests that the main gold deposition event occurred in a temperature range of 200^o to 450^o (epithermal to mesothermal). The ore mineralogy shows evidence of two overprinted assemblages reflecting at least two hydrothermal episodes at Lone Tree. Partial oxidation of the main stage mineralization occurred prior to a later, epithermal event characterized by open-space filling textures and weakly auriferous pyrite and marcasite. In the oxidized portions of the deposit, and particularly in the Havallah rocks, gold occurs as micron-sized particles in goethite and limonite. Post-mineral oxidation extends as much as 700 feet down major structures such as the Wayne Zone. No supergene effects or gold remobilization have been proven or documented at the Lone Tree Mine (K.C. Raabe, 1995). The Lone Tree Extension Project, Humboldt County, Nevada).

 

6.6	Deposit Type

The Lone Tree deposit is characterized as a pluton-related or distal-disseminated Ag- Au deposit. This deposit type is discussed by Wallace et al., 2004 and Munteen and Cline, 2018).

As discussed by Peters et al. (in Wallace et al. 2004) the Lone Tree deposit among others in the Battle Mountain district appears to be related genetically to porphyry systems, even though many deposits do not contain obvious near-surface features that would indicate this connection, mainly because the gold-silver mineralization in these deposits may be over one km away from the causative intrusions. This is why the deposit has been characterized as “distal disseminated”. Due to complex tectonic and extension in the region, the mineralization in these deposit types may have substantially different geometric relations to the intrusive centers and hosted in different stratigraphic horizons as shown in the Figure 6-5 (Wallace et al., 2004). The mineralization at Lone Tree occurs

 

 

35

 

 

in intensely fractured three stratigraphic horizons. These horizons are similar to but significantly different to the horizons found in other deposits in the region. Gold is associated with a low Ag:Au ratio (<2:1), As, Sb, Hg and Tl as well as elevated Bi, Mo and W. Gold is hosted in arsenopyrite indicating higher temperatures of ore formation in comparison to typical Carlin-type deposits where gold is hosted in arsenian pyrite.

Figure 6-5:Diagrammatic Model of Geology of Distal-Disseminated Ag-Au Deposit.

 

 

7.	EXPLORATION

 

7.1	Exploration History

The exploration history of the Lone Tree deposit is documented by Bloomstein et al. 1993. Part of this section is extracted from that publication. Prospecting around Lone Tree Hill is believed to have started in the middle 1860’s when the construction of the Central Pacific portion of the Transcontinental Railroad started about three kilometers northeast of Lone Tree. Sporadic exploration activities continued for copper and gold without much success until Duval Corp and Bear Creek explored the area in 1960’s and 1970’s for porphyry copper. These exploration activities aided in the discovery of low-grade gold mineralization in the area.

Exploration activities in the 1980s by Nerco, Freeport and several Canadian junior companies yielded intercepts of narrow, fracture filled gold mineralization. In 1989 Cordex Exploration and Santa Fe Mining formed a joint venture for exploration of the Lone Tree deposit resulting in a discovery of substantial gold mineralization about one km from Lone

 

 

36

 

 

Tree Hill. Subsequently, 12 additional holes were drilled and a north-south fault system controlling mineralization was discovered. The first gold was poured in 1991.

Later, Newmont acquired the deposit from Santa Fe Pacific Gold through a merger and assumed operations in 1997. Extensive surface mapping, sub-surface drill hole modeling, geochemical sampling, geophysics, and drilling resulted in the discovery of seven separate ore bodies of similar structural and lithologic genesis (Zacarias, P. A., 2006). All but one deposit located to the south of the active mine were actively mined. Newmont completed mining operations in 2006. Residual leaching continued through 2019. Reclamation began in 2007. In July 2019 the non-operating Lone Tree project became part of Nevada Gold Mines, a joint venture between Barrick and Newmont.

GeoGlobal is aware that various exploration activities were completed in this area. Even though geophysical and other exploration activities such as trenching, pitting, and trial mining were conducted in this area, supporting documents were not available to verify.

 

7.1.1

Drilling and Sampling

Between 1980 and 2015 a total of 1,904 drill holes, summarized in Table 7-1, were completed in and around the Lone Tree mine.

Table 7-1:Summary of Drilling by Hole Type

 

Out of these holes, 1,840 holes were selected for the resource estimation which are close to the Lone Tree mine (Figure 7-1). The 1,840 holes had 2,19,214 assay data, 113,862 lithological logs. Out of 1840 holes 362 holes had no lithological logs.

 

7.1.2

Recent Exploration Drilling

In 2020, a drill hole (LTE-20001) was drilled on the west side of the mine which tested for the existence of the Comus Formation below the Lone Tree Mine. The Comus Formation is significant because it is the host rock for the Turquoise Ridge, Twin Creeks, and Granite Creek mines. The drill hole intercept is shown in the Figure 7-2. Four zones of mineralization were encountered as listed below.

 

 

37

 

 

Figure 7-1:Location of Selected 1840 Drill Holes for Resource Estimation

 

 

i.

Upper zone of 10.7m @ 4.49 g/t above a QFP (quartz–feldspar porphyry) dike on the contact of the Permian Havallah Formation (P and Edna Mtn Formation. The Upper zones of mineralization are consistent with stratiform mineralization identified in wide-spaced drilling through the hanging wall to the Powerline Fault; this zone is open in three directions.

ii.

Zone along the contact of Edna sandstone and Valmy quartzite (Phv) (7.6m @ 6.04 g/t including 1.5m @ 13.5 g/t).

iii.

Zone of sulfide breccia in Valmy quartzite (38.1m @ 2.15 g/t w/ grades up to 18.95 g/t Au).

iv.

Lower zone of mineralization hosted within a QFP (Quartz Feldspar porphyry) dike with sooty pyrite on fractures and in the groundmass of the intrusive (40.3m @ 1.22 g/t).

The Lower Plate Ord. Comus Formation was intercepted at 1155 m (3790’). The Comus is characterized by strong calc-silicate hornfels intruded by fine grained diabase sills.

 

 

38

 

 

A narrow zone of mineralization was encountered down-dip on the Powerline Fault in the Comus Formation (3.0m @ 1.84 g/t). Additional drilling is warranted to vector from the strong calc-silicate alteration to intersect ore controlling structures in more reactive host rocks.

Figure 7-2:Exploration Drill Hole LTE-20001 (Source: NGM)

 

 

7.1.3

Rotary Drilling

Historic drilling, including rotary drilling, started in 1980. Samples were typically collected at the drill site after traversing through a rotary wet splitter attached to the return air hose. Most splitters allow for sample size changes by blocking some of the internal rotating vane

 

 

39

 

 

chambers, thus causing sample material excess to be discarded. The normal sample interval is every five feet, with dry sample weights ranging from 5 to 20 pounds.

Rotary air samples are normally produced by either a down hole percussion hammer bit or a rotary tricone roller bit, with the sample traversing from the bit face up the annulus between the bit and sub or hammer assembly, then into an opening into the drill pipe (“interchange”) center tube and then up to the surface. In the past ten years more use has been made of drill bits that direct the sample into the center tube through an opening in the drill bit face.

Typically, the sample bag (13” by 26” Tyvek 1680 series porous fabric) is clamped onto the splitter outlet. Note that early (circa mid 1980’s) rotary air sampling may have been accomplished in dry conditions using non-porous plastic bags.

The rotary drilling technique includes clearing the bottom of the hole after every rod change and before the next sample chips are collected and washing the splitter if any material is noted sticking to the sampling surfaces. Some early rotary holes were drilled using the conventional air circulation method wherein the sample returned in the annulus between the drill pipe and rock.

Rotary mud drilling includes conventional water-based mud systems in which the sample chips return up the annulus between the drill string and the rock suspended in a ‘mud’ solution. At the surface, the liquid either runs through a settling trough, and the chips manually scooped out of the trough into bags or is directed over a vibrating screen which allows the fluid to fall drain off while the chips progress into a random vane stationary (‘pinball’) splitter and then into sample bags.

 

7.1.4

Reverse Circulation Drilling

The Lone Tree Complex followed a standard procedure for Reverse Circulation (RC) drilling executed by a drilling contractor (Zacarias, 2006).

 

1.

Samples are collected by the drill contractors through a rotating splitter attached to the drill rig by the drilling contractor.

 

2.

Samples are collected in five-foot intervals and chip trays are simultaneously filled for later geologic interpretation by the drilling contractor.

 

3.

Nominal sample weight is between 8 and 12 pounds as collected by the drilling contractor

 

4.

Samples are collected in micro-pore bags to minimize loss of the fine fraction of sample. These bags are provided to the drill contractor by the Newmont drill services department. Bags are tagged with a bar code to track status and for ease of processing and marked with the hole number and sample footage interval for the lab and the project geologist by the drilling contractor.

 

 

40

 

 

5.

Problems with sample contamination in the rotating splitter (cyclone) are minimized by the strict practice of cleaning the inside of the cyclone regularly by the drilling contractor.

 

6.

All drilling problems, including lost circulation, poor sample recovery, and high water flow are discussed with the project geologist and personnel from drilling services and remedied, if possible, by the drilling contractor.

 

7.

Samples are prepared for shipment to the assay lab and placed in multi-sample bins by the drilling contractor.

 

8.

The geologist consults historical data and elects an assay procedure that is appropriate for the style of mineralization (e.g., whether there is a coarse gold issue or “nugget”, and what is the nature of the gold mineralization and gold digestion techniques) in the Lone Tree Complex geology.

 

9.

The geologist completes the sample submittal with all necessary analytical requests, and assay packages and submits quality-check standards (blanks) by the Lone Tree Complex geology.

 

10.

The geologist notifies the accredited assay lab to request a sample pick-up.

 

11.

Assay results are relayed to the database department and the project geologist upon completion.

 

12.

Sample pulps and coarse rejects are temporarily stored at the assay lab and then returned for storage at the Twin Creeks warehouse or the Winnemucca hangar-Independent assay lab by Newmont Drill Services.

 

13.

Significant drill intercepts or intercepts that appear anomalously low are often reanalyzed at a different lab as a quality control and verification measure as determined by Lone Tree Complex Geology personnel.

 

14.

Hard copies of the assay results are filed with the completed geology log for the respective hole in the geology logging facility at the Lone Tree offices by the Lone Tree Complex geology.

 

15.

Assay data are computerized and available for extraction by Database management.

 

7.1.5

Core Drilling

The following procedure pertains to core drilling and sampling at the Lone Tree Complex (Zacarias, 2006).

 

1.

The core is cut by the contractor by a diamond bit in 5 to 10-foot runs. The standard diameter for exploration drilling is HQ, 2 3⁄4-inch diameter.

 

2.

Samples are laid in boxes containing approximately 10-foot capacities by the drilling contractor.

 

3.

Records are maintained concerning core recovery, run length, core loss, rig time and hole conditioning, and drilling contractor.

 

4.

Blocks are placed in the boxes which mark the end of a core run and record the length of the run and the length of the core recovered by the drilling contractor.

 

5.

All drilling problems, including lost circulation, poor sample recovery, and high water flow are discussed with the project geologist and Drilling Services and remedied, if possible, by the drilling contractor.

 

 

41

 

 

6.

Any core loss is treated as serious and the proper remedies including fluid modification are implemented by the contractors and the drill services representative by the Drilling contractor and Newmont drill services.

 

7.

Boxes are stacked when filled and taken by geology to the logging facility by Lone Tree Complex geology.

 

8.

Core is washed (minimally) and logged for detailed geologic interpretation. Geotechnical and geology logging is done at the same time. Core loss is noted on the log by Lone Tree Complex geologists.

 

9.

Sample intervals are marked out in the core boxes with aluminum tags for later core cutting/sampling. Sample breaks are based on the geologist’s interpretation and lithology/structure/alteration contacts. In general samples in homogenous intervals are nominally 5 feet in length by Lone Tree Complex geology.

 

10.

The geologist consults historical data and elects an assay procedure that is appropriate for the style of mineralization (e.g., whether there is a coarse gold issue or “nugget”, and what is the nature of the gold mineralization and gold digestion techniques) by Lone Tree Complex Geology.

 

11.

The geologist completes the sample submittal with all necessary analytical requests, assay packages and submits quality-check standards (blanks) by Lone Tree Complex Geology team.

 

12.

The core is picked up by the drill services group and taken to Twin Creeks Mine for cutting and shipment to the assay lab. It is standard procedure to saw the core in half lengthwise and send half to the accredited assay lab and store half in the Twin Creeks warehouse. The geologist can request that the core be cut down a specific “cut line” marked and denoted on the piece of core but this is rare. Whole core (as in the 2003 program) has been sent for assay without cutting in areas where sample integrity must be ensured by Drill Services.

 

13.

Metallurgical/petrographic/geochemical/density testing may occur at this stage depending on the maturity of the project as determined by the Lone Tree Complex geology team, or by the One Tree Process group.

 

14.

The remaining half of the core is stored in the Twin Creeks warehouse or a company-rented hangar in Winnemucca by Drilling Services.

 

15.

Sample pulps and coarse rejects are temporarily stored at the assay lab and then returned for storage at the Twin Creeks warehouse or the Winnemucca hangar by Drill services.

 

16.

Assay results are relayed to the project geologist and the database manager, and a hard copy of the results is filed with the geologic log in the geology logging facilities at the Lone Tree offices by Lone Tree Complex Geology personnel.

 

17.

Significant drill intercepts or intercepts that appear anomalously low may are often reanalyzed at a different lab as a quality control and verification measure by Lone Tree Complex Geology personnel and an independent assay lab.

 

18.

Assay data is entered into an electronic database using computers and made available for extraction and geologic modeling, database management and Lone Tree Complex geology team to proceed to the data quality control and validation flowsheet.

 

 

42

 

 

Once core is collected, the footage blocks and cut list are checked for accuracy. The core is then laid out, washed, and logged for lithology, formation, alteration, mineralization, and structural measurements on a standardized Lone Tree Complex log form. Samples are then selected based on geologic changes or approximately every 5 feet in geologically homogenous rock. Samples are marked with aluminum tags. Core was then photographed and processed.

 

7.2	Collar Surveys/Locations

Collar grid coordinates have been determined by optical surveys (1960’s through late 1980’s), field estimates, Brunton compass and pacing, compass, and string distance, and most recently the use of laser survey or global positioning system measurements. Modern hole locations were transferred electronically to the database and loaded using automated data programs. Hole locations were field checked by geologists and support staff, then plotted on maps, and visually checked for reasonableness in the database.

Drills were oriented on-site using a foresight and backsight set of survey stakes. Normally these stakes are placed by the geologists using a compass to determine orientation.

Prior to the next higher-level study, additional work will be required to better understand the quality and completeness of the drill hole database.

.

 

7.3	Down-Hole Surveys

Determination of the hole trace was accomplished historically by projection of the initial collar orientation, using a down-hole single-shot or multi-shot film camera.

The most recent downhole survey practice includes the use of gyroscopic surveys, the results of which are automatically loaded to the drill hole database using a direct import function. Gyroscopic surveys are normally reported at 25-foot intervals. Readings are taken with reference to true north (adjustments for declination are made on-site). Magnetic interference is not generally a problem for most of the drill sites in Nevada. Care is taken to reduce the effects of nearby metal objects when compasses are used for survey tool orientation.

Standard procedure at Lone Tree was to perform a downhole survey on all holes greater than 300 feet in length. In some cases (e.g., important angle holes) shorter holes are surveyed as well. An independent contractor performs the survey. The azimuth of the drilled hole is determined using a correction from magnetic north to true north with a standard Brunton pocket transit/compass. The angle correction used for 2003 was 14.5 degrees west of magnetic north as read on the compass. This correction was standard for the contractors and the geologist lining up the drill rig. The downhole survey is done by lowering a gyro through the intact drilling steel and measuring the deviation of the original angle and the variance of the original azimuth. The survey data were recorded, and the

 

 

43

 

 

geologist received a hard (paper) copy immediately after the survey. An electronic copy of the data was sent to Newmont database managers for inclusion in the database. Possible errors were screened by the geologist and the database managers at this stage before the data became final.

 

7.4	Opinion of the Qualified Person

The drilling information available for this resource estimation is adequate for estimating mineral resources for this report.

 

8.	SAMPLE PREPARATION, SECURITY, AND ANALYSES

 

8.1

Sampling

Sampling methodology and security are discussed in Section 7.1.1 as part of the drilling procedures practiced by Newmont Mining Company for RC and core drilling programs.

 

8.2	Sample Preparation and Analysis

Exploration drill holes were assayed at various accredited laboratories throughout the life of the Lone Tree Mine. The most commonly used internal labs include the internal company labs of Newmont, Santa Fe, and Battle Mountain. The Chemex (now “ALS Chemex”) was the most used commercial laboratory.

Sample preparation occurs at analytical laboratories, and techniques vary depending upon the laboratory and the type of analysis to be performed. Two methods are commonly used to perform gold assays. The first is crushing the entire sample, pulverizing a sample split to minus 100 to 200 mesh, subjecting a 5 to 30-gram split of the pulp to acid or cyanide, and taking readings using an atomic absorption machine. The second method, a fire assay, is to pulp the sample, add a lead litharge charge, and fire the sample in a furnace (“Fire assay”). The resulting metal bead containing gold is then weighed and dissolved in acid for analysis.

In general, fire assays with an atomic absorption (AA) or gravimetric finish were standard using 1-assay ton samples. Fire assay methods account for 99.97% of the ‘best assays’ reported in the NGM database. Multi-element ICP geochemical analyses were common but not run on every sample. All gold assay certificates and geochemical reports were copied and filed with the geologic logs. These logs are available for review in the geology logging facilities at the Lone Tree offices.

Multi-elemental analysis contained in the source database includes ICP and wet geochemistry multi-element suites analyzed by commercial laboratories, consisting of several elements determined from one sample, and XRD/XRF semi-quantitative X-ray determinations. Most X-ray analyses were accomplished in-house by the Newmont Metallurgical Services Department.

 

 

44

 

 

8.3	Data Security

Newmont implemented the use of an acQuire database in 2002 to store all drilling related data including assays. The database is secured by Oracle permissions, user ODBC connections across a Novell Network, and user license permissions and is maintained by designated database managers.

The Newmont Laboratory at Gold Quarry was electronically connected to the acQuire database, and an automated process transferred data every two hours. Data from the Lone Tree lab (rare) is loaded using the acQuire data input forms.

Outside lab data, primarily from ALS Chemex, was loaded using an acQuire direct import protocol. The import program also generates quality control reports for standards and check samples. Data was normally downloaded from a secure ALS Chemex web site. Access to the site was restricted to three Newmont Nevada employees via a username/password scheme. The ALS Chemex internal QA samples and results are available to Newmont Data staff. Regular audits were conducted by ALS Chemex at the request of Newmont.

Survey data was loaded using emailed survey certificates. Sample intervals are electronically created via an automated form at the Newmont sample prep facilities. These intervals update the acQuire Sample table, and contain the sample ID, footages, and sample types.

Collar creation is accomplished using form inputs. Collar creation for surface holes is restricted to Newmont data staff. The coordinates and depths are left blank until an (normally) electronic survey is sent via email or placed on the network. Depths are taken from the Geologists email, the Drill cost report, from the last assay interval, or driller’s logs.

As a result of the loss of paper copies due to rodent infestation in the storage facility, starting in 2005 the certificates from Chemex have been sent in the form of non-editable, digitally signed, PDF files. These are archived on the network. No certificates are, or have ever been, available from the internal Newmont labs, nor is QA data generally shared.

Data extractions are accomplished either using the acQuire software interface, or by use of an in-house program. Extractions are normally done by one of the two database administrators.

 

8.4	QA/QC Procedures

Internal check assays are performed at all labs. Pulps are retained for all assays where pulps are returned by the lab. Either pulps or coarse rejects can be re-assayed.

 

 

45

 

 

8.4.1

Standards

A combination of in-house Standard Reference Material (SRM) and commercially prepared SRM’s were used to control assay accuracy. In-house SRMs have been developed over many years, mainly from gold deposits on the Carlin Trend. Commercial SRMs were obtained from Geostats Pty Ltd in Australia. SRMs represent all grade bins very high-grade, high-grade, medium-grade, and low-grade gold in oxide and refractory mineralization. Values have been established for the in-house SRMs for gold assays only, using round robin analysis. Earlier Standard reference materials (SRMs) were submitted at a nominal frequency of one every 60 meters (200 feet), or one SRM for every 40 samples.

 

8.4.2

Blanks

Generally, for RC drilling, blanks are inserted at intervals of 15 meters (50 ft) and multiples of 15 meters (50 ft). For core drilling samples, blanks are inserted at nominal 60 meters (200 feet) intervals. This results in a frequency of SRM insertion of between 2% to 5%. The actual rate of insertion depends on the time of operation.

 

8.4.3

Check Samples

Approximately 5% of the total material is dispatched to umpire laboratories as part of the check assay program. Typical checks will be conducted on pulps and coarse reject samples to test the analytical processes and preparation procedure. Overall, each sample batch submitted for analysis will contain between three to seven check samples.

 

8.5	Opinion of the Qualified Person

The QA/QC processes followed on-site for the collection of samples, and preparation for chemical analyses of industry standards. The use of blanks and check samples to cross-check the laboratories are similar to industry practices globally. Overall the QA/QC processes followed provide sufficient assurance for making the geological data reliable for use in the estimation of mineral resources.

 

9.	DATA VERIFICATION

 

9.1	On-site Verification of Data and Information

As a part of the S-K 1300 report work, Mr. Brian Arthur and Dr. Abani Samal made a site visit on Wednesday, August 28th, and Thursday, August 29th, 2024. A prior site visit was also completed on July 7^th and 8^th, 2021 as a part of the 2021 NI 43-101 report. During the site visit the following tasks were completed.

 

●

The general geology of the deposit was reviewed in the field.

 

●

Select drill hole intercepts were physically verified.

 

 

46

 

 

●

Verification of available core and core-logging, and cutting facilities at the new Lone Tree storage facility.

 

●

Visited to the leach pads and the mill facilities and had detailed discussions with site personnel.

 

●

Verification of the on-site laboratory procedures.

Drill Hole Locations: The verification of locations of select holes was completed in 2021 and those locations have not changed. No new holes have been drilled since the 2021 technical report was published. Therefore, the outcomes of the 2021 review of the drill hole locations are still valid.

The location of the most recent drill hole LTE-20001 drilled in 2020 is shown in Figure 9-1. Additionally, existence of other drill holes in the Sequoia zone were also verified during the 2021 site visit. Location of the LTE-20001 hole was cross-checked with the collar data and found to be accurate. The hole locations are preserved with a wooden stick and an aluminum plate (Figure 9-1). It should be noted that the numbers shown on the aluminum plate are not the actual drill hole numbers, but rather reference numbers that link to the drill hole numbers.

Figure 9-1:Location of LTE-20001 on the West Side of the Lone Tree Pit

 

 

 

47

 

 

Figure 9-2:Location Tag of an Exploration Drill Hole in Sequoia

 

Exploration holes were drilled over time while the Lone Tree mine was being developed and mining was progressing. This makes it impossible to cross check the actual locations of the drill holes inside the current pit limit.

Verification of Drill Core Logs: During the 2021 trip, the drill cores were personally checked and mineralizations on certain core intercepts were verified at the core-processing center of NGM at their Battle Mountain location. The drill cores were processed as per industry best practices. The drill core processing and logging facility of NGM was well equipped with core cutting tools and logging tables. Half of the mineralized portion of each drill core was sent to the laboratory for assay. The remaining halves of the core were well preserved in core trays, as shown in the Figure 9-3.

After the acquisition of the Lone Tree property, portions of the drill cores and RC chips of selected intercepts of the latest hole drilled by Newmont/NGM (LT 20001) were transferred to i-80. Half cores and chips of selected intercepts of this hole were laid on tables as shown in Figure 9-4 and Figure 9-5. During this onsite verification of drill cores and chip samples, a portion of the lithological logs for this hole was also reviewed. This core logging was done by NGM geologists.

 

 

48

 

 

Figure 9-3:An Example of a Mineralized Core Stored in a Core Box

 

Figure 9-4:Half Core of LTE-20001 from 2544 ft to 2549 ft with 1.215 ppm Gold Grade

 

 

 

49

 

 

Figure 9-5:The Chip Samples from the Upper Portion of the Hole (LTE-20001)

 

During both the 2021 and recent visits, discussions were held on the characteristics of mineralization and textural features with the geologists in charge. A few pictures of core boxes and some core logs were taken as examples of the detailed logging procedures. It was noted that the processes followed have been consistent throughout the life of the Lone Tree deposit.

Figure 9-6:The Pulps Preserved in a Storage Area of i-80

 

During this site visit, the storage facility of i-80 was inspected. The pulps of old drill holes were stored with a digital database and map of the storage area. Figure 9-6 is an example of how the pulps are labeled. No drill core from the older holes was available for inspection. Some pulps will be sent for re-analysis with selected cores from the LTE-20001 holes.

 

 

50

 

 

The rejects from geochemical analysis were stored in barrels. These were not well labelled and documented.

 

9.2	Review of the QA/QC procedure

During the 2021 site visit, the QP was given access to the core processing facilities and a review of the available documents on the QA/QC procedures. The onsite exploration QA/QC procedures were reviewed and discussed during meetings held during the above-mentioned visits. Nothing has changed since then.

 

9.2.1

Re-assay of pulps and drill cores

To cross-check the assay data of Lone Tree that was acQuired by i-80 for trustworthiness, it was decided to re-assay selected drill cores and pulps available to i-80. A list of selected intercepts of drill holes with available pulps was provided to the geologist in charge of i-80 for re-assay. A total of 194 samples were selected for re-assay. Out of 194 samples, 183 pulps were selected from 19 holes, and 11 core samples were selected from the drill hole LTE-20001. These samples were randomly chosen from various depths and with various known assay values as shown in Table 9-1:Details of the Samples Selected for Re-assay.

Table 9-1:Details of the Samples Selected for Re-assay

 

Hole Number		Number of re- assayed data		Depth_min (ft)		Depth_max (ft)		Type of samples
LTE-01473		12		180		320		Pulp
LTE-01474		13		95		280		Pulp
LTE-01475		8		190		260		Pulp
LTE-01476		11		60		260		Pulp
LTE-01478		9		195		340		Pulp
LTE-01479		9		180		340		Pulp
LTE-01480		13		115		420		Pulp
LTE-01481		10		120		315		Pulp
LTE-01482		10		30		300		Pulp
LTE-01484		11		175		250		Pulp
LTE-01485		7		25		245		Pulp
LTE-01487		9		140		280		Pulp
LTE-01488		7		160		255		Pulp
LTE-01489		9		205		280		Pulp
LTE-01490		7		260		330		Pulp
LTE-01491		7		70		320		Pulp
LTE-01492		13		140		265		Pulp
LTE-01500		9		65		200		Pulp
LTE-01502		9		130		270		Pulp
LTE-20001		11		1642		2572		Core

 

 

51

 

 

9.2.1.1

Summary of Re-assay Data

The samples were sent to the ALS laboratories, where certified reference materials (CRM) and blank samples were inserted. A CRM was inserted at every 8 to 10 samples. Four different certified reference materials (CRM) were used: Oreas 277, Oreas 264, Oreas 279, and CDN-GS-P6E. Details of the CRMs are shown in Table 9-2.

Table 9-2:Descriptions of the CRMs Used

 

The analytical results were compared to the original assay data. Figure 9-7 suggests that the re-assayed data were very close to the original assay data. However, there are some assay data with substantially large -differences from the original data, out of which most are very low-grade data (Figure 9-8). These results suggest that the original drill hole assay data acquired by i-80 from Newmont / NGM are of reliable quality without any major concerns.

Figure 9-7:Comparison of the Re-assayed Analytical Results with the Original Data.

 

 

 

52

 

 

Figure 9-8:The Relationship Between the % Differences Original Au Assay Data

 

 

9.2.2

Database Review

A detailed database review was conducted during 2021. The drill hole data was shared by the NGM staff via an electronic cloud-based data room facility and organized in multiple Excel files. Dr. Samal (the lead author of this report) compiled the data using Vulcan software. A total of 1839 drill hole data was selected for independent assessment of mineral resources. Using Vulcan software, drill hole data were checked for errors.

 

●

For this report, a small set of drill holes was selected to cross-verify the assay data. No errors in the drill hole database were found.

●

A significant number of holes had lithological logs. However, out of 1840 selected holes 362 holes had no lithological logs (Refer to Section 7.1). This had no impact on mineral resource estimates for this report.

The processes followed for drill core collection, storage, and sample preparation are well documented in the form of standard operational procedures. The procedures meet industry best practice guidelines for exploration data, which adds to the reliability of the geological interpretation and assay data.

 

●

Bias Study: A study was conducted by NGM (then Newmont) to examine potential bias in the database due to various types of drilling. In this study, the exploration data above

 

 

53

 

 

and below the water table were considered. The study found bias between rotary hole samples below the water table and core or blast holes. However, as the mine deepens, the proportion of core to rotary composites will increase making it unnecessary to correct for the defined bias. No bias adjustments were used in the resource model (Zacarias, 2006).

 

9.3	Opinion of the Qualified Person

The QP responsible for producing an independent assessment of mineral resources below the current pit reviewed the data and information available for the Lone Tree deposit. These included the topographic data, the drill hole data, the geological interpretation data, the density data, and documents supporting the processes and procedures followed for collection, compilation, storage, security, and quality control.

The above-mentioned reviews concluded that data collected by Newmont/NGM on the Lone Tree Project was acquired using adequate quality control procedures that generally meet industry best practices for an operating mine. The Quality Assurance and Quality Control (QA/QC) processes followed for maintaining the quality of the data meet the best practices guidelines as outlined in § 229.1305³ (Item 1305) of Regulation S-K (Subpart 1300). The data is adequate for use in undertaking a mineral resource estimate.

It is the opinion of the QP that the data provided by NGM in 2021 is suitable to be used as the basis of a mineral resource estimate in this project and can also be used in the future studies on Lone Tree. Therefore, no changes are required in the resource model parameters as discussed in Section 11.

 

10.	MINERAL PROCESSING AND METALLURGICAL TESTING

Newmont did a metallurgical study on ore from the Brooks deposit which was mined and processed between 2015 and 2020. During the ten years of operation prior to the acquisition by i-80, Newmont did not conduct any comprehensive metallurgical studies on ore from the Lone Tree deposit. Since its acquisition in 2021, i-80 has not conducted any metallurgical tests or pilot studies on Lone Tree ore(s).

The remaining mineralization in the Lone Tree deposit is located in extensions of the mineralized zones and structures that were mined and processed by Newmont between 1991 and 2019. Therefore, processing data drawn from historical production reported by Newmont/NGM was used to support the metallurgical performances reported herein.

Most of the remaining mineralization in Lone Tree is expected to be sulfidic and require autoclave pretreatment to facilitate gold leaching. Some low grade oxide and high grade

 

 

³ 17 CFR Subpart 229.1300 —Disclosure by Registrants Engaged in Mining Operations (Electronic Code of Federal Regulations (e-CFR) Title 17—Commodity and Securities Exchanges CHAPTER II—SECURITIES AND EXCHANGE COMMISSION PART 229—STANDARD INSTRUCTIONS FOR FILING FORMS UNDER SECURITIES ACT OF 1933, SECURITIES EXCHANGE ACT OF 1934 AND ENERGY POLICY AND CONSERVATION ACT OF 1975—REGULATION S-K)

 

 

54

 

 

oxide ores are also expected but not valued as significant in this study. The historical and proposed recoveries for each material type are shown in Table 10-1 and are expected to prevail in the remaining material.

Table 10-1:Recoveries and Material Types or Lone Tree

 

1.

Source - Zacarias, P., A., February 28, 2006, 2005 Mineral Resource and Ore Reserve Report as of December 31, 2005, pp65.

2.

Autoclave recovery based on acid autoclave.

3.

Flotation Recovery - Recovery is to Concentrate= 83.7% and then 93.9% recovery from the Concentrate results in a - Combined Recovery - 83.7(93.9) = 78.59%.

4.

Source - 2005 LT Summary.xls

5.

Source - Lone Tree Statistics (1998 - H1 2019).xlsx.

6.

Source - 2.4.4.1.3 Brooks leach curve EA.25.xlsx and i-80 Pad Tracking LoneTree.xlsx

Details of metal recovery and cost estimates for various processing methods are discussed in Section14.

 

10.1	Opinion of the Qualified Person

It is the opinion of the qualified person that the extension of the historical factors to ores that have yet to be mined is sufficient to support this Mineral Resource Estimate. The following comments in support of the declaration are believed to be true.

●

The same ore types and process methods are projected for future mining and process activities as Newmont exploited historically.

●

The historical production values reported by Newmont are believed to be accurate.

 

 

55

 

 

11.	MINERAL RESOURCE ESTIMATES

GeoGlobal was mandated to review the estimates of in-situ mineral resources of the Lone Tree deposit made in 2021 and update them as appropriate. The following data was available for use in the resource estimation process. Maptek’s Vulcan Version 2023.4.1 software tool was used for this purpose.

 

11.1

Datasets

As mentioned in Section 9, the database provided by Newmont/NGM in 2021 and used in the 2021 resource estimates contains reliable data and is valid for use in this project.

 

11.1.1

Drill Holes

The dataset contains 3,396 drill holes. This dataset includes holes from Lone Tree, Buffalo Mountain, Lynn, and Second Chance exploration properties. Drill holes close to Lone Tree were selected. This selection contains 1840 drill holes (Figure 11-1). The coordinate system used is the local Lone Tree mine-grid system.

 

11.1.2

Other Data Sets

 

●

Triangulations representing topography including the latest pit-outline and pre-mining topography.

 

●

Three dimensional geological interpretations of rock types and interpretation of fault planes were created using Leapfrog software tool. During this process geological units were combined as shown in Figure 11-2.

 

●

A block model was created using Newmont’s in-house software TSS 3-dimensional modeling Geomodel software. Details are discussed later in this section of the report.

 

 

56

 

 

Figure 11-1:Location of the Drill Holes at the Lone Tree Project

 

 

 

57

 

 

Figure 11-2:The Geological Codes Used In Creating Solid Model

 

 

11.2	Geological Interpretation and Lithological Models

As discussed in Section 7, the mineralization at Lone Tree is primarily controlled by fault systems within certain rock types. It is clear that not all rock types are mineralized equally; rather mineralization occurs variably within three Paleozoic rock sequences at the Lone Tree deposit: the Valmy Formation, the Antler Sequence and the Pennsylvanian-Permian Havallah sequence rocks. The Wayne zone is known for rich-mineralization due to the Powerline fault cutting through the favorable rock-types. The rock-type models include five lithologic groups as listed below.

 

o

Quaternary/tertiary alluvium, colluvium etc (QAL).

o

Mississippian Permian Havallah (Phv).

o

Permian Edna (Pem).

o

Pennsylvanian Battle Mountain (Pb).

o

Ordovician Valmy (Ova).

 

 

58

 

 

Figure 11-3 is a vertical Cross Section along 28000 N. This figure shows the geological model created by the NGM geologists that has been adopted for this resource estimation process.

Figure 11-3:A Vertical Cross Section at 28000N (Looking North)

 

The Power Line fault is the most important structural zone at the Lone Tree deposit. As shown in Figure 11-4, the mineralization appears to be controlled largely by these structural elements. The other major fault at the mine is the Sequoia fault on the south side of the deposit.

Figure 11-4:A Vertical Cross Section with Rock-type Models (27300N)

 

A block model with dimensions listed in Table 11-1, was created to estimate mineral resources of the Lone Tree deposit. The block model is oriented parallel to the Lone Tree mine grid coordinate system.

 

 

59

 

 

Table 11-1:Block Model Geometry

 

		East (X)		North (Y)		Elevation (Z)
Origin		78575		20475		-1200
Block dimensions		50		50		20
Number of blocks		200		300		310

 

11.3	Lithology Model

The lithology model was updated using the new lithology solids provided by NGM. The block model was coded based on the geology triangulation model. The variable is ‘newlith’. The codes assigned are presented in Table 11-2.

Table 11-2:The Lithology Codes Used in the Block Model

 

Lithology		‘newlith’ code in the block model		NEWGEOL variable in the composite data
QAL: Quarternary/ tertiary alluvium, colluvium, etc.		1		1
Phv: Missi., Perm. Havallah		2		2
Pem: Perm. Edna		3		3
Pb: Pennsylvanian Battle Mountain		4		4
Ova: Ordovician Valmy		5		5

The lithology block model shown in Figure 11-5 has been coded with the drill hole lithology codes as shown in Figure 11-3.

Figure 11-5:The Lithology Block Model (28000 N, Looking North)

 

 

11.4	Exploratory Data Analysis and Compositing

The purpose of the exploratory data analyses (EDA) is to characterize the dataset so that it can be effectively used in grade interpolation and resource estimation. The results of the EDA process help in developing parameters for grade interpolations as discussed below.

 

 

 

60

 

 

In this project, the EDA section was reviewed. No changes were made to the results of the EDA.

Figure 11-6:Histogram of Drill Hole Assay Lengths

 

 

11.4.1

Compositing

Nearly 93% of the drill hole intercepts are five feet long (Figure 11-6). To minimize grade dilution due to compositing and create a database with sample intervals with equal lengths the drill hole data were composited on five-foot (5.00 ft) intervals.

 

11.4.2

Statistical Analyses of Composited Data

The general statistics of the gold composited data (ounces per ton) are presented in Table 11-3. Figure 11-7 compares the means and standard deviations of all five lithology types.

Figure 11-7 shows that the Havallah formation (Phv) has the dominant number of composites. The figure also suggests that the Edna formation (Pem) data hosts higher gold assays compared to other lithology types. The variability of the gold assays (measured by two standard deviations in this figure) is also greatest in the Edna formation.

The use of confidence interval (CI) is a better measure of variances for comparing sample sets of different sizes, as in the CI, the standard deviation is normalized by the number of samples that compares the means and variabilities of the composites in different rock types. Figure 11-8 further confirms that the gold assays in the Pem (Edna formation) are of highest grade followed by Pb (Battle Formation) and Ova (Valmy).

 

 

61

 

 

Table 11-3:General Statistical Characteristics of the Gold (AuFA, opt)

 

The histograms of all composites are presented in the Figure 11-9. Histograms show that the Havallah (code 3, Phv) are relatively low-grade rocks. In the cumulative frequency plot of the same dataset

Figure 11-10), it appears that the gold composites of the Edna formation (Pem) have higher proportions of higher-grade intercepts compared to the other rock types.

Figure 11-7:Comparison of Data Statistics of All Lithology Types

 

 

 

62

 

 

Figure 11-8:Comparison of Sample Means and Confidence Intervals

 

Figure 11-9:Histograms of Gold Assay Values (AuFA) by Lithology

 

 

 

63

 

 

Figure 11-10:Cumulative Frequency Plots of Gold Composites (AuFA)

 

 

11.4.3

Contact Plots

Contact plot analyses of AuFA across different lithological boundaries are done to determine the behavior of AuFA near the lithological boundary. This information is important in deciding whether to treat the geological areas as formal ‘domains’ for grade estimation and whether to treat the boundaries as hard or soft boundaries. In this project, Vulcan software was used for contact plot analysis.

The contact plot of AuFA for the boundary between Qal (Quarternary Alluvium) and (Phv Havallah) shown in Figure 11-11 indicates that the Qal is relatively low grade compared to Phv. The gold values change gradually across the boundary. This interpretation is non-conclusive.

The contact plot of AuFA for the boundary between (Phv Havallah) and Pem (Edna) is presented in Figure 11-12. The Pem is of higher grade than the Phv. The contact between Phv and Pem is not sharp, but distinct.

The contact plot analyses shown in Figure 11-11 through Figure 11-14, indicate that the gold assays behave differently for different rock types. Even though the contacts are not sharp they are distinct.

 

 

64

 

 

Figure 11-11:Contact Plot of AuFA for the Boundary Between Qal and Phv

 

Figure 11-12:Contact Plot of AuFA for the Boundary Between Phv and Pem

 

Figure 11-13:Contact Plot of AuFA for the Boundary Between Pem and Pb

 

 

 

65

 

 

Figure 11-14:Contact Plot of AuFA for the Boundary Between Pb and Ova

 

 

11.5	Geological Domains

Based on the statistical analysis above the lithology units are considered as domains within which the mineralization is assumed to behave consistently throughout. The variogram analyses and interpolation parameters are derived for the gold grade estimation within the lithological domains.

 

11.6	Variogram Analysis

The statistical analysis, as discussed earlier, provides the information used for variogram analysis. The variogram analysis process is presented in the Figure 11-15. Variography is a stepwise process.

Figure 11-15:Steps Followed in Variogram Analysis

 

 

 

66

 

 

A detailed review of the variogram process and results used in the 2021 resource estimation project was conducted. The results of variogram analysis are valid for use in the resource estimation process.

 

i.

Declustering: When the drill hole data shows clustering effects, at certain locations the drill hole intercepts are closer to each other compared to other locations. A cell declustering process corrects potential bias due to preferential sampling of high-grade zones.

 

ii.

Variogram Map: To find the inherent spatial anisotropy of the database, variogram maps of each variable lithologic domain are calculated using declustered data.

 

●

Variogram maps are calculated for various lag lengths, tolerance angles and distances of tolerances. Angles of tolerances are ideally kept at half of the angular sectors in a variogram map. The maximum distances of tolerances are kept at half of the lag distance. The variogram maps are shown in Appendix B.

 

●

The variogram maps indicate a North-South and East-West orthogonal set of anisotropies. These anisotropy interpretations correspond to the structural controls of mineralization and hence are geologically valid.

 

iii.

Experimental variogram calculation: The experimental variograms are calculated along the three orthogonal directions as selected from the variogram maps. The angles of tolerance are ideally kept at half of the angular sectors in a variogram map. The maximum distances of tolerance are kept at half of the lag distance. The experimental variograms are saved for modelling.

 

iv.

Variogram model: An approved type of variogram model is selected for fitting to the experimental variograms calculated in the prior stage.

 

v.

A set of three orthogonal variogram models is fitted for each of the elements within each of the lithological domains. As variograms are fitted for the one domain, they do not show regional anisotropy and display geometric anisotropy. This implies same sill and nugget effects for all three variogram models in a set. The variogram ranges may change (anisotropy) in three directions. In this exercise, multiple structures for variogram models were not observed. Variogram model parameters are presented in the Table 11-4. The Variogram models are presented in Appendix C.

 

 

67

 

 

Table 11-4:Variogram Parameters of AuFA

 

Lithology units				Azimuth		Dip				Ranges
Newgeol: 1 (QAL)		Major Axis		0			0				90
		Semi-Major Axis		90			0				70
		Minor Axis		90			-90				200
		Nugget		0.00002
		Sill		0.000155
Newgeol: 2 (Phv)		Major Axis		0			0				90
		Semi-Major Axis		90			0				90
		Minor Axis		90			-90				200
		Nugget		0.0005
		Sill		0.001
Newgeol: 3 (Pem)		Major Axis		0			0				100
		Semi-Major Axis		90			0				60
		Minor Axis		90			-90				150
		Nugget		0.002
		Sill		0.0048
Newgeol: 4 (Pb)		Major Axis		0			0				100
		Semi-Major Axis		90			0				200
		Minor Axis		90			-90				120
		Nugget		0.0005
		Sill		0.004
Newgeol: 5 (Ova)		Major Axis		0			0				75
		Semi-Major Axis		90			0				75
		Minor Axis		90			-90				150
		Nugget		0.0003
		Sill		0.000995

 

11.7	Density /Tonnage Factor Model

NGM determined density factors for the rock types in the Lone Tree deposit in 2003. This work was reviewed and deemed satisfactory for use in this resource estimate. The block model used tonnage factors for various lithological units. This variable was imported from the NGM Block model. The statistics of the tonnage factors are shown in Table 11-5.

Table 11-5:Tonnage Factor by Geologic Unit (ft³/ton)

 

 

 

68

 

 

11.8	Grade Interpolation

Variogram models could be fitted for AuFA for all geological domains (Table 11-4 and Appendix C). Therefore, ordinary kriging (OK) was chosen as the interpolation technique over non-geostatistical techniques such as inverse distance power (IDP).

The different lithology units were considered unique geological domains. For the estimation of gold grades within a particular domain, the composites within that domain were used. The boundaries between various domains were considered hard boundaries.

The key points in the interpolation of AuFA grade are listed below.

 

i.		No data are treated as an absence of data.
ii.		Value zero is treated as zero value.
iii.		The search ellipsoids are designed according to the orientations of the variogram models. Multi-pass search ellipsoids are used for estimating copper grades in each domain.
iv.		The first search ellipsoid is the smallest one.
v.		The axes of the next consecutive passes are relatively larger.
vi.		A restricted search ellipsoid of 50ft X 50 ft X 30ft is used for the inclusion of high-grade values. A 0.25 opt Au was considered the high-grade value in the grade interpolation.

The following additional variables are saved along with the kriged gold values.

 

i.		Interpolation pass numbers.
ii.		Blocks estimated during the first pass are tagged as 1.
iii.		Blocks estimated during the second pass are tagged as 2.
iv.		Blocks estimated during the third pass are tagged as 3.
v.		Blocks estimated during the fourth pass are tagged as 4.
vi.		Blocks estimated during the fifth pass are tagged as 5.
vii.		The average distance from samples from block centers.
viii.		The distance of the closest sample from block centers.
ix.		Number of samples used to estimate each block.
x.		Number of holes.
xi.		Nearest Neighbor Estimate (closest sample value).
xii.		Kriging variance, which is a measure of error of estimation.
		Note: This parameter should be used in conjunction with other variables.
xiii.		Kriging efficiency: A measure of quality of grade estimation using ordinary kriging.

Note: This parameter should be used carefully as the mathematics are not well proven to be robust.

The interpolation parameters for AuFA estimation are shown in Table 11-6.

 

 

69

 

 

Table 11-6:Interpolation Parameters Used for Estimation of Gold Grades

 

		Drill hole limits										Sample Criteria										Axes												High Yield Limits
ID		Holes /  estimate		Minimum  / hole				Maximum  / holes				Min				Max				Max. /   hole		Major				Semi-  Major				Minor				Threshold				Major  axis				Semi-  major				HYL -  Minor
ova5_1		No			1				10				2				20			X			50				50				20				0				50				50				50
ova5_2		Yes			2				10				8				24			6			90				90				100				0.25				50				50				30
ova5_3		Yes			2				10				6				24			6			130				130				150				0.25				50				50				30
ova5_4		Yes			2				10				4				24			6			160				160				200				0.25				50				50				30
ova5_5		No			1				10				2				24			X			180				180				200				0.25				50				50				30
pb4_1		No			1				10				2				20			X			50				50				20				0				50				50				50
pb4_2		Yes			2				10				8				24			6			90				90				100				0.25				50				50				30
pb4_3		Yes			2				10				6				24			6			130				130				150				0.25				50				50				30
pb4_4		Yes			2				10				4				24			6			160				160				200				0.25				50				50				30
pb4_5		No			1				10				2				24			X			180				180				200				0.25				50				50				30
pem3_1		No			1				10				2				20			X			50				50				20				0				50				50				50
pem3_2		Yes			2				10				8				24			6			90				90				100				0.25				50				50				30
pem3_3		Yes			2				10				6				24			6			130				130				150				0.25				50				50				30
pem3_4		Yes			2				10				4				24			6			160				160				200				0.25				50				50				30
pem3_5		No			1				10				2				24			X			180				180				200				0.25				50				50				30
phv2_1		No			1				10				2				20			X			50				50				20				0				50				50				50
phv2_2		Yes			2				10				8				24			6			90				90				100				0.25				50				50				30
phv2_3		Yes			2				10				6				24			6			130				130				150				0.25				50				50				30
phv2_4		Yes			2				10				4				24			6			160				160				200				0.25				50				50				30
phv2_5		No			1				10				2				24			X			180				180				200				0.25				50				50				30
qal1_1		No			1				10				2				20			X			50				50				20				0				50				50				50
qal1_2		Yes			2				10				8				24			6			90				90				100				0.25				50				50				30
qal1_3		Yes			2				10				6				24			6			130				130				150				0.25				50				50				30
qal1_4		Yes			2				10				4				24			6			160				160				200				0.25				50				50				30
qal1_5		No			1				10				2				24			X			180				180				200				0.25				50				50				30

 

 

70