2025 Feasibility Study

Feasibility Highlights

Large, heap leach gold project with Mineral Reserves of 3.8 Moz gold in the Tier-1 mining jurisdiction of Nevada
10-year plus life of mine averaging over 300 koz gold per year, with 348 koz gold per year over the first five years
Life-of-mine (LOM) all-in sustaining costs (AISC) of ~$1,103/oz gold
After-tax NPV5% of $1.5B with an after-tax IRR of 36% with economics based on consensus gold price of $2,400/oz in 2028E and $2,200/oz LT from 2029E
Single, large open-pit mine design with a straightforward layout
Ore treated through one of two processing streams that includes higher-grade crushed and lower-grade-as-blasted run-of-mine (ROM) ore
Conventional heap leaching and an Adsorption Desorption Recovery (ADR) circuit and refinery that will produce doré onsite
Mineral Resources of 4.4 Moz gold of Indicated resources (inclusive of Reserves) and 0.6 Moz gold of Inferred resources calculated using a gold price of $1,700/oz and cut-off grade 0.004 oz/ton

Note: All dollar amounts are expressed in U.S. dollars, unless otherwise noted.

Area	Item	Unit	Total
Mine	Ore tons Mined	Mton	243
	Gold Grade	oz/ton Au	0.016
	Gold Contained	Moz Au	3.8
	Strip Ratio	Ore : Waste	2.9
	Average gold recovery	%	80.5
	Average gold production in first 5 years	koz pa	348
	Average gold production LOM^#	koz pa	303
Capital Cost	Initial Capital	$M	823
	Peak Investment	$M	820
	Total Investment	$M	1,282
Costs	NSR	$/ton ore	28.00
	Site Costs	$/ton ore	9.79
	Royalties	% of NSR	4.3
	All In-Sustaining Costs	$/oz Au	1,103
Financials	EBITDA	$/ton ore	17.00
	EBITDA Margin	EBITDA / NSR, %	61
	Annual FCF	$M	297
	Total EBITDA	$M	4,131
	LOM NCF	$M	2,381
	Post-Tax NPV_5%	$M	1,520
	Cash Flow Index	NPV : Peak Investment	1.85x
	IRR	%	36.1
	Simple Payback	year	1.8

Notes:

Excludes residual leach year.
Economics are based on consensus gold price of $2,400/oz in 2028E and $2,200/oz LT from 2029E onwards.
Includes closure expenses and salvage value. EBITDA = earnings before interest, taxes (excludes state net proceeds tax), depreciation and amortization; NSR = net smelter return; NPV = net present value; IRR = internal rate of return.
Post-tax NPV_5% / Peak Investment.

Mineral Resource Estimate

The Mineral Resources at the Project total 4.4 Moz gold of Indicated resources and 0.6 Moz gold of Inferred resources constrained within a $1,700/oz gold pit shell and cut-off gold grade of 0.004 oz/ton. During operations, RC grade control in advance of blasthole drilling will be carried out to assist with medium-term planning.

Spring Valley Mineral Resource Estimate (Effective Date: August 24, 2023)

Classification	Tonnage	Gold Grade	Contained Metal
Classification	(‘000 tons)	(oz/ton)	(koz Au)
Measured	—	—	—
Indicated	259,802	0.017	4,362
Total M&I	259,802	0.017	4,362
Inferred	44,354	0.014	618

Notes:

ton=short tons, oz/ton=ounces per short ton, koz= kilo troy ounce.
The Mineral Resource estimate was completed by Mr. Simeon Robinson, P.Geo., Principal Geologist of AMC. CIM Definition Standards (2014) were used for reporting.
There is no known depletion by mining within the model area.
Near surface Mineral Resources are constrained by a nominal optimized pit shell.
- Metal prices of $1,700/oz Au.
- Pit angles vary from 32° in alluvium to 43°.
- Crusher process recoveries of 88.7%, 87.4%, and 74.9% for oxide, transitional, and sulfide respectively, and ROM process recoveries of 80.1%, 71.10%, and 62.5% for oxide, transitional, and sulfide respectively.
- Mining costs $1.43/ton autonomous, processing costs $2.90/ton (ROM), $4.40/ton (crusher), G&A costs of $0.79/ton, selling costs of $1.42/oz Au.
The individual effective royalties are between 1% and 6% as described in the Feasibility Study.
Cut-off grade applied to the pit constrained Mineral Resources is 0.004 oz/ton (~0.137 ppm) Au.
Drilling results up to February 3, 2023.
Rounding of some figures may lead to minor discrepancies in totals.
Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
Measured and Indicated Mineral Resources are inclusive of Mineral Reserves.

Mine Plan

The mine plan will entail excavation of 957 million tons of material mined during ten years while process operations are active. Following the completion of pit operations, process operations will continue for a further 9 months of residual leaching.

Spring Valley is expected to be mined from a single open pit utilizing 320-ton autonomous haul trucks and hydraulic face shovel excavators. Blasthole drills will also use autonomous drill system technology.

The Project contains 3.8 Moz Au of proven and probable mineral reserves at an average gold grade of 0.016 oz/ton.

Spring Valley Annual Gold Production

Spring Valley Mineral Reserve Estimate (Effective Date: September 3, 2024)

Classification	Tonnage	Gold Grade	Contained Metal
Classification	(‘000 tons)	(oz/ton)	(koz Au)
Proven	—	—	—
Probable	242,977	0.016	3,799
Total	242,977	0.016	3,799

Notes:

The Mineral Reserve estimate was prepared in accordance with the 2014 CIM Definition Standards by Dave Penswick, P.Eng. an independent mining consultant.
The Mineral Reserve estimate is contained within pit designs using Indicated Mineral Resources only and a gold price of $1800/oz.
The Mineral Reserve estimate is based on an ore cut-off grade of 0.004 oz/ton gold.
Excludes contained gold in overliner material.
ROM design ore recovery: 79% of oxide contained; 70% of transition contained; 56% of sulfide contained. Crushed design ore recovery: 88% of oxide contained; 80% of transition contained; 74% of sulfide contained.
Mining costs: Average base mining cost: $1.53/ton Ore; $1.36/ton Waste Rock; $0.98/ton Alluvium; mining cost adjustment factor: $0.048/ton per 25 ft bench.
Process costs: $2.65/ton ROM ore; $3.23/ton crushed ore; refining costs: $0.75/oz; general and administrative (G&A) costs: $0.80/ton total ore; transport costs $0.63/oz gold.
The Mineral Reserve estimate is reported within a pit design that uses geotechnical parameters developed by WSP, where the recommended pit slope angles range from 34 to 47 degrees.
Unplanned dilution averaging 14.3% was estimated and included in the reserves.
There are no known legal political, or environmental risks that could materially affect the potential development of the Mineral Reserve estimate.
Royalties were applied to the Spring Valley Mineral Reserves with an average royalty burden of 4.3% of net smelter return (NSR). The individual effective royalties are between 1% and 6% as described in the Feasibility Study.

Processing

Gold recovery values are based on extensive metallurgical test work, trade-off studies and optimization.

Ore is expected to be treated through one of two process streams that include (1) higher-grade ore crushed in three stages and stacked on the crushed ore pad with conveyors, and (2) lower-grade material will be delivered by open pit haul trucks to the ROM ore pad.

Key Process Design Criteria

Description	Unit	Crushed Ore	ROM Ore
LOM Ore Reserve	Mton	123.4	119.6
Ore Throughput	Mton per annum	12.8	4.5 – 20.0
Stacking Method	–	Crushing & Stacking	ROM Truck Dump
Gold Head Grade, LOM avg	oz/ton	0.025	0.006
Average Gold Recovery	%	82.0	74.2

Capital Expenditure

The Project’s initial capital cost is $823 million expressed in Q3 2024 dollars. This estimate falls under AACE Class 3 Classification Guidelines, with an expected accuracy of ±15% of the final Project cost including contingency.

Sustaining capital is estimated to be $388 million. Reclamation capital and bond interest total $87 million ($84 million after discounting), and salvage value applied at the end of the LOM is $13 million. This results in a total LOM investment of $1,282 million.

Capital Cost Summary

Description	Initial Capex ($M)	Sustaining Capex ($M)	Total Capex ($M)
Mine Development	275.1	287.6	562.7
Site Preparation	143.4	6.8	150.2
Process Facilities	155.9	7.8	163.7
Heap Leach	81.8	73.5	155.3
Sub-Total Direct Costs	656.2	375.7	1,031.9
Indirect	86.9	5.3	92.2
Provisions (Contingency)	79.6	7.3	86.8
Sub-Total Indirect Costs	166.5	12.6	179.0
Project Total	822.7	388.3	1,211.0

Note: exclusive of reclamation, salvage and reclamation bond interest.

Operating Costs

Operating costs over the LOM were estimated at $2.4 billion, equivalent to $9.79/ton processed, and include mining, processing and G&A costs. The operating cost estimates are reflective of Q4 2024 pricing and don’t include allowances for inflation. The cost estimates align with the principles of a Class 3 Feasibility study level estimate with a ± 15% accuracy according to the AACE guidelines.

LOM Operating Cost Summary

Cost Area	$/ton Processed	Total ($M)	Percent of Total (%)
Mining	6.10	1,482	62.3
Process	2.88	701	29.5
G&A	0.80	195	8.2
Total	9.79	2,378	100.0

Notes:

Ore Processed includes 123.4 Mtons Crush Leach and 119.6 Mtons ROM Leach.
Ore Processed excludes 5.8 Mtons sub-grade material used as liner that contribute 4 koz payable Au.
Excludes TCRC costs which are equivalent to an additional $0.02/ton ore.

Exploration

There is strong potential for defining additional Mineral Resources outside the current resource pit, including extensions to the Spring Valley Deposit, multiple exploration targets nearby, and targets along a 7-mile strike length across the Black Ridge fault zone. The Project is located in the Humboldt Range that has a gold endowment of ~60 Moz within a ~50-mile radius.

Feasibility Study Report and Contributing Authors

The Feasibility Study for the Spring Valley Project was led by Ausenco Engineering Canada ULC with additional contributors to the report including Lincoln Metallurgical Inc, AMC Mining Consultants (Canada) Ltd, NewFields Mining Design & Technical Services LLC, Ray Walton Consulting Inc, Sunstone Environmental Solutions LLC, Gibsonian Inc, WSP USA Inc, and FloSolutions USA Ltd.

Execution Readiness

Solidus is advancing construction and operational readiness activities in anticipation of final permits in H1 2025. These activities include additions to the Solidus team in anticipation of construction, geotechnical investigation to further de-risk earthworks quantities and productivity estimates, formal tender of long-lead equipment and packages (mining and electrical equipment), and preparation for early works on site following receipt of permits.

Spring Valley Project