Item 2. Properties
Item 2. Properties.
Summary Disclosure
The Company has only one material mining property, the Stibnite Gold Project, a formerly abandoned, brownfield mine site in rural Idaho, USA. We hold the Stibnite Gold Project through our wholly owned subsidiary Idaho Gold Resources Company, LLC.
On January 3, 2025, the USFS issued the ROD approving the Modified Mine Plan for the Project. With receipt of the ROD, the Company is currently focused on advancing the Project towards a construction decision, including finalizing the remaining federal and state permits and securing project financing. The Modified Mine Plan, approved by the USFS in the ROD, contemplates mining the Yellow Pine, Hangar Flats and West End Deposits using conventional open pit methods, conventional processing methods to extract gold, silver and antimony, and on-site production of gold (“Au”) and silver (“Ag”) doré and an antimony (“Sb”) concentrate. Additionally, the USFS-approved Modified Mine Plan provides for an extensive reclamation and restoration program for certain historical legacy impacts to the site including the recovery and reprocessing of historical tailings, restoration of fish passage during and after operations, relocation of historical mining wastes to engineered storage facilities, stream restoration, and reforestation of impacted areas. Some environmental work has been completed under the ASAOC, which is designed to improve water quality on the Project site. Approvals from the U.S. EPA and USDA may be required with respect to environmental work at the Site, including both activities pursuant to the mine plan approved in the ROD and work not currently included in the Project. The Modified Mine Plan, approved by the USFS in the ROD, includes plans for decommissioning the site include progressive and concurrent remediation, reclamation, and restoration activities, beginning at the start of construction and continuing beyond the operations phase, through Project reclamation and closure.
Technical Report Summary
The disclosures in this Item 2, Properties regarding Perpetua Resources’ 100% interest in the Stibnite Gold Project have been prepared in accordance with the mining property disclosure rules specified in S-K 1300. Except for subsequent events or as otherwise
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noted, the disclosure in this Annual Report on Form 10-K of a scientific or technical nature for the Stibnite Gold Project is derived from, and in some instances is an extract from, the Technical Report Summary, dated as of December 31, 2021, and amended as of June 6, 2022 (the “Technical Report Summary” or “TRS”).
The TRS summarizes, as of December 31, 2021, in accordance with the mining property disclosure rules specified in S-K 1300, the information presented in the technical report titled “Stibnite Gold Project, Feasibility Study Technical Report, Valley County, Idaho” dated effective December 22, 2020 and issued January 27, 2021, which was prepared in accordance with mining property disclosure standards set forth in NI 43-101 (the “2020 Feasibility Study”). The TRS was filed by the Company on Form 8-K on EDGAR on June 8, 2022, and is included as Exhibit 96.1 of this Annual Report on Form 10-K. The 2020 Feasibility Study was filed on SEDAR on January 28, 2021 and is available on the Corporation’s website. The 2020 Feasibility Study is not incorporated by reference herein.
On February 13, 2025, the Corporation released an updated cash flow model for the Project, which is included as Exhibit 99.1 of this Annual Report on Form 10-K (the “Financial Update”) and incorporated by reference herein. The Financial Update was prepared by the Company and is based, in part, on the basic engineering work completed by Ausenco Engineering USA South Inc. (“Ausenco”), and with contributions from other mining engineers and consultants, utilities and financial advisors. It is intended to be read as a supplemental financial update to the cash flow forecast included in the TRS. The Financial Update, using the scientific and technical information presented in the TRS, reflects the progression of the Project plan to a Basic Engineering level and applies fourth quarter 2024 cost estimates for construction and operations, consistent with the Basic Engineering analysis, as well as commodity pricing that is current as of December 31, 2024. This advancement in engineering planning resulted in minor improvements and adjustments to certain infrastructure designs, equipment selection and processing designs, none of which resulted in a material change to the scientific and technical information presented in the TRS. Christopher Dail, the Qualified Person with respect to the Financial Update, determined that neither the Financial Update nor the Basic Engineering work resulted in a modification to the mineral reserves or resources presented in the TRS, and did not modify any of the assumptions underlying the modifying factors, price estimates, and scientific and technical information underlying the mineral reserves and resource estimates or the determination that the Project is financially viable. The information contained in the Financial Update is subject to the assumptions, exclusions and qualifications set forth in the Financial Update included as an exhibit to this Annual Report, as well as those contained in the TRS, except to the extent explicitly updated therein.
You should read the TRS and Financial Update as part of your review of the information in this Item 2. Properties .
Certain capitalized terms in this section not otherwise defined have the meanings ascribed to them in the TRS and Financial Update.
Information of a scientific or technical nature in the Financial Update and in this Annual Report has been approved by Christopher Dail, AIPG CPG #10596, Exploration Manager for Perpetua Resources Idaho, Inc. and a Qualified Person (as defined in NI 43-101 and as defined in S-K 1300).
Assumptions
Portions of the information presented in this Annual Report on Form 10-K and the information contained in the TRS and Financial Update rely on a number of estimates and assumptions, including estimates and assumptions which are inherently subject to significant scientific, business, economic and competitive uncertainties and contingencies that could be material should those assumptions be incorrect. These assumptions include, but are not limited to, certain assumptions as to capital costs, production rates, operating costs, recovery and timing of construction and production; assumptions that the current price and demand for gold and other metals will be sustained or will improve; assumptions that the equipment and personnel required for permitting, construction and operations will be available on a continual basis; there are no significant errors in calculations and information used in mineral resource and reserve estimates; there will be no unforeseen delays, unexpected geological or other effects, equipment failures, or significant permitting delays; and that the Corporation will be able to source funding for construction and operations when required and on acceptable terms. For a description of the key assumptions, parameters and methods used to estimate mineral reserves and mineral resources included in this Annual Report on Form 10-K, as well as data verification procedures and a general discussion of the extent to which the estimates may be affected by any known environmental, permitting, legal, title, taxation, sociopolitical, marketing or other relevant factors, please review the TRS, which is included as an exhibit to this Annual Report on Form 10-K. The cost estimates and assumptions contained in the TRS are dated as of December 31, 2020 and should be read in conjunction with the Financial Update, which supplements the cash flow information using cost estimate and commodity pricing that are current as of December 31, 2024. See “ Risk Factors ” and “ Cautionary Note Regarding Forward-Looking Statements ” for a discussion of additional industry and business risks and assumptions.
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Economic Highlights 1
The Stibnite Gold Project economics, as contemplated in the Financial Update, are summarized in the table below.
Early Production
Life-of-Mine
Component
Years 1-4
Years 1-15
Recovered Gold Total (Koz)
1,852
4,223
Recovered Antimony 2 Total (Mlbs)
69.1
106.5
Recovered Gold Annual Average (Koz)
463
296
Cash Costs (net of by-product credits, $/oz Au) 3
$217
$537
Total Cash Costs (net of by-product credits, $/oz Au) 4
$258
$583
All-In Sustaining Costs (net of by-product credits, $/oz Au) 5
$435
$756
Initial Capital, net – including contingency ($M) 6
$2,215
Early Production
Life-of-Mine
Component
Years 1-4
Years 1-15
Spot - $2,900/oz Au, $21.00/lb Sb, $31.50/oz Ag 7
After-Tax Net Present Value (NPV 5%) 8
$3,650 million
Annual Average EBITDA 9
$1,366 million
$745 million
Annual Average After-Tax Free Cash Flow 10
$1,117 million
$590 million
Internal Rate of Return (After - Tax) 11
27.1%
Payback Period in Years (After - Tax)
2.2 years
Consensus - $2,100/oz Au, $10.00/lb Sb, $27.00/oz Ag 12
After - Tax Net Present Value (NPV 5%) 8
$1,391 million
Annual Average EBITDA 9
$844 million
$445 million
Annual Average After-Tax Free Cash Flow 10
$704 million
$351 million
Internal Rate of Return (After-Tax) 11
15.4%
Payback Period in Years (After-Tax)
3.2 years
(1) The Financial Update assumes 100% equity financing.
(2) Antimony is a chemical element included on the U.S. Interior Department’s list of Critical Minerals.
(3) Cash Costs consist of mining costs, processing costs, mine-level G&A and by-product credits. By-product credits calculated based on consensus pricing. Cash Costs is a non-GAAP measure. See Non-GAAP Financial Measures at the end of Item 2.
(4) Total Cash Costs consist of Cash Costs, royalty costs, treatment costs, refining costs, and transportation costs. By-product credits calculated based on consensus pricing. Total Cash Costs is a non-GAAP measure. See Non-GAAP Financial Measures at the end of Item 2.
(5) AISC includes Cash Costs plus sustaining capital costs. By-product credits calculated based on consensus pricing. AISC is a non-GAAP measure. See Non-GAAP Financial Measures at the end of Item 2.
(6) Initial Capital, net, reflects estimated total capital expenditures of $2,215 million, including a contingency of $191.9 million, net of $33.6 million of pre-production revenue.
(7) Spot prices are defined as $2,900/oz gold, $21.00/lb antimony, and $31.50/oz silver. The precious metals prices selected for this scenario were based on the NYMEX gold and silver settlement prices of $2,887.60/oz and $32.44/oz, respectively, on February 7, 2025. The antimony price selected for the spot scenario was based on Rotterdam antimony price as of February 7, 2025.
(8) Net Present Value (NPV) is defined as the present value of future after-tax cash flows of the project discounted at an annual rate of 5%. The Financial Update assumed a combined state and federal effective tax rate of 26.45%.
(9) EBITDA consists of total revenue minus operating costs, offsite charges and royalties. EBITDA is a non-GAAP measure. See Non-GAAP Financial Measures at the end of Item 2.
(10) After-Tax Free Cash Flow consists of EBITDA as adjusted for changes in net working capital, all capital expenditures (initial, sustaining, and closure capital expenditures), and salvage value, less taxes payable. Free Cash Flow is a non-GAAP measure. See Non-GAAP Financial Measures at the end of Item 2.
(11) Internal rate of return (IRR) is defined as the after-tax discount rate at which the net-present value of the project reaches zero. The Financial Update assumed a combined state and federal effective tax rate of 26.45%.
(12) Consensus prices are defined as $2,100/oz gold, $10.00/lb antimony, and $27.00/oz silver based on a broad range of investment bank forecasts as of December 2024.
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Economic Sensitivities 1
The Financial Update was prepared using consensus average pricing of $2,100/oz gold, $10.00/lb antimony, and $27.00/oz silver, which was based on a broad range of investment bank forecasts as of December 2024.
The Company has also prepared a “Spot” metal price scenario, which is based on prevailing market prices of gold, silver and antimony as of February 7, 2025, and Cases A, B, C, and D, which were developed to illustrate the Stibnite Gold Project’s economic sensitivity to a range of metal price assumptions. Each of these is presented in the table below and prepared on the same basis as the Financial Update, except with respect to commodity prices.
The prices used in the Financial Update and in this Annual Report are consistent with accepted industry practices, analyst forecasts, and the range of prices being used for other project studies for gold and silver.
There is no guarantee that the gold, silver, and antimony prices used in the study cases would be realized at the time of production. Prices could vary higher or lower with a corresponding impact on Project economics. The Company’s mineral reserves and mineral resources continue to be estimated based on $1,600/oz and $1,500/oz gold prices, respectively, as set forth in the TRS.
Spot 5
Consensus 6
A
B
C
D
Gold Price Assumption ($/oz)
$
2,900
$
2,100
$
2,350
$
2,600
$
2,850
$
3,100
Antimony Price Assumption ($/lb)
$
21.00
$
10.00
$
12.00
$
14.00
$
16.00
$
22.00
Silver Price Assumption ($/oz)
$
31.50
$
27.00
$
29.00
$
31.00
$
33.00
$
35.00
LOM Average Annual EBITDA ($M) 2
$
745
$
445
$
529
$
614
$
699
$
809
After-Tax:
LOM Average Annual Free Cash Flow ($M) 2
$
590
$
351
$
419
$
487
$
554
$
640
Payback period (years)
2.2
3.2
2.8
2.5
2.3
2.1
Net Present Value 5% ($M) 3
$
3,650
$
1,391
$
2,031
$
2,662
$
3,288
$
4,117
Internal Rate of Return (%) 4
27.1
%
15.4
%
19.1
%
22.3
%
25.3
%
29.0
%
(1) The Financial Update assumes 100% equity financing.
(2) See Non-GAAP Measures at the end of Item 2.
(3) Net Present Value (NPV) is defined as the present value of future after-tax cash flows of the project discounted at an annual rate of 5%. The Financial Update assumed a combined state and federal effective tax rate of 26.45%.
(4) Internal rate of return (IRR) is defined as the after-tax discount rate at which the net-present value of the project reaches zero. The Financial Update assumed a combined state and federal effective tax rate of 26.45%.
(5) Spot prices are defined as $2,900/oz gold, $21.00/lb antimony, and $31.50/oz silver. The precious metals prices selected for this scenario were based on the NYMEX gold and silver settlement prices of $2,887.60/oz and $32.44/oz, respectively, on February 7, 2025. The antimony price selected for the spot scenario was based on Rotterdam antimony price as of February 7, 2025.
(6) Consensus prices are defined as $2,100/oz gold, $10.00/lb antimony, and $27.00/oz silver based on a broad range of investment bank forecasts as of December 2024.
Property Description and Location
The Project location is in central Idaho, USA approximately one hundred (100) miles (“mi”) northeast of Boise, Idaho, thirty-eight (38) mi east of McCall, Idaho, and approximately ten (10) mi east of Yellow Pine, Idaho. Mineral rights controlled by Perpetua Resources include patented lode claims, patented mill sites, unpatented federal lode mining claims, and unpatented federal mill sites and encompass approximately 28,536 acres (forty-five (45) square miles). The claims are 100% owned, except for surface rights on portions of six (6) patented mill site claims held by a third party and twenty-seven (27) patented lode claims that are held under an option to purchase. The Project is subject to a 1.7% net smelter return royalty on gold only and a 100% net smelter return royalty on silver; there is no royalty on antimony.
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Stibnite Gold Project Location
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Land Status Map
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PATENTED CLAIMS 4
Valley County
Number of Claims
Assessed
Assessed
Parcel ID
Owner 4
Lode
Millsite
Acres 3
Hectares 3
RP18N09E155300
IGRCLLC
—
16
80.00
32.37
RP18N09E020026
IGRCLLC
6
—
129.82
52.54
RP18N09E115495
IGRCLLC
—
14
53.57
21.68
RP14N05E074475 1
IGRCLLC 1
—
—
25.06
10.14
RP18N09E038995
IGRCLLC
4
—
81.63
33.03
RP18N09E108995
IGRCLLC
5
—
102.8
41.60
RP18N09E127345
IGRCLLC
6
—
99.87
40.42
RP18N09E030005
IGRCLLC
11
—
218.90
88.59
RP18N09E030020
IGRCLLC
6
—
81.17
32.85
RP18N09E12255
IGRCLLC 2
6
—
89.40
36.18
RP18N10E071525
IGRCLLC 2
2
—
38.95
15.76
RP18N09E18150
IGRCLLC 2
7
—
139.19
56.33
RP18N09E018435
IGRCLLC 2
4
—
80.23
32.47
RP18N09E013840
IGRCLLC 2
8
—
136.01
55.04
Totals
65
30
1,356.60
549.00
UNPATENTED CLAIMS
Number of Claims
Owner
Claim Type
Lode
Millsite
Acres
Hectares
IGRCLLC
Unpatented lode and millsite claims
1,421
253
28,536
11,548
Notes:
1. The Scott Valley parcel for the Stibnite Gold Logistics Facility is a 100% owned fee-simple parcel, that is approximately 25 acres, with no mineral rights.
2. IGRCLLC has an option to purchase (OTP), but no ownership of these parcels. The owner pays property taxes for these parcels until the OTP is exercised.
3. Not all values may sum due to rounding. Assessed acreage may not correspond exactly to surveyed acreage reported in text.
4. This table summarizes the mineral rights held by Perpetua Resources’ wholly owned subsidiary, IGRCLLC, as of December 31, 2024.
Patented Lode Claims and Patented Mill Sites
On June 11, 2009, a predecessor to SGC acquired and exercised an option to purchase (“OTP”) the Meadow Creek group of nine patented lode claims totaling approximately 184 acres from Bradley Mining Co. (“Bradley”).
A predecessor to IGRCLLC secured an OTP agreement from the J.J. Oberbillig Estate (the “Oberbilllig OTP agreement”) on June 2, 2009, to acquire 30 patented mill site claims totaling approximately 149 acres and six patented lode claims totaling approximately 124 acres. The Oberbillig OTP agreement was exercised and title to property rights were acquired on June 2, 2015. An associated transaction included the purchase and extinguishment of a 5% Net Smelter Return (“NSR”) royalty to the Oberbillig estate covering certain lands within the Project area. Most of the mineralization constituting the West End Deposit is located within portions of these patented lode claims. Hecla Mining Company (“Hecla”) retains surface rights on portions of six of the patented mill sites but no mineral rights and IGRCLLC holds certain rights for ingress and egress to access the property for assessment activities and environmental cleanup. IGRCLLC holds a right of first refusal for these mill sites with predefined terms should Hecla decide to sell the surface estate. The Company has engaged in discussions to acquire the surface rights held by Hecla. While there is no certainty that a transaction will be finalized, the Company believes that if it is unable to purchase this surface property, that outcome will not have a material effect on the Company’s ability to develop the Project.
An OTP for patented lode mining claims covering portions of the Yellow Pine Deposit was conveyed to Perpetua Resources in 2011 by way of a company merger between a predecessor to IGRCLLC and a subsidiary of Vista Gold Corp. that was agreed to February 22, 2011. The OTP for the subject patented claims was exercised on November 28, 2012. As a result of the merger, the predecessor to IGRCLLC became a wholly owned subsidiary of Perpetua Resources. The Yellow Pine claim group includes 17 patented lode mining claims totaling approximately 301 acres and eight unpatented lode mining claims (included in the unpatented total below).
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On April 28, 2011, a predecessor to SGC purchased 6 patented lode claims east of the Project area. This group of claims is referred to as the Fern claim group, totaling approximately 100 acres.
Unpatented Federal Lode Mining Claims and Unpatented Federal Mill Site Claims
A subsidiary of a predecessor to IGRCLLC acquired 229 federal unpatented claims by purchase from previous owners in 2009 and 2011. These included 46 federal mill site claims and 183 federal unpatented lode mining claims. In addition to the purchased claims, IGRCLLC predecessors or subsidiaries acquired by staking an additional 36 federal unpatented lode mining claims in 2009, 217 lode claims in 2010 and 901 federal unpatented lode-mining claims in 2011, and one federal unpatented lode mining claim in 2012. An additional 126 unpatented lode claims were staked in 2015. Minor modifications, including amended claim locations and changes in some claims have occurred since original staking and/or acquisition.
In 2021, SGC merged with IGRCLLC becoming the sole surviving entity and landowner of patented and unpatented mining claims and mill sites and various optioned properties. In 2022 and 2023, 53 of the Company’s unpatented lode mining claims were relinquished and re-staked with 205 unpatented mill sites over areas non-mineral in character and suitable for mill sites should a development decision be made. As of December 31, 2024, IGRCLLC owns 1,421 unpatented lode mining and 253 mill sites totaling approximately 28,536 acres (11,548 hectares).
Maintenance of unpatented federal claims requires that IGRCLLC provide a list of claims and serial numbers to the Bureau of Land Management along with annual maintenance fees, currently $200 for each lode-mining claim or mill site on or before September 1st each year. This was completed for the most recent filing year. There are no underlying royalties on the federal lode-mining claims and mill sites other than the Franco-Nevada Corporation (“Franco-Nevada”) royalties. None of the claims are subject to back-in rights; however, Franco-Nevada holds a right of first refusal should mining claims, mill sites or other mineral properties be relinquished. Property taxes are paid annually for the patented lode mining claims and mill sites and are current. Routine maintenance and claim adjustments have occurred periodically since the inception of land acquisitions as required.
Stibnite Gold Logistics Facility
On September 9, 2016, IGRCLLC agreed to purchase an undeveloped 25-acre property in fee simple from private interests. The property is situated in Section 7, Township 14N, Range 5E, Boise Meridian. The sale closed on October 26, 2016. The property’s metallic and non-metallic mineral rights, apart from aggregate materials needed for construction purposes on the property, were retained by the previous owners.
The property, in an area known locally as Scott Valley, has frontage on the Cascade-Warm Lake Highway and was purchased to serve as a project logistics facility. The agreement provides for maintenance of certain pre-existing rights-of-way, easements and rights, none of which would be expected to inhibit use of the property for the intended purposes. IGRCLLC applied for a Conditional Use Permit from the Valley County Planning and Zoning Commission that was granted on October 5, 2020.
Royalties, Option Agreements and Encumbrances
Option Agreements
On May 3, 2011, a predecessor to SGC entered into an option to purchase (“OTP”) 27 patented lode claims totaling approximately 485 acres from the J.J. Oberbillig Estate (the Cinnabar option claims). This agreement was modified in an Amended and Restated Real Property Purchase Agreement effective December 1, 2016 (the “amended agreement”). The amended agreement also includes an assignment of the right of first refusal to purchase the surface rights associated with portions of certain patented mill site claims that J.J. Oberbillig Estate sold to Hecla under a Real Estate Purchase and Sale Agreement effective December 30, 2002. The right of first refusal for the Hecla tracts includes fixed terms should Hecla decide to sell the parcel. Perpetua has since obtained Hecla’s acknowledgment of the assignment of the right of first approval from the J.J. Oberbillig Estate to the Company. The amended agreement also includes granting of a renewable easement for a communications tower. Perpetua Resources is obligated to make payments to maintain the OTP to obtain title to these claims. The agreement includes an option to extend up to 10 years after the original term of the agreement expires, through 2037.
On December 10, 2019, a Perpetua Resources subsidiary entered into an option agreement to purchase 3.74 acres from private interests for an electrical switching station site. The OTP has biannual payments of US$2,500 through 2033.
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Royalty Agreement
Effective May 9, 2013, Perpetua Resources and its subsidiaries granted a 1.7% NSR royalty on future gold production from the Project properties to Franco-Nevada, subject to adjustment based on final permitted capacity. The royalty does not apply to production of antimony and silver. The royalty agreement applies to all patented and unpatented mineral claims, except for the Cinnabar option claims where Perpetua Resources holds an OTP. Under the agreement, Franco-Nevada has the right, but not the obligation, to extend the property subject to the royalty to the Cinnabar option claims upon notice that the OTP is exercised by Perpetua.
On March 21, 2024, Perpetua Resources and its subsidiaries granted a 100% NSR royalty on the future payable silver production from the Project to Franco-Nevada. The silver royalty agreement applies to the same properties as the gold royalty. The silver royalty agreement provides a mechanism whereby Franco-Nevada can receive minimum payments equal to 100% of the payable silver from the sale of doré commencing in the seventh calendar year following commercial production and ending upon the completion of the fifteenth calendar year following commercial production. The silver royalty agreement also provides Franco-Nevada an option upon the occurrence of certain conditions precedent (including achieving commercial production) to pay the Company a contingent payment and receive a royalty on any silver payable from the production of antimony concentrate from the Project. The Company’s obligations under the gold and silver royalty agreements are secured by a continuing security interest and a first priority lien on certain collateral including the land and mineral interests comprising the Project.
Geologic Setting and Mineralization
Bedrock in the region can be subdivided into the pre-Cretaceous metasedimentary “basement,” the Cretaceous Idaho Batholith, Tertiary intrusions and volcanics, and Quaternary unconsolidated sediments and glacial materials. The Stibnite Gold Project is situated along the eastern edge of the Idaho Batholith, on the western edge of the Thunder Mountain caldera complex and within the Central Idaho Mineral Belt.
Large, north-south striking, steeply dipping structures exhibiting pronounced gouge and multiple stages of brecciation occur in the district and are often associated with east-west and northeast-southwest trending splays and dilatant structures.
The Yellow Pine and Hangar Flats deposits are hosted primarily by intrusive phases of the Idaho Batholith along the Meadow Creek Fault Zone. The West End Deposit is hosted primarily by Neoproterozoic to Paleozoic metasedimentary rocks of the Stibnite roof pendant along the West End Fault Zone.
Mineralization and alteration in the district are associated with multiple hydrothermal alteration events occurring through the Paleocene and early Eocene epochs. Main-stage gold mineralization and associated potassic alteration typically occurs in structurally prepared zones. The gold is associated with very fine grained disseminated arsenical pyrite and arsenopyrite to a lesser extent. The gold almost exclusively exists in solid solution in these minerals. Antimony mineralization occurs primarily as the mineral stibnite. Additional gold mineralization affecting rocks of the Stibnite roof pendant (i.e. the West End Deposit) is associated with epithermal quartz-adularia-carbonate veins.
Deposits of the district are not readily categorized based on a single generic deposit model due to complexities associated with multiple overprinting mineralization events and uncertainties regarding sources of mineralizing hydrothermal fluids.
Permits
The Project is subject to formal review by the USFS and the Army Corps under NEPA and by various state and federal agencies under various laws requiring permits to be obtained for the Project. Pursuant to NEPA, following the release of a DEIS on August 14, 2020 and a public comment period, the USFS published a SDEIS on October 28, 2022 for a 75-day public comment period which closed on January 10, 2023. On September 6, 2024, the USFS published the FEIS and a DROD with respect to the Project. The publication of the DROD commenced a 45-day pre-decisional objection period and 45-day resolution period prior to the publication of the ROD. On January 3, 2025, the USFS issued the ROD authorizing the Modified Mine Plan for the Project. Per the requirements of the FEIS and ROD, numerous plans comprising the suite of Environmental Monitoring and Management Plans are in process and will incorporate Project updates as well as required financial assurance, mitigation measures, environmental protection measures and design features. This will include preparation of a Final Mine Plan of Operations
Following the USFS’ publication of the ROD and FEIS authorizing the mine plan for the Project, claims were filed in the U.S. District Court for the District of Idaho against the USFS and other federal agencies on February 18, 2025 by a number of claimants, including Save the South Fork Salmon and the Idaho Conservation League, alleging violations of NEPA and other federal laws in the
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regulatory review process. Among other remedies, the claimants seek to vacate the ROD, FEIS, Final Biological Opinions and Project approvals and enjoin any further implementation of the Project. PRII has filed a motion with the court to intervene in this lawsuit. The Company believes the federal regulatory process was conducted thoroughly and completely by the relevant federal regulatory agencies. However, there can be no assurance that the permits and Project approvals will be upheld upon judicial review.
The Company’s CWA Section 404 permit application, proposed Compensatory Mitigation Plan, and associated financial assurance remain under review by The Army Corps after the public comment period ended in October 2023. The Army Corps has been a part of the review process as a cooperating agency since the Company began the federal NEPA process and has been formally evaluating the Section 404 permit application since 2023. The Section 404 permit is the last remaining federal permit required to be issued prior to a construction decision. Perpetua expects the permit to be issued in the first half of 2025. For additional detail regarding the NEPA and permitting processes, including ongoing challenges to the ROD see Item 1, Business – Permitting and Environmental Matters .
The Company will be required to obtain several permits from agencies of the State of Idaho in connection with the Project. All required Idaho applications have been filed, and the relevant agencies are at various stages in the permitting processes of reviewing and approving those applications under state law. See Item 7, Management’s Discussion and Analysis of Financial Condition and Results of Operations – Ancillary Permitting Update, below.
Work on other required ancillary permits, management and mitigation plans, financial assurance, and other permitting requirements continues.
Exploration
The Project area and the surrounding district has been the subject of exploration and development activities for nearly 100 years, yet much of the area remains poorly explored due to its remote location, poor level of outcrop and extensive glacial cover. Perpetua Resources has completed extensive exploration work since 2009 that has included: geophysics; rock, soil and stream sampling and analysis; geologic mapping; mineralogical and metallurgical studies; and drilling.
This newer data has been integrated with datasets from previous operators and provides a comprehensive toolkit for future exploration. These efforts have led to the identification of over 75 prospects with varying levels of target support. These prospective areas include targets within, under, and adjacent to existing deposits; bulk mineable prospects along known or newly identified mineralized trends; high grade underground targets and early-stage greenfield prospects and conceptual targets based on geophysics or geologic inference.
Exploration targets include conceptual geophysical targets, geochemical targets from soil, rock and trench samples, and results from widely spaced drill holes; as a result, the potential size and tenor of the targets are conceptual in nature. There has been insufficient exploration to define mineral resources on these prospects and this data may not be indicative of the occurrence of a mineral deposit. Such results do not provide assurance that further work will establish sufficient grade, continuity, metallurgical characteristics, and economic potential to be classed as a category of mineral resource. Mineral resources are not mineral reserves and do not have demonstrated economic viability.
The Project area, including the three main deposits, has been drilled by numerous operators, totaling 793,769 ft in 2,723 drill holes, of which Perpetua Resources drilled 637 holes totaling over 344,465 ft since 2009. Pre-Perpetua Resources drilling was undertaken by a wide variety of methods and operators while Perpetua Resources employed a variety of drilling methods including core, reverse circulation, auger, and sonic throughout the district, but with the primary method being core. Operators who conducted significant exploration and/or mineral extraction during this era included: United Mercury Mines. Yellow Pine Company, Bradley Mining Company, Louisiana Land and Exploration Company, Canadian Superior Mining (U.S.) Ltd., El Paso Oil and Gas, Rancher’s Exploration Company, Twin Rivers Exploration, MinVen Corporation, Pioneer Metals Corporation, Hecla Mining Company, Barrick Gold Corporation (formerly American Barrick Resources), Stibnite Mine Inc., and Dakota Mining Company.
No exploration drilling was conducted by the Company during the reporting period.
Mineral Resources and Mineral Reserves Estimates
The tables below present the estimated Mineral Resources and Mineral Reserves for the Project at December 31, 2024 presented in accordance with S-K 1300. There were no changes in reported Mineral Resources and Mineral Reserves reported for the years ended December 31, 2024 and 2023. The Qualified Person has reviewed the Mineral Resources and Mineral Reserves described herein and is of the opinion that there are no material changes to the Mineral Resources and Mineral Reserves as compared to the information
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presented in the TRS and that the material assumptions underlying the Mineral Resources and Mineral Reserves estimates set forth in the TRS are current as of December 31, 2024.
Mineral Resource Estimates
The following table presents the estimated Indicated and Inferred Mineral Resources for the Project at December 31, 2024 based on $1,500/oz gold price and are presented exclusive of Mineral Reserves in accordance with S-K 1300. There were no changes to Mineral Resources since December 31, 2023.
Consolidated Mineral Resource Statement for the Stibnite Gold Project at December 31, 2024, based on $1,500/oz gold, EXCLUSIVE OF RESERVES:
Gold
Contained
Silver
Contained
Antimony
Contained
Tonnage
Grade
Gold
Grade
Silver
Grade
Antimony
Classification
(000s)
(g/t)
(000s oz)
(g/t)
(000s oz)
(%)
(000s lbs)
Indicated
Yellow Pine
8,598
1.11
307
1.44
397
0.018
3,405
Hangar Flats
19,803
1.30
825
3.34
2,128
0.146
63,673
West End
15,133
0.76
369
0.91
445
—
—
Historical Tailings
—
—
—
—
—
—
—
Total Indicated
43,534
1.07
1,501
2.12
2,970
0.07
67,078
Inferred
Yellow Pine
8,021
0.85
219
0.59
153
—
62
Hangar Flats
17,021
1
548
2.3
1,259
0.09
32,146
West End
26,895
0.97
837
1.06
918
—
—
Historical Tailings
191
1.13
7
2.64
16
0.16
662
Total Inferred
52,128
0.96
1,611
1.4
2,345
0.03
32,870
Notes:
(1) Mineral Resources are reported in relation to a conceptual pit shell to demonstrate potential for economic viability; mineralization lying outside of these pit shells is not reported as a Mineral Resource. Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. These Mineral Resource estimates include Inferred Mineral Resources that are considered too speculative geologically to have economic considerations applied to them that would enable them to be categorized as Mineral Reserves. There is also no certainty that these Inferred Mineral Resources will be converted to the Indicated category through further drilling, or into Mineral Reserves once economic considerations are applied. All figures are rounded to reflect the relative accuracy of the estimate and therefore numbers may not appear to add precisely.
(2) Open pit sulfide Mineral Resources are reported at a cut-off grade of 0.40 g/t Au and open pit oxide Mineral Resources are reported at a cut-off grade of 0.35 g/t Au.
(3) Mineral Resources are reported in place (point of reference).
(4) All numbers have been rounded in above table and may not sum correctly.
Mineral Reserve Estimates
The following table presents the estimated Mineral Reserves for the Project at December 31, 2024 based on $1,600/oz gold price and presented in accordance with S-K 1300. There were no changes to Mineral Reserves since December 31, 2023. Under S-K 1300, a Proven Mineral Reserve is the economically mineable part of an indicated and, in some cases, a measured mineral resource and a Probable Mineral Reserve is the economically mineable part of a measured mineral resource and can only result from conversion of a measured mineral resource.
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Mineral Reserves Summary (Metric Units) at December 31, 2024 based on $1,600/oz gold:
Average Grade
Total Contained Metal
Deposit
Tonnage
Gold
Antimony
Silver
Gold
Antimony (3)
Silver
Metric Units
(kt)
(g/t)
(%)
(g/t)
(t)
(t)
(t)
Yellow Pine
Low Sb Sulfide –Probable
37,615
1.69
0.009
1.56
63.7
3,565
58.5
High Sb Sulfide –Probable
10,232
2.04
0.460
4.69
20.9
47,064
48.0
Yellow Pine Probable Mineral Reserves
47,847
1.77
0.106
2.23
84.5
50,629
106.5
Hangar Flats
Low Sb Sulfide – Probable
5,167
1.34
0.018
1.65
6.9
954
8.5
High Sb Sulfide – Probable
3,095
1.92
0.369
4.85
5.9
11,407
15.0
Hangar Flats Probable Mineral Reserves
8,262
1.56
0.150
2.85
12.9
12,361
23.5
West End (1)
Oxide – Probable
4,749
0.54
—
0.87
2.6
—
4.1
Low Sb Sulfide – Probable
15,242
1.33
—
1.30
20.2
—
19.7
Transitional – Probable
25,839
1.03
—
1.49
26.6
—
38.5
West End Probable Mineral Reserves
45,830
1.08
—
1.36
49.3
—
62.3
Historical Tailings (1)
Low Sb Sulfide – Probable
1,832
1.16
0.166
2.86
2.1
3,036
5.2
High Sb Sulfide – Probable
855
1.16
0.166
2.86
1.0
1,417
2.4
Historical Tailings Probable Mineral Reserves
2,687
1.16
0.166
2.86
3.1
4,453
7.7
Probable Mineral Reserves
Oxide – Probable
4,749
0.54
—
0.87
2.6
—
4.1
Low Sb Sulfide –Probable
59,856
1.55
0.013
1.54
92.9
7,555
92.0
High Sb Sulfide –Probable
14,181
1.96
0.422
4.61
27.8
59,888
65.4
Transitional – Probable
25,839
1.03
—
1.49
26.6
—
38.5
Total Probable Mineral Reserves (2)
104,625
1.43
0.064
1.91
149.9
67,443
200.0
Notes:
(1) Historical Tailings ore type classification is proportional to the pit-sourced mill feed during Historical Tailings processing.
(2) Metal prices used for Mineral Reserves: $1,600/oz Au, $20.00/oz Ag, $3.50/lb Sb.
(3) Antimony values are reported only for ore scheduled in the mine plan that is classified as High Sb Sulfide.
Mineral Reserves are reported from the reference point of delivery to the processing plant. These reserves are subject to variable metallurgical recoveries for gold, silver, and antimony depending on the host rock, process flowsheet, and product (i.e. doré bullion or antimony concentrate). The average recoveries into bullion are 87% for gold and 13% for silver. The average recoveries into antimony concentrate are 68% for antimony, 0.1% for gold, and 2% for silver.
All numbers have been rounded in above table and may not sum correctly.
Mining Methods
The mine plan developed for the Project incorporates the mining of the three in situ deposits: Yellow Pine, Hangar Flats, and West End and their related development rock; and the re-mining of Historical Tailings along with its cap of spent heap leach ore. The general sequence of open pit mining would be Yellow Pine deposit first, Hangar Flats deposit second, and West End Deposit last. This sequence generally progresses from mining highest value ore to lowest value ore and accommodates the sequential backfilling the Yellow Pine and Hangar Flats open pits with material mined from West End open pit. Lower grade ore extracted during mining of the three pits is stockpiled and then processed during the operating life of the mill. The spent ore that overlies the Historical Tailings would be used as tailings storage facility (“TSF”) construction material and is treated as stripping. Most development rock would be sent to one of five destinations: the TSF embankment, the TSF buttress, the Yellow Pine pit as backfill, the Hangar Flats pit as backfill, or the
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Midnight area within the West End pit as backfill. The Historical Tailings would be hydraulically transferred to the process plant during the first four years of operation, concurrent with mining and processing ore from the Yellow Pine open pit.
Mining at the Stibnite Gold Project would be accomplished using conventional open pit hard rock mining methods with a production fleet consisting of two 28-yd3 hydraulic shovels, one 28-yd3 wheel loader, and a fleet of approximately eighteen 150-ton haul trucks. Mining is planned to deliver 7.30 M tonnes of ore to the crusher per year (nominally 20 k tonnes per day) and approximately 22.1 M tonnes of development rock per year to DRSFs. Pre-stripping the open pits would begin two years prior to ore processing and open pit mining would continue until year 12 of operation. Once open pit mining is completed, the mining fleet will continue to provide ore to the mill from ore stockpiles until approximately the end of the first quarter in year 15. A total of 102 M tonnes of ore would be mined from the three open pits and an additional 2.7 M tonnes of historic tailings would be mined. Approximately 254 M tonnes of development rock would be mined from the three open pits for a total of 356 M tonnes mined from the open pits and an average strip ratio (waste:ore) of 2.5.
Long-term lower-grade ore stockpiles have been incorporated into the mine plan located for the most part within the footprint of the TSF buttress, thereby minimizing their incremental disturbance. The primary benefits to adding ore stockpile capacity are increased potential to optimize process ore feed value throughout the mine life, improved utilization of the Mineral Resource, reduced peak water treatment needs, reduced development rock tonnage and associated mining impacted water management. The stockpiling strategy is particularly significant during the first half of the mine life when Yellow Pine high value ore is mined at a rate greater than process plant throughput capacity. If stockpile capacity is not available, either the period-based cut-off value must increase resulting in ore converted to waste, or the mining rate reduced to align with process plant throughput capacity resulting in deferred access to high-value ore deeper in the open pit. The addition of long-term ore stockpiles allows for relatively high value ore mined from Yellow Pine open pit to be stockpiled and made available to process when lower value ore is being mined in West End open pit.
Recovery Methods
The process flowsheet for most of the Yellow Pine, Hangar Flats, and West End material uses bulk sulfide flotation to maximize recovery of gold to a sulfide concentrate amenable to treatment by pressure oxidation for materials assaying less than 0.1% antimony. High antimony materials would be first subject to a selective antimony flotation process, thereby producing a shippable antimony concentrate, with a gold-bearing bulk sulfide rougher concentrate to be floated from the antimony flotation tailings. Some of the oxidized West End ores are more transitional or free milling in nature, and an ore leaching process was developed to treat these materials. Testing was also conducted on samples of the historical (Bradley) tailings. This work showed the historical tailings could be processed using the same flowsheet as, and most likely as a blend with, fresh sulfide ores. A revised set of flotation models was developed for all ore bodies during the 2024 Basic Engineering studies. These models were developed using test results from the historical testwork programs and improved the predictability of the metallurgical performance.
Projected gold, silver and antimony recoveries vary by lithology, metal grade, sulfur content, mineralogy and oxidation state. Projected life of mine metal recoveries from low-antimony materials to a pyrite flotation concentrate averages 82.0% gold, 67.2% silver and 14.0% antimony. Projected life of mine metal recoveries for high-antimony materials to antimony sulfide concentrates average 71.6% antimony, 10.1% silver and 0.66% gold. Low reported antimony recovery for antimony reporting to the pyrite concentrates and low reported gold recoveries for gold reporting to the antimony concentrates are the result of misplacement of small amounts of antimony and gold bearing mineral phases to the respective concentrates. Sulfide material will be processed by flotation, concentrate pressure oxidation and cyanide leaching of the concentrate; transition material will be treated similarly; however, the flotation tailings will also be leached; oxide materials will just be leached. These projected recoveries differ slightly from the 2020 Feasibility Study based on updated and more refined analyses of test results completed during 2024 Basic Engineering. West End sulfide material is refractory while transition material has a significant free milling gold content.
Pressure oxidation testing results demonstrated that neutralization of acid inside the autoclave, or “in-situ acid neutralization” (“ISAN”) facilitates stabilization of arsenic in the pressure oxidation residue. Neutralization of acid inside the autoclave was accomplished by adding ground limestone in the pressure oxidation feed to control free acid and sulfate concentrations and limit the formation of jarosite and basic iron sulfates. Higher ferric concentrations available for scorodite formation and lower sulfate concentrations were found to inhibit pitticite (an unstable arsenic compound) formation. However, subsequent environmental geochemical testing completed on commingled flotation and detoxified cyanide leach tailings from the pilot plant indicated that arsenic destabilized at some point downstream of the pressure oxidation process. Further ISAN pressure oxidation tests with a terminal free acid of 8 to 13 mg/L of H 2 SO 4 , atmospheric arsenic precipitation, and a two-step neutralization procedure at an elevated temperature (92°C) by progressively adding limestone to achieve a pH of approximately 2 with a retention time of 4 to 5 hours produced a stable scorodite precipitate.
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The pressure oxidation testing confirmed consistent gold recoveries in the 96.5-99.0% range. The Project’s process plant has been designed to process sulfide, transition and oxide material from the Yellow Pine, Hangar Flats, and West End Deposits. The processing facility is designed to treat an average of 20,000 tonne/d, or 7.3 Mt/y. Additionally, the Historical Tailings would be reprocessed early in the mine life to recover precious metals and antimony, and to provide space for the TSF embankment and buttress.
The process operations include crushing, grinding, antimony and gold flotation, pressure oxidation, leaching and carbon-in-pulp (“CIP”) recovery, cyanide detoxification, carbon handling and pressure stripping, precious metal electrowinning, mercury retort removal, and doré bar production. Auxiliary operations include a plant to supply oxygen to the autoclave and mining, crushing, grinding, and limestone crushing and grinding circuit. A leaching, CIP recovery, and detoxification process is planned for late in the mine life to process crushed and ground oxide material and recover gold from the tailings of transitional (mixed oxide-sulfide) material. Two finished products from the Stibnite Gold Project ore processing facility will be doré bars and antimony‐silver concentrate.
Infrastructure
The Project will require upgrades to existing offsite infrastructure such as roads and power supply, as well as onsite and offsite infrastructure additions such as worker accommodations, water management systems, and tailings management systems.
Site Access
The site is currently accessed by the Stibnite Road, (National Forest road NF-412), from the village of Yellow Pine, with three alternative routes up to that point. Alternative access via the Burntlog Route was developed over several other possible alternatives because it provides safer year-round access for mining operations, reducing the proximity of roads to major fish-bearing streams, and this route respects the advice and privacy of community members close to the Project location. The route originates from the intersection of Highway 55 and Warm Lake Road and is approximately 71 miles long. The route consists of 34 miles of existing highway (Warm Lake Road), 23 miles of upgraded road, and 14 miles of new road. The 37 miles of new and upgraded road has a design speed of 20 mph, maximum 10% grade, a 21-foot width, and intermediate-sized tractor trailer loading criteria. A maintenance facility along the route is designed for a location on the southern section.
A through-site public access route will replace the current access through the Stibnite Gold Project site during mine operations. A new 16-foot-wide gravel road is planned to provide public access from Stibnite Road to Thunder Mountain Road through the mine site.
Logistics Facility
The offsite administrative offices, transportation hub, warehousing and Assay laboratory needed for the Project, referred to as Stibnite Gold Logistics Facility (“SGLF”), will be located on private land in Valley County, with easy access to State Highway 55. The SGLF will include offices for managers, safety and environmental services, human resources, purchasing and accounting personnel. Operating supplies for the mine will be staged and consolidated at the SGLF to reduce traffic to the site.
Power Supply and Transmission
Grid power planned for the Project needs to be upgraded to support the approximately 65-megawatt load including upgrading approximately 63 miles of existing powerlines to 138 kV and approximately 9 miles of new 138 kV line. The 138-kV line would be routed to the Project’s main electrical substation where transformers would step the voltage down to the distribution voltage of 34.5 kV.
Worker Accommodations
A new worker housing facility (camp) is planned approximately 2 miles south of the ore processing plant area to provide accommodations for most of the construction workforce and for the operations workforce. Leased accommodation units are planned during peak construction activity and would be demobilized following construction since the peak construction accommodation requirements (approximately 1,000 workers) are much greater than the operations requirements of approximately 400 workers on the site.
Water Management
Perpetua Resources has planned a water management system that protects or improves water quality in Project-area streams and provides water for ore processing, fire protection, exploration activities, surface mining (dust control), and potable water needs.
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These water management activities are subject to conditions imposed pursuant to the Modified Mine Plan approved by the USFS in the ROD and related regulatory documentation issued under NEPA and to water rights granted to Perpetua pursuant to an order of the IDWR. Additional federal and state permits required to be obtained for the Project may affect the Company’s water management activities.
The key water management consideration for the Project site is the large amount of snowmelt runoff during the months of April through June, making spring melt the critical time for water management, storage, and treatment. Surface water that has the potential to introduce mining- and process-related contaminants (contact water) will be kept separate from surface water that originates from undisturbed, uncontaminated ground (non-contact water). This will be accomplished by diverting clean water around mine facilities and collecting and reusing, evaporating, or treating and discharging contact water.
The water needed for ore processing is planned to come from meteoric and tailings consolidation water reclaimed from the TSF, water from pit dewatering, contact water, groundwater wells, and a surface intake near the upstream portal of the East Fork South Fork Salmon River (“EFSFSR”) diversion tunnel. Contact water from the pits, stockpiles, TSF buttress, truck shop, ore processing facilities, and legacy materials exposed during construction would be collected in lined ponds or in-pit sumps for later use in ore processing, dust control, or treatment for discharge. Excess dewatering water not used for ore processing would be treated, if required, and discharged to a surface outfall.
Major water diversions include construction of a tunnel and fishway to divert the EFSFSR and provide fish passage around the Yellow Pine pit, and surface diversions of Meadow Creek at the TSF, TSF Buttress, and Hangar Flats pit.
Tailings Management
The Project is projected to produce approximately 120 million tons of tailings solids. The tailings would contain trace amounts of cyanide and metals (including arsenic and antimony), so a fully lined containment facility utilizing a composite liner is proposed to isolate the tailings and process water.
The TSF would consist of a rockfill embankment, a fully lined impoundment, and appurtenant water management features including a surface diversion of Meadow Creek and its tributaries around the facility. A rockfill buttress abutting the TSF embankment would substantially enhance embankment stability. Historical spent heap leach ore would be reused in TSF construction, in locations isolated from interaction with water, but the majority of the rockfill would be development rock sourced from the open pits. Design criteria were established based on the facility size and risk using applicable dam safety and water quality regulations and industry best practice for the TSF embankment on a standalone basis; the addition of the buttress substantially increases the safety factor for the design to at least double the minimum requirements. The TSF impoundment, embankment, and associated water diversions would occupy approximately 420 acres at final buildout, with an approximately 480-foot ultimate height.
Capital and Operating Costs
Capital expenditures or capital costs (“CAPEX”) and operating expenditures or operating costs (“OPEX”) estimates as of December 31, 2024 were developed in connection with the completion of Basic Engineering and ongoing Detailed Engineering Work, and were presented in the Financial Update based on fourth quarter 2024, un-escalated U.S. dollars. Vendor quotes were obtained for all major equipment and operating consumables. Most costs were developed from first principles, although some were estimated based on factored references and experience with similar projects elsewhere. Reclamation financial assurance costs are not included in the capital costs. The CAPEX and OPEX estimates are forward-looking statements and remain subject to the risks and uncertainties set forth in the section titled “ Cautionary Note Regarding Forward-Looking Statements ” at the beginning of this Annual Report.
Capital Costs
The Project CAPEX estimate includes four components: (1) the initial CAPEX, including indirect and project costs to design, permit, pre-strip, construct, and commission the mine, plant facilities, ancillary facilities, utilities, operations camp, and pre-production on and off site restoration and environmental mitigation; (2) the sustaining CAPEX for mine costs, such as facilities expansions and other on-site and off-site infrastructure, mining equipment replacements, expected replacements of process equipment and ongoing concurrent restoration and environmental mitigation activities during the operating period; (3) working capital to cover delays in the receipts from sales and payments for accounts payable and financial resources tied up in inventory; and (4) closure CAPEX to cover post operations reclamation and restoration and water treatment costs. Initial and working capital are the two main categories that need to be available to construct the Project.
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The CAPEX estimate includes direct mining equipment and pre-stripping costs, process plant costs, on-site infrastructure such as the TSF and the operations camp, and off-site infrastructure such as the power transmission line, the mine access road, the SGLF, and reclamation and closure costs. The initial CAPEX includes indirect costs for detailed design and engineering, land acquisition, some environmental mitigation, and other costs. Initial CAPEX also includes an estimate of contingency based on the accuracy and level of detail of the cost estimate. The purpose of the contingency provision is to make allowance for uncertain cost elements that may occur but are not included in the cost estimate. These cost elements include uncertainties concerning completeness, accuracy and characteristics or nature of material takeoffs, accuracy of labor and material rates, accuracy of labor productivity expectations, and accuracy of equipment pricing. The CAPEX estimates are considered to have an accuracy range of -10% to +15%. Additional assumptions that were used to estimate CAPEX are presented in the TRS and Financial Update.
The table below provides a summary of CAPEX estimates for the Project.
Initial
Sustaining
Closure
Total
CAPEX 1
CAPEX
CAPEX 2
CAPEX 3
Component
(US$M)
(US$M)
(US$M)
(US$M)
Direct Costs - Mine Costs
$
183.6
$
215.4
—
$
399.0
Direct Costs - Processing Plant
643.7
88.1
—
731.8
Direct Costs - On-Site Infrastructure
336.3
287.8
—
624.1
Direct Costs - Off-Site Infrastructure
295.5
0.4
—
295.9
Indirect Costs and Project Delivery
348.8
—
—
348.8
Mitigation, Monitoring and Closure
11.5
106.0
118.1
235.5
Owner’s Costs
227.9
—
—
227.9
Contingency and Sales Tax
201.1
25.8
—
226.9
Sub-total CAPEX 3
$
2,248.5
$
723.5
118.1
$
3,090.0
Pre-Production Revenue
(33.6)
—
—
(33.6)
Total CAPEX 3
$
2,214.8
$
723.5
118.1
$
3,056.4
(1) Initial Capital (“Initial CAPEX”) includes capitalized preproduction and is presented net of pre-production revenue assuming a price of $2,100/oz gold.
(2) Defined as non-sustaining reclamation and closure costs in the post-operations period.
(3) Not all values may sum due to rounding.
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Operating Costs and All-In Costs
The Project OPEX estimate includes mine operating costs, process plant operating costs, and general and administrative (“G&A”) costs. Cash Costs consist of mining costs, processing costs, mine-level G&A and by-product credits. Cash Costs, expressed in dollars per short ton ($/ton) milled or dollars per troy ounce of gold ($/oz Au) produced, are typically expressed after by-product credits (from antimony concentrate sales) and are calculated based on consensus pricing as of December 31, 2024. Total Cash Costs consist of Cash Costs, royalty costs, treatment costs, refining costs, and transportation costs. The All-In Sustaining Costs (“AISC”) includes Cash Costs plus sustaining capital costs. A summary of these Project costs is presented below. The assumptions that were used to estimate OPEX are presented in the TRS and Financial Update. Cash Costs, Total Cash Costs and AISC are projected non-GAAP financial measures and are not historical measures of financial performance and are not presented in accordance with GAAP. For more information regarding financial measures not prepared in accordance with GAAP, see “ Non-GAAP Financial Measures ” at the end of Item 2. These non-GAAP measures are forward-looking statements and remain subject to the risks and uncertainties set forth in the section titled “ Cautionary Note Regarding Forward-Looking Statements ” at the beginning of this Annual Report.
Early Production
Life-of-Mine
Years 1 - 4
Years 1 - 15
Component
(US$/ton milled)
(US$/oz Au)
(US$/ton milled)
(US$/oz Au)
Mine Operating Costs
$
13.3
$
234.2
$
10.2
$
278.5
Mill Processing Costs
13.4
234.7
13.2
362.0
Mine-Level G&A Costs
4.3
72.4
4.3
117.0
By-Product Credits 2
(18.5)
(324.1)
(8.0)
(220.4)
Cash Cost Net of By-Products 2, 3, 5
$
12.5
$
217.2
$
19.7
$
537.1
Offsite Charges 4
0.3
4.7
0.1
4.0
Royalties 2
2.1
36.5
1.5
42.1
Total Cash Cost Net of By-Products 2, 3, 5
$
14.9
$
258.3
$
21.3
$
583.2
Sustaining Capital Costs
10.1
177.0
6.3
173.1
All-In Sustaining Cost (AISC) 2, 3, 5
$
24.9
$
435.3
$
27.6
$
756.3
(1) The Financial Update assumes 100% equity financing. Cost estimates are based on fourth quarter 2024 prices and power costs of US$0.059 per kilowatt-hour (kWh). Production and technical assumptions consistent with 2020 Feasibility Study.
(2) Consensus prices used in the calculation of by-product credits and royalties are defined as $2,100/oz gold, $10.00/lb antimony, and $27.00/oz silver based on a broad range of investment bank forecasts as of December 2024.
(3) See Non-GAAP Financial Measures at the end of Item 2.
(4) Offsite Charges consists of treatment costs, refining costs, and transportation costs.
(5) Not all values may sum due to rounding.
Mineral Resource and Reserve Internal Controls
Perpetua Resources’ field work on the Project from 2009 to 2015, including drilling, was carried out under the supervision of Christopher Dail, CPG and Richard Moses, CPG, who were Perpetua Resources’ senior geologists responsible for certain aspects of the programs during the periods they were employed by Perpetua Resources. Field work, including drilling, completed in 2015-2017 was carried out under supervision of Kent Turner, independent senior geology consultant and SME-Registered Member, and Austin Zinsser, Perpetua Resources’ Senior Resource Geologist and SME-Registered Member. The general mineral resource estimation methodology for all deposits involved the following procedures:
● generation of updated geological models and review of structural controls on mineralization;
● database verification and validation;
● exploration data analysis, compositing and evaluation of outliers;
● construction of estimation domains for gold, antimony and silver;
● spatial statistics and geostatistical analysis;
● block modeling and grade interpolation;
● mineral resource classification and validation;
● assessment of “reasonable prospects for eventual economic extraction;” and
● preparation of the mineral resource statement.
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Quality Assurance/Quality Control program results do not indicate any problems with the analytical programs. Independent data audits have been conducted and indicate that the sample collection and database entry procedures are acceptable. All core samples have been catalogued and stored in designated areas.
Mineral resources and mineral reserves are estimates that are imprecise and depend upon geologic interpretation and statistical inferences drawn from drilling and sampling analysis, which may prove to be unreliable. See Risk Factors – “Perpetua Resources’ mineral resource and mineral reserve estimates may not be indicative of the actual gold or other minerals that can be mined. ”
Non-GAAP Financial Measures
To provide investors with additional information in connection with our economic analysis as determined in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”), we disclose certain projected non-GAAP financial measures. The projected non-GAAP financial measures include expected Cash Costs, Total Cash Costs, AISC, Average Annual EBITDA and Annual Average Free Cash Flow (“FCF”) with respect to the expected results of the Project as presented in the Financial Update.
We define “Total Cash Costs” as the sum of Cash Costs, royalty costs, treatment costs, refining costs, and transportation costs; we define “All-In Sustaining Costs” as the sum of Total Cash Costs and sustaining capital costs (all costs required to sustain operations); we define earnings before interest, taxes and depreciation and amortization (“EBITDA”) as total revenue minus operating costs, offsite charges and royalties; we define “Free Cash Flow” as EBITDA as adjusted for changes in net working capital, all capital expenditures (initial, sustaining, and closure capital expenditures), and salvage value; and we define After-Tax FCF as FCF less taxes payable. FCF does not entirely represent cash available for discretionary expenditures due to the fact that the measure does not deduct payments required for debt service and other items. Annual averages of non-GAAP measures represent the total value of the non-GAAP measure divided by the number of years during the forecast period.
We believe the projected non-GAAP financial measures included in this Annual Report on Form 10-K provide additional meaningful comparisons between the Company’s economic analysis and its peer companies. These projected non-GAAP financial measures are not historical measures of financial performance and are not presented in accordance with U.S. GAAP. They may exclude items that will be significant in understanding and assessing our financial results. Therefore, these measures should not be considered in isolation or as an alternative or superior to GAAP measures. You should be aware that our presentation of these measures have no standardized meaning under U.S GAAP and may not be comparable to similarly-titled measures used by other companies.
As the Project is not in production, the prospective non-GAAP financial measures are based on the estimated revenues, costs and other metrics set forth in the Financial Update, and are subject to the assumptions, qualifications and exceptions set forth in the TRS, as updated by the Financial Update. See the economic model included as Exhibit 99.1 hereto for additional information regarding these measures. The economic model included in the Financial Update is not a true cash flow model as defined by financial accounting standards but rather a representation of Project economics at a level of detail appropriate for a feasibility study level of engineering and design. As such, the projected non-GAAP measures included in this Annual Report cannot be reconciled to comparable U.S. GAAP measures without unreasonable effort.