INTEGRA DELIVERS ROBUST FEASIBILITY STUDY FOR DELAMAR GOLD-SILVER HEAP LEACH PROJECT HIGHLIGHTING IMPROVED ECONOMICS AND REDUCED DEVELOPMENT RISK

2025-12-17

TSXV - TSX Venture Exchange · Gold · Silver · Arsenic · Mercury · Antimony · Selenium · Copper · Canada

PR Newswire

TSXV: ITR; NYSE American: ITRG

www.integraresources.com

VANCOUVER, BC, Dec. 17, 2025/PRNewswire/ - Integra Resources Corp. ("Integra" or the "Company") (TSXV: ITR) (NYSE American: ITRG) is pleased to announce the results of its Feasibility Study (the "FS") for the development of its wholly-owned DeLamar Gold and Silver Heap Leach Project ("DeLamar" or the "Project"), comprised of the DeLamar and Florida Mountain deposits, located in southwestern Idaho.

(All amounts in United States("U.S.") dollars unless otherwise stated)

2025 DeLamar Feasibility Study Highlights:

Robust and resilient project returns:After-tax net present value 5% ("NPV") of $774 million("M") and 46% after-tax internal rate of return ("IRR") using base case metal prices of $3,000per ounce ("/oz") gold ("Au") and $35/oz silver ("Ag"); After-tax NPV of $1.7 billion("B") and 89% after-tax IRR using spot metal prices of $4,250/oz Au and $60/oz Ag. Increased ounces and mine-life:Addition of stockpile material enhances mine life to 10 years and total life-of-mine ("LOM") production to 1.1 million ounces ("Moz") of gold equivalent ("AuEq"). Consistent and profitable production profile1,2,3: Average production of 119 thousand ounces ("koz") AuEq from year 1 to 5 with average LOM production of 106 koz AuEq at site level cash costs of $1,179/oz AuEq (co-product) and below industry average all-in sustaining costs ("AISC") of $1,480/oz AuEq (co-product); efficient mining supports low life-of mine strip ratio of 0.54:1. Realistic and financeable Project:Total initial capital cost of $389 M(includes $38 Mof owners' cost) and sustaining capital of $305 Mover the LOM; strong project financing pathway created by ongoing cash flow generation from the Company's operating Florida Canyon Mine ("Florida Canyon") and strong cash balance of ~$81 millionas at the third quarter 2025. Competitive Project metrics4:Base case NPV-to-capex ratio of 2.0 and payback of 1.8 years; spot NPV-to-capex ratio and payback improve to 4.4 and 1.1 years, respectively. Strong free cash-flow profile in early years2:Excellent profitability at beginning of mine life; Year 1-5 average after-tax free cash flow of $165 M; smooth transitioning from Florida Mountain to DeLamar deposits with no grade or tonnage "cliffs". Simplified Project layout and processing:Two oxide heap leach facilities ("HLF") (vs. single large HLF design in the 2022 Pre-Feasibility Study ("PFS")), and two-stage crushing (vs. three-stage in PFS); reduced mine-site footprint and enhanced water usage strategy brings potential permitting advantages. Meaningful benefits to local communities:Excellent local support for Project development built upon years of engagement and early inclusion of local interests in Project design; an average of 300 direct permanent jobs are expected to be created at DeLamar. Strong Tribal partnerships:Relationship Agreement with the Shoshone-Paiute Tribes of the Duck Valley Indian Reservation (the "Shoshone-Paiute") establishes a transformative and long-term partnership for the development of DeLamar; engagement underway with additional Tribal Nations near the Project area. Significant scarcity value:DeLamar remains one of the few large-scale precious metals projects in the U.S. at the Feasibility Study level that is actively being advanced toward National Environmental Protection Act ("NEPA") federal mine permitting. Visibility on short and long-term growth:Large Measured and Indicated sulphide resource material excluded from mine plan with multiple-near mine expansion targets open along strike and at depth; DeLamar is one of the largest undeveloped silver resources in the U.S. with a largely underexplored district scale land package. Opportune timing:With the FS now complete and federal permitting expected to commence in the near term, the Project is well positioned to advance in one of the strongest gold–silver price environments in history, supported by favorable U.S. permitting tailwinds.

| (1) Gold equivalent calculated using base case metal prices: $3,000/oz Au and $35/oz Ag | | (2) See Cautionary Note Regarding Non-GAAP Measures | | (3) World Gold Council reported average all-in sustaining cost for gold mining industry of $1,578/oz Au in Q2 2025 | | (4) NPV-to-capex ratio calculated as after-tax Project NPV5% divided by total initial capital cost |

George Salamis, President, CEO and Director of Integra commented: "The Feasibility Study confirms what we have long believed: DeLamar is one of the most compelling, resilient, and capital-efficient heap leach gold-silver projects in the U.S. preparing to enter federal permitting. The FS outlines a simplified, phased, and materially de-risked development plan with outstanding economics, including a rapid 1.8-year payback, strong early free cash flow profile, and one of the highest NPV-to-capex ratios among projects of this scale. Importantly, the FS is being delivered as federal permitting is expected to commence in early 2026, positioning Integra to advance DeLamar at an opportune time. While the FS reflects a conservative, oxide-only development case, it represents only the beginning for DeLamar. The Project also hosts a large sulphide mineral resource that is not included in the mine plan, multiple near-mine expansion opportunities that remain open, and largely underexplored district-style upside.

The updated two heap leach configuration materially improves constructability, operating flexibility, and capital efficiency, while providing meaningful leverage to higher metal prices and maintaining resilience in lower-metal price environments. Updated feasibility-level engineering, metallurgy, and costing significantly enhance Project confidence, reduce execution risk, and support future permitting through a more advanced and robust water management strategy. The delivery of the FS is a major milestone for Integra and underscores our confidence in DeLamar's ability to generate long-term value for our shareholders, Tribal Nation partners, and the communities of Idaho. DeLamar is expected to support an average workforce of approximately 300 high-quality, long-term jobs over the life-of-mine. We look forward to providing further permitting guidance as the Project enters a new phase in 2026."

Integra will host a conference call and webcast to discuss the FS on Thursday, December 18, 2025at 11:00 AM Eastern Time/ 8:00 AM Pacific Time, featuring a presentation from the senior management team and a live Q&A session. A recording will be available on Integra's corporate website. To register for the webcast, please use the following link (call details are listed below):

https://events.q4inc.com/attendee/518660974

Feasibility Study Summary

The FS confirms robust economics for a low-cost, large-scale, conventional open pit oxide heap leach operation, with competitive operating costs and high rate of return. The FS outlines total production of 1.1 Moz AuEq over a 10-year operating mine life (plus two years of residual leaching), resulting in an average annual production profile of 106 koz AuEq per annum at a co-product mine-site AISC of $1,480/oz. The Project generates an after-tax NPV5% of $774 Mwith an after-tax IRR of 46% at base case gold and silver prices of $3,000/oz and $35/oz, respectively.

The Company retained Forte Dynamics, Inc. (now SLR Consulting Limited) ("Forte") as lead consultants, along with other engineering consultants, to complete the FS and prepare a technical report in accordance with National Instrument 43-101 Standards of Disclosure for Mineral Projects ("NI 43-101"). The FS is derived from updated mineral reserve estimate effective December 8, 2025. The effective date of the FS is December 8, 2025, and a technical report prepared in accordance with NI 43-101 will be filed on the Corporation's website and under its SEDAR+ profile within 45 days of this news release.

Table 1: DeLamar Feasibility Study Highlights1

| Mining | | | Total Tonnage Mined (k tonnes) | 185,178 | | Total Ore Mined (k tonnes) | 119,972 | | Strip Ratio (Waste: Ore) | 0.54 | | Operating Mine Life (years) | 10 | | Contained | | | Contained Gold (koz Au) | 1,259 | | Contained Silver (koz Ag) | 52,310 | | Contained Gold Equivalent (koz AuEq) | 1,869 | | Production | | | Heap Leach Recovery | | | LOM Average Gold Recovery (%) | 72.3 % | | LOM Average Silver Recovery (%) | 33.2 % | | Payable Metals | | | LOM Gold Payable (koz Au) | 910 | | LOM Silver Payable (koz Ag) | 17,392 | | LOM Gold Equivalent Payable (koz AuEq) | 1,113 | | Avg. Annual Gold Payable (koz Au) - Yr 1 to Yr 10 | 88 | | Avg. Annual Silver Payable (koz Ag) - Yr 1 to Yr 10 | 1,602 | | Avg. Annual Gold Equivalent Payable (koz AuEq) - Yr 1 to Yr 10 | 106 | | Avg. Annual Gold Payable (koz Au) - Yr 1 to Yr 5 | 102 | | Avg. Annual Silver Payable (koz Ag) - Yr 1 to Yr 5 | 1,450 | | Avg. Annual Gold Equivalent Payable (koz AuEq) - Yr 1 to Yr 5 | 119 | | Costs per Tonne | | | Mining Costs ($/t mined) | $2.51 | | Mining Costs ($/t processed) | $3.87 | | Processing Costs ($/t processed) | $4.91 | | G&A Costs ($/t processed) | $1.51 | | Total Site Operating Cost ($/t processed) | $10.29 | | Cash Costs | | | LOM Cash Cost, net-of-silver by-product ($/oz Au)2 | $772 | | LOM Cash Cost, co-product ($/oz AuEq)2 | $1,179 | | LOM AISC, net-of-silver by-product ($/oz Au)2 | $1,142 | | LOM AISC, co-product ($/oz AuEq)2 | $1,480 | | Capital Expenditure (incl. Contingency) | | | Pre-production Capital – incl. Contingency ($M)3 | $347.0 | | Bonding Cash Collateral ($M) | $3.9 | | Owners' Cost ($M) | $38.2 | | Total Initial Capital ($M) | $389.1 | | Sustaining Capital / Equipment Financing – incl. Contingency ($M) | $304.9 | | Reclamation Cost ($M)4 | $65.5 | | Salvage Value ($M) | ($8.1) | | Bonding Cash Collateral Return ($M) | ($3.9) | | Total Capital ($M) | $747.5 | | Base Case Metal Price Assumptions | | | Gold Price ($/oz) | $3,000 | | Silver Price ($/oz) | $35 | | Base Case Project Economics | | | After-Tax IRR (%) | 46.0 % | | After-Tax NPV5% ($M) | $773.7 | | Payback Period (years) | 1.8 | | Average Annual Net Free Cash Flow ($M)2 – Yr 1 to Yr 10 | $142.8 | | Total Net Free Cash Flow ($M) | $1,066.3 |

| (1) Gold equivalent calculated using base case metal prices: $3,000/oz Au and $35/oz Ag | | (2) See Cautionary Note Regarding Non-GAAP Financial Measures | | (3) Assumes mobile equipment financing | | (4) Closure costs include $26.4 M ongoing water treatment reclamation liability |

Figure 1: DeLamar Project Production and Operating Cost Profile1,2

[](https://mma.prnewswire.com/media/2848174/Integra_Resources_CorpINTEGRA_DELIVERS_ROBUST_FEASIBILITY_STUD.html)

| (1) Gold equivalent calculated using base case metal prices: $3,000/oz Au and $35/oz Ag | | | (2) See Cautionary Note Regarding Non-GAAP Financial Measures | |

Figure 2: DeLamar Project After-tax Cash Flow Profile (base case)1,2

[](https://mma.prnewswire.com/media/2848175/Integra_Resources_CorpINTEGRA_DELIVERS_ROBUST_FEASIBILITY_STUD.html)

| (1) Cash flow profile shown using base case metal prices: $3,000/oz Au and $35/oz Ag | | (2) See Cautionary Note Regarding Non-GAAP Financial Measures | | |

Table 2: DeLamar Project After-Tax NPV, IRR and Payback Sensitivity Table

| $/oz Au | $/oz Ag | NPV5%($M) | IRR (%) | Payback (years) | | $2,250 | $20 | $178.3 | 16 % | 4.5 | | $2,500 | $25 | $391.1 | 27 % | 2.8 | | $2,750 | $30 | $584.6 | 37 % | 2.2 | | $3,000 | $35 | $773.7 | 46 % | 1.8 | | $3,250 | $40 | $961.6 | 55 % | 1.6 | | $3,500 | $45 | $1,149.0 | 63 % | 1.4 | | $3,750 | $50 | $1,336.2 | 72 % | 1.3 | | $4,000 | $55 | $1,523.5 | 80 % | 1.2 | | $4,250 | $60 | $1,710.3 | 89 % | 1.1 | | $4,500 | $65 | $1,897.1 | 97 % | 1.0 |

Property Description, Location and Access

The historic mine site and Delamar Project are located within southwestern Idahoin Owyhee Countyapproximately 80 air kilometers southwest of Idaho'sstate capital of Boise. The nearest town is Jordan Valley, Oregonwhich is situated near U.S. highway 95, a 1.5 hour drive from Boise. The Project is within the historical Carson mining district and includes the formerly producing DeLamar silver-gold mine, which was last operated by Kinross Gold Corporation. The Project is accessed via 28 kilometers of existing road east from Jordan Valley, Oregon.

Figure 3: DeLamar Project Location Map

[](https://mma.prnewswire.com/media/2848176/Integra_Resources_CorpINTEGRA_DELIVERS_ROBUST_FEASIBILITY_STUD.html)

Updated Mineral Resource Estimate

Mineral resources were re-estimated from the resource model released in 2023 which includes the Florida Mountain deposit, the DeLamar deposit, and historical stockpiles and backfill. The mineral resource estimate is based on 3,348 drillholes totaling ~383,000 meters ("m"). Gold and silver mineralization was modeled following industry-standard and Canadian Institute of Mining, Metallurgy & Petroleum ("CIM")-compliant protocols.

Key steps included:

Statistical evaluation of assay data and determination of natural grade populations. Construction of mineral-domain wireframes using 30-meter spaced sectional control. Projection and slicing of domain polygons across each deposit to ensure geological continuity. Coding of block models with gold and silver using level-plan geometries. Geostatistical analysis of mineralization trends to support estimation and classification. Grade interpolation using inverse-distance methods into 6 × 6 × 6 mblocks at the DeLamar deposit and 6 × 8 × 8 mblocks at the Florida Mountain deposit, with domain-specific coding to constrain estimates.

The mineral resource estimate for the FS includes updated price assumptions and metallurgical recovery inputs for the pit optimization used to constrain them. Sulphide material continues to be reported in this resource mineral update, consistent with prior studies, as it continues to show potential economic extraction. Importantly, the fundamental resource methodology has not changed from the 2023 mineral resource update.

Table 3: DeLamar Project Mineral Resources

| | | Measured | Indicated | Measured & Indicated | | | | | | | | Mineral Resources | | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | | GOLD (Au) | | (kt) | (g/t) | (koz) | (kt) | (g/t) | (koz) | (kt) | (g/t) | (koz) | | DeLamar Project | Oxide | 15,548 | 0.41 | 204 | 139,953 | 0.31 | 1,400 | 155,501 | 0.32 | 1,604 | | Sulphide | 21,643 | 0.51 | 357 | 68,629 | 0.45 | 984 | 90,272 | 0.46 | 1,341 | | | TOTAL | Mixed | 37,189 | 0.47 | 561 | 208,582 | 0.36 | 2,384 | 245,772 | 0.37 | 2,945 | | | | | | | | | | | | | | | | Measured | Indicated | Measured & Indicated | | | | | | | | Mineral Resources | | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | | SILVER (Ag) | | (kt) | (g/t) | (koz) | (kt) | (g/t) | (koz) | (kt) | (g/t) | (koz) | | DeLamar Project | Oxide | 15,548 | 20.46 | 10,230 | 139,953 | 13.72 | 61,750 | 155,501 | 14.40 | 71,979 | | Sulphide | 21,643 | 32.90 | 22,922 | 68,629 | 22.30 | 49,254 | 90,272 | 24.90 | 72,176 | | | TOTAL | Mixed | 37,189 | 27.70 | 33,152 | 208,582 | 16.60 | 111,004 | 245,772 | 18.20 | 144,155 |

| | | Inferred | | | | Inferred | | | | | | Mineral Resources | | Tonnes | Grade | Ounces | | Mineral Resources | | Tonnes | Grade | Ounces | | GOLD (Au) | | (kt) | (g/t) | (koz) | | SILVER (Ag) | | (kt) | (g/t) | (koz) | | DeLamar Project | Oxide | 19,813 | 0.26 | 163 | | DeLamar Project | Oxide | 19,813 | 20.94 | 13,336 | | Sulphide | 19,789 | 0.37 | 235 | | Sulphide | 19,789 | 10.10 | 1,529 | | | | TOTAL | Mixed | 39,603 | 0.31 | 398 | | TOTAL | Mixed | 39,603 | 11.70 | 14,865 |

| (1) | All Mineral Resource estimates have been prepared in accordance with NI 43-101 standards. | | (2) | Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. | | (3) | Jeffrey Bickel, of RESPEC Company LLC of Reno, Nevada, is a Qualified Person as defined in NI 43-101, and is responsible for reporting Mineral Resources for the DeLamar Project. Mr. Bickel is independent of the Company. | | (4) | "Oxide", as listed above, is an aggregate category inclusive of all material types amenable to heap-leaching, including In-Situ Oxide, Stockpiles, and In-Situ Mixed material. | | (5) | In-Situ Oxide/Mixed and Stockpile Mineral Resources are reported at a 0.17 and 0.1 g/t AuEq cut-off, respectively, in consideration of potential open-pit mining and heap leach processing. | | (6) | Sulphide Mineral Resources are reported at a 0.3 g/t AuEq cut-off at DeLamar and 0.2 g/t AuEq at Florida Mountain in consideration of potential open pit mining and grinding, flotation, ultra-fine regrind of concentrates, and either Albion or agitated cyanide-leaching of the reground concentrates. | | (7) | AuEq was calculated using a price of $2,650/oz Au and a price of $30/oz Ag, as well as metallurgical recoveries which were variable based on spatial area and each respective oxidation zone of the deposit. | | (8) | The Mineral Resources are constrained by pit optimizations using a price of $2,650/oz Au, a price of $30/oz Ag, mining cost of $2.50/tonne, variable processing costs ranging from $3.26-$5.30/tonne, and metallurgical recoveries ranging from 45%-95% for Au and 15%-92% for Ag. Variable metallurgical recoveries and processing costs correspond to various material types including Oxide, Transition, Sulphide, and Stockpile materials, as well as spatial zones of the deposit with defined metallurgical characteristics. The pit optimizations also used a G&A cost of $0.65/tonne, pad replacement cost of $1.00/tonne for heap leach material, and refining costs of $0.00/oz and $0.50/oz for Au and Ag, respectively. | | (9) | Rounding as required by reporting guidelines may result in apparent discrepancies between tonnes, grades, and contained metal content. | | (10) | The estimate of Mineral Resources may be materially affected by geology, environment, permitting, legal, title, taxation, sociopolitical, marketing, or other relevant issues. | | (11) | Mineral Resources reported are inclusive of Mineral Reserves. | | (12) | The Effective Date of the Mineral Resource Estimate is December 8, 2025 |

Updated Mineral Reserve Estimate

Proven and Probable Mineral Reserves for the Project utilized the updated resource model released in 2023, which was constrained by engineered pit designs based on Lerchs–Grossmann optimization shells, with appropriate cut-off grades that reflect updated metal prices, metallurgical recoveries, geotechnical criteria, and operating cost assumptions. No changes were made to the underlying reserve methodology since the PFS released in 2022. Variations in reserves from the previous PFS study are from the updated 2023 resources (which includes the addition of historical stockpile resources), revised cost assumptions, and metallurgical recoveries. Reserves have been updated for heap leach only material to streamline permitting, simplify processing and reduce capital. This removes sulphide material from the reserve. Additionally, drill-tested historic low grade ore stockpiles included in the resource have been included in the reserve.

Table 4: DeLamar Project Mineral Reserves

| | | Proven | Probable | Proven & Probable | | | | | | | | Mineral Reserves | | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | | GOLD (Au) | | (kt) | (g/t) | (koz) | (kt) | (g/t) | (koz) | (kt) | (g/t) | (koz) | | DeLamar Project | Oxide | 11,675 | 0.40 | 149 | 108,297 | 0.32 | 1,110 | 119,972 | 0.33 | 1,259 | | Sulphide | - | - | - | - | - | - | - | - | - | | | TOTAL | Mixed | 11,675 | 0.40 | 149 | 108,297 | 0.32 | 1,110 | 119,972 | 0.33 | 1,259 | | | | | | | | | | | | | | | | Proven | Probable | Proven & Probable | | | | | | | | Mineral Reserves | | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | Tonnes | Grade | Ounces | | SILVER (Ag) | | (kt) | (g/t) | (koz) | (kt) | (g/t) | (koz) | (kt) | (g/t) | (koz) | | DeLamar Project | Oxide | 11,675 | 16.34 | 6,132 | 108,297 | 13.26 | 46,173 | 119,972 | 13.56 | 52,305 | | Sulphide | - | - | - | - | - | - | - | - | - | | | TOTAL | Mixed | 11,675 | 16.34 | 6,132 | 108,297 | 13.26 | 46,173 | 119,972 | 13.56 | 52,305 |