The project has the potential to further enhance the long-term economics of the Ambler mining district. Trilogy Metals announced the results of the Bornite Preliminary Economic Assessment (PEA) on January 15, 2025.

The Bornite PEA describes the technical and economic viability of establishing an underground mining operation for a 6,000 tonne-per-day operation with a 17-year mine life. The PEA assumes re-purposing the infrastructure described in Trilogy’s 2023 Feasibility Study for the Arctic Project for use with the Bornite Project once the Arctic deposit has been depleted. The PEA was prepared on a 100% ownership basis and all amounts are in US dollars.

• 1.9 billion pounds of copper over 17-year mine life.
• Potential to extend mine activity for the Upper Kobuk Mineral Projects to over 30 years.
• Pre-tax Net Present Value (“NPV”)_8% of $552.1 million and an Internal Rate of Return (“IRR”) of 23.6%.
• After-tax NPV_8% of $393.9 million and after-tax IRR of 20.0%.

Metal Production and Assumed Metal Prices

Operating and Capital Costs

Notes:

1. G&A = general & administrative
2. Figures may not sum due to rounding
    

Financial Results

• Mineralization is hosted within the Devonian aged Bornite carbonate sequence.
• Widespread hydrothermal dolomitization is a characteristic of the belt and locally hosts the associated copper and cobalt mineralization.
• Bornite has characteristics similar to a series of districts and deposits including the Mount Isa district in Australia, the Tynagh deposit in Ireland, the Kipushi deposit in the DRC and the Tsumeb deposit in Namibia.
• All of these deposits show early epigenetic characteristics; emplacement in carbonate stratigraphy; and early pyrite-dolomite alteration followed by copper-dominant sulphide mineralization.
• Copper mineralization at Bornite is comprised of chalcopyrite, bornite, and chalcocite as stringers, veinlets, and breccia fillings distributed in stacked, stratabound zones exploiting favourable stratigraphy. Stringer and massive pyrite and locally significant sphalerite occur above and around the copper zones, while locally massive pyrite and sparse pyrrhotite occur in association with siderite alteration below and adjacent to copper mineralization.
• Cobalt mineralization at Bornite is composed of cobaltiferous pyrite within and enveloping the copper mineralized zones and cobalt sulphides including carrollite and cobaltite directly associated with copper bearing minerals.
• Mineralization occurs, in order of increasing grade, as disseminations, irregular and discontinuous stringer-style veining, breccia matrix replacement, and stratiform massive sulphides.
• From 1957 to 2019, a total of 273 holes targeted the Bornite deposit during 24 different campaigns. 222 surface core holes and 51 underground core holes were drilled, totalling 106,406 meters.

The South Reef includes a relatively high-grade mineralized zone that is amenable to underground mining methods. The table below illustrates the portions of the South Reef at a higher cut-off grade (sensitivity to cut-off grade), representing an opportunity that could be considered for mining of this material using only underground mining methods which is illustrated in the PEA.

Notes:

1. The 1.45% Cu break-even cut-off assumes sublevel stoping mine method. The cut-off grades assume a $4.60/lb Cu price, process recovery of 90.47%, process cost of $21.00/t processed, mining costs of $65.00/t mined and G&A cost of $14.50/t processed, treatment, refining, sales cost of $0.78/lb Cu in concentrate, road use cost of $8.04/t processed, and 2% NSR royalty.
2. Subset of the mineral resource using a higher cut-off to what was used in table above and is not additive to the in-pit mineral resource reported in table above.
3. Restatement of the mineral resources outside of the pit and is not additive to the mineral resource.

Notes

1. Mineral resources within the mine plan were estimated using sublevel stoping underground mining method and includes variable dilution and a mining recovery of 95%.
2. Mineral resources are not mineral reserves and do not have demonstrated economic viability.
3. Input assumptions used to determine mineable stope shapes include a Cu price of $4.20/lb, mine operating cost of $73.29/t, process operating cost of $19.84/t, G&A and surface costs of $9.64/t, haulage and road use costs of $28,78/t, closure and water treatment costs of $1.26/t, shipping, treatment, refining and selling costs of $0.78/lb Cu, process recovery of 90%, and NSR royalty of 2%.
4.  Production stope cut-off of 1.6% Cu and development cut-off of 0.7% Cu. The production stope cut-off input assumptions include a copper price of $4.20/lb, mine operating cost of $44.08/t, process operating cost of $24.82/t, G&A and surface cost of $17.3/t, and sustaining costs of $8.52/t, road use costs of $14.4/t, shipping, treatment, refining and selling costs of $0.78/lb Cu, process recovery of 90.89%, and average NSR royalty of 2.25%.