First Quantum Files NI 43-101 Technical Report for La Granja

Toronto, Ontario – First Quantum Minerals announces the filing of a Technical Report (the “Report”) with an updated Mineral Resource estimate for the La Granja project (the “Project”).

La Granja is located in northern Peru and is 55% owned by First Quantum and 45% by Rio Tinto.

Highlights

• La Granja is a large-scale copper porphyry-skarn-epithermal system with two adjacent mineralized domains at Paja Blanca and Mirador, both of which transition to porphyry-style mineralisation at depth.
• The updated Mineral Resource represents a substantial copper endowment, underpinned by improved geological confidence resulting from targeted drilling, detailed geological mapping and modelling, and geochemical test work to enhance spatial definition of the mineralized domains.
• Updated Mineral Resource includes approximately 4.831 billion tonnes of Measured and Indicated Resources at 0.48% copper (“Cu”), comprising 23.0 million tonnes of contained copper, and approximately 5.206 billion tonnes of Inferred Resources at 0.40% Cu, comprising an additional 20.7 million tonnes of contained copper (0.16% Cu cut‑off grade).
• Updated Mineral Resource estimate was prepared in accordance with NI 43-101 and the Canadian Institute of Mining, Metallurgy and Petroleum (“CIM”) Definition Standards.

Project Description

The La Granja deposit is located in the Querocoto District of Chota Province within the Cajamarca Region of northern Peru, on the eastern flank of the Western Cordillera of the Andes. The Project lies at moderate elevations of between 2,000 metres and 2,800 metres above sea level and is situated about 220 kilometres (“km”) by road from Chiclayo in the Lambayeque Region.

La Granja comprises a large-scale copper porphyry–skarn–epithermal system with two principal mineralized centers, Paja Blanca to the east and Mirador to the west. The upper levels of Paja Blanca are characterized primarily by breccia-dominated copper mineralization while skarn-hosted copper–zinc mineralization is more prominent at the upper levels of Mirador. Both mineralized centers transition to porphyry-style copper mineralization at depth.

MINERAL RESOURCE ESTIMATES

The updated Mineral Resource estimate for La Granja is supported by a systematic program of geological reinterpretation, database validation, and targeted drilling carried out between 2023 and 2025 to enhance the geological and geometallurgical understanding of the deposit. The drill program comprised approximately 45,998 metres of oriented diamond drilling, bringing the drillhole database to 832 diamond drill holes totaling 368,844 metres. A total of 748 diamond holes totaling 345,127 metres were used in the Mineral Resource estimate, with a number of early historical holes excluded due to insufficient supporting information.

The deposit remains open at depth, with recent analysis demonstrating large-scale continuity of copper mineralization. Further exploration target potential has been identified at depth within both the Mirador and Paja Blanca clusters.

Conceptual design and operations

Conceptual studies indicate that the deposit is amenable to conventional large-scale open pit mining using drill and blast, shovel loading, and off-highway truck haulage. A conceptual pit optimization for La Granja indicates a breakeven cut-off grade of 0.16% Cu on a copper-only basis at a copper price of $4.00 per pound, with potential additional by-product contributions from silver, gold, and molybdenum treated as value upside. Preliminary operating cost estimates were developed to support these optimizations to define the extents for Mineral Resource reporting and to demonstrate Reasonable Prospects for Eventual Economic Extraction.

Primary water supply will be sourced from desalinated seawater, with all site contact water captured and utilized for mineral processing to minimize impacts on natural environmental flows. This approach maximizes the efficient use of water resources and significantly reduces the need for additional water intake. The mine site is characterized by rugged terrain and high rainfall, which present important considerations for the safe, long‑term storage of tailings. Accordingly, ore comminution is planned to occur adjacent to the pit, after which material will be transported by pipeline through a 7km long access tunnel to a flat, arid Pacific coastal plain approximately 100km from the mine. This location provides suitable conditions for conventional flotation processing, together with tailings storage and management, and will reduce long‑term operational and environmental risk. The tailings storage facility will be designed, built, and operated in conformance with the Global Industry Standard on Tailings Management (“GISTM”).

Improved geological understanding has shown that the deposit exhibits variable arsenic content across the deposit, predominantly in the form of enargite with only very minor arsenopyrite present. The Company’s geological work to date demonstrates that a significant portion of the arsenic is structurally controlled and associated with high copper grades, lending itself to a conventional flotation flow sheet in the process plant. It is expected that arsenic can be managed by segregation, blending and through commercial offtake arrangements.

Next Steps

Further project development is focused on advancing the permitting process. Key priorities include the progression of baseline environmental and social studies, continued stakeholder engagement, and preparation for the Detailed Environmental Impact Assessment, which is scheduled to commence in 2026.