Osisko Metals Incorporated announced an updated Mineral Resource Estimate at Copper Mountain as part of the Gaspé Copper Project, located near Murdochville in the Gaspé Peninsula of Quebec. The updated MRE comprises an open-pit Indicated Resource of 495 million tonnes grading 0.37% CuEq, representing a 30% increase in copper-equivalent metal content over the previously reported copper-only Inferred Resource, as well as greater than 99% conversion rate from Inferred to Indicated category. At 3.25 billion pounds (1.47 million tonnes)of contained copper, not including significant molybdenum (180 million pounds) and silver (28 million ounces) resources, the Copper Mountain in-pit Indicated Resource hosts the undeveloped copper asset in Eastern North America.

Other improvements in the updated MRE include a 38% reduction of the strip ratio (now estimated at 1.23) from the estimate in the previously reported Inferred Resource, based on the mineralization geometry that surrounds the former open pit mine. Building upon the information released in this updated MRE, an 8,000 to 10,000 metre drill program is planned to commence in May that aims to 1) partially define Measured Resources and improve grades in the higher-grade core of the Copper Mountain deposit, which could provide approximately 60 Mt of higher grade ?starter-pit? material estimated from a 0.40% Cu lower cut-off grade; and 2) test the potential for near-surface mineralization around the historical Needle Mountain mine that was the starter operation for Gaspé Copper in the 1950?s (A and B Zones).

This resource is pit-constrained to mineralization surrounding the past-producing Copper Mountain open pit mine and uses, amongst other parameters, a long-term price of USD 4.00/lb copper (cutoff of 0.12% Cu) for pit shell modelling, pre-set eastern and southeastern geographical constraints on pit limits to minimize impacts on the town of Murdochville from future potential mining operations, and a lower cut-off grade of 0.15% copper for base case in-pit resource estimation. The resource was estimated using data from historical drilling completed between the 1950?s and 2019 and 37,390 metres of drilling completed by the Company in 2022 and 2023. See the Appendix at the end of this news release for detailed parameters.

End-of-mine historical mineral resources at Gaspé Copper that are not NI 43-101 compliant are reported in the Noranda/Falconbridge Annual Reports 1998-2000, Quebec government mining assessment reports and in Hussey & Bernard (SME Aug. 1998, p. 36-44). The following disclosure describes areas of remaining mineralization at Gaspé Copper that the Company believes offer excellent potential for additional mineral resources.

Osisko Metals? strategy at the present time is to focus on the economic viability of the currently defined Copper Mountain resource, and if this can be achieved, evaluation of mineralized zones described below will follow with additional drill programs. The current modelled Whittle pit shell includes pre-set eastern and southeastern geographical constraints on pit limits designed to minimize impacts on the town of Murdochville from potential future mining operations, namely leaving the southern portion of Copper Mountain intact. Geological modelling of stockwork mineralization and residual disseminated skarn mineralization occurring between the Copper Mountain and Needle Mountain historical open pits, the latter located 1.6 kilometers south of Copper Mountain, indicates potential for a significantly larger open pit resource at Gaspé Copper.

Further geological and pit modelling is required to evaluate such potential and this work is ongoing. In the event that a larger viable pit-constrained resource can be defined, the Company will evaluate the possibility of reconfiguring the current layout of the site to minimize disturbance and ensure the protection and safety of the residents of Murdochville and the surrounding environment. Modelling of the residual copper mineralization along the perimeter and below the open pit A Zone and the underground B Zone at Needle Mountain, including residual pillars in the B Zone, indicates potential for a higher-grade, secondary open-pit resource that would be distinct from the Copper Mountain resource.

The modelling is based entirely on 1950?s and 1960?s historical drill holes, which were only partially assayed for copper and not for molybdenum nor silver. This area will be tested with a Phase I, 4,000-metre drill program starting at the end of May and if successful, will be followed by a Phase II program later in the season. Residual underground skarn mineralization still remains in the form of pillars in the mined portion of the C Zone (grades of 1% to 2% copper), as well as massive sulfide/skarn mineralization in the deeper E Zone (grades of 3% to 4% copper) within the E-38 deposit and up to 800 metres north of this deposit.

The E Zone skarn aureole received little follow-up drilling north of the E-38 deposit and offers excellent potential for further resource definition at significantly higher copper and molybdenum grades. Drilling of the E Zone skarn is planned for 2025. Copper Equivalent grades are expressed for purposes of simplicity and are calculated taking into account 1) metal grades; 2) estimated long-term prices of metals: USD 4.00/lb copper, $19.00/lb molybdenum and USD 22/oz silver; 3) estimated recoveries of 92%, 70% and 70% for Cu, Mo and Ag respectively and 4) net smelter return value of metals as percentage of the price, estimated at 86.5%, 90.7% and 75.0% for Cu, Mo and Ag respectively.