On November 14, 2024, Osisko Metals announced a significant increase to its previously announced Mineral Resource Estimate (MRE) for the Gaspé Copper Project in Québec.

The updated MRE includes pit-constrained resources comprising 824 million tonnes grading 0.34% copper equivalent of Indicated category and 670 million tonnes grading 0.38% copper equivalent of Inferred category. This MRE represents a 53% increase in copper-equivalent metal content over the previously reported Indicated Resource and a 100-fold increase in copper-equivalent metal content in Inferred Resources.

This significantly larger resource estimate is the result of:

  • Geological re-interpretation of the mineralized system, whereby most of the mineralized stratigraphic units above the base of the C-Zone skarn, including up-dip extensions toward Needle Mountain, were included in the resource model.
  • Extension of the Whittle pit model to the south towards Needle Mountain, eliminating the possibility of a potential mill complex on the site of the original Gaspé Copper mill. Two other sites for the potential mill are now under consideration.
  • Lowering of cut-off grade from 0.15% copper to 0.12% copper on the basis of potentially larger mine throughput and replacement of SAG mill by HPGR in the grinding circuit.

At 4.91 billion pounds (2.23 million tonnes) of contained copper, as well as significant molybdenum (274 million pounds) and silver (46.0 million ounces), the latest Gaspé Copper in-pit Indicated Resource hosts by far the largest undeveloped copper-molybdenum deposit in Eastern North America, exclusive of Inferred resources.

Table 1: Mineral Resource Estimate (MRE) Base Case at 0.12% Copper Cut-off
Table 1: Mineral Resource Estimate (MRE) Base Case at 0.12% Copper Cut-off

  1. The independent qualified persons for the MRE, as defined by National Instrument (“NI”) 43-101 guidelines, is Pierre-Luc Richard, P.Geo., of PLR Resources Inc. with contributions from François Le Moal, P.Eng., of G-Mining for cut-off grade and Pit shell optimization, and Christian Laroche, P.Eng., from Synectic, for metallurgical parameters. The effective date of the MRE is November 4, 2024.
  2. These Mineral Resources are not mineral reserves as they have no demonstrated economic viability. No economic evaluation of these Mineral Resources has been produced. The quantity and grade of reported Inferred Resources in this MRE are uncertain in nature and there has been insufficient drilling to define these Inferred Resources as Indicated. However, it is reasonably expected that the majority of Inferred Mineral Resources could be upgraded to Indicated category with additional drilling.
  3. The Qualified Persons are not aware of any known environmental, permitting, legal, title-related, taxation, socio-political, financial, or other relevant issues that could materially affect the MRE.
  4. Calculations used metric units (metres, tonnes). Metal contents in the above table are presented in percent, pounds or tonnes. Metric tonnages and pounds were rounded, and any discrepancies in total amounts are due to rounding errors.
  5. CIM definitions and guidelines for Mineral Resource Estimates have been followed. See Cautionary Note below for copper equivalency (CuEq) values.

General parameters of the updated Mineral Resource Estimate

This MRE is pit-constrained and includes stockwork mineralization surrounding the past-producing Copper Mountain open pit mine as well as disseminated, stratiform mineralization in both skarn and potassic-altered hornfels (porcellanite) that extends up-dip from Copper Mountain towards Needle Mountain to the south.

The MRE uses, amongst other parameters, a long-term price of US$4.00/lb copper, a lower cut-off of 0.12% Cu for pit shell modelling and a lower cut-off grade of 0.12% copper for base case in-pit resource estimation. The resource was estimated using data from historical drilling completed between the 1950s and 2019 and 42,100 metres of drilling completed by the Company between 2022 and 2024 (see Appendix for detailed parameters).

Potential for resource expansion

Building upon the information released in this updated MRE, a minimum 70,000 metre drill program is planned to commence in May 2025 that will aim to:

  • convert Inferred resources to Indicated category by reducing drill spacing to 100 metres or less within the pit volume
  • better define higher-grade (0.5 to 1.5% % Cu) mineralization within pit boundaries in the B-Zone and C-Zone skarn horizons
  • extend up-dip, shallower B-Zone and C-Zone skarn mineralization (near Needle Mountain) beyond current pit boundaries
  • test shallower (above 600 m depth) portions of the high grade (2%-3% Cu) E-Zone skarn for inclusion into the pit volume.

Implications of larger open pit resource at Gaspé Copper

The current modelled Whittle pit shell extends from the current flooded Copper Mountain pit towards the base of Needle Mountain to the south. Further drilling, geological modelling and pit optimization will be required to refine pit boundaries. The Company will evaluate future pit limits and 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.

Please read the full November 14, 2024, news release for further details.