Osisko’s Gaspé copper hits: resource, pit shell and capex lens for mine planners
Reviewed by Tom Sullivan

First reported on MINING.com
30 Second Briefing
Osisko Metals has extended mineralisation beneath the historic Gaspé Copper mine in eastern Quebec, with hole 30-1228 cutting 257 m at 0.85% Cu and 5.13 g/t Ag from 33 m, including 28.5 m at 4.74% Cu and 27.4 g/t Ag about 200 m downhole, 50 m below the historical C zone to 275 m vertical depth. The porphyry copper-skarn project now hosts 1.83 billion measured and indicated tonnes at 0.27% Cu and 0.017% Mo, supporting a planned 160,000 t/d operation with estimated initial capex of about US$1.4 billion. Infill and expansion drilling, including June’s 80 m at 1.93% Cu at Needle Mountain, is aimed at upgrading inferred resources and testing zones currently modelled as waste inside the conceptual pit.
Technical Brief
- Hole 30-1228 extends mineralisation 50 m below the historical C zone to 275 m vertical depth.
- June Needle Mountain hole reported 80 m at 1.93% Cu from 196 m, including 30 m at 3.49% Cu.
- Latest release covers 28 mineralised intercepts from 12 holes, indicating broad spatial coverage of drilling.
- Hole 30-1235 intersected 258 m at 0.39% Cu and 3.6 g/t Ag from 47 m depth.
- Deeper hole 30-1225 returned 6 m at 1.19% Cu and 6.1 g/t Ag from 260 m.
- Infill drilling is explicitly targeting conversion of inferred resources to measured and indicated categories.
- Expansion holes are testing zones currently modelled as waste inside the conceptual pit shell.
- Mineralisation is porphyry copper–skarn, with disseminated and stockwork chalcopyrite plus pyrite/pyrrhotite, minor bornite and molybdenite.
- Updated resource in April more than doubled contained copper metal relative to the previous estimate.
Our Take
The measured and indicated inventory of 10.77 billion lb. copper plus significant molybdenum and silver at Gaspé puts Osisko Metals in the upper tier of undeveloped copper resources in our database, but the modest 0.27% Cu head grade means the newly reported 4.74% Cu zones could materially improve early‑years economics if they prove laterally continuous.
With initial capex estimated at about US$1.4 billion and an early‑2030s timeline, the project sits in the same capital intensity bracket as other large Canadian copper porphyries in our coverage, implying that long‑term copper price assumptions and access to project finance will be as critical as the geology in determining whether Gaspé is restarted.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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