"The addition of this new resource further strengthens our portfolio for near term advancement and towards possible production," the company's president Chris Lodder said.
The indicated mineral resource is of 576,000 ounces of gold and 1.37 million oz of silver with 14.9 million tonnes grading 1.2g/t Au and 2.9g/t Ag, Osisko said.
And the inferred mineral resource is of 544,000oz Au and 1.76 million oz Ag with 16.6 million tonnes grading 1.0g/t Au and 3.3g/t Ag.
Osisko—which acquired San Antonio in November 200—has constructed a leach pad and carbon in column plant and has been processing a stockpile since Q4 last year with 680,000 tonnes of mineralized material currently placed and processed, the company said.
The stockpile has a total of 1.1 million tonnes with an average grade of 0.57g/t Au.
National Bank of Canada Financial Markets analyst Don DeMarco said: "We're encouraged by the de-risking step showing a sizeable initial endowment, though overall, ascribe a neutral bias as San Antonio represents a modest ~30% of our [Net Asset Value]".
The MRE was made using an assumed gold price of US$1,750 per oz.
Osisko's share price was down 5% day on day at C$6.19 (US$4.79) on June 30. The company has a market capitalization of C$370.25 million.