A hole targeting the down-plunge extension intercepted widths including 81.8g/t Au over 3.5 metres and 22.3g/t Au over 4.1 metres - 625 metres down from the nearest block from the latest mineral resource estimate.

CEO John Burzynski said the results are a "strong indication of a much larger deposit, underscoring the consistency and predictability of the geology model we have developed".

"Windfall has scale and grade unparalleled in the global near-term development category," he said.

Canaccord Genuity Capital Markets analyst Kevin MacKenzie agreed that the results, along with previous > 1,200-metre high-grade intercepts highlight the potential for a "materially larger system" and a greater overall production profile.

National Bank of Canada Financial Markets analyst Don DeMarco called the intercepts "impressive" and supportive of an upside scenario of an expanded deposit.

The project has district potential and benefits from a favourable jurisdiction, elevated grades, and a long mine life, tempered by the industry-wide issue of inflationary pressures on capital expenditure and costs, he said.

Osisko is aiming to complete a feasibility study on the project before year-end, so that it can start the permitting process, with first production targeted for late 2024 or early 2025. The company believes production could be as much as 350,000 ounces per year, compared with the planned 300,000oz/y.

Located in the Abitibi greenstone belt in James Bay, Windfall hosts measured and indicated resources of 4.1 million oz grading 11.4g/t.

"By the time we get into production, Windfall will be 10 million-15 million oz. This is where we expect this deposit to go," Burzynski said this month at the 2022 Americas Gold Forum in Colorado Springs in Colorado, USA.

Osisko's share price was up 3% day on day at C$2.45 on 27 September. The company has a market capitalisation of C$850.94 million.