Osisko Hits New Discovery One Kilometre North of Windfall

Recon Drilling Returns High-Grade: 27.4 g/t Au Over 6.7 Metres

TORONTO, June 15, 2021 (GLOBE NEWSWIRE) -- Osisko Mining Inc. (OSK:TSX. "Osisko" or the "Corporation") is pleased to announce that a significant new high-grade gold discovery has been made north of its 100% owned Windfall gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec.

Reconnaissance drilling approximately one kilometre north of Windfall identified the discovery area (“Golden Bear”), located along a sub-parallel splay of the Windfall Bank Fault.

Osisko Mining Chief Executive Officer John Burzynski commented: “It’s early days, but it looks like we’ve found another new high-grade system near Windfall in an area with little drilling. We are very excited by the Golden Bear discovery, particularly as this new mineralization is located less than a kilometre from the footprint of where we hope to build the Windfall mine and milling facility. When Osisko discovered the Lynx deposit in 2016 it was a game-changer for the overall scale and grade of Windfall. We believe that this new high-grade discovery may similarly have a significant positive effect on our development plans for the Windfall camp. It certainly underscores the highly prospective nature of Osisko’s strategic land package surrounding Windfall, the vast majority of which has yet to see any drilling.”

Golden Bear is situated within a package of andesitic to dacitic rock intruded by felsic porphyries. Mineralization in the discovery intersection consists of pyrrhotite ± pyrite-sphalerite-chalcopyrite with local visible gold in pervasive silica alteration and quartz-carbonate veins. Drilling on Golden Bear is now focused on confirming the discovery, its orientation and the extent of the mineralization. Additional drilling will include tight and wide step outs, and new results will be released as they are received.

Maps showing the drill hole location and full analytical results are available at www.osiskomining.com

Discovery Hole OSK-UB-21-232
Hole No.	From (m)	To (m)	Interval (m)	Au (g/t) uncut	Au (g/t) cut to 100 g/t	Zone	Corridor
OSK-UB-21-232	503.0	509.7	6.7	27.4	17.2	New