Osisko Windfall Results From Discovery 1 Deep Drill Hole

Highly Anomalous Mineralization at Depth

1.04 g/t Au Over 191 metres Including 10.1 g/t Au Over 2.5 metres

TORONTO, Feb. 25, 2020 (GLOBE NEWSWIRE) -- Osisko Mining Inc. (OSK: TSX. "Osisko" or the "Corporation") is pleased to provide an update on the Discovery 1 (OSK-W-19-1970) drill hole. Discovery 1 is a 3467 metre drill hole, the longest diamond drill hole in Canada, which successfully intersected the targeted down plunge extensions of two known gold zones and investigated the projected source area of the Windfall deposit at depth.

Prior results from Discovery 1 include the successful intersection of the targeted Underdog Zone (500 metre extension:  14.1 g/t Au over 2.1 metres) and Triple 8 Zone (100 metres extension:  9.58 g/t Au over 7.6 metres) (see Osisko news release dated September 11, 2019). Discovery 1 also intersected wide anomalous gold zones including 116 metres of 0.46 g/t Au (see Osisko news release dated December 10, 2019). Similar wide anomalous gold zones have been observed in the proximity of Triple 8, Triple Lynx, and Lynx zones.

Previously reported intersection 1.05 g/t Au over 96.0 metres (see Osisko news release dated January 29, 2020) has been extended by new analytical results to 1.04 g/t Au over 191 metres, including a high-grade intersection of 10.1 g/t Au over 2.5 metres. The intersection begins at 3139 metres down hole and now ends at 3330 metres. All analytical results for Discovery 1 have been received. Mineralization, up to 3% pyrite and pyrrhotite, occurs in biotite, chlorite, and sericite altered mafic volcanics with occasional felsic volcanics and local felsic porphyritic intrusions. The high value intercept is within a breccia textured interval with an increased intensity of carbonate alteration in fracture filling.

Osisko President and Chief Executive Officer John Burzynski commented: “Discovery 1 has been a great success for Osisko. We are very pleased to have intersected the down plunge extensions of known zones, especially Underdog. This 500 metre extension provides us with a high potential zone ready for infill drilling to continue to grow our world class deposit. The wide zones of anomalous gold interspersed with high-grade intervals throughout the bottom half of the hole are a strong indication the Windfall gold system is extensive. We are planning a down hole IP geophysical survey to further investigate the potential for new Lynx-like zones nearby.”