Mr. John Burzynski reports

OSISKO WINDFALL RESULTS FROM DISCOVERY 1 DEEP DRILL HOLE

Osisko Mining Inc. has provided an update on the Discovery 1 (OSK-W-19-1970) drill hole. Discovery 1 is a 3,467-metre drill hole, the longest diamond drill hole in Canada, which successfully intersected the targeted downplunge 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 grams per tonne (g/t) gold (Au) over 2.1 metres) and Triple 8 zone (100-metre extension -- 9.58 g/t Au over 7.6 metres) (see Osisko news release dated Sept. 11, 2019). Discovery 1 also intersected wide anomalous gold zones, including 116 metres of 0.46 g/t Au (see Osisko news release dated Dec. 10, 2019). Similar wide anomalous gold zones have been observed in the proximity of Triple 8, Triple Lynx and Lynx zones.

Previously reported intersection of 1.05 g/t Au over 96.0 metres (see Osisko news release dated Jan. 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 3,139 metres downhole and now ends at 3,330 metres. All analytical results for Discovery 1 have been received. Mineralization, up to 3 per cent 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 downplunge 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 downhole IP geophysical survey to further investigate the potential for new Lynx-like zones nearby."

OSK-W-19-1970-W1 intersected 10.1 g/t Au over 2.5 metres. The interval consists of 1 per cent disseminated pyrite and quartz-carbonate veins hosted in a strong biotite and moderate chlorite and carbonate altered andesite.

Qualified person

The scientific and technical content of this news release has been reviewed, prepared and approved by Louis Grenier, master of science, applied, professional geoscientist (OGQ 800), project manager of Osisko's Windfall gold project, who is a qualified person as defined by National Instrument 43-101 (Standards of Disclosure for Mineral Projects).

Quality control and reporting protocols

True width determination is estimated at 55 to 80 per cent of the reported core length interval for the zone. Assays are uncut except where indicated. Intercepts occur within geological confines of major zones but have not been correlated to individual vein domains at this time. Except when specified, reported intervals include minimum weighted averages of three g/t Au diluted over core lengths of at least two metres. All NQ core assays reported were obtained by either one-kilogram screen fire assay or standard 50-gram fire assaying AA finish or gravimetric finish at (i) ALS Laboratories in Val d'Or, Que.; Thunder Bay, Ont.; Sudbury, Ont.; or Vancouver, B.C., or (ii) Bureau Veritas in Timmins, Ont. The one-kilogram screen assay method is selected by the geologist when samples contain coarse gold or present a higher percentage of pyrite than surrounding intervals. Selected samples are also analyzed for multielements, including silver, using an aqua regia ICP-AES method at ALS laboratories. Drill program design, quality assurance/quality control (QA/QC) and interpretation of results is performed by qualified persons employing a QA/QC program consistent with National Instrument 43-101 and industry best practices. Standards and blanks are included with every 20 samples for QA/QC purposes by the corporation, as well as the lab. Approximately 5 per cent of sample pulps are sent to secondary laboratories for check assay.

About Osisko Mining Inc.

Osisko is a mineral exploration company focused on the acquisition, exploration and development of precious metal resource properties in Canada. Osisko holds a 100-per-cent interest in the high-grade Windfall gold deposit located between Val d'Or and Chibougamau in Quebec and holds a 100-per-cent undivided interest in a large area of claims in the surrounding Urban Barry area and nearby Quevillon area (over 2,700 square kilometres).

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