Osisko Mining Inc. (TSX:OSK)  is pleased to announce the discovery of a significant new area of mineralization at its 100% owned Windfall gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec.

Exploration drilling immediately below the main Lynx deposit to test the Windfall model has discovered four new high-grade zones in a new mineralized corridor named “Triple Lynx”. The new high-grade mineralized corridor lies below the main mafic unit associated with the Lynx deposit between vertical depths of 650 and 980 metres. This area of the Lynx deposit has no previous drilling and is open in all directions.

With the new discovery and recent discoveries at Windfall North, Lynx Extension and Triple 8, Osisko will increase the drill definition and exploration program at Windfall by an additional 200,000 metres for a total program of 1,000,000 metres drilling.

Osisko President and Chief Executive Officer John Burzynski commented: “With every additional hole we drill in and around Lynx, it appears more and more to be the main component of the Windfall system.  Today’s announcement of the discovery of another new corridor with wide and high-grade mineralization at Lynx is very good news.  Triple Lynx adds the potential to develop a whole new area of mineralization that may be of similar scale to what we’ve seen at the original Lynx discovery.  The Triple Lynx discovery area had not previously been drilled and represented a blank spot on our sections.  We have a significant open area to now drill out and see how this new discovery unfolds. We have moved four drills to Triple Lynx to immediately begin defining this exciting new zone.”

True width determination is estimated at 65-80% of the reported core length interval for the zone.

The style of mineralization in the Triple Lynx discovery is very similar to the known Lynx deposit.  Mineralization is hosted in a moderately sericitized and strongly silicified rhyolite near the contact with gabbro and felsic intrusions. The mineralized intervals contain up to 10% fine-grained pyrite as disseminations and stringers, and traces of sphalerite – chalcopyrite with strong pervasive silica alteration, local quartz-tourmaline veinlets and local visible gold.

Maps and sections showing the location of the new analytical results are available at www.osiskomining.com.

Qualified Person

The scientific and technical content in this news release has been reviewed, prepared and approved by Mr. Louis Grenier, M.Sc.A., P.Geo. (OGQ 800), Project Manager of the Windfall Lake gold project, who is a “qualified person” as defined by National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”).

Quality Control and Reporting Protocols

True width determination is estimated at 65-80% 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. Reported intervals include minimum weighted averages of 3.0 g/t Au diluted over core lengths of at least 2.0 metres. All NQ core assays reported were obtained by either 1-kilogram screen fire assay or standard 50-gram fire-assaying-AA finish or gravimetric finish at (i) ALS Laboratories in Val d’Or, Québec, Thunder Bay, Ontario, Sudbury, Ontario or Vancouver, British Colombia, or (ii) Bureau Veritas in Timmins, Ontario. The 1-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 multi-elements, 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 NI 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% of sample pulps are sent to secondary laboratories for check assay.

About the Windfall Lake Gold Deposit

The Windfall gold deposit is located between Val-d’Or and Chibougamau in the Abitibi region of Québec, Canada. The mineral resource defined by Osisko, as disclosed in the Windfall Lake Technical Report (as defined below) and November 27, 2018 Lynx resource update, comprises 2,874,000 tonnes at 8.17 g/t Au (754,000 ounces) in the indicated mineral resource category and 10,352,000 tonnes at 7.11 g/t Au (2,366,000 ounces) in the inferred mineral resource category. For details regarding the key assumptions, parameters and methods used to estimate the mineral resources presented in respect of the Windfall Lake gold project, please see the technical report entitled “Technical Report and Mineral Resource Estimate for the Windfall Lake Project, Windfall Lake and Urban-Barry Properties” and dated June 12, 2018 (effective date of May 14, 2018), which has been prepared by InnovExplo Inc. from Val-d’Or, Québec (the “Windfall Lake Technical Report”) and the press release “Osisko Releases Mineral Resource Update for Lynx” dated November 27, 2018, which has been prepared by Osisko and reviewed and approved by Micon International, Ltd. from Toronto, Ontario. The Windfall Lake Technical Report and press release are available on Osisko’s website at www.osiskomining.com and on SEDAR under Osisko’s issuer profile at www.sedar.com. The Windfall Lake gold deposit is currently one of the highest-grade resource-stage gold projects in Canada. Mineralization occurs in four principal zones: Lynx, Zone 27, Caribou and Underdog. All zones comprise sub-vertical lenses following intrusive porphyry contacts plunging to the northeast. The deposit is well defined from surface to a depth of 900 metres and remains open along strike and at depth. Mineralization has been identified 30 metres from surface in some areas and as deep as 2,000 metres in others, with significant potential to extend mineralization down-plunge and at depth.

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% interest in the high-grade Windfall gold deposit located between Val-d’Or and Chibougamau in Québec and holds a 100% undivided interest in a large area of claims in the surrounding the Urban Barry area and nearby Quévillon area (over 2,700 square kilometres).