Osisko Mining Intersects 71.9 g/t Au Over 2.9 Metres at Lynx

TSX: OSK
www.osiskomining.com

Mr. John Burzynski reports:

TORONTO, ONTARIO--(Marketwired - Feb. 27, 2018) - Osisko Mining Inc. (OSK:TSX) ("Osisko" or the "Corporation") is pleased to provide new results from the ongoing drill program at its 100% owned Windfall Lake gold project located in the Abitibi greenstone belt, Urban ownship, Eeyou Istchee James Bay, Qu?(C)bec. The 800,000 metre drill program combines definition, expansion and exploration drilling in and around the main Windfall gold deposit and the adjacent Lynx deposit (located immediately NE of Windfall).

Significant new analytical results from 31 intercepts in 22 drill holes and 3 wedges focused on infill and expansion drilling in the Lynx deposit are presented below. Osisko continues to extend the known Lynx zones of mineralization through the application of the Windfall geological model and as the density of drilling increases.

Highlights from the new results include: 71.9 g/t Au over 2.9 metres OSK-W-17-941; 76.4 g/t Au over 2.4 metres and 52.5 g/t Au over 2.1 metres in OSK-W-17-1367-W1, 52.3 g/t Au over 2.1 metres in OSK-W-17-967, 40.6 g/t Au over 2.3 metres in OSK-W-17-1413; 48.0 g/t Au over 2.0 metres in OSK-W-18-1422 and 10.1 g/t Au over 6.5 metres in OSK-W-18-1415. Maps showing hole locations and full analytical results are available at www.osiskomining.com.

OSK-W-17-898 intersected Lynx 3 with 3.75 g/t Au over 5.2 metres. Mineralization is composed of 4% disseminated pyrite and 3% pyrite stringers hosted in quartz-tourmaline and quartz-carbonates veins in a fragmental felsic dike.

OSK-W-17-907 intersected Lynx 4 with 5.71 g/t Au over 2.0 metres. Mineralization is composed of 1% quartz-tourmaline veins with pyrite and 1% pyrite-silica flooding within a strongly sericitized and silicified rhyolite.

OSK-W-17-941 intersected 71.9 g/t Au over 2.9 metres in Lynx 2. Mineralization is composed of local visible gold within a silicified and weakly sericitized fragmental felsic dike.

OSK-W-17-967 intersected crustiform veins returning 52.3 g/t Au over 2.1 metres in the Lynx 2 Mineralization is composed of 1% disseminated pyrite in quartz-carbonate-chlorite veins within a sericitized gabbro.

OSK-W-17-1099 intersected 3.04 g/t Au over 2.1 metres in Lynx 2. Mineralization is composed of up to 2% pyrite clusters, 10% pyrite in pervasive silica flooding and 3% pyrite-tourmaline stringers hosted in a silica altered fragmental felsic dike.

OSK-W-17-1104 intersected 4.30 g/t Au over 2.0 metres and 4.06 g/t Au over 2.2 metres in Lynx HW. Mineralization is composed of up to 3% disseminated and stringer pyrite within a gabbro with sericite and fuchsite alteration.

OSK-W-17-1113 intersected 3.33 g/t Au over 2.6 metres. Mineralization is composed of quartz veins with trace pyrite stringers and 1% pyrite clusters and quartz-carbonate veins in a weakly sericitized rhyolite.

OSK-W-17-1115 intersected 11.7 g/t Au over 2.0 metres related to vein type mineralization. The interval is composed of 5% pyrite-tourmaline stringers and quartz veins within a chloritized andesite.

OSK-W-17-1147 intersected 3.29 g/t Au over 3.7 metres in Lynx 4. Mineralization is composed of 1% pyrite clusters with ptygmatic tourmaline veins within a sericitized rhyolite.

OSK-W-17-1177 intersected Lynx 1 with 3.21 g/t Au over 2.0 metres. Mineralization is composed of 1% pyrite stringers and tourmaline veins at a fuchsite altered contact between a gabbro and a porphyritic felsic dike.

OSK-W-17-1181-W3 intersected Lynx 4 with 6.11 g/t Au over 2.7 metres. Mineralization is composed of disseminated pyrite and tourmaline ptygmatic veins in a porphyritic felsic dike crosscutting a gabbro.

OSK-W-17-1187 intersected Lynx 3 with 3.43 g/t Au over 2.7 metres. Mineralization is composed of 4% pyrite clusters and 2% pyrite stringers with pervasive silica alteration in a sericitized porphyritic felsic dike.

OSK-W-17-1190 intersected 5.91 g/t Au over 2.0 metres in Lynx 1. Mineralization is composed of 5% pyrite stringers and 3% pyrite-silica flooding within a moderate sericite altered porphyritic felsic dike.

OSK-W-17-1193 intersected Lynx 4 with 4.48 g/t Au over 2.8 metres. Mineralization is composed of up to 2% pyrite stringers within a strongly sericitized felsic porphyritic dike.

OSK-W-17-1290 intersected 34.5 g/t Au over 4.0 metres in a vein within the Lynx Corridor. Mineralization is composed of traces of disseminated pyrite within a gabbro with strong chlorite and carbonate alteration.

OSK-W-17-1293 intersected Lynx 1 with 14.4 g/t Au over 2.5 metres. Mineralization is composed of disseminated pyrite, pyrite stringers and quartz-carbonates veins in a chloritized mafic intrusion bordered by the Bank fault deformation zone.

OSK-W-17-1356 intersected Lynx 1 with 4.14 g/t Au over 2.4 metres. Mineralization is composed of traces of pyrite clusters and/or fragments and pyrite stringers at the contact between a sericitized fragmental intrusive unit and an andesite.

OSK-W-17-1367-W1 intersected Lynx 4 with 52.5 g/t Au over 2.1 metres and 76.4 g/t Au over 2.4 metres. The first interval is composed of 4% pyrite clusters in 10 centimetres quartz-tourmaline veins and disseminated pyrite in a strongly fuchsite altered gabbro. The second interval is composed of trace pyrite-tourmaline stringer, 1% disseminated pyrite and 4% pyrite in ptygmatic tourmaline veinlets with trace chalcopyrite. Local visible gold is present in brittle fractures crosscutting tourmaline ptygmatic veins at contact between a small porphyritic dike and a fuchsite altered gabbro.

OSK-W-17-1396 intersected 6.13 g/t Au over 2.8 metres in Lynx 4. The mineralization is composed of up to 15% pyrite in quartz-tourmaline veins and 1% chalcopyrite within a sericitized and bleached mafic intrusion.

OSK-W-17-1413 intersected Lynx 2 with 40.6 g/t Au over 2.3 metres and Lynx 6 with 8.35 g/t Au over 2.4 metres. The first interval is composed of local visible gold and 1% pyrite clusters within a rhyolite with intense pervasive silica flooding. The second interval is composed of local visible gold and 3% disseminated pyrite in carbonate fracture filling, 2% pyrite stringers in smoky quartz veins hosted in a sheared andesite with chlorite alteration.

OSK-W-18-1414-W1 intersected Lynx 1 with 8.20 g/t Au over 3.6 metres and 26.5 g/t Au over 2.7 metres. The first interval is composed of up to 7% pyrite clusters, up to 3% pyrite stringers and ptygmatic quartz-tourmaline veins within a sericitized gabbro and rhyolite contact. The second interval is composed of up to 5% pyrite-silica flooding and 3% pyrite stringers within a strong silica altered rhyolite.

OSK-W-18-1415 intersected Lynx HW with 10.1 g/t Au over 6.5 metres. Mineralization is composed of local visible gold, up to 15% pyrite with pervasive silica flooding within a weakly bleached, sericitized and fuchsite altered gabbro.

OSK-W-18-1418 intersected Lynx 4 with 8.09 g/t Au over 2.3 metres and 4.02 g/t Au over 2.2 metres. Mineralization is composed of up to 5% pyrite stringers and 3% pyrite clusters in smoky quartz with, local carbonate in fracture filling and disseminated tourmaline hosted in a sericitized and silicified rhyolite.

OSK-W-18-1422 intersected Lynx hanging wall with 48.0 g/t Au over 2.0 metres. Mineralization is composed of up to 5% pyrite stringers, up to 3% pyrite clusters and 2% disseminated pyrite within a sericite, fuchsite and silica altered gabbro.

OSK-W-18-1423 intersected two interval 7.77 g/t Au over 2.1 metres in Lynx 1 and 4.65 g/t Au over 2.5 metres in a crustiform vein. The first interval is composed of 3% pyrite stringers, 1% pyrite clusters and crustiform quartz-carbonates veins within a strongly sericitized felsic porphyritic dike. The second interval is composed of up to 4% pyrite-tourmaline stringer and quartz-carbonate vein within a sericite, fuchsite, chlorite and carbonate altered andesite.

Qualified Person

The scientific and technical content of 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 widths determinations are estimated at 65-80% of the reported core length intervals for most of the zones. 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 ALS Laboratories in Val d'Or, Qu?(C)bec, Thunder Bay and Sudbury, Ontario or Vancouver, British Colombia or 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 Lake gold deposit is located between Val-d'Or and Chibougamau in the Abitibi region of Qu?(C)bec, Canada. The mineral resource defined by the previous operator comprises 2,762,000 tonnes at 8.42 g/t Au (748.000 ounces) in the indicated category and 3,512,000 tonnes at 7.62 g/t Au (860,000 ounces) in the inferred category (sourced from a technical report dated June 10, 2015 entitled "Preliminary Economic Assessment of the Windfall Lake Gold Property, Qu?(C)bec, Canada" with an effective date of April 28, 2015, prepared in accordance with NI 43-101). The Windfall Lake gold deposit is currently one of the highest grade resource-stage gold projects in Canada. The bulk of the mineralization occurs in the Main Zone, a southwest/northeast trending zone of stacked mineralized lenses, measuring approximately 600 metres wide and at least 1,400 metres long. The deposit is well defined from surface to a depth of 500 metres, and remains open along strike and at depth. Mineralization has been identified only 30 metres from surface in some areas and as deep as 870 metres in others, with significant potential to extend mineralization up and 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% in the high-grade Windfall Lake gold deposit located between Val-d'Or and Chibougamau in Qu?(C)bec and holds a 100% undivided interest in a large area of claims in the surrounding Urban Barry area and nearby Quevillon area (over 3,300 square kilometres), a 100% interest in the Marban project located in the heart of Qu?(C)bec's prolific Abitibi gold mining district, and properties in the Larder Lake Mining Division in northeast Ontario, including the Jonpol and Garrcon deposits on the Garrison property, the Buffonta past producing mine and the Gold Pike mine property. The Corporation also holds interests and options in a number of additional properties in northern Quebec and Ontario. Osisko continues to be well financed with approximately $190 million in cash and investments (based on figures available as of December 31, 2017).

Cautionary Note Regarding Forward-Looking Information

This news release contains "forward-looking information" within the meaning of the applicable Canadian securities legislation that is based on expectations, estimates, projections and interpretations as at the date of this news release. The information in this news release about the Windfall Lake gold deposit being one of the highest grade resource-stage gold projects in Canada; the current 800,000 metre drill program; the significance of new results from the ongoing drill program at the Windfall Lake gold project; the significance of assay results presented in this press release describing the analytical results from 31 intercepts in 22 holes and 3 wedges focused on infill and expansion drilling in the Lynx deposit; the high-grade core developing at Lynx 4; the type of drilling included in the drill program (definition, expansion and exploration drilling in and around the main Windfall Lake gold deposit and the adjacent Lynx deposit, and exploration drilling on the greater deposit and Urban-Barry project area); potential mineralization; the potential to extend mineralization up and down-plunge and at depth at the Windfall Lake gold deposit; the ability to realize upon any mineralization in a manner that is economic; the ability to complete any proposed exploration activities and the results of such activities, including the continuity or extension of any mineralization; and any other information herein that is not a historical fact may be "forward-looking information". Any statement that involves discussions with respect to predictions, expectations, interpretations, beliefs, plans, projections, objectives, assumptions, future events or performance (often but not always using phrases such as "expects", or "does not expect", "is expected", "interpreted", "management's view", "anticipates" or "does not anticipate", "plans", "budget", "scheduled", "forecasts", "estimates", "believes" or "intends" or variations of such words and phrases or stating that certain actions, events or results "may" or "could", "would", "might" or "will" be taken to occur or be achieved) are not statements of historical fact and may be forward-looking information and are intended to identify forward-looking information. This forward-looking information is based on reasonable assumptions and estimates of management of the Corporation. at the time it was made, involves known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of Osisko to be materially different from any future results, performance or achievements expressed or implied by such forward-looking information.
Such factors include, among others, risks relating to the ability of exploration activities (including drill results) to accurately predict mineralization; errors in management's geological modelling; the ability of Osisko to complete further exploration activities, including drilling; property interests in the Windfall Lake gold project; the ability of the Corporation to obtain required approvals and complete transactions on terms announced; the results of exploration activities; risks relating to mining activities; the global economic climate; metal prices; dilution; environmental risks; and community and non-governmental actions. Although the forward-looking information contained in this news release is based upon what management believes, or believed at the time, to be reasonable assumptions. Osisko cannot assure shareholders and prospective purchasers of securities of the Corporation that actual results will be consistent with such forward-looking information, as there may be other factors that cause results not to be as anticipated, estimated or intended, and neither Osisko nor any other person assumes responsibility for the accuracy and completeness of any such forward-looking information, Osisko does not undertake, and assumes no obligation, to update or revise any such forward-looking statements or forward-looking information contained herein to reflect new events or circumstances, except as may be required by law.