Osisko Intersects 12.5 g/t Au Over 8.5 Metres at Windfall

TORONTO, ONTARIO--(Marketwired - Jun 7, 2017) - Osisko Mining Inc. (TSX:OSK) ("Osisko" or the "Corporation") is pleased to announce new results from the ongoing drill program at its 100% owned Windfall Lake gold project located in Urban Township, Québec. The current 400,000 metre drill program combines definition drilling above the Red Dog intrusion ("Red Dog"), expansion drilling above and below Red Dog, expansion drilling to the NE of the main deposit, and exploration drilling on the greater deposit and Urban-Barry Project area. Significant new assay results from fifteen intercepts in eleven drill holes focused on infill and expansion drilling in the high-grade Lynx discovery and the main Windfall deposit are reported in the table below.

Highlights from the new results include: 12.5 g/t Au over 8.5 metres in DDH OSK-OBM-16-667 in the Underdog Corridor and 12.4 g/t Au over 5.0 metres in DDH OSK-W-17-805 in Lynx 2 and 15.9 g/t Au over 3.0 metres in DDH OSK-EAG-13-504 in a new extension of the Wolf Zone in the Caribou Corridor. Maps showing hole locations and full analytical results are available at www.osiskomining.com.

Notes:

1. True widths are estimated at 65 - 80% of the reported core length interval. See "Quality Control" below.
2. Definitions: FW = foot wall; HW = hanging wall and VNCR = crustiform vein.

Lynx Corridor

OSK-W-17-805 returned 12.4 g/t Au over 5.0 metres (including 17.7 g/t Au over 3.1 metres and 64.6 g/t Au over 0.5 metre). Mineralization is associated with 5 to 10% quartz-carbonate veins (locally crustiform) and consists of trace to 1% disseminated pyrite, trace to 1% pyrite within pyrite-tourmaline stringers, and trace to 1% pyrite associated with quartz-carbonate veins. Local visible gold was observed in quartz-carbonates veins with 5 to 20% pyrite (+/- tourmaline). The host rock is a sericitized and silicified rhyolite. The intersection represents the Lynx 2 Zone, extending it 130 metres below and 30 metres west of previously released OSK-W-16-761 (71.3 g/t Au over 2.3 metres).

OSK-W-17-816 returned 9.46 g/t Au over 2.0 metres (including 18.7 g/t Au over 1.0 metre). Mineralization consists of trace to 2% pyrite with disseminated tourmaline and occurs at a moderately sericitized contact between a small quartz porphyritic intrusive with a felsic volcanic unit. This interval extends the Lynx 1 HW Zone 75 metres northeast of OSK-W-17-837 (43.9 g/t Au over 3.4 metres previously released May 24, 2017).

OSK-W-17-827 returned 22.5 g/t Au over 2.1 metres (including 30.0 g/t Au over 1.5 metres) in the Lynx 3 Zone. Mineralization consists of trace to 3% pyrite disseminated within a fragmental felsic intrusive with local silica flooding.

OSK-W-17-837 returned 15.6 g/t Au over 2.9 metres. Mineralization consists of 2 to 5% disseminated to massive pyrite within 50% veins and veinlets (quartz-tourmaline and quartz-carbonate) which crosscut a strongly altered gabbro. This interval is located within the Lynx Corridor, 50 metres below OSK-W-17-799 (11.0 g/t Au over 6.5 metres previously released April 5, 2017).

OSK-W-17-839 returned 10.5 g/t Au over 2.1 metres (including 17.9 g/t Au over 0.9 metres). Mineralization consists of 8 to 10 % disseminated pyrite, 5% pyrite stringers and 1 to 2% ptygmatic quartz-tourmaline veins, located within the hanging wall of Lynx 1 Zone, 16 metres below OSK-W-17-825 (5.27 g/t Au over 2.7 metres previously released May 24, 2017).

Underdog Corridor

OSK-OBM-16-667 is an extension of previously drilled hole OBM-16-667, intersecting the FW3U Zone. The hole returned 12.5 g/t Au over 8.5 metres (including 37.4 g/t Au over 2.0 metres and 50.1 g/t Au over 1.2 metres). Mineralization consists of 3 to 7% pyrite stringers and 3 to 5% disseminated pyrite associated with rhyolite cut by crustiform veins and patches of silica flooding. Mineralization remains open in the hanging-wall of FW3U and is interpreted to represent new mineralization in the increasingly large FW3 corridor. This new intercept is located 120 metres southwest of OSK-W-16-704-W1 (15.5 g/t Au over 2.9 metres previously released October 25, 2017).

OSK-W-17-789-W2 returned two intersections in the FW1 Zone: 5.00 g/t Au over 2.3 metres and 4.79 g/t Au over 2.7 metres, infilling the zone 40 metres to the southeast of OSK-W-17-789 (16.4 g/t Au over 7.9 metres previously released April 11, 2017). The FW3 intersection returned 8.03 g/t Au over 3.0 metres, located 30 meters east of previously released OSK-W-17-789-W1 (14.6 g/t Au over 2.6 metres). Mineralization consists of trace to 10% pyrite-tourmaline stringers, 2 to 3% disseminated pyrite and occurs in felsic porphyry with large quartz eyes.

OSK-W-17-807-W2 intersected 4.29 g/t Au over 2.0 metres (including 8.20 g/t Au over 1.0 metre) between Zones FW3 and FW4. Mineralization consists of up to 10% pyrite-tourmaline stringers with 1% chalcopyrite hosted in an altered felsic intrusive dike. This intersection is located 40 metres west of OSK-W-16-311-W2 (5.21 g/t Au over 2.7 metres previously released November 8, 2017).

OSK-W-17-821 returned 5.25 g/t Au over 2.2 metres (including 15.4 g/t Au over 0.6 metres). Mineralization consists of 10 to 15% pyrite-tourmaline stringers or irregular clusters with a low core angle and a strong silicified halo. The host rock is a moderate to strongly altered fragmental porphyry dike.

OSK-W-17-826 returned two intersections: 3.79 g/t over 2.0 metres and 16.0 g/t Au over 2.4 metres (including 21.3 g/t Au over 1.8 metres). These mineralized intervals contain up to 5% disseminated pyrite and 5 to 10% pyrite in stringers and are hosted in a strongly bleached and sericitized andesite. The first intercept extends the FW0 Zone 40 metres to the northeast of OBM-16-614 (11.2 g/t Au over 3.4 metres previously released April 14, 2017). The second intercept is an extension of FW3 Zone.

Caribou Corridor

OSK-EAG-13-504 intersected the Wolf Zone returning 15.9 g/t over 3.0 metres (including 4.22 g/t Au over 2.1 metres). Mineralization comprises 10 to 15% pyrite-tourmaline stringers within a small quartz eye porphyritic intrusive. This intersection is located 25 metres northeast of OBM-15-559 (7.00 g/t Au over 10.0 metres, previously released January 14, 2017).

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 width determinations are estimated at 65 - 80% true core lengths. Assay are uncut except where indicated, and calculated intervals are reported over a minimum length of 2 metres using a lower cutoff of 3 g/t Au. All NQ core assays reported were obtained by either 1 kilogram whole rock metallic screen/fire assay or standard 50 gram fire-assaying with AA or gravimetric finish at ALS Laboratories in Val d'Or, Québec or Sudbury, Ontario. The 1 kilogram metallic screen assay method is selected by the geologist when samples contain coarse gold or present a higher percentage of pyrite than surrounding intervals. All 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 and interpretation of results is performed by qualified persons employing a Quality Assurance/Quality Control program consistent with NI 43-101 and industry best practices. Standards and blanks are included with every 20 samples for Quality Assurance/Quality Control purposes by the Corporation as well as the lab. Approximately 5% of sample pulps are sent to secondary laboratories for check assays.

About the Windfall Lake Gold Deposit

The Windfall Lake gold deposit is located between Val-d'Or and Chibougamau in the Abitibi region of Québec, Canada. The current mineral resource 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, Québec, 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 Québec and holds a 100% undivided interest in a large area of claims in the surrounding Urban Barry and Quévillon areas(over 3,300 square kilometres), a 100% interest in the Marban project located in the heart of Québec'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 Corporation also holds interests and options in a number of additional properties in northern Ontario and Québec. Osisko continues to be well financed with approximately $190 million in cash and investments.

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 400,000 metre drill program at Red Dog; 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; the type of drilling included in the drill program (definition drilling above Red Dog, expansion drilling above and below Red Dog, expansion drilling to the NE of the main 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.

Contact

John Burzynski
President and Chief Executive Officer
(416) 363-8653