Osisko Intersects 403 g/t Au Over 2.7 Metres at Lynx

TORONTO, ONTARIO--(Marketwired - April 5, 2018) - Osisko Mining Inc. (TSX:OSK) ("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 township, Eeyou Istchee James Bay, Québec. 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 16 intercepts in 5 drill holes and 5 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: 403 g/t Au over 2.7 metres in OSK-W-18-1412-W1; 151 g/t Au over 2.2 metres in OSK-W-18-1414-W2, 40.1 g/t Au over 2.0 metres in OSK-W-17-1363, and 36.3 g/t Au over 2.0 metres in OSK-W-18-1436. Maps showing hole locations and full analytical results are available at www.osiskomining.com.

Hole Number	From (m)	To (m)	Interval (m)	Au (g/t) uncut	Au (g/t) cut to 100 g/t	Zone	Corridor
OSK-W-17-1166-W3	661.0	664.8	3.8	6.38		Lynx	Lynx
including	663.5	664.8	1.3	14.3
	1341.0	1343.0	2.0	4.06		Lynx 6	Lynx
	1385.0	1387.0	2.0	6.26		Lynx 6	Lynx
including	1386.0	1386.3	0.3	41.3
OSK-W-17-1193	1659.8	1662.0	2.2	5.66		Vein	Lynx
including	1659.8	1660.6	0.8	15.5
	1682.0	1684.0	2.0	11.0		Vein	Lynx
including	1682.5	1683.1	0.6	33.6
OSK-W-17-1343-W1	560.8	563.9	3.1	3.32		Lynx HW	Lynx
OSK-W-17-1363	222.0	224.0	2.0	3.28		Lynx HW	Lynx
	470.5	472.5	2.0	40.1		VNCR	Lynx
including	470.5	471.5	1.0	79.9
OSK-W-17-1379	136.4	138.5	2.1	5.62		Lynx 1	Lynx
including	136.4	137.0	0.6	18.9
OSK-W-17-1413	534.6	537.0	2.4	5.77		Lynx 4	Lynx
	742.0	744.0	2.0	3.83		Lynx 4	Lynx
OSK-W-18-923-W1	876.2	878.2	2.0	3.39		Lynx 4	Lynx
OSK-W-18-1412-W1	720.0	722.7	2.7	403	50.9	Lynx 1	Lynx
including	721.7	722.7	1.0	1050	100
	731.0	733.0	2.0	10.4		Lynx 1	Lynx
including	731.9	733.0	1.1	17.9
OSK-W-18-1414-W2	934.5	936.7	2.2	151	83.5	Lynx 4	Lynx
including	934.5	935.0	0.5	369	100
including	935.8	936.7	0.9	117	100
OSK-W-18-1436	546.0	548.0	2.0	36.3		Lynx 2	Lynx
including	547.0	547.6	0.6	91.0

Notes:	True widths are estimated at 65 - 80% of the reported core length interval. See "Quality Control" below.
	Definitions: HW = Hanging Wall; VNCR = Crustiform Vein.

Hole Number	Azimuth (°)	Dip (°)	Length (m)	UTM E	UTM N	Section
OSK-W-17-1166-W3	132	-59	1551	453621	5435639	4050
OSK-W-17-1193	141	-59	1803	453806	5435726	4275
OSK-W-17-1343-W1	137	-56	870	453570	5435490	3950
OSK-W-17-1363	341	-72	513	453458	5435025	3625
OSK-W-17-1379	332	-66	540	452781	5434772	2900
OSK-W-17-1413	137	-53	996	453153	5435214	3450
OSK-W-18-923-W1	137	-56	962	453607	5435603	4025
OSK-W-18-1412-W1	133	-51	825	453684	5435676	4125
OSK-W-18-1414-W2	133	-58	1095	453654	5435648	4100
OSK-W-18-1436	139	-52	1128	453372	5435509	3775

President and CEO John Burzynski commented: "We continue to see good results from our drilling at Lynx and are looking forward to our initial mineral resource estimate which is on schedule for delivery in May. The Lynx Corridor was discovered by the Osisko team just a year ago and has been traced out over a length of almost two kilometres and remains open along strike. As we closed the database for the mineral resource calculation in mid-March, today's results will not be included but will add to the upside potential of the Lynx deposit as we head towards the feasibility study in early 2019."

OSK-W-17-1166-W3 intersected three intervals: 6.38 g/t Au over 3.8 metres in Lynx Corridor, 4.06 g/t Au over 2.0 metres and 6.26 g/t Au over 2.0 metres in Lynx 6. The first interval is composed of 2% pyrite clusters and 1% pyrite stringers in a strongly sericitized felsic fragmental intrusion. The second interval is composed of 3% pyrite clusters and one pyrite stringers within a strongly sericitized rhyolite. The last interval is composed of pyrite stringers and pyrite-silica flooding within a weak sericite altered felsic porphyritic dike.

OSK-W-17-1193 intersected two intervals in a shear zone, 200 metres south of Lynx 6 returned 5.66 g/t Au over 2.2 metres and 11.0 g/t Au over 2.0 metres. In the first interval, mineralization is composed of 3% disseminated pyrrhotite and the second interval is composed of 2% pyrite clusters and pyrrhotite traces. Small quartz veins are with the mineralization and hosted in a sheared, strongly sericitized andesite.

OSK-W-17-1343-W1 intersected 3.32 g/t Au over 3.1 metres in Lynx HW. Mineralization is composed of trace pyrite within moderate sericite altered gabbro.

OSK-W-17-1363 intersected two intervals: 3.28 g/t Au over 2.0 metres in the Lynx HW and 40.1 g/t Au over 2.0 metres in a crustiform vein. In the first interval, mineralization is composed of disseminated pyrite and pyrite stringers within a chloritized rhyolite. The second interval is composed of 7% pyrite stringers and pyrite-silica flooding within a strong chlorite, strong fuchsite and weak silica altered gabbro. The interval is 85 metres down plunge of OSK-W-17-1121 (8.62 g/t over 2.7 metres previously reported Octobre 12, 2017).

OSK-W-17-1379 intersected 5.62 g/t Au over 2.1 metres in Lynx 1. Mineralization is composed of up to 5% pyrite stringers within a strong sericite, chlorite and fuchsite altered felsic porphyritic dike.

OSK-W-17-1413 intersected two intervals in Lynx 4: 5.77 g/t Au over 2.4 metres and 3.83 g/t Au over 2.0 metres. In the first interval, mineralization is composed of 1% disseminated pyrite and 1% pyrite-silica flooding within a strongly silicified, large quartz eyes, felsic porphyritic intrusion. The interval is 100 metres south-west of OSK-W-17-827 (3.63 g/t over 3.0 metres previously reported July 12, 2017). The second interval is composed of disseminated pyrite within a strong chlorite and weak fuchsite altered andesite.

OSK-W-18-923-W1 intersected 3.39 g/t Au over 2.0 metres in Lynx 4. Mineralization is composed of 2% pyrite clusters, 1% pyrite stringers and 1% disseminated pyrite in quartz vein fracture filling. Mineralization is at a sericite and fuchsite altered contact between a gabbro and a rhyolite.

OSK-W-18-1412-W1 intersected two intervals: 403 g/t Au over 2.7 metres and 10.4 g/t Au over 2.0 metres in Lynx 1. The first interval is composed of up to 5% pyrite as stringers, clusters, and disseminated, 2% disseminated chalcopyrite and local visible gold within a moderate sericite, silica and fuchsite altered gabbro. The second interval is composed of up to 10% disseminated pyrite, up to 10% pyrite-tourmaline veins and 5% disseminated pyrite within a moderate silica, moderate sericite and weak fuchsite altered gabbro.

OSK-W-18-1414-W2 intersected 151 g/t Au over 2.2 metres in Lynx 4. Mineralization is composed of 1% pyrite-tourmaline veins, 1% pyrite clusters, up to 8% disseminated pyrite and local visible gold within a strong silica, sericite and fuchsite altered gabbro.

OSK-W-18-1436 intersected 36.3 g/t Au over 2.0 metres in Lynx 2. Mineralization is composed of up to 2% pyrite stringers and 2% ptygmatic quartz-tourmaline veins within strong silica and sericite altered gabbro.

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, Québec, 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 Québec, 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, 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 area and nearby Quevillon area (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 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.