Osisko Intersects 57.0 g/t Au Over 2.7 Metres At Lynx

Lynx Discovery Confirmed Over 1.7 Kilometre Strike Length

(Toronto, July 25, 2017)  Osisko Mining Inc. (OSK:TSX, “Osisko” or the “Corporation”) is pleased to provide new results and a geological update on the Lynx deposit 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 at Windfall combines definition drilling above the Red Dog intrusion (“Red Dog”), expansion drilling above and below Red Dog, and expansion/definition drilling in the adjacent Lynx deposit located immediately to the NE of Windfall.  Maps depicting Lynx and the new drill hole locations and full analytical results are available at www.osiskomining.com.

  • Lynx deposit discovery extended by drilling to currently over 1.7 kilometres length and remains open to NE and SE
  • Recently defined “Bank Fault” interpreted as key structure associated with intrusion-related gold mineralization at Windfall and Lynx, with potential regional extent
  • 12 drills currently active on Lynx, 12 additional drills continue to define Windfall Deposit

Twenty-four drills are active on the overall Windfall Project.  Twelve of those drills are currently focused on the principal Lynx deposit (Lynx HW, Lynx 1 and Lynx 2) and other subparallel Lynx zones (Lynx 3, 4, 5, and 6 and undesignated zones). Mineralization within individual zones of the Lynx deposit follow the same principal northeast oriented pathways along dike contacts as seen throughout the main Windfall deposit. One-hundred and sixty-five (165) holes have been completed in the Lynx deposit to date:  complete assays have been received and released from 42 holes; partial assays have been received and released from an additional 41 holes; 82 holes are awaiting analysis.

Significant new assays from twenty-four intercepts in nineteen drill holes focused on infill and expansion drilling in the Lynx deposit are reported in the table below.  Highlights from the new results include: 159 g/t Au over 2.7 metres, including 1.06 kilograms/tonne over 0.4 metres (17.0 g/t Au over 2.7 metres cut) from DDH OSK-W-17-857; 57.0 g/t Au over 2.7 (50.1 g/t Au over 2.7 metres cut) in DDH OSK-W-17-827; 57.8 g/t Au over 2.3 metres from DDH OSK-W-17-877; and 52.8 g/t Au over 2.3 metres from DDH OSK-W-17-879.

President and Chief Executive Officer John Burzynski noted:  “Our exploration team has been working particularly hard over the past number of months absorbing the huge amount of new data from our large-scale drilling program, and with the new work on the Lynx discovery we are starting to see the emergence of a whole new high-grade deposit within our high-grade Windfall project.  Windfall and Lynx are intrusive-related gold deposits with a proximal relationship to the Bank Fault.  Although we are drilling towards a new resource estimate for Windfall by the end of this year, we believe the potential for expanding Windfall, Lynx and making new discoveries within the main deposit area is still completely wide-open.”

Hole Number From
(m)
To
(m)
Interval (m) Au (g/t) uncut Au (g/t)
cut to 100 g/t
Zone
OSK-W-17-827 664.3 667.0 2.7 57.0 50.1 Lynx 4
including 666.0 667.0 1.0 119 100
OSK-W-17-843 450.4 452.8 2.4 5.93   VNCR
including 450.4 451.1 0.7 19.0  
OSK-W-17-845 316.2 318.2 2.0 10.7   Lynx 1
including 316.7 317.5 0.8 26.3  
OSK-W-17-857 361.5 364.2 2.7 159 17.0 VNCR
including 363.8 364.2 0.4 1060 100
OSK-W-17-870 230.9 233.7 2.8 18.9   Lynx 1
including 230.9 231.6 0.7 69.0  
OSK-W-17-873 327.0 329.5 2.5 4.29   VNCR
including 328.0 328.6 0.6 12.4  
OSK-W-17-875 851.0 853.0 2.0 13.7   Vein
including 852.0 853.0 1.0 27.3  
OSK-W-17-877 308.0 310.3 2.3 57.8   VNCR
OSK-W-17-878 234.2 236.4 2.2 14.6   VNCR
including 235.8 236.4 0.6 51.5  
  364.0 366.0 2.0 16.8   VNCR
including 364.3 365.3 1.0 33.2  
OSK-W-17-879 108.1 110.4 2.3 52.8   Lynx 2
including 108.6 109.4 0.8 96.2  
  115.8 117.8 2.0 14.5   Lynx 2
including 115.8 116.8 1.0 28.3  
OSK-W-17-881 732.7 734.8 2.1 4.70   VNCR
including 733.3 733.9 0.6 14.2  
OSK-W-17-883 254.0 256.0 2.0 12.4   Lynx 1 + Lynx 2
including 254.9 255.4 0.5 36.8  
  259.0 261.0 2.0 7.52   Lynx 1 + Lynx 2
including 259.7 260.0 0.3 44.4  
  274.5 276.5 2.0 18.6   Lynx 2
including 275.5 276.5 1.0 32.5  
OSK-W-17-887 492.0 494.6 2.6 24.3   VNCR
including 492.9 493.5 0.6 91.6  
OSK-W-17-888 238.3 240.0 1.7 23.7   Lynx 2
including 238.3 238.8 0.5 65.3  
OSK-W-17-895 221.0 225.0 4.0 9.81   Lynx 2
including 221.0 222.0 1.0 34.7  
OSK-W-17-898 411.0 413.5 2.5 12.2   Lynx 2
  449.7 452.0 2.3 17.3   Lynx 1
OSK-W-17-906 279.0 280.0 1.0 8.37   Lynx 2 FW
OSK-W-17-916 108.0 111.5 3.5 14.3   Lynx HW
including 108.0 108.5 0.5 75.1  
OSK-W-17-924 278.4 280.7 2.3 12.5   Lynx 2
including 280.0 280.7 0.7 35.0  

OSK-W-17-827 returned 57.0 g/t Au over 2.7 metres including 119 g/t Au over 1.0 metre (50.1 g/t Au over 2.7 metres cut).  Mineralization consists of 5% pyrite stringers and trace to 10% disseminated pyrite at a felsic porphyritic intrusion/felsic volcanic contact. Corresponds to Lynx 4, 335 metres southwest of previously reported OSK-W-17-816 which returned 11.7 g/t Au over 7.7 metres.

OSK-W-17-843 intersected 5.93 g/t Au over 2.4 metres, including 19 g/t Au over 0.7 metres. Mineralization comprises 60% crustiform veins and trace disseminated pyrite within an intermediate volcanic unit with strong chlorite, weak carbonate alteration. Corresponds to Lynx 3.

OSK-W-17-845 intersected 10.7 g/t Au over 2.0 metres, including 26.3 g/t Au over 0.8 metres. Mineralization consists of traces to 3% of disseminated pyrite, trace to 1% pyrite stringers and 5 to 8% quartz veins containing pyrite and sphalerite within an intensely silicified rhyolite. Corresponds to Lynx 1, 25 metres northeast of OSK-W-17-839 which returned 6.6 g/t Au over 8.3 metres (previously released, July, 12th, 2017).

OSK-W-17-857 returned 159 g/t Au over 2.7 metres, including 1060 g/t Au over 0.4 metres, (17.0 g/t Au over 2.7 metres cut). Up to 1% visible gold occurs in a massive crustiform vein cross cut and overprinted by secondary quartz veins and pyrite – tourmaline stringers. The host rock has strong silica flooding with fuchsite infilling fractures, and locally very weak sericite and chlorite alteration infilling fractures. Corresponds to the Lynx 2, 25 metres northeast of previously reported OSK-W-17-800 which returned 35.2 g/t Au over 2.8 metres (see April 25, 2017 press release).

OSK-W-17-870 returned 18.9 g/t Au over 2.8 metres, including 69 g/t Au over 0.7 metres. Mineralization consists of trace to 5% pyrite stringers hosted in fragmental felsic intrusion. Corresponds to Lynx 1, 35 metres northwest of OSK-W-17-873 which returned 10.7 g/t Au over 4.9 metres (previously released, July, 12, 2017).

OSK-W-17-873 intersected 4.29 g/t Au over 2.5 metres, including 12.4 g/t Au over 0.6 metres within a crustiform vein system, with 3% pyrite and tourmaline infilling.

OSK-W-17-875 intersected 13.7 g/t Au over 2.0 metres, including 27.3 g/t Au over 1.0 metres. Mineralization comprises traces to 1% of disseminated pyrite and trace pyrite-tourmaline stringers within a felsic volcanic unit with strong chlorite, sericite and silica flooding, located between Lynx 4 and Lynx 5.

OSK-W-17-877 intersected 57.8 g/t Au over 2.3 metres. Crustiform veins with 2 to 3% pyrite stringers in a bleached gabbro unit. Corresponds to Lynx 2, 55 metres southwest of OSK-W-17-779 which returned 21.6 g/t Au over 7.9 metres (previously released March 28, 2017).

OSK-W-17-878 intersected two mineralized zones: 14.6 g/t A over 2.2 metres, including 51.5 g/t Au over 0.6 metres within the Lynx HW Zone and 16.8 g/t Au over 2.0 metres, including 33.2 g/t Au over 1.0 metres within Lynx 3.  Lynx HW mineralization comprises brecciated crustiform veins, 1 to 2% disseminated pyrite and 3% pyrite stringers in an andesite with strong sericite and chlorite alteration. Lynx 3 consists of crustiform veins hosted in gabbro with silica, carbonate, chlorite and fuchsite alteration, with 1 to 5% disseminated pyrite and trace to 2% pyrite stringers.  Lynx 3 intercept is 25 metres northeast of OSK-W-17-859 which returned 73.5 g/t Au over 2.2 metres (previously released July 12, 2017).

OSK-W-17-879 returned two intersections:  52.8 g/t Au over 2.3 metres, including 96.2 g/t Au over 0.8 metres and 14.5 g/t Au over 2.0 metres, including 28.3 g/t Au over 1.0 metres. Mineralization consists of trace to 5% disseminated pyrite and local semi-massive sulphides hosted in a silicified and sericitized fragmental felsic intrusion.  Correlates with Lynx 2 close to surface, 50 metres northeast of OSK-W-16-761 which returned 19.4 g/t Au over 2.0 metres and 71.3 g/t Au over 2.3 metres (previously released, February 15, 2017).

OSK-W-17-881 intersected 4.70 g/t Au over 2.1 metres, including 14.2 g/t Au over 0.6 metres within Lynx 4, mineralization consists of 3% pyrite-tourmaline stringers, 1 to 2% quartz-tourmaline veins, 5 to 10% disseminated and clustered pyrite, and 10% quartz veins hosted in a gabbroic unit with fuchsite, chlorite and silica alteration.

OSK-W-17-883 returned four intersections: 12.4 g/t Au over 2.0 metres, including 36.8 g/t Au over 0.5 metres and 7.52 g/t Au over 2.0 metres, including 44.4 g/t Au over 0.3 metres between Lynx 1 and Lynx 2; 18.6 g/t Au over 2.0 metres, including 32.5 g/t Au over 1.0 metres for Lynx 2 and 3.07 g/t Au over 2.2 metres, including 5.90 g/t Au over 1.1 metres for Lynx 3.  Lynx 1 mineralization consists of 7 to 10% pyrite within a highly pervasive silica-flooding horizon hosted within a fragmental felsic intrusion and 1% of quartz-tourmaline veins. Lynx 2 mineralization is within a strongly pervasive silicified horizon with minor fuchsite at the contact of a rhyolite and a large quartz eye porphyritic felsic intrusion containing up to 10% of disseminated pyrite, stringers and ptygmatic tourmaline stringers and minor veins.  Local visible gold occurs within the pervasive silica alteration. Lynx 3 consists of a crustiform vein with 5 to 8% disseminated pyrite, brecciated by pyrite-tourmaline stringers. Lynx 2 intersection is 30 metres southwest of OSK-W-17-878 (5.32 g/t Au over 15.7 metres, released July 12, 2017). Lynx 3, 22 metres southwest of OSK-W-17-878 (16.8 g/t Au over 2.0 meters (this press release).

OSK-W-17-887 returned 24.3 g/t Au over 2.6 metres, including 91.6 g/t Au over 0.6 metres. Mineralization consists of two main crustiform veins, 1 to 2% disseminated pyrite cross-cut by 5 to 6% pyrite stringers and local visible gold. The second crustiform vein contains 5 to 6% pyrite stringers and 1 to 2% disseminated sphalerite hosted in a gabbro.

OSK-W-17-888 intersected 23.7 g/t Au over 1.7 metres, including 65.3 g/t Au over 0.3 metres, consists of a large pervasive silica-flooded interval with fuchsite, up to 5% disseminated pyrite and 5% disseminated sphalerite. Local visible gold occurs along fractures concentrated in the pervasive silica intervals. Correlates with Lynx 2 thirty metres southwest of OSK-W-17-895 which returned 9.81 g/t Au over 4.0 metres (this press release).

OSK-W-17-895 returned 9.81 g/t Au over 4.0 metres, including 34.7 g/t Au over 1.0 metres. Mineralization consists of up to 8% disseminated pyrite and patches of semi-massive sulphides in a silicified and sericitized fragmental felsic intrusion.  Correlates with Lynx 2, 30 metres southwest of OSK-W-17-888 which returned 23.7 g/t Au over 1.7 metres (this press release).

OSK-W-17-898 returned two intersections 12.2 g/t Au over 2.5 metres and 17.3 g/t Au over 2.3 metres. Mineralization for the first consists of 10% pyrite-quartz-tourmaline veins, 5% disseminated pyrite-tourmaline clusters and 2% pyrite in ptygmatic tourmaline veins in a fragmental felsic intrusion. Extends Lynx 2, 85 metres down plunge from OSK-W-17-812 (18.6 g/t Au over 4.1 metres, previously released April 25, 2017). The second interval is at the contact of a gabbro and a quartz-eye felsic intrusion containing 5% pyrite in a quartz-tourmaline vein, 7% pyrite-tourmaline stringers and 3% disseminated pyrite. Extends Lynx 1, 75 metres down plunge from OSK-W-17-799 (10.6 g/t Au over 1.9 metres, previously released April 5, 2017).

OSK-W-17-906 returned 8.37 g/t Au over 1.0 metre. Mineralization consists of trace to 2% disseminated pyrite hosted in a weak sericitized and strong silicified felsic volcanic unit.

OSK-W-17-916 intersected 14.3 g/t Au over 3.5 metres, including 75.1 g/t Au over 0.5 metres. Mineralization includes 3% pyrite-tourmaline stringers, 2 to 3% disseminated pyrite with pervasive silica flooding and 1% crustiform veins hosted within moderate to strong silicified rhyolite. Corresponds to Lynx HW, 25 metres southeast of OSK-W-17-846 (previously reported 113 g/t Au over 2.0 metres, July 12, 2017).

OSK-W-17-924 returned 12.5 g/t Au over 2.3 metres, including 35.0 g/t Au over 0.7 metres. Pervasive silica flooding containing up to 3% pyrite stringers and 2% pyrite-tourmaline stringers hosted in a sericitized and silicified rhyolite.  Corresponds with Lynx 2, 20 metres north of OSK-W-17-834 (16.6 g/t Au over 2.4 metres, previously released, May 24, 2017).

Lynx Deposit Corridor Extended

The mineralized corridor hosting the Lynx deposit is represented by a silica-sericite alteration envelope following felsic porphyritic dikes hosted by volcanic rocks, and is further constrained between a gabbro, a brecciated felsic intrusion, and the Bank Fault which is believed to be regionally significant. The greatest abundance of visible gold observed to date in the Windfall area appears to be contained in the Lynx deposit and associated corridor. Gold mineralization follows very continuous zones of silicification that are surrounded by an outer and larger sericite envelope, accompanied by pyrite-tourmaline mineralization and hydrothermal breccias. Most drill intercepts to date range from 2 to 9 metres (core length) and reach up to 17.3 metres (core length); OSK-W-17-788, see April 5, 2017 press release).  

Lynx begins near-surface, is sub-vertical, plunging 35 degrees to the northeast, and in drilling to date has been intersected 700 meters vertically below surface. The strike length of the Lynx discovery has been confirmed between sections 3050E and 4750E, extending the favourable geology 1.7 kilometers horizontally, and 1.8 kilometres in true length taking the plunge of the deposit into account.  The deposit remains open to the northeast, and in potential parallel zones down-dip along the Bank Fault.  Assays from holes up to section 3825E have been received and released. To date, step-out drilling has intersected geology, alteration and mineralization characteristic of the Lynx deposit to section 4750E, with 15 holes drilled between sections 3825E and 4750E, all with pending analytical results.  Additional holes are planned to continue exploring the deposit which remains open in this direction.

Lynx 3, 4, 5, 6, and other new zones (undesignated at present) are subparallel mineralized zones to the main Lynx deposit (i.e. Lynx 1 + Lynx 2).  Porphyritic felsic dikes hosted by volcanic rocks and associated silica-sericite alteration envelopes define these zones. Lynx 6 and other undesignated new zones are currently defined by geology, alteration and mineralization, with analytical results pending.  Gold mineralization is associated with corridors of silicification with pyrite-tourmaline-sericite alteration mineralogy. Drill intercepts range from 2 to 5 meters width (core length) up to 7.7 metres width (core length).  To date, Lynx 3, 4, 5, 6, and the undesignated new zones extend up to 175 metres length between sections 3350E and 3825E.  The subparallel Lynx zones start within 100 metres of surface (Lynx 3) and to date have been traced to 800 metres below surface (Lynx 5).  All zones remain open towards the southwest and the northeast.

A one to two metre thick corridor of quartz-carbonate crustiform veins with local visible gold is hosted within gabbro immediately below Lynx 1 / Lynx 2 and follows the same orientation. This zone has been followed up to 200 metres along strike and remains open to the NE.

The previously announced step-out hole (the “1400 metre” step-out, see February 3, 2017 press release, and subsequent “2200” metre step-out hole, which respectively correspond to deposit grid lines 4400E and 5200E) helped build the understanding of the geology the Windfall gold system.  Further step-out holes along the NE corridor are planned while drilling at the Lynx deposit continues to infill the known zones and to test the continuity and extent of the Lynx deposit towards the northeast.


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 dOr, Québec or Sudbury, Ontario, or Bureau Veritas in Timmins, Ontario, using the same protocols. 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. 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 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-dOr 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-dOr and Chibougamau in Québec and holds a 100% undivided interest in a large area of claims in the surrounding Urban Barry area (82,400 hectares), a 100% interest in the Marban project located in the heart of Québecs 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 Ontario.  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, including the potential extension of the Lynx deposit corridor; the significance of assay results presented in this news release; the type of drilling included in the drill program (definition drilling above Red Dog, expansion drilling above and below Red Dog, and expansion/definition drilling in the adjacent Lynx deposit located immediately to the northeast of Windfall); the extension of the Lynx deposit by drilling to currently over 1.6 kilometres in length; the significance, if any, of the recently defined “Bank Fault”; the number of drills active on the Lynx discovery and Windfall deposit; the potential emergence of a new high-grade deposit within the Windfall project; potential mineralization, including Windfall and Lynx being intrusive-related gold deposits with a proximal relationship to the “Bank Fault”; the timing and ability, if at all, to prepare a new resource estimate for Windfall by the end of 2017; the prospectivity of the main deposit area; the regional significance, if any, of the “Bank Fault”; the significance, if any, of the visible gold observed to date in the Windfall (including Lynx) area; the continuity of 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”, “managements 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 managements 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.

For further information please contact:
John Burzynski, President and Chief Executive Officer
Telephone: (416) 363-8653

Osisko Intersects 24.9 g/t Au Over 31 Metres At Windfall

Wide Zone of High Grade Mineralization Intercepted in Deep Underdog Zone

(Toronto, July 19, 2017)  Osisko Mining Inc. (OSK:TSX, “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, and expansion/definition drilling in the Lynx deposit located immediately to the NE of Windfall.  Significant new assays from twenty-eight intercepts in thirteen drill holes focused on infill and expansion drilling in the Underdog Zone of the Windfall deposit are reported in the table below.

Highlights from the new results include: 24.9 g/t Au over 31.0 metres (16.4 g/t Au over 31.0 metres cut) and 5.3 g/t Au over 22.0 metres from DDH OSK-W-17-821-W1; 56.9 g/t Au over 2.8 metres (35.5 g/t Au over 2.8 metres cut) in DDH OSK-W-17-844; and 21.6 g/t Au over 3.2 metres from DDH OSK-W-17-820-W1. Maps with 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
OSK-OBM-16-609 635.0 637.0 2.0 3.07   FW3U HW
OSK-W-17-789-W1 1119.8 1122.0 2.2 16.4   Z14-2
Including 1120.4 1121.2 0.8 44.1  
OSK-W-17-789-W2 801.0 803.0 2.0 13.2    New
  1152.1 1155.2 3.1 25.6   Z14-2
Including 1152.1 1152.7 0.6 44.0  
Including 1154.5 1155.2 0.7 67.9  
  1163.0 1165.7 2.7 5.62   Z14-2
OSK-W-17-820 976.3 982.6 6.3 5.79   FW0 FW
Including 982.1 982.6 0.5 28.7  
OSK-W-17-820-W1 876.1 881.3 5.2 3.25   FW0
  981.8 985.0 3.2 21.6   FW0 FW
Including 981.8 983.4 1.6 40.4  
OSK-W-17-821-W1 865.0 867.0 2.0 7.31   FW0 HW
Including 865.7 866.0 0.3 44.3  
  1110.0 1141.0 31.0 24.9 16.4 FW1
  1144.0 1150.0 6.0 10.5   FW1
  1158.0 1180.0 22.0 5.33   FW1
Including 1175.6 1176.3 0.7 29.3  
Including 1178.0 1179.0 1.0 19.5  
  1192.0 1194.0 2.0 3.35   FW1
  1202.8 1207.0 4.2 5.65   FW1 FW
Including 1202.8 1203.1 0.3 48.0  
  1219.4 1223.0 3.6 15.4    New
Including 1222.2 1223.0 0.8 40.8  
  1278.0 1285.0 7.0 3.84    New
Including 1278.0 1279.0 1.0 9.58  
Including 1284.0 1285.0 1.0 9.62  
OSK-W-17-826 1204.0 1206.2 2.2 9.26   Z14-2
Including 1205.6 1206.2 0.6 24.7  
  1246.8 1250.0 3.2 4.61   Z14 HW
  1298.0 1300.2 2.2 4.67   Z14
  1308.3 1310.6 2.3 3.37   Z14 FW
Including 1309.0 1309.6 0.6 12.4  
OSK-W-17-830 670.5 673.5 3.0 3.59   FW3U HW
OSK-W-17-833 1086.0 1088.5 2.5 8.94   Z14
  1125.0 1127.4 2.4 8.97   Z14 FW
Including 1125.0 1126.1 1.1 17.1  
OSK-W-17-833-W1 853.7 857.7 4.0 11.8   FW1 HW
  862.0 864 2.0 5.79    New
OSK-W-17-842 923.7 925.8 2.1 4.01   FW1
OSK-W-17-844 954.8 957.6 2.8 56.9 35.5 FW3
including 957.1 957.6 0.5 220 100
OSK-W-17-854-W1 800.5 803.3 2.8 4.65   FW3U

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.
Hole Number Azimuth (°) Dip (°) Length (m) UTM E UTM N Section

OSK-OBM-16-609

331 -49 738 452459 5434642 2550

OSK-W-17-789-W1

333 -59 1199 452546 5434390 2525

OSK-W-17-789-W2

333 -59 1196 452546 5434388 2525

OSK-W-17-820

332 -66 1106 452669 5434484 2675

OSK-W-17-820-W1

332 -66 1358 452669 5434484 2675

OSK-W-17-821-W1

334 -66 1416 452738 5434475 2725

OSK-W-17-826

330 -67 1335 452799 5434556 2825

OSK-W-17-830

329 -55 819 452487 5434622 2575

OSK-W-17-833

330 -58 1149 452597 5434395 2550

OSK-W-17-833-W1

330 -58 1173 452597 5434395 2550

OSK-W-17-842

330 -60 948 452509 5434390 2475

OSK-W-17-844

333 -57 1092 452727 5434546 2750

OSK-W-17-854-W1

330 -53 844 452483 5434596 2550

 

OSK-OBM-16-609 returned 3.07 g/t Au over 2.0 metres. Mineralization consists of 1 to 10% disseminated pyrite, 1 to 10% pyrite tourmaline stringers and local semi-massive (5 to 15 cm) pyritic bands. The host unit is highly foliated and altered (sericite and bleached). This interval is within the FW3 Zone.

OSK-W-17-789-W1 intercepted 16.4 g/t Au over 2.2 metres (including 44.1 g/t Au over 0.8 metres). Mineralization contains 3% of disseminated pyrite, 10% of pyrite-tourmaline stringers (locally semi-massive) with local visible gold. The host rock is a silica altered fragmental felsic intrusion with small quartz eyes and a tourmaline pegmatitic vein (1.2 cm diameter). This intersect corresponds to the footwall of the FW3 Zone and is located 60 metres above OSK-W-17-789-W2 (25.6 g/t Au over 3.1 metres, this press release).

OSK-W-17-789-W2 intersected three zones of mineralization. The first returned 13.2 g/t Au over 2.0 metres hosted in felsic intrusion with small quartz eyes, 2% disseminated pyrite, 1% pyrite-tourmaline stringers and 4% pyrite-chlorite stringers. The second interval returned 25.6 g/t Au over 3.1 metres (including 44.0 g/t Au over 0.6 metres and 67.9 g/t Au over 0.7 metres) within the FW3U FW Zone. Mineralization contains up to 15% pyrite-tourmaline stringers and local visible gold associated with the outer limits of the stringers in a smokey quartz vein. The host rock consists of large quartz eye fragmental porphyritic dikes with silica and sericite. The third zone returned 5.62 g/t Au over 2.7 metres within the FW3 FW Zone. Mineralization includes 2% pyrite-stringers 2% disseminated pyrite at a silica, chlorite and sericite altered contact between a fragmental intrusion and a fragmental porphyritic intrusion, situated in the footwall of the FW3 Zone and located 60 metres below OSK-W-17-789-W1 (16.4 g/t Au over 2.2 metres, this press release).

OSK-W-17-820 returned 5.79 g/t Au over 6.3 metres (including 28.7 g/t Au over 0.5 metres) within the FW0 FW Zone between FW0 and FW1. Mineralization consists of 2% pyrite-tourmaline stringers with local visible gold, 2 to 3% disseminated and clusters of pyrite (up to 20% locally). The host rocks consists of fragmental porphyritic dikes with silica and sericite alteration. These intercepts are located 80 metres southwest of OSK-W-17-821 (5.25 g/t Au over 2.2 metres, previously released June 7, 2017), 50 metres south of OSK-W-17-820-W1 (21.6 g/t Au over 3.2 metres, this press release) and 75 metres north of OSK-W-16-754 (4.94 g/t Au over 3.0 metres, previously released January 23, 2017).

OSK-W-17-820-W1 returned two intersections: 3.25 g/t Au over 5.2 metres and 21.6 g/t Au over 3.2 metres (including 40.4 g/t Au over 1.6 metres). Mineralization consists of 5% pyrite stringers (1-10mm), up to 10% of disseminated pyrite, 1% chalcopyrite in 1 mm veinlets, with disseminated tourmaline and presence of gray quartz veinlets. The host rock is a small quartz eyes fragmental felsic intrusion strongly altered in sericite and silica. The interval is within the footwall of FW0 area, between FW0 and FW1, infills the FW0 Zone 50 metres northeast of OBM-15-564 (7.49 g/t Au over 7.0 metres, previously released February 29, 2016).

OSK-W-17-821-W1 intercepted multiple mineralized intervals. The first returned 7.31 g/t Au over 2.0 metres (including 44.3 g/t Au over 0.3 metres) within the hanging wall of the FW0 Zone. Mineralization consists of pyrite stringers and local visible gold. The host rock is a weakly bleached porphyritic felsic volcanic unit. Six mineralized intercepts over a 100 metre section of the FW1 Zone returned: 24.9 g/t Au over 31 metres (including 145 g/t Au over 1.0 metre and 319 g/t Au over 1.0 metre), 10.5 g/t Au over 6.0 metres, 5.33 g/t Au over 22.0 metres (including 29.3 g/t over 0.7 metre and 19.5 g/t Au over 1.0 metre), 3.35 g/t Au over 2.0 metres, 5.65 g/t Au over 4.2 metres and 15.4 g/t Au over 3.6 metres (including 40.8 g/t Au over 0.8 metres). The mineralization occurs as traces to 5% pyrite-tourmaline stringers with local trace chalcopyrite, and traces to 15% of pyrite-tourmaline stringers. The pyrite-tourmaline stringers show strong silicified halos hosted in large quartz eye porphyritic intrusion with sericite alteration. The last interval returned 3.84 g/t Au over 7.0 metres and consists of 2-3% pyrite-tourmaline stringers with strong silicified halos hosted in a large quartz eye porphyry dike.
 
OSK-W-17-826 returned four intersections: 9.26 g/t Au over 2.2 metres (including 24.7 g/t Au over 0.6 metres), 4.61 g/t Au over 3.2 metres, 4.67 g/t Au over 2.2 metres, 3.37 g/t Au over 2.3 metres (including 12.4 g/t Au over 0.6 metres). Mineralization consists of trace to 3% pyrite stringers and local visible gold, up to 50% semi-massive pyrite, 1% disseminated pyrite and trace to 1% chalcopyrite. The host rock is a fragmental felsic intrusion strongly altered with sericite, silica and chlorite. The intercept is located within the FW3 Zone, approximately 45 metres northeast of OSK-W-17-780 (34.1 g/t Au over 4.0 metres and 9.38 g/t Au over 4.0 metres, previously released April 6, 2017).

OSK-W-17-830 returned 3.59 g/t Au over 3.0 metres. Mineralization contains traces of pyrite stringers and disseminated pyrite in felsic porphyritic dykes with trace to abundant large quartz eyes, located in the FW3U HW Zone.

OSK-W-17-833 returned two intersections: 8.94 g/t Au over 2.5 metres and 8.97 Au over 2.4 metres (including 17.1 g/t Au over 1.1 metres) within the FW3 Zone. Mineralization consists of 15 to 20% of semi-massive pyrite within a quartz-tourmaline vein with local visible gold, 5 to 7% pyrite stringers. The host rock is a small quartz eye porphyritic fragmental felsic intrusion with strong silica and weakly to moderate sericite.

OSK-W-17-833-W1 returned two intersections: 11.8 g/t Au over 4.0 metres and 5.79 Au over 2.0 metres within a fragmental felsic porphyry dike. Mineralization is composed of 3% pyrite stringers and trace of chalcopyrite and strong silica alteration. These intercepts extend the FW1 Zone 60 metres below previously reported EAG-12-320 (6.00 g/t Au over 13.3 metres).

OSK-W-17-842 returned 4.01 g/t Au over 2.1 metres. Mineralization consists of 2% pyrite stringers and disseminated pyrite located at the altered contact (sericite, chlorite and bleached) between the highly porphyritic felsic intrusion and the fragmental intrusion. This interval is within the FW1 Zone.

OSK-W-17-844 intersected 56.9 g/t Au over 2.8 metres (including 220 g/t Au over 0.5 metres). Mineralization consists of 5% pyrite stringers with trace chalcopyrite and local visible gold, 5% disseminated pyrite, hosted in an intensely silicified intermediate volcanic unit. This interval is within the FW3 Zone.

OSK-W-17-854-W1 returned 4.65 g/t Au over 2.8 metres in a bleached and carbonate altered gabbro. Mineralization comprises 5 to 10% disseminated pyrite and 1% pyrite stringers, and two crustiform veins with 5% pyrite.

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 dOr, 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-dOr 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-dOr and Chibougamau in Québec and holds a 100% undivided interest in a large area of claims in the surrounding Urban Barry area (82,400 hectares), a 100% interest in the Marban project located in the heart of Québecs 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 Ontario.  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”, “managements 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 managements 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.

For further information please contact:
John Burzynski, President and Chief Executive Officer
Telephone: (416) 363-8653