Osisko Intersects 4.96 g/t Au Over 13.5 Metres At Garrison

(Toronto, October 31, 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 Garrison gold project located in Garrison Township, Ontario.  Over 70,000 metres of new drilling have been conducted by Osisko on the Garrison Project to date.  A total of twenty-four new intercepts in eighteen holes are reported in this release, with significant assay results presented in the table below.

Significant new results include:  4.96 g/t Au over 13.5 metres in OSK-G17-414; 2.01 g/t Au over 21.5 metres and 3.10 g/t Au over 17.0 metres in OSK-G17-395; 3.60 g/t Au over 9.0 metres and 4.45 g/t Au over 5.5 metres in OSK-G17-423; 6.12 g/t Au over 6.0 metres and 10.6 g/t Au over 3.5 metres in OSK-G17-438; 2.13 g/t Au over 17.0 metres in OSK-G17-380; 8.14 g/t Au over 2.7 metres in OSK-G17-426; 7.69 g/t Au over 4.5 metres in OSK-G17-427; 1.34 g/t Au over 22.2 metres in OSK-G17-388; 1.24 g/t Au over 20.9 metres in OSK-G17-391.

The new results continue to confirm the extent of known mineralization in the Garrcon zone. The 2017 drill program is exploring the extensions of the mineralized zones within the Garrcon, Jonpol and 903 zones.  Maps and sections showing hole locations and complete drilling results are available at www.osiskomining.com.

Notes:  True Widths are estimated at 65 – 80% of the reported core length interval.  See “Quality Control” below.

OSK-G17-388, 391, 395, 401, 403, 405, 407, 409 were drilled as part of a program to test the extension of a mineralized zone bulk sampled in prior work.  During a bulk sample program conducted in 2014 – 2015 by the previous property operator, testing focused on a N-NE trending mineralized corridor marked by zones of quartz-iron carbonate breccias. The mineralized corridor was found to dip shallowly to the east. New drilling involved a series of shallow west oriented holes designed to intersect the mineralized corridor at high angles to its strike.

The new results include:

•  1.34 g/t Au over 22.2 metres in OSK-G17-388
•  1.24 g/t Au over 20.9 metres in OSK-G17-391
•  2.01 g/t Au over 21.5 metres and
•  3.10 g/t Au over 17.0 metres in OSK-G17-395
•  1.16 g/t Au over 19.8 metres in OSK-G17-401
•  1.50 g/t Au over 15.0 metres in OSK-G17-403
•  4.28 g/t Au over   6.9 metres in OSK-G17-405
•  1.57 g/t Au over   8.9 metres in OSK-G17-409

Previous reported holes (see August 22, 2017 press release) from this program included OSK-G17-386 (1.20 g/t Au over 33.8 metres), OSK-G17-393 (1.12 g/t Au over 59.3 metres) and OSK-G17-398 (1.13 g/t Au over 22.8 metres).

OSK-G17-410, 414, 419, 423, 426 were designed to test the mineralized zone dipping below the Garrcon east bulk sample pit. The east bulk sample pit tested in 2014 – 2015 showed a parallel zone to the west bulk sample pit trending N-NE and comprised mainly of multiple parallel 1-10 cm quartz-iron carbonate veins hosted within metasediment. Similar to the west bulk sample pit, the mineralized corridor has a shallow east dip.

The new results include:

•  1.16 g/t Au over   8.8 metres in OSK-G17-410
•  4.96 g/t Au over 13.5 metres in OSK-G17-414
•  1.44 g/t Au over 10.0 metres and
•  4.63 g/t Au over   3.5 metres in OSK-G17-419
•  3.60 g/t Au over   9.0 metres and
•  4.45 g/t Au over   5.5 metres in OSK-G17-423
•  6.30 g/t Au over   2.0 metres and
•  8.14 g/t Au over   2.7 metres in OSK-G17-426

In both bulk sample pits the mineralization is closely associated with the N-NE trending quartz iron carbonate veins, breccias and fractures showing a strong iron carbonate alteration of the host rock.  Mineralization consists of pyrite concentrations up to 2% along with local visible gold.

OSK-G17-336 was drilled north west of the Garrcon west bulk sample pit intersecting a fracture zone within metasediment near the collar of the hole, with local visible gold returning 37.1 g/t Au over 1.0 metre.

OSK-G17-402, 380 were infill holes in the Garrcon Zone along section 1200W, drilling across the host metasediment.  OSK-G17-380 intersected 2.13 g/t Au over 17.0 metres within a zone of quartz-iron carbonate fracturing showing moderate hematite alteration. OSK-G17-402 intersected two significant mineralized zones including 2.86 g/t Au over 9.8 metres comprised of a broad zone of quartz-iron carbonate veins from 1-5 cm containing 1-2% pyrite, and local visible gold within an iron carbonate alteration halo.  A second interval returned 1.71 g/t Au over 10.0 metres within a fractured zone including minor quartz-iron carbonate and disseminated pyrite.

OSK-G17-427 intersected 7.69 g/t Au over 4.5 metres within a broad quartz-iron carbonate breccia within iron carbonate altered metasediment. This zone correlates with historical drill hole GAR-11-70, 25 metres north which intersected 5.65 g/t Au over 3.0 metres and GAR-12-159 located 40 metres south which intersected 8.39 g/t over 2.0 metres. A second mineralized zone within the hole returned 58.1 g/t Au over 1.0 metre within a zone containing quartz-iron carbonate fracturing and pervasive hematite altered metasediment.

OSK-G17-438 was drilled vertically between the two bulk sample pits at Garrcon. The hole intersected the down dip extension of the mineralized zone in the west bulk sample pit averaging 6.12 g/t Au over 6.0 metres. This interval is hosted within iron carbonate altered metasediment containing multiple 1 cm quartz-iron carbonate. A second intercept of the Garrcon deep zone returned 10.6 g/t Au over 3.5 metres.

OSK-G17-407 did not intersect significant mineralization.

Qualified Person
The scientific and technical content of this press release has been reviewed, prepared and approved by Mr. Greg Matheson, P.Geo. Senior Project Manager of the Garrison gold project, who is a “Qualified Person” as defined by National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”).

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 ongoing drill program at the Garrison gold project; results of the current drill program; the significance of new drill results reported in this press release; the ability of new drill results to demonstrate potential for expansion of the previously defined Garrcon, Jonpol and 903 mineralized zones at the Garrison project; the scope of the 2017 drill program; that the 2017 drill program will follow new extensions of these mineralized zones to further define the scale of mineralization at the Garrison project; potential mineralization; 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; 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; 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