Osisko Releases Resource Estimate For Osborne-Bell

(Toronto, March 15, 2018). Osisko Mining Inc. (OSK:TSX, “Osisko” or the “Corporation”) is pleased to provide a mineral resource estimate for its 100% owned Osborne-Bell gold deposit, located 15 kilometres northwest of the town of Lebel-sur-Quévillon, Québec. This estimate is the result of 927 drill holes (279,925 metres) completed by previous operators on the project since 1994, including 50 that were completed after their last resource estimate was published in 2012, and 4 new drill holes completed by Osisko in December 2017.

The mineral resource estimate has been prepared by Innov-Explo from Val-d’Or, Québec and the technical report, to be prepared and filed in accordance with National Instrument 43-101– Standards of Disclosure for Mineral Projects (“NI-43-101”) will be available on SEDAR (www.sedar.com) under the Corporation’s profile within 45 days.

Highlights

  • Inferred resource of 2,587,000 tons at 6.13 g/t Au for 510,000 ounces of gold assuming US$1,300 per ounce gold price and a lower cut-off grade of 3.0 g/t Au
  • Ongoing 50,000 metre 2018 exploration drill program, including definition/expansion drilling at Osborne-Bell
  • Osborne-Bell deposit remains open at depth below 500 meters

John Burzynski, President and Chief Executive Officer commented, “We are very pleased with our initial resource estimate on Osborne-Bell, a project we acquired for approximately $1.5 million less than a year ago. We had made no assumptions regarding resources during the bankruptcy acquisition of the deposit and surrounding properties in 2017; this first estimate points to a potentially significant deposit that is located very close to the possible site for a planned future Windfall-Lynx gold mill in Lebel-sur-Quévillon. By virtue of its proximity to the proposed Lebel-sur-Quévillon mill site, mining of Osborne-Bell could be realized with essentially immaterial capital expenditures, assuming material can be transported directly to the nearby proposed mill site. We are continuing our 50,000 metre drill program at Osborne-Bell and the surrounding Quévillon area in order to expand the deposit, which remains open at depth, and focus on upgrading inferred resources to M&I categories. This is an excellent start to our year of building a resource base in the Urban-Barry – Quévillon camp. We are also on track for the eagerly awaited Windfall-Lynx resource update coming in May 2018.”

The total inferred mineral resource for the Osborne-Bell deposit has been estimated at 2,587,000 tonnes with an average grade of 6.13 g/t Au for 510,000 ounces of gold, using a 3.0 g/t lower cut-off grade (See Table 1: Osborne-Bell Inferred Mineral Resources below). The model for the resource estimate includes nine (9) individual, sub-vertical and tabular mineralized zones that were defined using a two-metre minimum true thickness. All mineral resources were classified as inferred mineral resources. Additional drilling and historical data validation through core re-assaying are underway to potentially upgrade portions of the resource to measured mineral resource and indicated mineral resource categories.

 

Table 1: Osborne-Bell Inferred Mineral Resources

Cut-off Grade Tonnes (t)(1) Grade (g/t) Oz Au(2)
> 6.00 g/t 883,000 9.77 277,000
> 5.00 g/t 1,273,000 8.44 346,000
> 4.00 g/t 1,816,000 7.26 424,000
> 3.50 g/t 2,156,000 6.70 465,000
> 3.00 g/t 2,587,000 6.13 510,000
> 2.50 g/t 3,166,000 5.51 560,000

Notes:

(1) Rounded to nearest thousand which may cause apparent discrepancies.

(2) Rounded to nearest thousand which may cause apparent discrepancies.

This mineral resource estimate reflects geological re-modeling of the Osborne-Bell deposit, the re-evaluation of historical drilling results from previous operators and the addition of new information from drilling comprising 50 drill holes performed after the 2012 mineral resource estimate released by the previous owner (see the “43-101 Technical Report and Mineral Resource Estimate – Osbell Deposit, Comtois Property”, dated effective October 26, 2012, and filed on SEDAR on December 7, 2012, under the issuer profile of Maudore Minerals Ltd, at www.sedar.com) and four new Osisko verification drill holes completed in December 2017. The model focuses on definition of higher-grade sub domains as compared to the broad mineralized domain approach of earlier estimates. This estimate only considers mineralized zones potentially minable by underground methods at a lower cut-off grade of 3.0 g/t Au. The cut-off calculation is based on assumptions of (a) a mining cost of C$80/t mined, (b) a processing and transportation cost of C$58/t milled, (c) a G&A cost of C$10/t milled, (d) a gold price of US$1,300/oz and (e) an exchange rate of USD:CAD of 1.29. Other parameters are described in Table 2: Parameters used for Resource Estimation, below. The effective date of the current resource estimation is March 2, 2018.

Table 2: Parameters used for Resource Estimation

Parameters Unit Value
Gold Price US$/oz 1,300
Exchange Rate US$/C$ 1.29
Mill Recovery % 93
Selling Cost C$/oz 5
Mining Cost C$/t mined 80
G&A Cost C$/t milled 10
Processing Cost C$/t milled 40
Transport C$/t milled 18
Calculated Cut-Off Grade Au g/t 2.96

 

Further details regarding the curent mineral resource estimate, including the key assumptions, parameters and methods used to prepare the mineral resource estimate of the Osborne-Bell gold deposit will be available on SEDAR (www.sedar.com) under the Corporation’s profile within 45 days. For further details about the 2012 resource estimate, please see the ” 43-101 Technical Report and Mineral Resource Estimate – Osbell Deposit, Comtois Property, dated effective October 26, 2012, and filed on SEDAR on December 7, 2012, under the issuer profile of Maudore Minerals Ltd at www.sedar.com.

Mineral Resource Estimate Notes:

  1. Resources are presented undiluted and in situ and are considered to have reasonable prospects for economic extraction.
  2. The estimate encompasses nine tabular gold-bearing zones each defined by individual wireframes with a minimum true thickness of 2 metres.
  3. High grade capping was done on composite data and established on a per zone basis for gold. It varies from 25 g/t Au to 55 g/t Au.
  4. Density values were applied on the following lithological basis (g/cm3): volcanic host rocks = 2.80; late barren dykes and Beehler stock = 2.78; Zebra felsic unit = 2.72.
  5. Grade model mineral resource estimation was evaluated from drill hole data using an Ordinary Kriging interpolation method on a block model using a block size of 2.5 metres x 2.5 metres x 2.5 metres.
  6. The mineral resource estimate presented herein is categorized as inferred mineral resource. The inferred mineral resource category is only defined within the areas where drill spacing is less than 100 metres and shows reasonable geological and grade continuity.
  7. The mineral resource estimate was prepared using Geovia GEMS 6.8. The estimate is based on 931 surface diamond drill holes. A minimum true thickness of 2.0 metres was applied, using the grade of the adjacent material when assayed, or a value of zero when not assayed.
  8. Estimates use metric units (metres, tonnes and g/t). Metal contents are presented in troy ounces (metric tonne x grade / 31.10348).
  9. The number of metric tonnes was rounded to the nearest thousand. Any discrepancies in the totals are due to rounding errors.
  10. InnovExplo is not aware of any known environmental, permitting, legal, title-related, taxation, socio-political or marketing issues, or any other relevant issue not reported in the technical report, that could materially affect the mineral resource estimate.
  11. These mineral resources are not mineral reserves as they do not have demonstrated economic viability. The quantity and grade of reported Inferred resources in this Mineral Resource Estimate are uncertain in nature and there has been insufficient exploration to define these Inferred resources as Indicated or Measured, and it is uncertain if further exploration will result in upgrading them to these categories.

Qualified Person

This mineral resource estimate was prepared by Pierre-Luc Richard, P.Geo., M.Sc., who is a “qualified person” within the meaning of NI 43-101. Mr. Richard is an employee of Innov-Explo and is considered to be independent of Osisko for purposes of section 1.5 of NI 43-101. The effective date of the mineral resource estimate is March 2, 2018.

The scientific and technical information contained in this news release has been reviewed and approved by Mr. Mathieu Savard, P.Geo., who is a “qualified person” within the meaning of NI 43-101, and serves as the Vice President Exploration Québec of Osisko.

Quality Control

For the sample processed by Osisko during late 2017 campaign and included in this resource estimation, 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 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 as of the end of Q4, 2017.

Cautionary Statements Regarding Estimates of Mineral Resources

This news release uses the terms measured mineral resource, indicated mineral resource and inferred mineral resource as a relative measure of the level of confidence in the mineral resource estimate. Readers are cautioned that mineral resources are not economic mineral reserves and that the economic viability of resources that are not mineral reserves has not been demonstrated. The estimate of mineral resources may be materially affected by environmental, permitting, legal, title, socio-political, marketing or other relevant issues. It cannot be assumed that all or any part of an inferred mineral resource will ever be upgraded to indicated mineral resource or measured mineral resource categories. The mineral resource estimate is classified in accordance with the Canadian Institute of Mining, Metallurgy and Petroleum’s “CIM Definition Standards- For Mineral Resources and Mineral Reserves” incorporated by reference into NI 43-101. Under Canadian rules, estimates of inferred mineral resources may not form the basis of feasibility or pre-feasibility studies or economic studies except for a “preliminary economic assessment” as defined under NI 43-101. Readers are cautioned not to assume that further work on the stated mineral resources will lead to mineral reserves that can be mined economically.

  • 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. 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 news release contains the forward-looking information pertaining to, among other things, the timing and ability of Osisko to file a technical report in respect of this resource estimate; the prospects of the Osborne-Bell gold deposit; the potential for the Osborne-Bell gold deposit being a significant deposit; the potential future mill site for the Windfall Lake gold deposit; the timing and ability of Osisko, if at all, to publish a resource update for Windfall-Lynx; the projected capital expenditures of mining activities at the Osborne-Bell gold deposit; upgrading a inferred mineral resource to a measured mineral resource or indicated mineral resource category; the significance of historic exploration activities and results. 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 Quevillon project and the Osborne-Bell Gold Deposit; the ability of the Corporation to obtain required approvals; 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 INFORMATION:

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

Osisko Intersects 265 g/t Au Over 2.4 Metres At Windfall

High-Grade Infill Hits in Underdog, Caribou, Caribou Extension, Bobcat and Mallard

(Toronto, March 2, 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 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 61 intercepts in 34 drill holes and 5 wedges focused on infill and expansion drilling in the Main Windfall lake deposit are presented below.

Highlights from the new results include: 265 g/t Au over 2.4 metres in OSK-W-17-1168; 191 g/t Au over 2.6 metres in OSK-W-17-1087; 198 g/t Au over 2.3 metres and 116 g/t Au over 2.1 metres in OSK-EAG-12-333; 173 g/t Au over 2.3 metres in OSK-W-17-1383; 47.7 g/t Au over 2.2 metres in OSK-W-17-1402, 42.7 g/t Au over 2.0 metres in OSK-W-17-1391 and 9.53 g/t over 8.9 metres in OSK-W-18-823-W2. 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-EAG-12-333 818.2 823.0 4.8 3.07 FW3 Underdog
including 822.7 823.0 0.3 23.1
848.1 850.2 2.1 116 59.4 FW3 Underdog
including 849.2 850.2 1.0 219 100
934.0 936.3 2.3 198 21.8 FW3U Underdog
including 935.2 935.7 0.5 910 100
OSK-EAG-12-427 1110.0 1112.2 2.2 4.29 VNCR Underdog
OSK-EAG-13-480 522.3 524.3 2.0 37.1 20.6 Vein
including 524.0 524.3 0.3 210 100
692.0 694.0 2.0 6.68 FW1 FW Underdog
including 692.0 693.0 1.0 12.4
OSK-W-16-762 1158.0 1160.5 2.5 6.59 FW3 Underdog
including 1158.0 1158.8 0.8 17.8
OSK-W-17-795 1110.3 1113.7 3.4 5.53 FW1 Underdog
including 1110.3 1110.9 0.6 23.1
OSK-W-17-866-W2 933.3 935.5 2.2 4.92 FW0 Underdog
1221.0 1223.0 2.0 7.59 FW3 Underdog
including 1221.7 1222.3 0.6 23.7
OSK-W-17-901 675.5 678.0 2.5 8.27 FW3U Underdog
including 676.6 676.9 0.3 65.9
OSK-W-17-903-W2 556.0 560.9 4.9 3.72 Z27 Zone 27
including 556.0 557.1 1.1 8.88
including 560.0 560.9 0.9 8.94
593.0 595.0 2.0 8.52 Z27 FW Zone 27
including 593.0 594.0 1.0 16.7
OSK-W-17-937-W1 756.2 758.6 2.4 26.6 Wolf 2 Wolf
including 757.0 758.6 1.6 39.0
OSK-W-17-943 491.0 493.0 2.0 3.00 CS1 Caribou
including 492.0 493.0 1.0 5.57
614.0 616.0 2.0 4.51 Wolf HW Wolf
688.0 690.0 2.0 4.96 Wolf Wolf
including 688.0 689.0 1.0 9.64
OSK-W-17-1025 690.0 692.3 2.3 3.13 FW0 Underdog
OSK-W-17-1051 954.0 956.4 2.4 7.60 FW3 Underdog
OSK-W-17-1087 354.0 356.6 2.6 191 19.6 Mallard Mallard
including 354.0 354.5 0.5 991 100
OSK-W-17-1168 503.6 506.0 2.4 265 13.3 VNCR Caribou
including 504.3 504.6 0.3 2110 100
OSK-W-17-1221 771.0 773.0 2.0 4.61 Vein Wolf
including 771.0 771.8 0.8 11.5
OSK-W-17-1226 662.0 664.0 2.0 11.5 Caribou Ext. Caribou
including 662.6 663.5 0.9 24.4
673.0 675.0 2.0 10.4 Caribou Ext. Caribou
including 673.0 674.0 1.0 20.3
823.8 826.0 2.2 6.57 Caribou Ext. Caribou
including 823.8 825.0 1.2 12.0
OSK-W-17-1232 331.0 333.0 2.0 4.70 Vein Caribou
OSK-W-17-1275 553.1 556.1 3.0 4.49 Z27 Zone 27
including 554.1 555.0 0.9 11.5
OSK-W-17-1293 802.7 805.0 2.3 6.54 Vein
including 803.7 804.0 0.3 49.7
OSK-W-17-1295 387.0 389.0 2.0 3.36 FW3 Underdog
OSK-W-17-1310 54.0 57.0 3.0 3.61 Caribou Caribou
354.0 357.0 3.0 3.37 Vein Mallard
OSK-W-17-1319 162.0 165.0 3.0 5.80 Z27 Zone 27
including 162.0 163.5 1.5 11.4
OSK-W-17-1320 557.5 560.8 3.3 3.46 Caribou Ext. Caribou
OSK-W-17-1334 86.0 88.0 2.0 4.05 Bobcat Bobcat
OSK-W-17-1336 277.4 279.5 2.1 4.16 Vein
810.0 813.0 3.0 17.0 FW0 Underdog
972.0 974.0 2.0 4.10 FW2 Underdog
OSK-W-17-1337 19.0 21.5 2.5 3.39 Mallard Mallard
including 20.0 20.4 0.4 13.7
OSK-W-17-1342 211.9 214.0 2.1 8.19 Mallard HW Mallard
including 211.9 231.0 1.1 15.4
OSK-W-17-1347 164.0 166.0 2.0 4.64 Vein
including 165.2 166.0 0.8 11.5
249.4 252.2 2.8 11.1 Mallard FW Mallard
including 250.4 251.3 0.9 27.3
OSK-W-17-1350 724.0 726.0 2.0 4.16 Caribou Ext. Caribou
OSK-W-17-1376 198.7 201.0 2.3 10.2 Vein
including 198.7 199.0 0.3 72.7
816.5 818.6 2.1 33.6 FW2 Underdog
including 816.5 817.3 0.8 73.3
OSK-W-17-1383 38.1 40.4 2.3 173 18.2 Bobcat Bobcat
including 39.0 39.4 0.4 990 100
OSK-W-17-1391 453.0 455.0 2.0 42.7 33 Caribou Ext. Caribou
including 454.0 454.6 0.6 133 100
OSK-W-17-1399 684.5 686.5 2.0 3.72 Caribou Ext. Caribou
OSK-W-17-1402 462.2 464.5 2.3 3.39 Caribou Caribou
820.1 822.3 2.2 47.7 18.4 FW1 Underdog
including 822.0 822.3 0.3 315 100
863.6 865.6 2.0 3.48 FW1 FW Underdog
including 864.1 864.9 0.8 7.60
873.5 876.3 2.8 3.35 FW1 FW Underdog
938.2 940.2 2.0 4.27 FW2 Underdog
OSK-W-18-823-W2 510.6 519.5 8.9 9.53 CS1 Caribou
including 510.6 513.5 2.9 18.0
526.0 528.0 2.0 5.22 CS1 Caribou
OSK-W-18-1402-W1 804.2 806.5 2.3 5.79 FW0 Underdog
including 805.0 805.5 0.5 23.5
OSK-W-18-1418 660.0 665.0 5.0 4.78 Caribou Ext. Caribou
710.0 717.0 7.0 5.95 Caribou Ext. Caribou
including 710.7 712.6 1.9 11.9
930.0 932.0 2.0 5.85 Caribou Ext. Caribou
OSK-W-18-1421 231.0 233.9 2.9 17.7 CW2 Caribou
OSK-W-18-1423 521.2 523.5 2.3 6.04 Caribou Ext. Caribou
556.0 559.0 3.0 3.97 Caribou Ext. Caribou

Notes:

  1. True widths are estimated at 65 – 80% of the reported core length interval.  See “Quality Control” below.
  2. Definitions: HW = Hanging Wall, FW = footwall, VNCR = Crustiform Vein, Ext = extension.
Hole Number Azimuth (°) Dip (°) Length (m) UTM E UTM N Section
OSK-EAG-12-333 333 -58 983 452459 5434565 2525
OSK-EAG-12-427 330 51 1215 452701 5434438 2675
OSK-EAG-13-480 331 -57 991 452400 5434486 2450
OSK-W-16-762 332 -56 1311 452730 5434409 2675
OSK-W-17-795 333 -65 1428 452646 5434421 2625
OSK-W-17-866-W2 332 -57 1332 452633 5434280 2525
OSK-W-17-901 328 -55 810 452391 5434638 2500
OSK-W-17-903-W2 329 -56 795 452539 5434692 2650
OSK-W-17-937-W1 333 -57 945 452897 5434430 2850
OSK-W-17-943 331 -55 744 452660 5434495 2675
OSK-W-17-1025 330 -58 990 452486 5434439 2475
OSK-W-17-1051 138 -68 1248 452313 5435323 2775
OSK-W-17-1087 328 -61 381 452255 5434830 2475
OSK-W-17-1168 329 -57 717 453464 5435090 3650
OSK-W-17-1221 335 -51 1079 453082 5434544 3050
OSK-W-17-1226 331 -51 934 453371 5434726 3400
OSK-W-17-1232 154 -47 351 452025 5434834 2275
OSK-W-17-1275 331 -55 912 452499 5434592 2575
OSK-W-17-1293 329 -70 828 452904 5434849 3050
OSK-W-17-1295 334 57 801 451559 5434288 1600
OSK-W-17-1310 312 -45 375 452209 5434617 2325
OSK-W-17-1319 310 -50 291 452222 5434607 2325
OSK-W-17-1320 328 -76 852 452904 5434849 3050
OSK-W-17-1334 334 -70 657 452839 5434895 3025
OSK-W-17-1336 335 -61 1149 452616 5434449 2600
OSK-W-17-1337 140 -57 360 452053 5434963 2350
OSK-W-17-1342 333 -50 282 452086 5434761 2300
OSK-W-17-1347 151 -61 489 452160 5435159 2550
OSK-W-17-1350 328 -55 843 452993 5434557 2975
OSK-W-17-1376 330 -50 1125 452426 5434380 2400
OSK-W-17-1383 331 -63 597 452767 5434864 2925
OSK-W-17-1391 327 -62 663 452981 5434900 3150
OSK-W-17-1399 332 -61 1053 453411 5434870 3500
OSK-W-17-1402 330 -59 1122 452616 5434449 2600
OSK-W-18-823-W2 330 -56 918 452565 5434414 2550
OSK-W-18-1402-W1 330 -59 1224 452616 5434449 2600
OSK-W-18-1418 334 -45 1077 453288 5434531 3225
OSK-W-18-1421 340 -47 918 452216 5434360 2200
OSK-W-18-1423 327 -61 792 453025 5434853 3150

OSK-EAG-12-333 intersected FW3 returning 3.07 g/t au over 4.8 metres and 116 g/t Au over 2.1 metres, and FW3U with 198 g /t Au over 2.3 metres in Underdog Corridor. The first interval is composed of up to 10% pyrite within pervasive silica flooding and 1% disseminated pyrite hosted in a porphyritic felsic dike with moderate chlorite, silica and sericite alteration. The second interval contains up to 20% pyrite and local visible gold within intense silica alteration. The third interval is composed of 3% pyrite stringers and local visible gold within a strongly sericitized and silicified felsic porphyritic dike.

OSK-EAG-12-427 intersected crustiform veins in FW4 returning 4.29 g/t Au over 2.2 metres in the Underdog Corridor. Mineralization is composed of 30% pyrite and 1% chalcopyrite in quartz-tourmaline-sericite veins.

OSK-EAG-13-480 intersected a vein in the Red Dog intrusion returning 37.1 g/t Au over 2.0 metres and FW1 FW with 6.68 g/t au over 2.0 metres. The first interval is composed of local visible gold in a quartz-carbonate vein with up to 3% pyrite and 1 % chalcopyrite. The second interval is composed of 1% pyrite stringers within porphyritic felsic dikes with moderate sericite, chlorite and fuchsite alteration.

OSK-W-17-762 intersected FW3 with 6.59 g/t Au over 2.5 metres in Underdog. Mineralization is composed of local visible gold within 10 centimetre silica flooding bands and 10% pyrite hosted in a porphyritic felsic intrusion.

OSK-W-17-795 intersected FW1 with 5.53 g/t Au over 3.4 metres in Underdog. Mineralization is composed of up to 10% pyrite stringers in silica flooding alteration hosted in a sericite altered felsic porphyritic dike.

OSK-W-17-866-W2 intersected FW0 with 4.92 g/t Au over 2.2 metres and FW3 with 7.59 g/t Au over 2.0 metres in Underdog Corridor. Mineralization from FW0 corresponds with 70% massive pyrite over 30 centimetres hosted within a felsic porphyritic dike with strong sericitization. The second interval is composed of up to 15% pyrite stringers and 1% disseminated pyrite hosted in a porphyritic felsic dike with moderate silica and sericite alteration.

OSK-W-17-901 intersected 8.27 g/t Au over 2.5 metres in FW3U. Mineralization is composed of a 10 centimetres silica flooding zone with 55% pyrite, 1% pyrite stringers and 7% disseminated pyrite in a bleached andesite.

OSK-W-17-903-W2 intersected 3.72 g/t Au over 4.9 metres in Zone 27 and 8.52 g/t Au over 2.0 metres in Z27 FW. The first interval is composed of disseminated and stringer pyrite at the contact between a silicified and weakly sericitized porphyritic dike and a weak chlorite, sericite altered andesite. The second interval is composed of pyrite traces hosted in an andesite with strong chlorite and carbonates alteration.

OSK-W-17-937-W1 intersected 26.6 g/t Au over 2.4 metres in Wolf 2. Mineralization is composed of up to 9% disseminated pyrite and 5% tourmaline-pyrite stringers at the contact between a bleached and strongly sericitized andesite and a small sericitized porphyritic felsic dike.

OSK-W-17-943 intersected 3.00 g/t Au over 2.0 metres in Caribou, and 4.51 g/t Au over 2.0 metres and 4.96 g/t Au over 2.0 metres in Wolf. The first interval is composed of up to 10% pyrite stringers and 2% disseminated pyrite hosted in a sericitized rhyolite and a sericitized porphyritic felsic dike. The second interval is composed of 3% pyrite stringers within a sericitized and chloritized porphyritic felsic dike. The third interval is composed of disseminated pyrite within an andesite with chlorite and carbonate alteration.

OSK-W-17-1025 intersected FW0 with 3.13 g/t Au over 2.3 metres. Mineralization is composed of 3% pyrite in silica flooding and 1% pyrite stringers in weakly sericitized porphyritic felsic dike.

OSK-W-17-1051 intersected FW3 with 7.6 g/t Au over 2.4 metres in Underdog Corridor. Mineralization is composed of up to 1% pyrite clusters and disseminated pyrite within a weak sericite and silica altered felsic porphyritic dike.

OSK-W-17-1087 intersected Mallard with 191 g/t Au over 2.6 metres. Mineralization is composed of 5% pyrite stringers and 1% disseminated pyrite within a sericite altered andesite.

OSK-W-17-1168 intersected 265 g/t Au over 2.4 metres in Caribou Corridor. Mineralization is composed of a crustiform vein with local visible gold and 1% pyrite clusters with tourmaline and fuchsite hosted in a gabbro with moderate chlorite alteration. The interval is 150 metres East of OSK-W-17-787 (7.21 g/t Au over 6.5 metres previously reported March 21, 2017).

OSK-W-17-1221 intersected 4.61 g /t Au over 2.0 metres in Wolf corridor. Mineralization is composed of a centimetre scale quartz carbonate vein in a chloritized and slightly silicified porphyritic felsic dike with traces of pyrite stringer.

OSK-W-17-1226 intersected 11.5 g/t Au over 2.0 metres, 10.4 g/t Au over 2.0 metres and 6.57 g/t Au over 2.2 metres in Caribou Extension. First and second intervals are composed of up to 10% pyrite-tourmaline stringers and disseminated pyrite in a sericitized rhyolite. The third interval is composed of 1% pyrite stringers hosted in porphyritic felsic dike with sericite alteration.

OSK-W-17-1232 intersected a vein returning 4.70 g/t Au over 2.0 metres in Caribou Corridor. Mineralization is composed of 3% disseminated pyrite and 7% ptygmatic tourmaline veins within a weak sericite altered rhyolite.

OSK-W-17-1275 intersected 4.49 g/t Au over 3.0 metres in Zone 27. Mineralization is composed of traces of pyrite stringers within a sericitized porphyritic felsic dike.

OSK-W-17-1293 intersected 6.54 g/t Au over 2.3 metres. Mineralization is composed of 1% pyrite and 1% chalcopyrite in quartz veins within a silicified, chloritized and carbonate altered monzonite (Red Dog intrusion).

OSK-W-17-1295 intersected FW3 with 3.36 g/t Au over 2.0 metres in Underdog. Mineralization is composed of 2% pyrite clusters in a sericitized and weakly silicified porphyritic felsic dike.

OSK-W-17-1310 intersected 3.61 g/t Au over 3.0 metres in Caribou and 3.37 g/t Au over 3.0 metres in Drake. The first interval is composed of 1% pyrite stingers within a chloritized and sericitized rhyolite. The second interval is composed of chloritized and sericitized andesite with 5% quartz-carbonate veins.

OSK-W-17-1319 intersected 5.80 g/t Au over 3.0 metres in Zone 27. Mineralization is composed of traces of disseminated pyrite within a sericitized porphyritic felsic dike.

OSK-W-17-1320 intersected 3.46 g/t Au over 3.3 metres in Caribou Extension. Mineralization is composed of disseminated pyrite and quartz-pyrite clusters in a chloritized, sericitized and silicified andesite.

OSK-W-17-1334 intersected 4.05 g/t Au over 2.0 metres in Bobcat. Mineralization is composed of disseminated pyrite and crustiform quartz-carbonate veins in a chloritized, silicified and carbonate altered gabbro.

OSK-W-17-1336 intersected three intervals: 4.16 g/t Au over 2.05 metres in a vein, 17.0 g/t Au over 3.0 metres in FW0 and 4.10 g/t Au over 2.0 metres in FW2, Underdog Corridor. The first interval is composed of 1% disseminated pyrite in a quartz vein within a strongly chloritized gabbro. The second interval is composed of up to 2% disseminated pyrite and 1% pyrite stringers in a sericitized porphyritic felsic dike. The third interval is composed of 1% pyrite stringers and 1% pyrite in quartz-carbonate veins within a moderate sericite and silica altered felsic porphyritic dike.

OSK-W-17-1337 intersected 3.39 g/t Au over 2.5 metres in Mallard. Mineralization is composed of up to 20% pyrite stringers within a sericitized, silicified and bleached andesite.

OSK-W-17-1342 intersected Mallard HW with 8.19 g/t Au over 2.1 metres. Mineralization is composed of traces of disseminated and clustered pyrite within a chloritized andesite.

OSK-W-17-1347 intersected 4.64 g/t Au over 2.0 metres in a vein and 11.1 g/t Au over 2.8 metres in Mallard FW. The first interval is composed of a five centimetre quartz vein with 15% pyrite clusters hosted in a chloritized, silicified and weakly sericitized andesite. The second interval is at the contact between a strongly chlorite, fuchsite altered andesite and a porphyritic felsic dike. Mineralization is composed of 10% pyrite clusters and 3% pyrite stringers. The vein is located 100 metres north-west of Mallard corridor and is not related to any known zones.

OSK-W-17-1350 intersected Caribou Extension with 4.16 g/t Au over 2.0 metres. The mineralization is composed of up to 2% pyrite stringers within a sericitized, chloritized and carbonate altered large quartz eyes felsic porphyritic dike.

OSK-W-17-1376 intersected a vein returning 10.2 g/t Au over 2.3 metres and FW2 with 33.6 g/t Au over 2.1 metres. The first interval is composed of 5-10% quartz-carbonate veining with 5% disseminated pyrite in an andesite with chlorite, carbonate, sericite and silica alteration. Mineralization in FW2 is composed of a silica and sericite altered porphyritic dike with up to 5%, locally 80%, pyrite-tourmaline stringers.

OSK-W-17-1383 intersected 173 g/t Au over 2.3 metres in Bobcat. Mineralization is composed of local visible gold, 3% pyrite stringers with pervasive silica flooding within a gabbro with silica, carbonate and sericite alteration.

OSK-W-17-1391 intersected 42.7 g/t Au over 2.0 metres in Caribou Extension. Mineralization is composed of up to 10% pyrite stringers and 1% chalcopyrite, local visible gold, tourmaline ptygmatic veins, quartz-tourmaline veins and crustiform veins hosted in a silicified and bleached andesite.

OSK-W-17-1399 intersected 3.72 g/t Au over 2.0 metres in Caribou Extension. Mineralization is composed of up to 10% pyrite-tourmaline stringers within a strongly silicified rhyolite.

OSK-W-17-1402 intersected Caribou with 3.39 g/t Au over 2.3 metres and multiples intervals in Underdog corridor: FW1 with 47.7 g/t Au over 2.2 metres, FW1 FW with 3.48 g/t Au over 2.0 metres and 3.35 g/t Au over 2.8 metres, and FW2 with 4.27 g/t au over 2.0 metres. The first interval is composed of 3% pyrite stringers, 5% pyrite clusters within a sericitized andesite with weak silica and fuchsite alteration. The second interval is composed of local visible gold, 2% disseminated pyrite and 1% pyrite clusters, hosted in a moderately sericitized porphyritic dike. The third and fourth intervals are composed of 3% pyrite stringers and 1% disseminated pyrite in pervasive silica flooding within a sericitized porphyritic felsic dike. The last interval is composed of 2% pyrite stringers and 1% pyrite-silica flooding within a sericite, silica and fuchsite altered felsic porphyritic dike.

OSK-W-18-823-W2 intersected CS1 with 9.53 g/t Au over 8.9 metres and 5.22 g/t Au over 2.0 metres in Caribou. Mineralization is composed of 10% semi-massive pyrite bands, 10% pyrite stringers, up to 10% disseminated pyrite and up to 2% ptygmatic tourmaline veinlets hosted in a sericitized, chloritized and bleached andesite.

OSK-W-18-1402-W1 intersected 5.79 g/t Au over 2.3 metres in FW0. The mineralization is composed of 3% pyrite in a ptygmatic tourmaline vein at low core angle within a silicified and sericitized fragmental felsic intrusion.

OSK-W-18-1418 intersected 4.78 g/t Au over 5.0 metres, 5.95 g/t Au over 7.0 metres and 5.85 g/t Au over 2.0 metres in Caribou Extension. The first interval is composed of up to 5% pyrite stringers within a silicified and sericitized felsic porphyritic dike. The second interval is composed of up to 15% pyrite-tourmaline stringers hosted in a silicified and sericitized rhyolite. The third interval is composed of up to 10% pyrite-silica flooding within a silica altered andesite.

OSK-W-18-1421 intersected CW2 with 17.7 g/t Au over 2.9 metres in Caribou Corridor. Mineralization is composed of up to 8% pyrite stringers, 1% chalcopyrite, 1% sphalerite, ptygmatic tourmaline veins and local visible gold within a strongly silica altered rhyolite.

OSK-W-18-1423 intersected 6.04 g/t Au over 2.3 metres and 3.97 g/t Au over 3.0 metres in Caribou Extension. The first interval is composed of 7% disseminated pyrite within a bleached andesite. The second interval is composed of 4% disseminated pyrite, 2% pyrite stringers at a bleached andesite contact with a felsic porphyritic dike.

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 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; the type of drilling included in the drill program (definition drilling, expansion drilling to the NE of the main deposit and 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.

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