OSISKO EXPANSION DRILLING ADDS NEW HIGH GRADE AT WINDFALL

58.7 g/t Au Over 4.6 Metres in Caribou

(Toronto, March 15, 2021) Osisko Mining Inc. (OSK:TSX. “Osisko” or the “Corporation”) is pleased to provide new analytical results from the ongoing drill program at its 100% owned Windfall gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec.

Significant new analytical results presented below include 40 intercepts in 18 drill holes (15 from surface, 3 from underground) and 11 wedges. The intercepts are located outside the February 2021 mineral resource estimate (see Osisko news release dated February 17, 2021) and either expand resource wireframes or are located in a defined zone or corridor but do not yet correlate to a specific wireframe.

Osisko Chief Executive Officer John Burzynski commented: “Windfall continues to grow in scale across the deposit as demonstrated by today’s results in five different zones, all of which still remain open to growth.”

Selected intercepts include: 58.7 g/t Au over 4.6 metres in OSK-W-20-2421; 39.2 g/t Au over 2.5 metres in OSK-W-20-2399-W1; 36.8 g/t Au over 2.3 metres in OSK-W-20-2410-W1; 21.2 g/t Au over 3.6 metres in OSK-W-21-2467-W1; and 36.2 g/t Au over 2.0 metres in OSK-W-21-2462. Maps showing hole locations and full analytical results are available at www.osiskomining.com

Expansion Drilling

Hole No. From (m) To (m) Interval (m) Au (g/t) uncut Au (g/t)         cut to 100 g/t Zone Corridor
OSK-W-20-2354-W1 705.8 707.8 2.0 3.62   Caribou Caribou
including 706.6 707.1 0.5 12.5
OSK-W-20-2354-W2 633.5 638.1 4.6 8.60   Caribou Caribou
including 633.5 634.9 1.4 20.0
OSK-W-20-2354-W4 629.0 633.0 4.0 11.2   Caribou Caribou
including 629.0 630.0 1.0 34.8
OSK-W-20-2359 673.0 675.0 2.0 4.87   Caribou Caribou
OSK-W-20-2366 299.9 302.0 2.1 3.61   Caribou Caribou
OSK-W-20-2377-W1 889.5 895.5 6.0 7.36   Caribou Caribou
including 889.5 890.0 0.5 25.5
OSK-W-20-2387 575.5 577.5 2.0 4.70   Caribou Caribou
including 576.1 576.6 0.5 15.2
OSK-W-20-2387-W1 521.0 523.0 2.0 18.8   Caribou Caribou
including 521.8 523.0 1.2 29.7
OSK-W-20-2390 622.6 625.0 2.4 4.91   Caribou Caribou
including 623.8 624.5 0.7 14.7
OSK-W-20-2399-W1 621.5 624.0 2.5 39.2   Caribou Caribou
650.0 652.4 2.4 6.67   Caribou Caribou
including 651.0 651.4 0.4 36.5
OSK-W-20-2399-W2 580.0 582.4 2.4 3.83   Caribou Caribou
including 582.1 582.4 0.3 18.5
656.0 658.0 2.0 3.66   Caribou Caribou
OSK-W-20-2400 768.0 770.2 2.2 4.20   Caribou Caribou
OSK-W-20-2401 382.0 384.0 2.0 6.16   Caribou Caribou
including 382.0 383.0 1.0 11.8
OSK-W-20-2407-W1 686.0 688.0 2.0 9.14   Underdog Underdog
including 686.5 687.0 0.5 29.5
OSK-W-20-2410-W1 720.7 723.0 2.3 36.8   Caribou Caribou
including 722.0 723.0 1.0 67.0
OSK-W-20-2414 837.0 839.1 2.1 3.92   Caribou Caribou
OSK-W-20-2415-W1 453.0 455.0 2.0 24.7 20.2 Caribou Caribou
including 453.9 454.3 0.4 123 100
OSK-W-20-2421 530.0 532.1 2.1 6.56   Caribou Caribou
including 530.0 531.0 1.0 13.3
534.0 538.6 4.6 58.7 40.6 Caribou Caribou
including 536.0 537.0 1.0 123 100
and 537.0 537.4 0.4 251 100
OSK-W-20-2424 109.2 111.5 2.3 4.70   F11 F11
including 109.8 110.3 0.5 17.8
OSK-W-20-2433 78.0 80.0 2.0 3.60   F11 F11
including 78.8 79.3 0.5 13.9
216.0 218.0 2.0 3.95   F11 F11
including 216.0 216.5 0.5 11.7
OSK-W-20-2439 45.3 48.0 2.7 4.05   F11 F11
OSK-W-21-2451 647.4 649.4 2.0 4.90   Caribou Caribou
including 648.0 648.4 0.4 15.0
748.0 750.5 2.5 19.1   Caribou Caribou
OSK-W-21-2460 535.8 538.0 2.2 18.8   Caribou Caribou
724.6 726.7 2.1 3.95   Caribou Caribou
OSK-W-21-2462 480.0 482.0 2.0 36.2 25.7 Caribou Caribou
including 480.9 481.4 0.5 142 100
678.0 680.4 2.4 5.78   Caribou Caribou
OSK-W-21-2466 539.0 541.0 2.0 9.76   Caribou Caribou
OSK-W-21-2467-W1 421.0 423.0 2.0 3.65   Caribou Caribou
602.0 604.0 2.0 21.9   Caribou Caribou
including 603.0 604.0 1.0 43.6
636.1 639.7 3.6 21.2   Caribou Caribou
including 636.1 636.6 0.5 89.3
687.0 689.0 2.0 14.0   Caribou Caribou
including 687.0 688.0 1.0 25.0
WST-20-0519 148.0 150.0 2.0 6.76   Z27 Zone 27
WST-20-0558 98.0 100.0 2.0 4.57   Bobcat Bobcat
including 98.4 99.1 0.7 12.8
166.0 168.0 2.0 7.15   Bobcat Bobcat
including 167.7 168.0 0.3 47.5
WST-20-0566A 93.9 96.3 2.4 3.57   Z27 Zone 27
including 95.0 95.6 0.6 12.0

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See “Quality Control and Reporting Protocols” below.

Drill hole location

Hole Number Azimuth (°) Dip (°) Length (m) UTM E UTM N Elevation Section
OSK-W-20-2354-W1 336 -60 792 452739 5434474 401 2725
OSK-W-20-2354-W2 336 -60 750 452739 5434474 401 2725
OSK-W-20-2354-W4 336 -60 783 452739 5434474 401 2725
OSK-W-20-2359 335 -61 726 452694 5434440 401 2675
OSK-W-20-2366 323 -55 534 452682 5434624 398 2750
OSK-W-20-2377-W1 132 -49 1314 452702 5435548 409 3225
OSK-W-20-2387 336 -59 717 452694 5434440 401 2675
OSK-W-20-2387-W1 336 -59 738 452694 5434440 401 2675
OSK-W-20-2390 330 -65 647 452595 5434393 401 2550
OSK-W-20-2399-W1 333 -54 876 452874 5434552 398 2875
OSK-W-20-2399-W2 333 -54 876 452874 5434552 398 2875
OSK-W-20-2400 336 -53 884 452876 5434419 402 2825
OSK-W-20-2401 330 -55 705 452688 5434637 397 2750
OSK-W-20-2407-W1 347 -55 1044 452315 5434419 399 2325
OSK-W-20-2410-W1 338 -62 750 452727 5434358 402 2650
OSK-W-20-2414 337 -54 882 452880 5434419 402 2825
OSK-W-20-2415-W1 328 -54 762 452738 5434474 401 2725
OSK-W-20-2421 332 -59 699 452632 5434280 400 2525
OSK-W-20-2424 150 -45 267 452638 5436000 403 3375
OSK-W-20-2433 148 -47 411 452558 5436073 405 3350
OSK-W-20-2439 147 -50 360 452515 5436029 406 3275
OSK-W-21-2451 330 -58 803 452809 5434415 404 2750
OSK-W-21-2460 332 -55 789 452732 5434537 399 2750
OSK-W-21-2462 338 -57 888 452874 5434552 398 2875
OSK-W-21-2466 330 -66 639 452597 5434393 401 2550
OSK-W-21-2467-W1 331 -54 708 452687 5434471 402 2675
WST-20-0519 136 -45 162 452282 5434976 262 2575
WST-20-0558 155 -32 169 452955 5435003 253 3175
WST-20-0566A 132 -16 368 452208 5434898 248 2475

 

Caribou Zone

Mineralization most commonly occurs in gold-bearing pyrite stockworks as well as semi-massive pyrite replacement zones associated with phyllic alteration (sericite-pyrite ± silica) with sulphides, pyrite dominated with minor chalcopyrite and sphalerite ranging from trace to up to 20%, and local visible gold. Mineralization is hosted in rhyolites or mafic-intermediate volcanics frequently at or near faults or the contact with felsic porphyritic intrusions.

 

Zone 27

Mineralization most commonly occurs as replacement-type characterized by 5% to 50% disseminated, stringer, semi-massive or stockwork pyrite, ptygmatic tourmaline veins, quartz-tourmaline crustiform veins, local quartz-carbonate veins, and local visible gold. Mineralization is associated with moderate to strong sericite, weak to strong silica, weak chlorite and carbonate and locally weak fuchsite and is hosted in strongly altered andesites, in or at the contact of the rhyolite, or along the contacts with felsic porphyritic intrusions.

F-Zone

Mineralization is hosted in sheared andesites with carbonate replacement or quartz veining and occurs as quartz ± ankerite veinlets or as replacement type in shear zones and is characterised by trace to 10% pyrite with local visible gold. Alteration is dominated by sericite-fuchsite-tourmaline-pyrite.

 

Bobcat

Mineralization most commonly occurs in gold-bearing quartz-pyrite veins controlled by northeast trending faults and shears and to a lesser extent in minor crustiform quartz-tourmaline-ankerite-pyrite veins and pyrite replacement zones and stockwork. Mineralization is hosted in sheared mafic volcanics, rhyolites near faults, or at the contact with felsic porphyritic intrusions.

Underdog

Mineralization most commonly occurs in gold-bearing quartz-pyrite (± tourmaline) veins and as disseminated, stringer, semi-massive to massive pyrite with minor sphalerite, chalcopyrite and molybdenite associated with strong sericite and silica alteration. Mineralization is hosted along the intrusive contacts of a three-phase composite felsic porphyritic unit which cross-cuts felsic and mafic volcanic sequences.

 

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 Osisko’s 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 determination is estimated at 55-80% of the reported core length interval for the zone. 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. NQ core assays were obtained by either 1-kilogram screen fire assay or standard 50-gram fire-assaying-AA finish or gravimetric finish at (i) ALS Laboratories in Val d’Or, Québec, Vancouver, British Colombia, Lima, Peru or Vientiane, Laos (ii) 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 a Four Acid Digestion-ICP-MS 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 Gold Deposit

The Windfall gold deposit is located between Val-d’Or and Chibougamau in the Abitibi region of Québec, Canada. The mineral resource defined by Osisko, as disclosed in the news release dated February 17, 2021 and supported by the technical report entitled “Mineral Resource Estimate Update for the Windfall Project, Eeyou Istchee James Bay, Québec, Canada” dated March 8, 2021 (with an effective date of November 30, 2020), and assuming a cut-off grade of 3.50 g/t Au, comprises 521,000 tonnes at 11.3 g/t Au (189,000 ounces) in the measured mineral resource category, 5,502,000 tonnes at 9.4 g/t Au (1,668,000 ounces) in the indicated mineral resource category and 16,401,000 tonnes at 8.0 g/t Au (4,244,000 ounces) in the inferred mineral resource category. The key assumptions, parameters and methods used to estimate the mineral resource estimate disclosed in the February 17, 2021 news release are further described in the full technical report prepared by BBA Inc. in accordance with NI 43-101 and is available on SEDAR (www.sedar.com) under the Corporation’s issuer profile. The Windfall gold deposit is currently one of the highest-grade resource-stage gold projects in Canada and has world-class scale. Mineralization occurs in three principal zones: Lynx, Main Zone, and Underdog. Mineralization is generally comprised of sub-vertical zones following intrusive porphyry contacts plunging to the northeast. The resources are defined from surface to a depth of 1,600 metres as it now includes the Triple 8 (T8) zone. The resources excluding T8 are defined from surface to a depth of 1,200 metres. The deposit remains open along strike and at depth. Mineralization has been identified at surface in some areas and as deep as 2,625 metres in others with significant potential to extend mineralization 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% interest in the high-grade Windfall 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 Quévillon area (over 2,700 square kilometres).

 

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 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”, “potential”, “feasibility”, “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 Windfall gold deposit being one of the highest-grade resource-stage gold projects in Canada and having world-class scale; the key assumptions, parameters and methods used to estimate the mineral resource estimate disclosed in this news release; the prospects, if any, of the Windfall gold deposit; timing and ability of Osisko to file a technical report for the mineral resource estimate disclosed in this news release; the timing and ability of Osisko, if at all, to publish a feasibility study for the Windfall gold deposit; the amount and type of drilling to be completed and the timing to complete such drilling; the focus of the remaining infill drilling; the trend of grade increase; the Lynx zone remaining open to expansion down plunge; upgrading a inferred mineral resource to a measured mineral resource or indicated mineral resource category; future drilling at the Windfall gold deposit; the significance of historic exploration activities and results. 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 (infill) drilling; property and royalty interests in the Windfall 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
Chief Executive Officer
Telephone (416) 363-8653