Category: Silver / Gold

Osisko Windfall Infills With High-Grade in Multiple Zones

35.7 g/t Au Over 9.8 Metres in Underdog
65.6 g/t Au over 4.2 meters in Caribou
 
TORONTO, March 03, 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.
 
Today’s infill results are from the southwestern areas of the deposit including Zone 27, Underdog, Caribou, F11, Mallard, and Bobcat. Osisko Chief Executive Officer John Burzynski commented: “Infill drilling continues to deliver impressive grade and width results from the Windfall deposit.”
 
The table below contains resource definition infill intercepts located inside defined February 2021 mineral resource estimate blocks (see Osisko news release dated February 17, 2021). Significant new analytical results are presented below, including 73 intercepts in 33 drill holes (24 from surface, 9 from underground) and 10 wedges.
 
 
Selected intercepts include: 35.7 g/t Au over 9.8 metres, 70.7 g/t Au over 2.0 metres, and 50.4 g/t Au over 3.6 metres in OSK-W-20-2407; 65.6 g/t Au over 4.2 metres in OSK-W-20-2390; 60.8 g/t Au over 2.0 metres in OSK-W-20-2405; 39.0 g/t Au over 3.0 metres in OSK-W-20-2400; 55.2 g/t Au over 2.0 metres in OSK-W-20-2399 and 18.9 g/t Au over 5.5 metres in OSK-W-20-2354-W2. Maps showing hole locations and full analytical results are available at www.osiskomining.com
Infill 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-20-852-W4 725.0 727.0 2.0 6.83   Caribou_2212 Caribou
including 725.6 726.0 0.4 27.6  
OSK-W-20-913-W1 634.7 637.0 2.3 3.39   Caribou_2523 Caribou
including 634.7 635.0 0.3 18.6  
  851.0 853.3 2.3 11.1   Caribou_2219 Caribou
including 851.0 851.5 0.5 47.2  
OSK-W-20-913-W2 715.0 717.8 2.8 3.89   Caribou_2210 Caribou
  846.0 848.0 2.0 15.5   Caribou_2219 Caribou
including 846.0 846.7 0.7 44.0  
OSK-W-20-2354-W1 647.0 650.5 3.5 14.6   Caribou_2233 Caribou
  674.2 677.4 3.2 24.7   Caribou_2208 Caribou
including 677.0 677.4 0.4 77.9  
OSK-W-20-2354-W2 641.0 646.5 5.5 18.9   Caribou_2233 Caribou
including 642.8 643.1 0.3 61.9  
OSK-W-20-2354-W3 632.0 635.0 3.0 8.61   Caribou_2214 Caribou
  665.7 670.0 4.3 7.53   Caribou_2208 Caribou
including 669.0 670.0 1.0 17.1  
OSK-W-20-2354-W4 498.8 501.0 2.2 3.79   Caribou Caribou
  649.0 651.0 2.0 6.43   Caribou_2233 Caribou
  673.0 676.0 3.0 16.7   Caribou_2208 Caribou
  708.0 711.0 3.0 4.97   Caribou_2220 Caribou
OSK-W-20-2359 360.8 363.0 2.2 5.96   Caribou Caribou
OSK-W-20-2359-W1 361.0 363.0 2.0 6.17   Caribou Caribou
  662.0 664.9 2.9 4.88   Caribou_2206 Caribou
OSK-W-20-2366 459.0 461.0 2.0 4.90   Caribou_2210 Caribou
including 460.0 461.0 1.0 9.13  
OSK-W-20-2373 600.0 602.0 2.0 3.14   Caribou_2241 Caribou
including 600.6 601.4 0.8 7.07  
OSK-W-20-2376 320.3 322.3 2.0 3.56   Caribou_2116 Caribou
  432.6 436.0 3.4 5.32   Caribou_2235 Caribou
including 435.0 436.0 1.0 13.3  
OSK-W-20-2377 741.0 743.2 2.2 3.22   Caribou_2553 Caribou
OSK-W-20-2387 661.2 663.2 2.0 8.69   Caribou_2233 Caribou
OSK-W-20-2388 537.0 539.7 2.7 4.76   Caribou_2215 Caribou
  610.7 614.2 3.5 13.8   Caribou_2217 Caribou
including 610.7 611.0 0.3 87.5  
  639.3 641.8 2.5 4.14   Caribou_2218 Caribou
including 640.4 641.1 0.7 11.0  
  645.4 647.5 2.1 3.87   Caribou_2218 Caribou
including 646.0 646.5 0.5 16.1  
OSK-W-20-2390 594.8 599.0 4.2 65.6 51.2 Caribou_2241 Caribou
including 596.9 597.2 0.3 147 100
and 597.5 598.1 0.6 178 100
OSK-W-20-2399 673.0 675.0 2.0 55.2 20.2 Caribou_2212 Caribou
including 674.0 674.4 0.4 275 100
OSK-W-20-2400 750.0 753.0 3.0 39.0 36 Caribou_2215 Caribou
including 752.0 753.0 1.0 109 100
  797.0 802.0 5.0 6.32   Caribou_2220 Caribou
including 798.0 799.0 1.0 16.4  
  858.0 861.7 3.7 6.19   Caribou_2219 Caribou
including 860.0 861.3 1.3 12.6  
OSK-W-20-2405 262.0 264.0 2.0 60.8 42.4 Caribou_2106 Caribou
including 262.7 263.5 0.8 146 100
  622.0 624.0 2.0 4.35   Caribou_2214 Caribou
including 622.0 622.6 0.6 11.2  
  626.5 630.0 3.5 16.8   Caribou_2214 Caribou
including 627.5 628.0 0.5 56.0  
OSK-W-20-2405-W1 655.9 657.9 2.0 16.6   Caribou_2233 Caribou
including 656.5 657.0 0.5 44.4  
OSK-W-20-2407 662.0 665.6 3.6 50.4 46.6 Underdog_4101 Underdog
including 663.6 664.4 0.8 184 100
  681.0 683.0 2.0 3.77   Underdog_4100 Underdog
  690.0 699.8 9.8 35.7   Underdog_4100 Underdog
including 690.0 691.0 1.0 85.0  
and 695.0 696.0 1.0 76.4  
  705.0 707.0 2.0 70.7 21.9 Underdog_4102 Underdog
including 706.3 706.7 0.4 344 100
OSK-W-20-2410 686.4 688.4 2.0 6.69   Caribou_2214 Caribou
OSK-W-20-2414 628.0 630.0 2.0 12.0   Caribou_2524 Caribou
including 629.0 630.0 1.0 23.7  
OSK-W-20-2415 608.8 611.0 2.2 9.96   Caribou_2211 Caribou
including 608.8 609.2 0.4 45.9  
  703.4 707.4 4.0 17.4   Caribou_2220 Caribou
including 703.4 703.7 0.3 78.4  
OSK-W-20-2415-W1 638.3 643.2 4.9 12.0   Caribou_2233 Caribou
including 638.3 639.3 1.0 32.5  
OSK-W-20-2425 621.0 624.1 3.1 19.3 14.2 Caribou_2220 Caribou
including 623.8 624.1 0.3 152 100
  709.4 711.4 2.0 3.91   Caribou_2219 Caribou
including 710.0 710.6 0.6 11.5  
OSK-W-20-2432 749.6 751.7 2.1 11.0   Caribou_2208 Caribou
including 750.2 750.9 0.7 28.9  
OSK-W-20-2437 608.4 610.4 2.0 6.62   Caribou_2214 Caribou
including 608.4 609.1 0.7 17.6  
OSK-W-20-2438 600.0 603.9 3.9 10.4   Caribou_2211 Caribou
including 600.0 601.0 1.0 18.6  
OSK-W-20-2440 690.0 692.0 2.0 6.68   Caribou_2217 Caribou
  702.0 705.0 3.0 10.3   Caribou_2220 Caribou
  738.0 740.0 2.0 3.29   Caribou_2218 Caribou
OSK-W-21-2444 451.2 453.4 2.2 4.06   Caribou_2236 Caribou
  558.1 562.1 4.0 17.5   Caribou_2215 Caribou
including 561.1 562.1 1.0 38.1  
  572.0 574.0 2.0 4.30   Caribou_2250 Caribou
including 572.9 573.2 0.3 19.8  
OSK-W-21-2451 729.0 734.6 5.6 8.55   Caribou_2208 Caribou
including 734.0 734.6 0.6 34.0  
  739.5 742.3 2.8 20.7   Caribou_2208 Caribou
OSK-W-21-2455 594.0 596.1 2.1 5.35   Caribou_2211 Caribou
  666.7 668.8 2.1 3.55   Caribou_2208 Caribou
OSK-W-21-2460 438.9 441.7 2.8 9.51   Caribou_2116 Caribou
including 441.4 441.7 0.3 28.0  
WST-20-0479B 36.4 38.5 2.1 4.19   Mallard_5208 Mallard
  269.0 271.0 2.0 9.08   Z27_1123 Zone 27
including 269.0 270.0 1.0 18.0  
WST-20-0517 77.4 79.5 2.1 18.9   Mallard_5211 Mallard
including 77.4 78.0 0.6 47.1  
WST-20-0519 59.0 61.0 2.0 6.07   Mallard_5208 Mallard
WST-20-0520 176.2 178.3 2.1 6.20   Z27_1123 Zone 27
including 176.2 176.7 0.5 20.5  
WST-20-0521 191.3 193.7 2.4 4.40   Z27_1102 Zone 27
  195.2 197.2 2.0 4.76   Z27_1102 Zone 27
  231.9 234.3 2.4 7.99   Z27_1123 Zone 27
including 233.9 234.3 0.4 31.7  
WST-20-0555 118.8 121.6 2.8 10.8   Bobcat_2350 Bobcat
including 119.5 119.9 0.4 24.6  
and 121.0 121.6 0.6 23.2  
WST-20-0566 13.0 15.3 2.3 5.64   Mallard_5211 Mallard
including 14.0 14.3 0.3 15.7  
WST-20-0566A 255.5 259.3 3.8 13.4   Caribou_2100 Caribou
including 255.8 256.1 0.3 37.6  
and 259.0 259.3 0.3 83.6  
WST-20-0627 14.0 16.9 2.9 8.32   Mallard_5211 Mallard

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-20-852-W4 330 -55 873 452874 5434552 398 2875
OSK-W-20-913-W1 334 -52 939 452878 5434419 401 2825
OSK-W-20-913-W2 334 -52 913 452878 5434419 401 2825
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-W3 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-20-2359-W1 335 -61 696 452694 5434440 401 2675
OSK-W-20-2366 323 -55 534 452682 5434624 398 2750
OSK-W-20-2373 335 -65 647 452595 5434393 401 2550
OSK-W-20-2376 325 -55 510 452689 5434637 397 2750
OSK-W-20-2377 132 -49 1326 452702 5435548 409 3225
OSK-W-20-2387 336 -59 717 452694 5434440 401 2675
OSK-W-20-2388 326 -61 699 452715 5434606 397 2775
OSK-W-20-2390 330 -65 647 452595 5434393 401 2550
OSK-W-20-2399 333 -54 864 452874 5434552 398 2875
OSK-W-20-2400 336 -53 884 452876 5434419 402 2825
OSK-W-20-2405 332 -58 723 452694 5434440 401 2675
OSK-W-20-2405-W1 332 -58 716 452694 5434440 401 2675
OSK-W-20-2407 347 -55 993 452315 5434419 399 2325
OSK-W-20-2410 338 -62 768 452727 5434358 402 2650
OSK-W-20-2414 337 -54 882 452880 5434419 402 2825
OSK-W-20-2415 328 -54 755 452738 5434474 401 2725
OSK-W-20-2415-W1 328 -54 762 452738 5434474 401 2725
OSK-W-20-2425 336 -60 747 452715 5434606 397 2775
OSK-W-20-2432 333 -57 864 452809 5434415 404 2750
OSK-W-20-2437 329 -62 630 452597 5434393 401 2550
OSK-W-20-2438 331 -60 729 452695 5434401 402 2650
OSK-W-20-2440 330 -52 807 452738 5434474 401 2725
OSK-W-21-2444 337 -59 636 452715 5434606 397 2775
OSK-W-21-2451 330 -58 803 452809 5434415 404 2750
OSK-W-21-2455 328 -53 780 452738 5434474 401 2725
OSK-W-21-2460 332 -55 786 452732 5434537 399 2750
WST-20-0479B 138 -59 402 452281 5434975 262 2575
WST-20-0517 140 -55 400 452281 5434975 262 2575
WST-20-0519 136 -45 162 452282 5434976 262 2575
WST-20-0520 135 -46 388 452281 5434975 263 2575
WST-20-0521 153 -57 385 452281 5434975 262 2575
WST-20-0555 145 -25 160 452955 5435003 254 3175
WST-20-0566 132 -16 20 452208 5434898 248 2475
WST-20-0566A 132 -16 368 452208 5434898 248 2475
WST-20-0627 130 -18 84 452208 5434899 249 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.

Underdog
Mineralization most commonly occurs in gold-bearing quartz-pyrite (± tourmaline) veins and as disseminated and 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.

F-Zone
Mineralization is hosted in sheared andesites with carbonate replacement or quartz veining and occurs as quartz ± ankerite veinlets or in shear zones as replacement, 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.

Mallard
Mineralization is hosted in sheared mafic volcanics with felsic porphyritic intrusions and occurs as veins associated with sericite-pyrite ± silica ± chlorite alteration and contains pyrite ranging from trace to 30% and local visible gold.

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
Truewidthdeterminationisestimatedat55-80%ofthereportedcorelengthintervalforthezone.Assaysareuncutexceptwhere 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 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, certain of which are described in the February 17, 2021 news release, will be further described in the full technical report being prepared for this updated mineral resource estimate in accordance with NI 43-101, and will be available on SEDAR (www.sedar.com) under the Corporation's issuer profile within 45 days from February 17, 2021. The Windfall gold deposit is currently one of the highest-grade resource-stage gold projects in Canada and has world-class scale. Mineralization occursinthreeprincipalzones:Lynx,Main Zone,andUnderdog.   Mineralization is generallycomprised ofsub-vertical zonesfollowingintrusive porphyrycontactsplungingtothenortheast.The resources are defined fromsurfacetoadepthof1,600metres 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 remainsopen alongstrikeandatdepth.Mineralizationhasbeenidentifiedatsurfaceinsomeareasandasdeepas2,625metres in others with significant potential to extend mineralization down-plunge and atdepth.

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 ChibougamauinQuébecandholdsa100%undividedinterestinalargeareaofclaimsinthesurroundingUrbanBarryarea and nearby Quévillon area (over 2,700 squarekilometres).

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