Category: Silver / Gold

Osisko Infill Drilling Returns High Grade at Windfall

73.3 g/t Au over 4.4 metresin Underdog
67.3 g/t Au Over 2.3 Metres in Caribou
 
TORONTO, March 30, 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 52 intercepts in 15 drill holes (12 from surface, 3 from underground) and 7 wedges. The intercepts are located inside defined February 2021 mineral resource estimate (“MRE”) blocks (see Osisko news release dated February 17, 2021).
 
Selected high-grade intercepts include: 73.3 g/t Au over 4.4 metres in OSK-W-20-2407-W1; 36.7 g/t Au over 5.9 metres in OSK-W-20-2423; 67.3 g/t Au over 2.3 metres in OSK-W-21-2460-W1; 21.3 g/t Au over 5.2 metres in OSK-W-20-2415-W1 and 50.2 g/t Au over 2.1 metres in OSK-W-20-2414. 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-20-2359 631.7 633.7 2.0 21.1   Caribou_2214 Caribou
  636.1 644.0 7.9 10.2   Caribou_2214 Caribou
including 642.0 643.0 1.0 30.6  
OSK-W-20-2387 639.0 641.0 2.0 6.72   Caribou_2214 Caribou
  647.0 649.4 2.4 4.55   Caribou_2214 Caribou
OSK-W-20-2387-W1 652.4 654.7 2.3 16.7   Caribou_2233 Caribou
including 653.0 653.6 0.6 55.9  
OSK-W-20-2399 663.0 665.0 2.0 9.93   Caribou_2212 Caribou
including 663.7 664.6 0.9 20.6  
OSK-W-20-2399-W2 690.0 692.0 2.0 44.9 15.4 Caribou_2212 Caribou
including 691.7 692.0 0.3 297 100
OSK-W-20-2405-W2 631.4 633.4 2.0 7.61   Caribou_2214 Caribou
including 631.9 632.4 0.5 24.9  
OSK-W-20-2407-W1 649.0 651.1 2.1 28.2   Underdog_4101 Underdog
including 649.0 649.8 0.8 44.1  
  702.6 707.0 4.4 73.3   Underdog_4102 Underdog
  748.0 750.0 2.0 18.0   Underdog_4106 Underdog
including 748.3 749.3 1.0 35.1  
  812.0 814.3 2.3 13.6   Underdog_4906 Underdog
including 812.0 812.8 0.8 38.0  
OSK-W-20-2414 827.6 829.7 2.1 50.2 33.3 Caribou_2252 Caribou
including 829.2 829.7 0.5 171 100
  858.0 860.1 2.1 30.6 24.8 Caribou_2219 Caribou
including 858.7 859.2 0.5 125 100
OSK-W-20-2415-W1 703.0 708.0 5.0 4.45   Caribou_2220 Caribou
  714.0 716.0 2.0 9.34   Caribou_2218 Caribou
  722.2 727.4 5.2 21.3   Caribou_2218 Caribou
including 722.2 722.6 0.4 79.8  
  729.7 731.8 2.1 5.17   Caribou_2218 Caribou
including 729.7 730.0 0.3 29.7  
OSK-W-20-2423 276.0 279.0 3.0 18.3   Caribou_2106 Caribou
including 277.0 277.5 0.5 48.3  
  595.0 597.0 2.0 3.58   Caribou_2241 Caribou
  817.7 820.0 2.3 8.64   Underdog_4121 Underdog
including 817.7 818.3 0.6 17.8  
  843.0 845.0 2.0 4.92   Underdog_4116 Underdog
including 843.5 844.0 0.5 18.8  
  943.0 948.9 5.9 36.7 28.4 Underdog_4102 Underdog
including 948.2 948.9 0.7 171 100
  1019.0 1021.0 2.0 7.97   Underdog_4511 Underdog
  1048.0 1050.0 2.0 26.5   Underdog_4501 Underdog
including 1049.2 1050.0 0.8 66.2  
  1187.8 1193.0 5.2 13.1   Underdog_4514 Underdog
  1200.3 1203.0 2.7 8.75   Underdog_4512 Underdog
OSK-W-20-2425 556.6 558.7 2.1 18.2   Caribou_2215 Caribou
including 557.1 557.4 0.3 86.2  
  561.0 563.0 2.0 5.85   Caribou_2215 Caribou
OSK-W-20-2439 196.8 199.0 2.2 5.54   F11_6001 F-11
OSK-W-21-2442 747.0 749.0 2.0 3.61   Underdog_4107 Underdog
  754.0 756.0 2.0 6.78   Underdog_4107 Underdog
OSK-W-21-2460 652.0 654.0 2.0 16.1   Caribou_2220 Caribou
including 653.1 654.0 0.9 35.5  
  708.6 711.4 2.8 4.06   Caribou_2219 Caribou
OSK-W-21-2460-W1 530.1 533.0 2.9 8.66   Caribou_2236 Caribou
including 530.1 531.0 0.9 19.6  
  559.0 563.2 4.2 3.14   Caribou_2210 Caribou
  667.0 669.3 2.3 67.3 42.8 Caribou_2220 Caribou
including 668.5 669.0 0.5 209 100
  709.0 711.4 2.4 5.11   Caribou_2218 Caribou
including 710.5 711.4 0.9 13.1  
OSK-W-21-2462 586.0 592.7 6.7 3.58   Caribou_2523 Caribou
  710.6 712.9 2.3 3.09   Caribou_2212 Caribou
  840.5 845.0 4.5 8.34   Caribou_2549 Caribou
including 844.0 844.4 0.4 17.9  
OSK-W-21-2462-W1 480.9 483.0 2.1 20.4   Caribou_2536 Caribou
including 480.9 481.9 1.0 42.3  
  594.8 597.0 2.2 4.77   Caribou_2523 Caribou
including 595.6 596.2 0.6 13.7  
OSK-W-21-2463 582.1 586.0 3.9 6.72   Caribou_2241 Caribou
OSK-W-21-2476 506.4 508.6 2.2 6.94   Caribou_2536 Caribou
including 508.2 508.6 0.4 28.4  
  671.6 674.0 2.4 11.0   Caribou_2212 Caribou
including 671.6 672.4 0.8 24.8  
WST-20-0595 82.7 84.8 2.1 10.3   Bobcat_2350 Bobcat
including 83.1 83.7 0.6 28.2  
WST-20-0604 332.2 334.5 2.3 3.91   Caribou_2253 Caribou
including 332.5 333.3 0.8 11.0  
  336.3 338.5 2.2 6.00   Caribou_2253 Caribou
including 336.3 336.6 0.3 36.8  
WST-21-0598 53.0 55.3 2.3 3.18   Bobcat Bobcat
  104.6 106.6 2.0 4.34   Bobcat_2335 Bobcat
  120.0 122.0 2.0 3.57   Bobcat Bobcat
including 120.7 121.0 0.3 20.6  

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-20-2359 335 -61 726 452694 5434440 401 2675
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-20-2399 333 -54 864 452874 5434552 398 2875
OSK-W-20-2399-W2 333 -54 876 452874 5434552 398 2875
OSK-W-20-2405-W2 332 -58 710 452694 5434440 401 2675
OSK-W-20-2407-W1 347 -55 1044 452315 5434419 399 2325
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-20-2423 332 -60 1326 452616 5434449 403 2600
OSK-W-20-2425 336 -60 747 452715 5434606 397 2775
OSK-W-20-2439 147 -50 360 452515 5436029 406 3275
OSK-W-21-2442 347 -53 1053 452315 5434419 399 2325
OSK-W-21-2460 332 -55 789 452732 5434537 399 2750
OSK-W-21-2460-W1 332 -55 795 452732 5434537 399 2750
OSK-W-21-2462 338 -57 888 452874 5434552 398 2875
OSK-W-21-2462-W1 338 -57 855 452874 5434552 398 2875
OSK-W-21-2463 339 -65 1335 452616 5434449 403 2600
OSK-W-21-2476 337 -58 807 452840 5434569 398 2850
WST-20-0595 111 -23 150 452818 5434944 274 3025
WST-20-0604 153 -58 373 452281 5434975 262 2575
WST-21-0598 135 5 144 452817 5434944 275 3025

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.

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
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 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 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 gold 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