Category: Silver / Gold

Osisko Drilling Adds More High Grade at Windfall

TORONTO, May 18, 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 61 intercepts in 20 drill holes (15 from surface, 5 from underground) and 9 wedges. The infill intercepts are located inside defined February 2021 mineral resource estimate (“MRE”) blocks (see Osisko news release dated February 17,2021). The expansion intercepts are located outside the February 2021 MRE blocks 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: “Today’s drilling results in the Main Zone areas of Windfall, including Underdog, mirror the results reported over the past weeks in Lynx: infill drilling continues to define grade continuity inside our MRE blocks and expansion drilling is adding ounces in the immediate surrounding areas. All infill and expansion drilling at Windfall is in support of our upcoming feasibility study.”

Selected high-grade intercepts include: 78.5 g/t Au over2.0metres58.3 g/t Au over 2.0 metres and 40.0 g/t Au over 2.0 metres in OSK-W-21-2479, 43.5 g/t Au over 2.7 metres and 38.5 g/t Au over 2.7 metres in OSK-W-21-2442-W1, 18.3 g/t Au over 6.1 metres in OSK-W-21-2496, 40.3 g/t Au over 2.4 metres in OSK-W-21-2455-W1, 44.4 g/tAu over 2.0 metres in OSK-W-21-2463, 42.8 g/t Auover 2.0 metres in WST-21-0643, and 40.2 g/t Auover 2.0 metres in OSK-W-20-2439. Maps showing hole locations and full analytical results are available at www.osiskomining.com

Infill Drilling

Hole Number From
(m)
To
(m)
Interval
(m)
Au (g/t)
uncut
Au (g/t)
cut to
100 g/t
Zone Corridor
OSK-W-17-777 839.0 841.0 2.0 3.52   Underdog_4101 Underdog
  849.0 851.0 2.0 5.41   Underdog_4101 Underdog
including 850.6 851.0 0.4 20.0  
  856.9 858.9 2.0 5.63   Underdog_4101 Underdog
including 857.5 857.8 0.3 27.0  
OSK-W-20-913-W2 801.0 803.0 2.0 5.04   Caribou_2220 Caribou
OSK-W-21-1827-W2 504.0 506.0 2.0 15.3   Caribou_2231 Caribou
including 504.9 505.5 0.6 42.7  
  511.3 513.9 2.6 5.11   Caribou_2231 Caribou
including 511.3 512.1 0.8 11.5  
OSK-W-21-2442-W1 447.0 449.0 2.0 5.81   Z27_1203 Zone 27
including 448.3 449.0 0.7 16.3  
  637.3 640.0 2.7 43.5 31.5 Underdog_4101 Underdog
including 637.3 637.6 0.3 74.5  
and 639.6 640.0 0.4 181 100
  960.1 962.8 2.7 38.5 34.7 Underdog_4910 Underdog
including 962.5 962.8 0.3 134 100
OSK-W-21-2455-W1 588.6 590.7 2.1 4.72   Caribou_2232 Caribou
  661.6 663.6 2.0 5.50   Caribou_2208 Caribou
including 663.0 663.6 0.6 17.0  
  666.5 668.8 2.3 4.86   Caribou_2208 Caribou
  770.6 773.0 2.4 40.3 37.6 Caribou Caribou
including 772.1 773.0 0.9 107 100
OSK-W-21-2463 843.0 845.0 2.0 44.4 22.6 Underdog_4111 Underdog
including 843.3 843.7 0.4 209 100
OSK-W-21-2463-W2 840.6 843.0 2.4 3.75   Underdog_4110 Underdog
including 840.6 840.9 0.3 15.9  
  927.0 929.0 2.0 17.3   Underdog_4101 Underdog
including 927.4 928.1 0.7 41.2  
  959.0 961.0 2.0 4.27   Underdog_4100 Underdog
including 960.0 960.5 0.5 14.3  
  972.0 974.0 2.0 4.77   Underdog_4102 Underdog
including 972.0 972.5 0.5 18.1  
  1082.0 1084.0 2.0 5.38   Underdog_4511 Underdog
including 1082.6 1083.0 0.4 26.5  
OSK-W-21-2479 638.0 640.0 2.0 40.0 37.2 Underdog_4100 Underdog
including 639.0 639.7 0.7 108 100
  642.6 649.5 6.9 8.06   Underdog_4100 Underdog
including 645.3 646.1 0.8 22.0  
and 649.0 649.5 0.5 22.8  
OSK-W-21-2486 533.0 535.3 2.3 4.89   Caribou_2232 Caribou
including 534.6 535.3 0.7 10.2  
OSK-W-21-2496 208.0 214.1 6.1 18.3   F51_6008 F-51
including 209.0 210.0 1.0 45.3  
OSK-W-21-2504 163.0 165.4 2.4 5.69   F51_6008 F-51
including 163.5 164.5 1.0 13.3  
OSK-W-21-777-W1 610.7 612.9 2.2 17.1   Caribou_2233 Caribou
OSK-W-21-777-W2 568.0 570.0 2.0 35.2   Caribou_2211 Caribou
  572.0 574.4 2.4 4.90   Caribou_2211 Caribou
  611.0 613.0 2.0 9.76   Caribou_2233 Caribou

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

Expansion Drilling

Hole Number From
(m)
To
(m)
Interval
(m)
Au (g/t)
uncut
Au (g/t)
cut to
100 g/t
Zone Corridor
OSK-W-20-2399-W1 451.0 453.6 2.6 4.00   Caribou Caribou
OSK-W-20-2406 404.0 406.0 2.0 4.76   Caribou Caribou
  506.0 508.0 2.0 11.5   Caribou Caribou
including 506.4 507.0 0.6 28.2  
OSK-W-20-2432 405.0 407.0 2.0 3.65   Caribou Caribou
  763.0 767.0 4.0 11.7   Caribou Caribou
including 763.0 764.0 1.0 40.7  
OSK-W-20-2439 35.0 37.0 2.0 40.2   F11 F11
including 35.0 36.0 1.0 77.0  
OSK-W-20-2440 314.0 316.9 2.9 3.67   Caribou Caribou
OSK-W-20-2441 181.5 184.4 2.9 5.07   Caribou Caribou
OSK-W-21-1882-W1 744.0 746.0 2.0 5.16   Underdog Underdog
OSK-W-21-2442-W1 945.0 947.1 2.1 8.49   Underdog Underdog
  948.0 950.0 2.0 3.52   Underdog Underdog
OSK-W-21-2451 436.0 438.0 2.0 4.32   Caribou Caribou
including 436.4 437.0 0.6 14.0  
OSK-W-21-2455 440.0 442.0 2.0 3.66   Caribou Caribou
OSK-W-21-2463 323.0 325.0 2.0 3.55   Caribou Caribou
including 324.0 324.4 0.4 10.2  
  962.0 964.1 2.1 5.85   Underdog Underdog
including 963.1 964.1 1.0 12.2  
  1126.9 1129.0 2.1 7.07   Underdog Underdog
including 1126.9 1127.3 0.4 28.1  
OSK-W-21-2463-W2 940.0 942.0 2.0 4.23   Underdog Underdog
  1051.0 1053.0 2.0 4.17   Underdog Underdog
OSK-W-21-2479 482.0 484.0 2.0 78.5 16.8 Z27 Zone 27
including 482.3 482.6 0.3 511 100
  485.4 489.0 3.6 10.4   Z27 Zone 27
  616.0 618.3 2.3 11.3   Underdog Underdog
including 617.0 617.3 0.3 84.3  
  625.1 627.1 2.0 27.8   Underdog Underdog
including 626.3 627.1 0.8 69.0  
  630.0 632.0 2.0 4.97   Underdog Underdog
including 630.6 631.0 0.4 22.6  
  899.9 901.9 2.0 58.3 37.3 Underdog Underdog
including 900.2 900.9 0.7 160 100
  913.7 916.8 3.1 25.0 17.7 Underdog Underdog
including 916.5 916.8 0.3 176 100
OSK-W-21-2483 282.2 284.5 2.3 7.55   Caribou Caribou
OSK-W-21-2490 436.9 439.0 2.1 5.06   Caribou Caribou
including 437.9 438.2 0.3 35.0  
  560.1 562.1 2.0 4.32   Caribou Caribou
including 561.3 561.6 0.3 10.7  
WST-21-0597 17.7 19.9 2.2 6.48   Bobcat Bobcat
WST-21-0642 150.0 152.0 2.0 4.13   Bobcat Bobcat
including 150.6 151.0 0.4 16.8  
WST-21-0643 163.0 165.0 2.0 42.8   Bobcat Bobcat
including 163.0 164.0 1.0 85.4  
WST-21-0644 86.4 89.6 3.2 6.69   Bobcat Bobcat
including 86.4 87.2 0.8 17.2  
WST-21-0651 88.0 90.2 2.2 3.83   Bobcat Bobcat
including 88.3 89.0 0.7 8.60  

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-17-777 330 -59 1221 452678 5434500 403 2675
OSK-W-20-2399-W1 333 -54 876 452875 5434553 398 2875
OSK-W-20-2406 333 -56 693 452633 5434281 400 2525
OSK-W-20-2432 333 -57 864 452809 5434415 404 2750
OSK-W-20-2439 147 -50 360 452515 5436029 406 3275
OSK-W-20-2440 330 -52 807 452738 5434475 401 2725
OSK-W-20-2441 338 -59 405 452715 5434606 397 2775
OSK-W-20-913-W2 334 -52 913 452878 5434419 401 2825
OSK-W-21-1827-W2 331 -58 690 452506 5434390 403 2475
OSK-W-21-1882-W1 328 -57 1197 452469 5434405 400 2450
OSK-W-21-2442-W1 347 -53 1011 452315 5434419 399 2325
OSK-W-21-2451 330 -58 803 452809 5434415 404 2750
OSK-W-21-2455 328 -53 780 452738 5434476 401 2725
OSK-W-21-2455-W1 328 -53 798 452738 5434476 401 2725
OSK-W-21-2463 339 -65 1335 452616 5434449 403 2600
OSK-W-21-2463-W2 339 -65 1325 452616 5434449 403 2600
OSK-W-21-2479 344 -55 993 452315 5434419 399 2325
OSK-W-21-2486 334 -57 1167 452596 5434392 401 2550
OSK-W-21-2483 328 -58 756 452731 5434634 397 2800
OSK-W-21-2490 338 -61 786 452756 5434466 400 2725
OSK-W-21-2496 158 -50 279 453484 5435967 403 4100
OSK-W-21-2504 161 -47 186 453533 5435947 403 4125
OSK-W-21-777-W1 330 -59 969 452678 5434500 403 2675
OSK-W-21-777-W2 330 -59 1170 452678 5434500 403 2675
WST-21-0597 151 -2 132 452817 5434943 275 3025
WST-21-0642 149 -38 172 452955 5435003 253 3175
WST-21-0643 129 -41 220 452955 5435003 253 3175
WST-21-0644 130 -4 120 452955 5435003 254 3175
WST-21-0651 153 -52 400 452954 5435003 253 3175

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-Zones
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), Director of Exploration for Osisko's Windfall 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 Estimate (MRE) defined by Osisko, as disclosed in the news release dated February 17, 2021 is supported by the technical report entitled “Preliminary Economic Assessment Update for the Windfall Project” dated April 26, 2021 (that includes Windfall Mineral Resource Estimate 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