OSISKO DRILLING ADDS HIGH-GRADE ACROSS WINDFALL DEPOSIT

388 g/t Au over 2.2 Metres Lynx Main

135 g/t Au over 6.3 Metres in Lynx 4

(Toronto, August 17, 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 39 intercepts in 17 drill holes (11 from surface, 6 from underground) and 10 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 in a defined zone or corridor but do not yet correlate to a specific wireframe.

Osisko Chief Executive Officer John Burzynski commented: “This week’s drill results demonstrate once again the strong continuity of the Windfall mineralization with high-grade intercepts in multiple different zones across the deposit, namely Lynx Main, Lynx 4, and Underdog. Expansion results continue to confirm that many zones remain open to growth, as demonstrated by hole OSK-W-21-2540-W1, which extends Triple Lynx 3163 wireframe 80 meters to the east.”

Selected high-grade intercepts include: 388 g/t Au over 2.2 metres in WST-21-0823; 135 g/t Au over 6.3 metres and 24.3 g/t Au over 5.2 metres in WST-21-0828; 187 g/t Au over 2.5 metres in WST-21-0763A; 113 g/t Au over 3.7 metres in OSK-W-21-2479-W5; 130 g/t Au over 2.9 metres and 38.8 g/t Au over 3.2 metres in OSK-W-21-2287-W3; 61.5 g/t Au over 3.0 metres in OSK-W-21-2544; and 41.5 g/t Au over 4.4 metres in OSK-W-21-2520. 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-17-1260 1067.4 1073.0 5.6 9.38   UDD_4123 Underdog
including 1072.0 1073.0 1.0 23.8
OSK-W-20-2283-W5 826.0 828.0 2.0 16.7 16.5 TLX_3184 Triple Lynx
including 826.8 827.1 0.3 101 100
OSK-W-21-1432-W4 938.0 940.0 2.0 7.17   LX4_3437 Lynx 4
including 938.5 939.0 0.5 26.6
OSK-W-21-1827-W5 510.0 512.4 2.4 17.3   CA2_2231 Caribou
including 511.1 511.7 0.6 60.9
OSK-W-21-2287-W3 1229.8 1233.0 3.2 38.8   LX4_3449 Lynx 4
including 1232.0 1233.0 1.0 98.5
1243.6 1246.5 2.9 130 73.1 LX4_3449 Lynx 4
including 1245.3 1245.6 0.3 324 100
and 1245.6 1245.9 0.3 258 100
OSK-W-21-2467 564.0 566.0 2.0 7.44   CA2_2232 Caribou
568.0 570.2 2.2 51.2 47.9 CA2_2232 Caribou
including 568.5 569.2 0.7 111 100
OSK-W-21-2470-W6 1057.0 1059.5 2.5 16.4   TLX_3170 Triple Lynx
including 1058.0 1058.4 0.4 42.3
OSK-W-21-2479-W6 775.4 777.5 2.1 5.14   UDD_4107 Underdog
OSK-W-21-2512-W1 772.0 778.0 6.0 13.8   UDD_4104 Underdog
including 772.0 773.5 1.5 38.2
OSK-W-21-2520 813.7 816.0 2.3 6.19   UDD_4121 Underdog
including 814.4 814.9 0.5 27.6
818.6 823.0 4.4 41.5 30.8 UDD_4121 Underdog
including 818.6 818.9 0.3 257 100
including 821.0 821.8 0.8 96.7
1089.0 1091.4 2.4 11.0   UDD_4911 Underdog
including 1089.9 1090.7 0.8 32.2
OSK-W-21-2531 1071.0 1076.0 5.0 5.83   UDD_4915 Underdog
OSK-W-21-2537 985.5 988.1 2.6 18.1   TLX_3163 Triple Lynx
including 987.5 988.1 0.6 51.9
1057.7 1059.8 2.1 13.8   TLX_3170 Triple Lynx
including 1058.9 1059.3 0.4 68.1
OSK-W-21-2544 795.0 798.0 3.0 61.5 36.9 TLX_3171 Triple Lynx
including 795.0 795.8 0.8 192 100
818.0 820.0 2.0 15.0   TLX_3184 Triple Lynx
including 818.0 819.0 1.0 29.3
OSK-W-21-2554 136.9 139.2 2.3 4.75   F51_6008 F-51
WST-20-0505A 49.0 51.5 2.5 9.42   LXM_3339 Lynx
including 50.2 50.8 0.6 38.8
WST-21-0763A 169.5 172.0 2.5 187 69.3 LXM_3304 Lynx
including 170.2 171.1 0.9 377 100
WST-21-0802A 390.0 392.0 2.0 19.0   LSW_3556 Lynx SW
including 390.0 390.4 0.4 59.9
394.0 396.0 2.0 6.37   LSW_3556 Lynx SW
408.0 410.0 2.0 31.8   LSW_3556 Lynx SW
including 408.8 409.6 0.8 77.8
WST-21-0823 165.2 167.4 2.2 388 47.4 LXM_3304 Lynx
including 165.2 165.5 0.3 2600 100
WST-21-0828 489.1 494.3 5.2 24.3 23.3 LX4_3430 Lynx 4
including 493.4 494.3 0.9 106 100
520.0 526.3 6.3 135 48.5 LX4_3440 Lynx 4
including 521.6 522.9 1.3 303 100
including 525.0 526.0 1.0 380 100

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See “Quality Control and Reporting Protocols” below. LXM = Lynx Main, LX4 = Lynx 4, LSW = Lynx Southwest, TLX = Triple Lynx, CA2 = Caribou and UDD = Underdog.

 

 

 

 

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-20-2437 313.0 315.0 2.0 5.89   Caribou Caribou
OSK-W-21-2479-W5 728.0 731.7 3.7 113 39.3 UDD Underdog
including 731.0 731.7 0.7 488 100
OSK-W-21-2520 935.7 943.3 7.6 13.1 12.4 UDD Underdog
including 938.6 939.0 0.4 114 100
OSK-W-21-2532 809.0 815.2 6.2 9.91   UDD Underdog
including 809.0 809.5 0.5 40.4
including 812.5 813.1 0.6 35.4
OSK-W-21-2540-W1 966.0 968.3 2.3 5.05   TLX_3163 Triple Lynx
969.9 976.3 6.4 18.1   TLX_3163 Triple Lynx
including 969.9 970.5 0.6 57.8
including 974.5 975.1 0.6 67.3
OSK-W-21-2540-W2 927.0 929.4 2.4 14.1   TLX_3163 Triple Lynx
including 927.0 927.5 0.5 55.0
OSK-W-21-2544 859.9 862.0 2.1 11.2   TLX_3198 Triple Lynx
including 861.0 861.4 0.4 34.4
OSK-W-21-2549 626.4 628.4 2.0 5.73   Caribou Caribou
OSK-W-21-2559 586.0 588.0 2.0 6.70   Caribou Caribou
including 586.0 587.0 1.0 13.2
WST-21-0841 286.0 288.0 2.0 12.1   LSW Lynx SW
including 287.0 288.0 1.0 23.7

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See “Quality Control and Reporting Protocols” below. LSW = Lynx Southwest, TLX = Triple Lynx, UDD = Underdog.

 

Drill hole location

Hole Number Azimuth (°) Dip (°) Length (m) UTM E UTM N Elevation Section
OSK-W-17-1260 329 -49 1134 452865 5434568 397 2875
OSK-W-20-2283-W5 135 -50 1043 452997 5435607 425 3500
OSK-W-20-2437 329 -62 630 452597 5434393 401 2550
OSK-W-21-1432-W4 132 -55 1053 453811 5435779 400 4300
OSK-W-21-1827-W5 331 -58 1164 452506 5434390 403 2475
OSK-W-21-2287-W3 116 -53 1368 453607 5435714 404 4075
OSK-W-21-2467 331 -54 717 452685 5434474 402 2675
OSK-W-21-2470-W6 132 -59 1119 453304 5435639 415 3775
OSK-W-21-2479-W5 344 -55 978 452315 5434419 399 2325
OSK-W-21-2479-W6 344 -55 1014 452315 5434419 399 2325
OSK-W-21-2512-W1 331 -54 1089 452448 5434465 400 2475
OSK-W-21-2520 337 -56 1140 452596 5434392 401 2550
OSK-W-21-2531 344 -62 1188 452566 5434415 403 2550
OSK-W-21-2532 341 -60 1107 452480 5434428 401 2475
OSK-W-21-2537 114 -54 1243 452981 5435549 420 3450
OSK-W-21-2540-W1 117 -60 1053 453465 5435640 410 3925
OSK-W-21-2540-W2 117 -60 1314 453465 5435640 410 3925
OSK-W-21-2544 128 -50 1161 452961 5435529 419 3425
OSK-W-21-2549 332 -58 723 452703 5434455 401 2675
OSK-W-21-2554 131 -57 189 453426 5435858 405 4000
OSK-W-21-2559 327 -51 589 452829 5434550 398 2850
WST-20-0505A 183 -46 331 453227 5435125 134 3475
WST-21-0763A 120 -39 567 453507 5435332 -47 3800
WST-21-0802A 149 -65 448 452953 5435003 253 3175
WST-21-0823 120 -35 545 453507 5435332 -47 3800
WST-21-0828 123 -42 645 453507 5435331 -48 3800
WST-21-0841 125 -65 438 453106 5435066 231 3325

 

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, 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.

 

Lynx Zone

Mineralization occurs as grey to translucent quartz-carbonate-pyrite-tourmaline veins and pyrite replacement zones and stockworks. Vein-type mineralization is associated with haloes of pervasive sericite-pyrite ± silica alteration and contain sulphides (predominantly pyrite with minor amounts of chalcopyrite, sphalerite, galena, arsenopyrite, and pyrrhotite) and local visible gold. Replacement mineralization is associated with strong pervasive silica-sericite-ankerite ± tourmaline alteration and contains disseminated pyrite from trace to 80% with local visible gold. Pyrite stockworks can form envelopes that reach several tens of metres thick. Fuchsite alteration is common and is spatially constrained to near the gabbros. Mineralization occurs at or near geological contacts between felsic porphyritic or fragmental intrusions and the host rhyolites or gabbros and locally can be hosted along the gabbro-rhyolite contact.

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.

 

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

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 3.5 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 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 gold 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

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