OSISKO INFILL DRILLING RETURNS HIGH GRADE AT LYNX

106 g/t Au Over 2.4 Metres

(Toronto, April 20, 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 41 intercepts in 17 drill holes (4 from surface, 13 from underground) and 6 wedges. The infill intercepts are located inside defined February 2021 mineral resource estimate (“MRE”) blocks (see Osisko news release dated February 17, 2021).

Osisko Chief Executive Officer John Burzynski commented: “Infill drilling in Lynx and Triple Lynx continues to nicely intersect the inferred blocks from the February 2021 MRE, as expected, and increase our confidence in converting those blocks into the indicated or measured categories. We are currently drilling over 5,000 metres a week at Windfall, on target to complete the infill program by this fall.”

Selected high-grade intercepts include: 106 g/t Au over 2.4 metres in WST-21-0746; 90.4 g/t Au over 2.1 metres in OSK-W-21-2416-W3; 28.3 g/t Au over 4.9 metres in WST-21-0690, 60.9 g/t Au over 2.2 metres in OSK-W-21-2452, and 63.5 g/t Au over 2.0 metres in OSK-W-21-2416-W1. 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-20-2363-W3 659.2 662.0 2.8 3.76   TLX_3178 Triple Lynx
OSK-W-21-2252-W12 916.0 918.0 2.0 15.4   TLX_3161 Triple Lynx
  921.0 923.4 2.4 7.13   TLX_3161 Triple Lynx
including 921.0 921.4 0.4 27.6
  932.4 937.0 4.6 6.60   TLX_3161 Triple Lynx
including 932.4 932.8 0.4 17.3
and 936.0 937.0 1.0 15.9
  971.0 974.0 3.0 12.2   TLX_3163 Triple Lynx
including 973.3 974.0 0.7 39.0
  998.0 1000.0 2.0 3.91   TLX_3163 Triple Lynx
  1024.9 1027.2 2.3 29.2 13.4 TLX_3164 Triple Lynx
including 1024.9 1025.2 0.3 221 100
OSK-W-21-2394-W4 874.8 877.0 2.2 14.3   TLX_3130 Triple Lynx
including 874.8 875.1 0.3 30.0
OSK-W-21-2416-W1 910.0 912.0 2.0 5.18   TLX_3161 Triple Lynx
  969.1 971.1 2.0 6.02   TLX_3164 Triple Lynx
including 970.7 971.1 0.4 28.9
  974.0 976.0 2.0 63.5 25.5 TLX_3164 Triple Lynx
including 975.5 976.0 0.5 252 100
OSK-W-21-2416-W2 965.4 967.4 2.0 8.32   TLX_3163 Triple Lynx
including 965.4 966.5 1.1 14.7
  976.0 978.0 2.0 6.19   TLX_3163 Triple Lynx
  982.8 985.0 2.2 10.3   TLX_3164 Triple Lynx
  1006.1 1009.2 3.1 10.4   TLX_3164 Triple Lynx
including 1008.7 1009.2 0.5 46.9
  1050.0 1053.0 3.0 9.79   TLX_3170 Triple Lynx
including 1052.0 1053.0 1.0 17.0
OSK-W-21-2416-W3 924.5 926.6 2.1 7.06   TLX_3161 Triple Lynx
  934.5 938.4 3.9 8.78   TLX_3161 Triple Lynx
  1024.0 1029.0 5.0 11.2   TLX_3162 Triple Lynx
including 1024.0 1024.3 0.3 57.9
and 1026.0 1027.0 1.0 28.0
  1047.8 1049.9 2.1 90.4 36.3 TLX_3170 Triple Lynx
including 1047.8 1048.2 0.4 384 100
  1069.0 1071.5 2.5 4.82   TLX_3172 Triple Lynx
including 1070.8 1071.5 0.7 11.2
  1080.0 1082.0 2.0 36.4   TLX_3172 Triple Lynx
 OSK-W-21-2452 829.7 831.9 2.2 60.9 30.6 TLX_3195 Triple Lynx
including 831.0 831.6 0.6 211 100
OSK-W-21-2459 883.4 885.6 2.2 5.68   TLX_3184 Triple Lynx
including 883.4 884.1 0.7 13.8
OSK-W-21-2493 559.2 561.5 2.3 19.8   TLX_3184 Triple Lynx
including 560.8 561.1 0.3 72.6
OSK-W-21-2495 633.3 635.8 2.5 3.99   LXM_3304 Lynx
including 633.3 633.8 0.5 18.2
WST-20-0481 111.5 113.5 2.0 12.3   LXM_3304 Lynx
including 113.0 113.5 0.5 45.1
  115.0 117.0 2.0 5.29   LXM_3304 Lynx
including 116.6 117.0 0.4 10.8
WST-20-0605A 265.0 267.3 2.3 28.6   LXSW_3500 Lynx SW
including 266.4 267.0 0.6 86.9
WST-21-0619A 214.0 216.0 2.0 20.0   TLX_3161 Triple Lynx
including 214.0 214.4 0.4 96.4
WST-21-0674 168.7 171.1 2.4 26.9   LXM_3304 Lynx
including 169.1 169.6 0.5 94.1
WST-21-0689A 316.7 318.7 2.0 31.2 29.3 TLX_3169 Triple Lynx
including 317.6 317.9 0.3 89.0
and 318.4 318.7 0.3 113 100
WST-21-0690 231.0 235.9 4.9 28.3   TLX_3161 Triple Lynx
including 231.6 232.2 0.6 86.7
and 234.4 235.0 0.6 72.1
WST-21-0691 218.4 222.0 3.6 20.4   TLX_3161 Triple Lynx
including 219.4 220.0 0.6 65.4
WST-21-0696 448.8 451.0 2.2 5.06   LX4_3450 Lynx 4
WST-21-0701 126.0 128.0 2.0 27.9   LXM_3304 Lynx
including 126.5 127.3 0.8 69.8
  142.5 144.8 2.3 17.3   LXM_3359 Lynx
including 143.5 144.5 1.0 39.5
WST-21-0702 121.9 124.2 2.3 24.7   LXM_3304 Lynx
WST-21-0740 122.0 124.8 2.8 3.58   LXM_3304 Lynx
including 123.0 123.4 0.4 18.7
WST-21-0745 184.5 187.0 2.5 31.1   LXM_3304 Lynx
including 185.7 186.1 0.4 85.6
WST-21-0746 190.5 192.9 2.4 106 66.8 LXM_3304 Lynx
including 190.5 191.0 0.5 109 100
and 191.0 191.5 0.5 152 100
and 191.5 192.1 0.6 207 100

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, TLX = Triple Lynx and LXSW = Lynx Southwest.

 

Drill hole location

Hole Number Azimuth

(°)

Dip

(°)

Length (m) UTM E UTM N Elevation Section
OSK-W-20-2363-W3 139 -52 1185 452930 5435548 419 3425
OSK-W-21-2252-W12 129 -54 1161 453241 5435694 415 3750
OSK-W-21-2394-W4 138 -52 920 452923 5435467 414 3375
OSK-W-21-2416-W1 123 -54 1083 453169 5435624 412 3650
OSK-W-21-2416-W2 123 -54 1266 453169 5435624 412 3650
OSK-W-21-2416-W3 123 -54 1128 453169 5435624 412 3650
OSK-W-21-2445-W3 141 -50 753 452906 5435434 415 3325
OSK-W-21-2452 137 -56 891 453008 5435388 412 3400
OSK-W-21-2459 132 -52 1227 452997 5435607 425 3500
OSK-W-21-2493 134 -54 1080 453008 5435388 412 3400
OSK-W-21-2495 123 -54 1257 453426 5435565 410 3850
WST-20-0481 154 1 179 453450 5435264 116 3725
WST-20-0605A 148 -61 532 453105 5435065 231 3325
WST-21-0619A 174 -61 249 453507 5435327 -7 3800
WST-21-0672 141 -44 327 453508 5435327 -7 3800
WST-21-0674 134 -46 261 453508 5435327 -7 3800
WST-21-0689A 161 -64 397 453356 5435272 16 3650
WST-21-0690 150 -63 307 453356 5435272 16 3650
WST-21-0691 152 -58 385 453356 5435272 16 3650
WST-21-0696 137 -49 492 453229 5435127 134 3475
WST-21-0701 148 -22 172 453356 5435272 17 3650
WST-21-0702 151 -14 166 453356 5435272 17 3650
WST-21-0740 168 -25 150 453507 5435326 -6 3800
WST-21-0745 130 -51 246 453508 5435327 -7 3800
WST-21-0746 117 -44 240 453508 5435327 7 3800

 

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.

 

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 3.0 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 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