Category: Silver / Gold

Osisko Windfall Drilling Returns More High-Grade

TORONTO, Sept. 07, 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 142 intercepts in 32 drill holes (16 from surface, 16 from underground) and 24 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: “Windfall continues to deliver high-grade intercepts, especially in the Lynx and Underdog zones. Infill drilling has consistently delivered throughout our drill campaign, which is winding down this fall as we approach the completion of our drilling for the feasibility study next year. The great potential for growth at Windfall continues to be demonstrated by new high-grade intercepts located outside the February 2021 resource blocks.

Windfall has shown its ability to deliver high-grade results time and time again, it’s a strong and consistent mineralized system. As we move to completion of the infill program at Windfall, we are also beginning to move additional drills to the new Golden Bear discovery area and expect to have an update on our progress there in the coming weeks.”

Selected high-grade intercepts include: 512 g/t Au over 2.4 metres in WST-21-0833;   212 g/t Au over 2.4 metres in WST-21-0842; 86.8 g/t Au over 3.4 metres in OSK-W-21-2287-W4; 141 g/t Au over 2.0 metres and 29.0 g/t Au over 5.5 metres in OSK-W-21-2503-W4; 108 g/t Au over 2.3 metres in OSK-W-21-2531-W1; 42.1 g/t Au over 4.8 metres in OSK-W-21-2470; 17.3 g/t Au over 11.4 metres in OSK-W-21-2537-W1; 83.0 g/t Au over 2.0 metres in OSK-W-21-2548-W2, and 57.6 g/t Au over 2.1 metres in WST-21-0854A. 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-20-2292-W6 862.7 864.8 2.1 5.68   TLX_3184 Triple Lynx
OSK-W-20-2400 1051.7 1054.3 2.6 4.57   UDD_4903 Underdog
  1060.9 1063.0 2.1 17.7   UDD_4904 Underdog
including 1060.9 1061.9 1.0 37.0  
OSK-W-21-1432-W5 932.8 935.0 2.2 3.76   LX4_3437 Lynx 4
  943.0 946.1 3.1 12.5   LX4_3437 Lynx 4
OSK-W-21-1827-W5 1101.7 1104.7 3.0 37.4   UDD_4513 Underdog
including 1102.7 1103.7 1.0 85.9  
  1135.0 1137.0 2.0 5.12   UDD_4514 Underdog
OSK-W-21-1827-W6 503.7 505.7 2.0 8.94   CA2_2231 Caribou
  507.5 510.4 2.9 15.7   CA2_2231 Caribou
including 507.5 508.4 0.9 42.2  
  514.1 516.3 2.2 6.59   CA2_2231 Caribou
including 514.1 514.6 0.5 27.2  
  523.8 526.1 2.3 5.53   CA2_2241 Caribou
including 524.8 525.3 0.5 19.6  
OSK-W-21-1882-W5 903.3 905.6 2.3 16.4   UDD_4515 Underdog
including 903.3 904.2 0.9 39.6  
  957.0 959.0 2.0 4.30   UDD_4501 Underdog
  1020.5 1023.0 2.5 19.2   UDD_4910 Underdog
including 1020.5 1021.4 0.9 52.4  
OSK-W-21-1949-W7 746.4 748.5 2.1 27.0 14.5 LXM_3345 Lynx
including 746.4 746.7 0.3 187 100
  1082.0 1084.0 2.0 3.51   LX4_3430 Lynx 4
OSK-W-21-2067-W7 1089.6 1093.0 3.4 7.02   TLX_3162 Triple Lynx
OSK-W-21-2287-W4 1285.2 1288.6 3.4 86.8 42.1 LX4_3449 Lynx 4
including 1285.9 1286.2 0.3 448 100
and 1286.2 1286.5 0.3 215 100
OSK-W-21-2287-W5 1252.9 1254.9 2.0 8.28   LX4_3449 Lynx 4
  1308.0 1310.7 2.7 23.2   LX4_3445 Lynx 4
OSK-W-21-2470 965.0 969.8 4.8 42.1 34.9 TLX_3163 Triple Lynx
including 969.2 969.8 0.6 158 100
OSK-W-21-2479-W6 906.0 908.0 2.0 6.29   UDD_4502 Underdog
including 907.0 907.5 0.5 24.3  
OSK-W-21-2479-W7 793.6 796.1 2.5 5.90   UDD_4107 Underdog
OSK-W-21-2479-W8 920.7 923.0 2.3 9.74   UDD_4502 Underdog
including 920.7 921.1 0.4 49.5  
  959.8 961.8 2.0 8.06   UDD_4910 Underdog
OSK-W-21-2503-W4 967.1 972.6 5.5 29.0 23.3 TLX_3163 Triple Lynx
including 967.9 968.3 0.4 179 100
  990.0 992.0 2.0 17.8   TLX_3164 Triple Lynx
including 991.3 992.0 0.7 39.7  
  1009.0 1011.0 2.0 141 20.1 TLX_3164 Triple Lynx
including 1009.7 1010.1 0.4 704 100
OSK-W-21-2522-W4 656.0 658.8 2.8 12.3   LXM_3304 Lynx
OSK-W-21-2531-W1 789.0 791.0 2.0 5.48   UDD_4111 Underdog
including 790.0 790.7 0.7 11.3  
  823.0 825.0 2.0 5.91   UDD_4110 Underdog
  887.6 891.5 3.9 22.0 21.1 UDD_4101 Underdog
including 887.6 888.0 0.4 109 100
  896.0 898.0 2.0 12.0   UDD_4100 Underdog
including 897.5 898.0 0.5 31.6  
  901.0 903.0 2.0 10.7   UDD_4100 Underdog
including 901.0 902.0 1.0 20.5  
  905.7 908.0 2.3 108 43.7 UDD_4100 Underdog
including 905.7 906.7 1.0 247 100
  1070.4 1072.8 2.4 8.05   UDD_4501 Underdog
including 1072.1 1072.8 0.7 27.3  
  1181.0 1183.9 2.9 9.72   UDD_4512 Underdog
including 1182.8 1183.1 0.3 53.0  
OSK-W-21-2532-W1 567.9 570.3 2.4 24.2   CA2_2206 Caribou
including 569.2 570.3 1.1 51.6  
  758.0 760.0 2.0 3.96   UDD_4121 Underdog
  783.0 785.0 2.0 5.54   UDD_4101 Underdog
  800.3 804.0 3.7 20.2   UDD_4101 Underdog
including 802.3 803.1 0.8 69.7  
  807.9 810.0 2.1 22.5   UDD_4100 Underdog
  815.0 817.0 2.0 6.57   UDD_4120 Underdog
including 816.2 816.7 0.5 25.6  
  971.0 973.0 2.0 8.53   UDD_4511 Underdog
including 971.0 971.5 0.5 30.0  
OSK-W-21-2532-W2 828.0 830.1 2.1 40.8 34.2 UDD_4100 Underdog
including 829.1 829.6 0.5 128 100
  887.4 889.4 2.0 9.66   UDD_4106 Underdog
  953.0 955.0 2.0 6.26   UDD_4107 Underdog
  983.6 985.9 2.3 16.4   UDD_4511 Underdog
including 983.6 984.0 0.4 40.2  
and 985.5 985.9 0.4 53.1  
  1015.2 1017.5 2.3 4.76   UDD_4501 Underdog
OSK-W-21-2537 909.4 914.4 5.0 6.90   TLX_3171 Triple Lynx
including 912.4 913.4 1.0 14.9  
  916.9 921.2 4.3 4.47   TLX_3171 Triple Lynx
  925.0 928.8 3.8 3.92   TLX_3171 Triple Lynx
  935.0 943.0 8.0 11.4   TLX_3161 Triple Lynx
including 939.4 940.4 1.0 42.6  
  1018.0 1020.0 2.0 10.3   TLX_3164 Triple Lynx
including 1019.0 1019.5 0.5 30.6  
OSK-W-21-2537-W1 559.0 561.0 2.0 5.91   TLX_3196 Triple Lynx
  586.8 589.0 2.2 11.2   TLX_3178 Triple Lynx
including 586.8 587.7 0.9 27.2  
  901.0 903.0 2.0 4.91   TLX_3171 Triple Lynx
  912.6 924.0 11.4 17.3   TLX_3171 Triple Lynx
including 912.6 913.7 1.1 52.0  
and 918.8 919.4 0.6 46.5  
OSK-W-21-2544 987.6 989.6 2.0 3.72   TLX_3195 Triple Lynx
including 987.6 987.9 0.3 15.3  
OSK-W-21-2548 721.0 723.0 2.0 22.5   CA2_2220 Caribou
including 721.0 721.6 0.6 73.8  
OSK-W-21-2548-W1 758.0 760.0 2.0 3.86   CA2_2219 Caribou
including 759.0 760.0 1.0 7.67  
OSK-W-21-2548-W2 757.0 759.0 2.0 83.0 53.0 CA2_2219 Caribou
including 757.0 758.0 1.0 160 100
  771.0 773.0 2.0 8.27   Caribou Caribou
OSK-W-21-2551-W1 837.1 840.1 3.0 10.8   LX4_3414 Lynx 4
OSK-W-21-2552 600.0 602.2 2.2 3.60   UDD_4914 Underdog
including 600.5 600.8 0.3 17.9  
  615.8 617.9 2.1 22.0   UDD_4103 Underdog
including 616.6 617.5 0.9 51.0  
OSK-W-21-2555 635.0 637.1 2.1 7.43   CA2_2223 Caribou
OSK-W-21-2556 139.0 141.0 2.0 12.0   F51_6008 F-51
OSK-W-21-2560 603.9 609.4 5.5 19.3 15.0 UDD_4914 Underdog
including 609.0 609.4 0.4 159 100
OSK-W-21-2561 555.0 557.0 2.0 3.88   TLX_3178 Triple Lynx
  659.9 662.9 3.0 16.0   TLX_3171 Triple Lynx
OSK-W-21-2562 656.2 658.2 2.0 5.48   CA2_2208 Caribou
  683.0 692.0 9.0 11.6   CA2_2217 Caribou
including 685.2 685.6 0.4 97.1  
and 688.5 689.0 0.5 42.3  
OSK-W-21-2566 134.0 136.0 2.0 4.81   F51_6008 F-51
OSK-W-21-2567 137.7 139.8 2.1 22.1   F51_6008 F-51
including 138.1 139.0 0.9 43.3  
WST-21-0718 79.5 82.1 2.6 3.95   LXM_3304 Lynx
including 81.7 82.1 0.4 10.0  
WST-21-0772 347.0 349.0 2.0 4.62   TLX_3166 Triple Lynx
including 348.4 349.0 0.6 14.6  
WST-21-0797A 599.2 601.4 2.2 6.53   LX4_3429 Lynx 4
including 600.5 600.9 0.4 25.3  
WST-21-0833 278.0 280.4 2.4 512 45.3 LHW_3201 Lynx HW
including 278.0 279.0 1.0 1220 100
WST-21-0835 281.0 283.0 2.0 4.67   LHW_3221 Lynx HW
  328.9 331.0 2.1 25.7   LHW_3215 Lynx HW
including 329.5 330.4 0.9 56.6  
WST-21-0840 713.0 715.0 2.0 3.72   LX4_3412 Lynx 4
WST-21-0842 250.6 253.0 2.4 212 42.1 TLX_3161 Triple Lynx
including 251.1 251.6 0.5 917 100
WST-21-0850 83.0 85.4 2.4 6.47   LXM_3339 Lynx
including 85.0 85.4 0.4 16.7  
  267.8 270.1 2.3 8.14   LSW_3500 Lynx SW
including 268.3 268.9 0.6 29.6  
  326.8 329.3 2.5 10.2   TLX_3166 Triple Lynx
including 326.8 327.3 0.5 49.0  
WST-21-0851A 168.6 170.7 2.1 13.4   LXM_3304 Lynx
including 169.1 169.4 0.3 87.5  
  480.0 482.4 2.4 6.06   LX4_3430 Lynx 4
including 481.8 482.4 0.6 24.0  
  518.6 521.0 2.4 5.93   LX4_3440 Lynx 4
including 518.6 519.4 0.8 16.4  
  528.0 530.0 2.0 5.84   LX4_3434 Lynx 4
including 528.5 529.0 0.5 20.0  
  590.0 592.2 2.2 4.93   LX4_3439 Lynx 4
including 590.0 590.6 0.6 16.1  
WST-21-0852A 127.5 129.6 2.1 7.07   LXM_3334 Lynx
including 128.8 129.3 0.5 26.1  
  420.1 422.3 2.2 3.98   LX4_3452 Lynx 4
including 420.6 421.3 0.7 11.3  
  487.2 489.2 2.0 23.2   LX4_3450 Lynx 4
including 487.2 487.7 0.5 90.7  
  648.0 650.0 2.0 11.1   LX4_3438 Lynx 4
including 649.3 649.6 0.3 34.7  
  669.7 672.2 2.5 3.75   LX4_3415 Lynx 4
 
including 669.7 670.2 0.5 10.4  
WST-21-0853A 289.3 291.3 2.0 6.49   TLX_3161 Triple Lynx
including 290.6 291.3 0.7 16.2  
  347.6 349.7 2.1 6.72   TLX_3163 Triple Lynx
including 348.4 349.1 0.7 19.0  
WST-21-0854A 185.9 188.0 2.1 57.6   TLX_3161 Triple Lynx
including 187.0 188.0 1.0 93.1  
  300.0 302.1 2.1 4.59   TLX_3182 Triple Lynx
including 300.8 301.5 0.7 12.8  
  353.7 356.0 2.3 3.91   TLX_3188 Triple Lynx
including 355.3 355.6 0.3 22.0  
  654.0 656.0 2.0 10.6   LX4_3448 Lynx 4
including 654.8 655.2 0.4 48.1  
WST-21-0869 357.0 359.0 2.0 12.4   TLX_3167 Triple Lynx
  510.6 512.9 2.3 6.91   LX4_3450 Lynx 4
WST-21-0870 288.6 290.6 2.0 13.8   LSW Lynx SW
including 289.8 290.2 0.4 51.0  
  299.0 301.0 2.0 18.0   LSW Lynx SW
including 300.1 301.0 0.9 38.9  
  329.9 335.0 5.1 19.3   LSW_3556 Lynx SW
including 332.4 332.7 0.3 84.6  
WST-21-0871 324.6 327.0 2.4 4.45   TLX_3131 Triple Lynx
including 324.6 324.9 0.3 35.0  

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, LHW = Lynx Hanging Wall, LSW = Lynx SouthWest, TLX = Triple Lynx and UDD = Underdog, CA2 = Caribou.

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-21-1432-W5 895.5 898.0 2.5 5.81   LX4 Lynx 4
including 896.2 897.0 0.8 17.6  
OSK-W-21-1827-W5 1087.0 1089.5 2.5 14.7   UDD Underdog
including 1087.0 1088.0 1.0 28.8  
OSK-W-21-2287-W4 1304.8 1307.0 2.2 4.26   LX4 Lynx 4
including 1305.4 1305.7 0.3 19.0  
  1373.0 1375.0 2.0 4.84   LX4 Lynx 4
OSK-W-21-2478-W5 555.0 557.0 2.0 4.90   Triple Lynx Triple Lynx
OSK-W-21-2479-W7 759.0 761.0 2.0 3.88   UDD Underdog
OSK-W-21-2513 256.2 259.0 2.8 3.95   F51 F51
OSK-W-21-2522-W4 697.0 700.0 3.0 4.68   Lynx Lynx
OSK-W-21-2532-W1 826.6 829.1 2.5 11.6   Underdog Underdog
including 827.6 828.2 0.6 47.4  
OSK-W-21-2537 971.0 975.0 4.0 4.33   Triple Lynx Triple Lynx
OSK-W-21-2540-W1 1132.1 1134.4 2.3 4.47   Triple Lynx Triple Lynx
  1141.6 1143.7 2.1 4.27   Triple Lynx Triple Lynx
including 1143.4 1143.7 0.3 17.7  
OSK-W-21-2546-W1 579.0 581.4 2.4 4.06   Caribou extension Caribou
including 580.0 580.4 0.4 23.0  
  631.9 635.8 3.9 4.27   Caribou extension Caribou
including 631.9 632.2 0.3 14.6  
and 635.1 635.8 0.7 13.2  
  819.7 822.0 2.3 4.78   Caribou extension Caribou
including 819.7 820.5 0.8 11.0  
OSK-W-21-2548 731.0 733.2 2.2 5.08   Caribou Caribou
OSK-W-21-2548-W1 790.8 792.8 2.0 5.99   Caribou Caribou
including 792.4 792.8 0.4 27.3  
OSK-W-21-2549 461.0 463.0 2.0 13.4   Caribou Caribou
including 461.5 461.9 0.4 55.5  
  641.5 645.0 3.5 11.5   Caribou Caribou
including 642.6 643.2 0.6 37.6  
  705.4 708.0 2.6 14.7   Caribou Caribou
including 705.4 706.1 0.7 32.2  
OSK-W-21-2555 610.0 612.3 2.3 3.70   Caribou Caribou
including 611.9 612.3 0.4 12.7  
OSK-W-21-2559 656.0 658.0 2.0 5.86   Caribou Caribou
OSK-W-21-2562 649.9 654.8 4.9 22.4   Caribou Caribou
including 651.0 651.6 0.6 48.2  
WST-21-0772 242.0 244.0 2.0 44.7   LSW Lynx SW
including 242.7 243.6 0.9 99.1  
  249.0 251.0 2.0 3.63   LSW Lynx SW
including 249.5 249.8 0.3 23.3  
WST-21-0831 160.8 163.0 2.2 4.45   LSW Lynx SW
including 160.8 161.4 0.6 15.8  
  403.4 405.4 2.0 5.45   LSW Lynx SW
including 403.8 404.4 0.6 17.2  
WST-21-0840 343.0 345.9 2.9 5.91   TLX Triple Lynx
  374.5 377.0 2.5 11.4   TLX Triple Lynx
WST-21-0850 417.7 420.0 2.3 42.5   LSW Lynx SW
including 417.7 418.5 0.8 95.6  
WST-21-0852A 29.6 32.0 2.4 17.5   Lynx Lynx
including 29.6 30.2 0.6 65.8  
  146.0 148.0 2.0 4.19   Lynx Lynx
including 146.3 146.7 0.4 20.4  
WST-21-0854A 546.0 548.1 2.1 4.64   LX4 Lynx 4
WST-21-0871 570.9 573.0 2.1 9.34   LX4 Lynx 4

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See "Quality Control and Reporting Protocols" below. LX4 = Lynx 4, 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-20-2292-W6 125 -54 1110 453035 5435561 420 3500
OSK-W-20-2400 336 -53 1230 452878 5434419 401 2825
OSK-W-21-1432-W5 132 -55 1041 453811 5435779 400 4300
OSK-W-21-1827-W5 331 -58 1203 452506 5434390 403 2475
OSK-W-21-1827-W6 331 -58 1281 452506 5434390 403 2475
OSK-W-21-1882-W5 328 -58 1071 452469 5434405 400 2450
OSK-W-21-1949-W7 105 -57 1312 453440 5435479 401 3825
OSK-W-21-2067-W7 123 -53 1166 453241 5435697 416 3750
OSK-W-21-2287-W4 116 -53 1437 453607 5435714 404 4075
OSK-W-21-2287-W5 116 -53 1380 453607 5435714 404 4075
OSK-W-21-2470 132 -59 1230 453304 5435639 415 3775
OSK-W-21-2478-W5 128 -54 1166 452997 5435607 425 3500
OSK-W-21-2479-W6 344 -55 1014 452315 5434419 399 2325
OSK-W-21-2479-W7 344 -55 999 452315 5434419 399 2325
OSK-W-21-2479-W8 344 -55 1026 452315 5434419 399 2325
OSK-W-21-2503-W4 126 -58 1191 453333 5435641 413 3800
OSK-W-21-2513 147 -45 281 453518 5436030 405 4150
OSK-W-21-2522-W4 128 -54 1208 453451 5435594 411 3900
OSK-W-21-2531-W1 344 -62 1215 452566 5434415 403 2550
OSK-W-21-2532-W1 341 -60 1035 452480 5434428 401 2475
OSK-W-21-2532-W2 341 -60 1145 452480 5434428 401 2475
OSK-W-21-2537 114 -54 1243 452981 5435549 420 3450
OSK-W-21-2537-W1 114 -54 1020 452981 5435549 420 3450
OSK-W-21-2540-W1 117 -60 1200 453465 5435640 410 3925
OSK-W-21-2544 128 -50 1161 452960 5435539 419 3425
OSK-W-21-2546-W1 140 -58 843 452768 5435312 406 3150
OSK-W-21-2548 331 -57 774 452829 5434550 398 2850
OSK-W-21-2548-W1 331 -57 837 452829 5434550 398 2850
OSK-W-21-2548-W2 331 -57 801 452829 5434550 398 2850
OSK-W-21-2549 332 -58 723 452703 5434455 401 2675
OSK-W-21-2551-W1 120 -55 978 453622 5435635 405 4050
OSK-W-21-2552 335 -52 684 452404 5434674 400 2525
OSK-W-21-2555 329 -59 741 452728 5434472 401 2700
OSK-W-21-2556 124 -50 198 453426 5435858 405 4000
OSK-W-21-2559 327 -51 825 452829 5434550 398 2850
OSK-W-21-2560 333 -53 684 452404 5434674 400 2525
OSK-W-21-2561 142 -51 801 452886 5435484 409 3350
OSK-W-21-2562 331 -56 753 452733 5434488 401 2725
OSK-W-21-2566 178 -58 189 453426 5435858 405 4000
OSK-W-21-2567 146 -60 186 453426 5435858 405 4000
WST-21-0718 162 0 100 453359 5435194 83 3625
WST-21-0772 148 -68 411 453104 5435065 231 3325
WST-21-0797A 138 -46 751 453321 5435235 54 3600
WST-21-0831 157 -63 526 452954 5435003 253 3175
WST-21-0833 122 -16 334 453463 5435327 32 3775
WST-21-0835 122 -27 385 453462 5435327 32 3775
WST-21-0840 143 -48 778 453258 5435209 96 3525
WST-21-0842 156 -69 445 453506 5435327 -7 3800
WST-21-0850 151 -64 532 453105 5435065 231 3325
WST-21-0851A 123 -40 618 453507 5435332 -48 3800
WST-21-0852A 141 -43 709 453321 5435236 54 3600
WST-21-0853A 150 -72 376 453505 5435328 -5 3800
WST-21-0854A 134 -41 724 453374 5435296 -26 3675
WST-21-0869 142 -47 622 453258 5435210 96 3525
WST-21-0870 134 -56 360 453106 5435066 231 3325
WST-21-0871 140 -50 582 453321 5435236 54 3600

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
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 3.5 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 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

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