Category: Silver / Gold

Osisko Step-out Drilling Expands High Grade at Windfall

TORONTO, Oct. 07, 2020  -- 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.
 
Drilling is currently focused on the Lynx deposit. Osisko Chief Executive Officer John Burzynski commented: “Windfall continues to grow in scale with impressive results flowing in from the Lynx deposit. Today’s new intersections are all from outside the published resource area and include 15 intercepts with uncut average grades of over one oz/t. The ongoing expansion drilling continues to show the incredible upside growth potential of our deposit.”
 
The table below shows intercepts located outside the February 2020 mineral resource estimate wireframes (see Osisko news release dated February 19, 2020). These intercepts either expand the resource wireframes or are located in a defined zone/corridor but not yet correlated to a specific wireframe. Significant new analytical results are presented below and include 110 intercepts in 43 drill holes and 24 wedges.
 
Selected high-grade intercepts from the new results include: 391 g/t Au over 2.4 metres, 70 metres toward surface from wireframe Lynx_361, in OSK-W-20-2133-W2; 142 g/t Au over 2.3 metres in OSK-W-20-2307; 86.0 g/t Au over 2.1 metres in WST-20-0341A; 73.8 g/t Au over 2.0 metres in WST-20-0470; 54.4 g/t Au over 4.8 metres in OSK-W-20-2252-W2; and 49.8 g/t Au over 2.2 metres in OSK-W-20-2292. Maps showing hole locations and full analytical results are available at www.osiskomining.com

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-17-1258 971.7 973.7 2.0 3.33   Lynx 4 Lynx
including 971.7 972.7 1.0 6.56  
OSK-W-18-1727 782.9 784.9 2.0 12.7   Lynx Lynx
OSK-W-19-1857-W11 1301.8 1304.6 2.8 7.39   Lynx 4 Lynx
OSK-W-19-2100-W4 1212.5 1214.7 2.2 5.22   Triple Lynx Triple Lynx
  1242.0 1244.0 2.0 6.47   Triple Lynx Triple Lynx
OSK-W-19-2101 664.4 667.0 2.6 5.48   Triple Lynx Triple Lynx
OSK-W-20-2133-W2 783.6 786.0 2.4 391 31.1 Lynx_361 Triple Lynx
including 784.2 784.6 0.4 2260 100
OSK-W-20-2139-W7 1081.0 1083.5 2.5 9.53   Triple Lynx Triple Lynx
including 1081.0 1081.9 0.9 26.1  
OSK-W-20-2139-W8 543.0 545.0 2.0 6.68   Triple Lynx Triple Lynx
including 543.5 544.4 0.9 14.5  
OSK-W-20-2139-W10 1196.0 1198.0 2.0 11.7   Triple Lynx Triple Lynx
including 1196.0 1197.1 1.1 21.3  
OSK-W-19-2169 893.9 895.9 2.0 5.59   Lynx 4 Lynx
including 894.7 895.3 0.6 18.2  
  1256.3 1258.4 2.1 15.8   Lynx 4 Lynx
including 1257.5 1258.4 0.9 36.2  
OSK-W-20-2170-W6 1384.0 1386.4 2.4 6.70   Lynx 4 Lynx
OSK-W-19-2173 29.0 31.0 2.0 3.07   F11 F11
OSK-W-19-2177 200.0 202.0 2.0 3.10   F11 F11
OSK-W-20-2197-W2 768.7 771.4 2.7 10.3   Lynx_361 Triple Lynx
including 769.7 770.7 1.0 26.0  
  1045.0 1047.0 2.0 5.66   Lynx 4 Lynx
OSK-W-20-2217-W2 860.0 862.0 2.0 14.0   Triple Lynx Triple Lynx
including 860.0 860.5 0.5 55.6  
OSK-W-20-2217-W3 830.0 832.3 2.3 7.53   Lynx_363 Triple Lynx
including 831.0 831.4 0.4 26.8  
  1111.7 1114.0 2.3 16.4   Triple Lynx Triple Lynx
including 1113.5 1114.0 0.5 66.3  
OSK-W-20-2249 730.0 732.0 2.0 5.66   Lynx SW Lynx
including 730.5 730.9 0.4 22.8  
OSK-W-20-2250 1002.2 1005.0 2.8 18.1 15.6 Triple Lynx Triple Lynx
including 1002.2 1002.5 0.3 123 100
OSK-W-20-2250-W1 1009.0 1011.1 2.1 5.08   Triple Lynx Triple Lynx
OSK-W-20-2250-W2 1024.7 1028.0 3.3 28.8   Triple Lynx Triple Lynx
including 1026.4 1027.0 0.6 63.0  
OSK-W-20-2250-W3 714.0 716.5 2.5 14.7   Triple Lynx Triple Lynx
OSK-W-20-2250-W4 727.7 734.5 6.8 4.58   Triple Lynx Triple Lynx
including 727.7 728.4 0.7 10.3  
and 730.5 731.0 0.5 12.0  
  855.4 858.0 2.6 6.29   Triple Lynx Triple Lynx
including 857.2 858.0 0.8 18.6  
OSK-W-20-2252-W2 812.0 814.0 2.0 7.64   Triple Lynx Triple Lynx
  817.2 822.0 4.8 54.4 10.4 Triple Lynx Triple Lynx
including 817.2 817.5 0.3 804 100
OSK-W-20-2252-W3 824.3 829.7 5.4 3.58   Triple Lynx Triple Lynx
  845.1 847.1 2.0 4.01   Triple Lynx Triple Lynx
OSK-W-20-2253 387.5 389.5 2.0 4.30   Caribou Corridor Caribou
OSK-W-20-2256 870.0 872.8 2.8 9.81   Triple Lynx Triple Lynx
OSK-W-20-2256-W2 815.0 817.0 2.0 3.17   Triple Lynx Triple Lynx
OSK-W-20-2260-W2 1091.0 1093.0 2.0 6.47   Triple Lynx Triple Lynx
including 1091.4 1092.1 0.7 18.1  
  1174.4 1176.5 2.1 9.43   Triple Lynx Triple Lynx
including 1176.0 1176.5 0.5 28.0  
OSK-W-20-2263 94.0 96.0 2.0 8.58   Bobcat Bobcat
including 94.0 95.0 1.0 16.9  
  106.7 108.8 2.1 6.12   Bobcat Bobcat
including 108.0 108.8 0.8 14.1  
  710.0 712.0 2.0 42.6 21.4 Lynx SW Lynx
including 711.2 711.6 0.4 206 100
OSK-W-20-2266 1027.4 1029.5 2.1 5.58   Triple Lynx Triple Lynx
including 1028.7 1029.0 0.3 33.1  
OSK-W-20-2266-W1 776.8 779.2 2.4 5.73   Triple Lynx Triple Lynx
including 778.0 779.2 1.2 11.1  
  797.3 799.3 2.0 3.08   Lynx_364 Triple Lynx
OSK-W-20-2266-W2 717.4 719.4 2.0 19.9   Lynx_363 Triple Lynx
OSK-W-20-2267 50.4 52.8 2.4 15.4   Bobcat Bobcat
including 51.0 51.5 0.5 46.4  
OSK-W-20-2268-W1 737.1 739.3 2.2 7.46   Triple Lynx Triple Lynx
including 738.3 739.0 0.7 19.0  
  819.0 821.3 2.3 27.4   Triple Lynx Triple Lynx
including 819.0 820.0 1.0 45.7  
  1027.0 1029.0 2.0 6.70   Triple Lynx Triple Lynx
including 1027.4 1028.2 0.8 16.5  
OSK-W-20-2268-W2 999.0 1001.0 2.0 5.08   Triple Lynx Triple Lynx
OSK-W-20-2269 97.3 99.5 2.2 8.21   Bobcat Bobcat
including 98.0 98.4 0.4 30.8  
  518.2 520.6 2.4 3.37   Lynx SW Lynx
  886.0 888.0 2.0 14.0   Lynx SW Lynx
including 886.5 886.8 0.3 92.5  
OSK-W-20-2271 809.6 815.2 5.6 6.69   Lynx Lynx
including 814.2 815.2 1.0 17.4  
  841.1 843.1 2.0 18.2   Lynx Lynx
including 842.1 843.1 1.0 35.0  
  877.0 879.0 2.0 5.36   Lynx Lynx
including 877.9 878.2 0.3 27.8  
OSK-W-20-2272 683.0 685.1 2.1 13.0   Triple Lynx Triple Lynx
including 683.0 683.9 0.9 29.7  
OSK-W-20-2273 706.7 708.7 2.0 8.32   Lynx_363 Triple Lynx
including 706.7 707.2 0.5 22.4  
  1013.8 1017.3 3.5 4.78   Triple Lynx Triple Lynx
including 1015.1 1015.5 0.4 16.1  
OSK-W-20-2280 1013.2 1016.7 3.5 5.23   Triple Lynx Triple Lynx
including 1013.8 1014.2 0.4 26.7  
and 1016.4 1016.7 0.3 11.3  
  1084.7 1087.0 2.3 4.27   Triple Lynx Triple Lynx
OSK-W-20-2280-W1 1090.0 1092.0 2.0 11.8   Triple Lynx Triple Lynx
OSK-W-20-2282 308.4 310.8 2.4 6.13   Bobcat Bobcat
including 309.0 309.5 0.5 16.6  
OSK-W-20-2283 808.0 813.4 5.4 33.5 29.0 Triple Lynx Triple Lynx
including 810.8 811.3 0.5 73.1  
and 811.7 812.0 0.3 182 100
  819.0 821.0 2.0 7.27   Triple Lynx Triple Lynx
including 819.6 820.0 0.4 24.1  
  823.2 825.5 2.3 4.30   Triple Lynx Triple Lynx
including 823.6 824.4 0.8 10.6  
  1001.0 1003.2 2.2 44.8 23.6 Triple Lynx Triple Lynx
including 1002.7 1003.2 0.5 194 100
  1018.0 1020.0 2.0 19.3   Triple Lynx Triple Lynx
including 1018.9 1019.5 0.6 54.4  
OSK-W-20-2288 467.0 469.8 2.8 8.13   Lynx SW Lynx
including 467.0 467.4 0.4 38.9  
OSK-W-20-2292 390.0 392.0 2.0 7.18   Lynx Lynx
including 391.7 392.0 0.3 19.3  
  835.4 837.8 2.4 4.47   Triple Lynx Triple Lynx
  845.0 847.0 2.0 11.8   Lynx_361 Triple Lynx
including 845.8 846.3 0.5 41.0  
  882.0 884.0 2.0 8.01   Lynx_364 Triple Lynx
including 883.0 884.0 1.0 15.7  
  1007.2 1009.2 2.0 49.8 21 Lynx_372 Triple Lynx
including 1008.8 1009.2 0.4 244 100
OSK-W-20-2295 651.2 658.0 6.8 12.4   Triple Lynx Triple Lynx
including 652.4 652.7 0.3 28.7  
and 653.4 654.0 0.6 45.9  
and 656.1 656.7 0.6 56.9  
  891.7 893.7 2.0 11.6   Lynx SW Triple Lynx
including 891.7 892.7 1.0 23.0  
OSK-W-20-2295-W1 648.6 651.4 2.8 45.1 30.1 Triple Lynx Triple Lynx
including 650.0 650.7 0.7 160 100
OSK-W-20-2298 169.0 171.7 2.7 7.41   Bobcat Bobcat
including 169.0 169.7 0.7 20.2  
  245.0 247.0 2.0 6.59   Bobcat Bobcat
including 245.0 245.7 0.7 18.4  
  373.0 375.0 2.0 16.7   Lynx SW Lynx
including 373.8 374.3 0.5 65.2  
OSK-W-20-2305 630.8 635.0 4.2 4.47   Triple Lynx Triple Lynx
including 634.0 635.0 1.0 9.32  
  876.0 878.3 2.3 10.7   Triple Lynx Triple Lynx
including 877.6 878.3 0.7 31.6  
  882.2 884.6 2.4 43.0 18.0 Triple Lynx Triple Lynx
including 883.4 883.8 0.4 250 100
OSK-W-20-2306 137.8 140.0 2.2 4.30   Bobcat Bobcat
  147.1 149.4 2.3 3.12   Bobcat Bobcat
  275.0 277.3 2.3 8.58   Bobcat Bobcat
including 275.8 276.5 0.7 20.7  
  386.1 388.3 2.2 3.94   Lynx SW Lynx
including 386.6 387.0 0.4 11.5  
OSK-W-20-2307 689.6 691.9 2.3 142 75.8 Lynx_341 Lynx
including 690.0 690.4 0.4 413 100
OSK-W-20-2310 69.7 72.0 2.3 35.6 13.8 Mallard_5200 Mallard
including 70.8 71.1 0.3 267 100
OSK-W-20-2312 85.0 87.3 2.3 7.19   Mallard Mallard
including 85.7 86.2 0.5 25.4  
OSK-W-20-2324 90.0 92.5 2.5 8.43   Mallard Mallard
WST-20-0135 293.0 295.1 2.1 35.1 19.2 Lynx SW Lynx
including 293.7 294.1 0.4 184 100
  351.8 354.7 2.9 3.15   Lynx SW
 
Lynx

 
including 351.8 352.3 0.5 8.55  
and 354.1 354.7 0.6 7.76  
  360.4 362.6 2.2 13.4   Triple Lynx Triple Lynx
including 360.4 361.4 1.0 28.9  
  397.3 399.4 2.1 23.6 14.5 Lynx SW Lynx
including 397.8 398.1 0.3 164 100
WST-20-0318 377.4 379.6 2.2 8.05   Lynx SW Lynx
  463.3 466.0 2.7 9.06   Lynx 4 Lynx
WST-20-0339 199.1 202.2 3.1 4.57   Lynx HW Lynx
WST-20-0341A 306.1 308.2 2.1 86.0 19.9 Lynx SW Lynx
including 306.1 306.5 0.4 447 100
  346.1 348.1 2.0 10.6   Lynx SW Lynx
including 347.3 347.7 0.4 50.2  
WST-20-0345 361.7 363.9 2.2 3.75   Caribou corridor Caribou
including 362.3 363.1 0.8 9.43  
WST-20-0400 158.0 160.2 2.2 11.2   Lynx_301 Lynx
including 159.0 160.2 1.2 19.7  
WST-20-0411 148.2 150.4 2.2 38.1 36.1 Lynx HW Lynx
including 149.2 149.9 0.7 107 100
WST-20-0412 155.0 157.2 2.2 3.06   Lynx_328 Lynx
including 156.9 157.2 0.3 11.2  
WST-20-0417 190.6 192.6 2.0 22.4   Lynx Lynx
including 190.6 191.2 0.6 41.5  
  428.2 430.2 2.0 4.06   Lynx 4 Lynx
WST-20-0423 125.0 127.0 2.0 5.23   Lynx Lynx
including 125.0 125.7 0.7 14.9  
WST-20-0459 204.3 206.4 2.1 20.6   Lynx SW Lynx
including 205.9 206.4 0.5 76.2  
WST-20-0462 171.0 173.0 2.0 40.4   Lynx Lynx
including 171.5 172.5 1.0 79.1  
  454.0 456.0 2.0 3.50   Lynx_336 Lynx
including 454.0 454.8 0.8 8.19  
  638.9 643.2 4.3 3.82   Lynx Lynx
including 638.9 639.6 0.7 12.6  
WST-20-0470 86.2 88.2 2.0 73.8 15.0 Lynx Lynx
including 87.5 87.8 0.3 492 100

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

Drill hole location

Hole Number Azimuth (°) Dip (°) Length (m) UTM E UTM N Elevation Section
OSK-W-17-1258 126 -51 1128 452972 5435211 416 3275
OSK-W-18-1727 331 -61 810 453461 5435040 396 3625
OSK-W-19-1857-W11 108 -58 1385 453525 5435704 405 4000
OSK-W-19-2100-W4 122 -47 1260 453095 5435726 423 3650
OSK-W-19-2101 18 -68 909 453426 5434779 396 3475
OSK-W-19-2169 130 -50 1268 453215 5435512 410 3650
OSK-W-19-2173 156 -46 234 452182 5435722 407 2850
OSK-W-19-2177 153 -51 396 452454 5435997 406 3225
OSK-W-20-2133-W2 118 -49 1139 453080 5435531 417 3525
OSK-W-20-2139-W7 115 -52 1164 452980 5435549 420 3450
OSK-W-20-2139-W8 115 -52 1125 452980 5435549 420 3450
OSK-W-20-2139-W10 115 -52 1212 452980 5435549 420 3450
OSK-W-20-2170-W6 128 -59 1407 453425 5435657 413 3900
OSK-W-20-2197-W2 121 -48 1064 453087 5435526 417 3550
OSK-W-20-2217-W2 134 -48 893 452944 5435565 418 3425
OSK-W-20-2217-W3 134 -48 1128 452944 5435565 418 3425
OSK-W-20-2249 132 -56 759 452775 5435192 411 3100
OSK-W-20-2250 132 -57 1064 453129 5435505 419 3575
OSK-W-20-2250-W1 132 -57 1060 453129 5435505 419 3575
OSK-W-20-2250-W2 132 -57 1134 453129 5435505 419 3575
OSK-W-20-2250-W3 132 -57 1170 453129 5435505 419 3575
OSK-W-20-2250-W4 132 -57 1005 453129 5435505 419 3575
OSK-W-20-2252-W2 129 -54 1194 453241 5435694 415 3750
OSK-W-20-2252-W3 129 -53 1062 453241 5435694 415 3750
OSK-W-20-2253 128 -54 924 452831 5435326 413 3225
OSK-W-20-2256 125 -51 1179 453160 5435686 414 3675
OSK-W-20-2256-W2 125 -51 957 453160 5435686 414 3675
OSK-W-20-2260-W2 127 -48 1191 453201 5435667 413 3700
OSK-W-20-2263 128 -49 1029 452926 5435187 413 3225
OSK-W-20-2266 128 -55 1050 453067 5435478 418 3500
OSK-W-20-2266-W1 128 -55 1116 453067 5435478 418 3500
OSK-W-20-2266-W2 128 -55 1131 453067 5435478 418 3500
OSK-W-20-2267 135 -52 66 452972 5435210 416 3275
OSK-W-20-2268-W1 127 -55 1073 453148 5435488 418 3575
OSK-W-20-2268-W2 127 -55 1038 453148 5435488 418 3575
OSK-W-20-2269 133 -50 933 452972 5435210 416 3275
OSK-W-20-2271 120 -53 1247 453462 5435683 410 3950
OSK-W-20-2272 149 -45 1004 452967 5435265 412 3300
OSK-W-20-2273 129 -51 1059 453067 5435478 417 3500
OSK-W-20-2280 127 -58 1161 453304 5435639 415 3775
OSK-W-20-2280-W1 127 -58 1170 453304 5435639 415 3775
OSK-W-20-2282 148 -56 588 452875 5435181 409 3175
OSK-W-20-2283 135 -50 1151 452997 5435607 425 3500
OSK-W-20-2288 146 -51 749 452875 5435181 409 3175
OSK-W-20-2292 125 -54 1059 453037 5435563 420 3525
OSK-W-20-2295 132 -51 987 452938 5435472 415 3375
OSK-W-20-2295-W1 132 -51 960 452938 5435472 415 3375
OSK-W-20-2298 137 -50 596 452847 5435059 407 3100
OSK-W-20-2305 124 -55 911 453026 5435408 413 3425
OSK-W-20-2306 152 -55 531 452872 5435155 407 3175
OSK-W-20-2307 124 -54 878 453397 5435557 413 3825
OSK-W-20-2310 333 -51 144 451970 5434835 407 2225
OSK-W-20-2312 334 -51 192 451964 5434816 408 2225
OSK-W-20-2324 334 -51 167 451944 5434811 406 2200
WST-20-0135 187 -58 444 453226 5435125 134 3475
WST-20-0318 148 -52 502 453228 5435127 134 3475
WST-20-0339 146 -18 295 453410 5435229 114 3675
WST-20-0341A 163 -42 493 453228 5435126 134 3475
WST-20-0345 136 -21 401 452282 5434975 263 2575
WST-20-0400 167 16 172 453493 5435287 118 3775
WST-20-0411 156 38 171 453450 5435264 118 3725
WST-20-0412 164 24 165 453450 5435264 117 3725
WST-20-0417 138 -50 759 453228 5435126 134 3475
WST-20-0423 134 -18 142 453359 5435209 154 3625
WST-20-0459 153 -47 579 453227 5435126 135 3475
WST-20-0462 152 -53 680 453227 5435125 134 3475
WST-20-0470 158 9 184 453493 5435287 118 3775

Lynx Zone
Mineralization occurs as grey to translucent quartz-carbonate-pyrite-tourmaline veins and pyrite replacement zones and stockworks. The vein-type 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.

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 in shear zones as replacement, 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.

Mallard
Mineralization is hosted in sheared mafic volcanics with felsic porphyritic intrusions and occurs as veins associated with sericite-pyrite ± silica ± chlorite alteration and contains pyrite ranging from trace to 30% and local visible gold.

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. All NQ core assays reported 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, Thunder Bay, Ontario, Sudbury, Ontario or Vancouver, British Colombia, or (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 an Aqua Regia-ICP-AES method at ALS Laboratories. Drill program design, QualityAssurance/QualityControl("QA/QC")andinterpretationofresultsisperformedbyqualifiedpersonsemployingaQA/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 inEeyou Istchee James Bay,Québec, Canada. The mineral resource defined by Osisko, as disclosed in the news release dated February 19, 2020 and supported by the technical report entitled “An updated mineral resource estimate for the Windfall Lake Project, Located in the Abitibi Greenstone Belt, Urban Township, Eeyou Istchee James Bay, Québec, Canada” and dated April 3, 2020 (with an effective date of January 3, 2020)and assuming a cut-off grade of 3.5 g/t, comprises 4,127,000 tonnes at 9.1 g/t Au (1,206,000 ounces) in the indicated mineral resource category and 14,532,000 tonnes at 8.40 g/t Au (3,938,000 ounces) in the inferred mineral resource category. The key assumptions, parameters and methods used to estimate the mineral resource estimatedisclosed in the February 19,2020 news release are further described in the full technical report prepared by Micon International Limited ("Micon") and BBA Inc ("BBA")in accordance with NI 43-101available 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 ofdeformed sub-vertical zonesplunging to the northeast.Vein-type or pyrite replacement-type styles of mineralization crosscut syn-volcanic host rocks and syn-deformation felsic porphyry intrusionsand are spatially associated with the contacts of the intrusions.Thedepositiswelldefinedfromsurfacetoadepthof1,200metresandremainsopen alongstrikeandatdepth.Mineralizationhasbeenidentified30metresfromsurfaceinsomeareasandasdeepas2,000metres 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 precious metal 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; the prospects, if any, of the Windfall gold deposit; the timing and ability of Osisko, if at all, to publish a feasibility study for the Windfall gold deposit; the projected capital expenditures of mining activities at the Windfall gold deposit; upgrading an inferred mineral resource to a measured mineral resource or indicated mineral resource category; future drilling at the Windfall gold deposit; the deposit remaining open along strike to the northeast and at depth; significant high-grade zones (Lynx 4, Triple Lynx) remaining open down plunge; the plunge potential of the Lynx and Underdog zones; 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 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