OSISKO WINDFALL INFILL DRILLING CONTINUES TO CONFIRM HIGH-GRADE

510 g/t Au Over 5.2 Metres in Lynx
742 g/t Au Over 2.2 Metres in Zone 27

NOT FOR DISTRIBUTION TO UNITED STATES NEWSWIRE SERVICES OR FOR DISSEMINATION IN THE UNITED STATES

(Toronto, August 22, 2018)  Osisko Mining Inc. (OSK:TSX. “Osisko” or the “Corporation”) is pleased to provide new infill drilling results from the ongoing drill definition and expansion program at its 100% owned Windfall Lake gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec. The 800,000 metre drill program commenced in late 2015. The program is now focussed on infill drilling within the main Windfall gold deposit and the adjacent Lynx deposit (located immediately NE of Windfall), and exploration and expansion drilling on main mineralized zones with several deep holes in progress to investigate the down-plunge areas in and around the Underdog and Lynx zones.

 

Significant new analytical results from 80 intercepts in 53 drill holes and one wedge focused on infill of the Main Windfall Lake and Lynx deposits and on deep-exploration targets are presented below.

Highlights from the new results include: 510 g/t Au over 5.2 metres in OSK-W-18-1639; 742 g/t Au over 2.2 metres in OSK-W-18-1589; 21.6 g/t Au over 19.4 metres in OSK-W-18-1655; 198 g/t Au over 2.0 metres in OSK-W-18-1638; 25.7 g/t Au over 8.9 metres in OSK-W-17-1313. Maps showing hole locations and full analytical results are available at www.osiskomining.com.

 

Hole No. From (m) To (m) Interval (m) Au (g/t) uncut Au (g/t)         cut to 100 g/t Type Mineralized Zone
OSK-W-17-907 436.7 441.6 4.9 7.56 infill Lynx
including 440.0 440.7 0.7 31.3
OSK-W-17-936-W2 522.4 524.8 2.4 16.7 infill Caribou
including 523.4 523.8 0.4 95.0
OSK-W-17-958 480.9 483.0 2.1 36.5 25.9 infill Lynx
including 481.5 482.0 0.5 145 100
OSK-W-17-1070 21.0 23.8 2.8 8.12 infill Zone 27
including 22.0 22.7 0.7 32.3  
OSK-W-17-1119 548.1 551.0 2.9 5.63 infill Caribou
including 548.1 549.0 0.9 17.0  
OSK-W-17-1143 85.0 87.0 2.0 20.4 15.4 infill Lynx
including 86.0 86.3 0.3 134 100
OSK-W-17-1158 145.0 147.0 2.0 71.4 50.1 Bobcat Bobcat
including 146.0 147.0 1.0 143 100
OSK-W-17-1186 770.0 772.0 2.0 18.0 15.3 infill Underdog
including 771.0 771.3 0.3 118 100
OSK-W-17-1313 351.4 360.3 8.9 25.7 infill Zone 27
OSK-W-18-1440 144.1 146.5 2.4 6.61 infill Caribou
including 145.6 146.5 0.9 17.6  
OSK-W-18-1518 218.0 221.0 3.0 3.74 infill Caribou
OSK-W-18-1530 90.0 92.0 2.0 11.4 infill Lynx
including 91.0 92.0 1.0 22.7
OSK-W-18-1552 316.0 318.0 2.0 3.70 infill Zone 27
including 316.0 316.3 0.3 19.9
OSK-W-18-1559 303.0 305.0 2.0 4.47 infill Zone 27
OSK-W-18-1561 195.0 197.2 2.2 7.33 infill Lynx
including 195.0 196.0 1.0 15.7
OSK-W-18-1564 160.0 162.0 2.0 4.49 infill Caribou
  279.0 281.0 2.0 4.71 infill Caribou
OSK-W-18-1589 101.6 103.8 2.2 742 24.0 infill Zone 27
including 102.9 103.4 0.5 3260 100
OSK-W-18-1594 177.8 180.4 2.6 10.4 infill Zone 27
OSK-W-18-1598 434.8 437.0 2.2 5.47 infill Lynx
including 435.4 436.1 0.7 14.7
OSK-W-18-1613 171.7 174.0 2.3 8.12 infill Lynx
including 173.0 174.0 1.0 18.2
OSK-W-18-1618 160.5 163.0 2.5 3.00 infill Caribou
including 160.8 161.4 0.6 11.0
OSK-W-18-1622 32.5 34.6 2.1 16.0 infill Zone 27
OSK-W-18-1623 175.0 177.3 2.3 6.51 Caribou Caribou
including 175.5 176.0 0.5 19.7
and 177.0 177.3 0.3 14.3
OSK-W-18-1624 62.2 65.1 2.9 6.01 Caribou Caribou
including 62.2 62.9 0.7 15.5
  181.6 184.0 2.4 7.97 Caribou Caribou
including 181.6 182.1 0.5 36.1
  306.2 311.0 4.8 4.30 Zone 27 Zone 27
OSK-W-18-1627 406.6 409.0 2.4 9.25 VNCR VNCR
OSK-W-18-1628 533.1 535.7 2.6 57.5 38.8 infill Lynx
including 533.1 533.7 0.6 181 100
  555.5 557.6 2.1 23.0 infill Lynx
including 555.9 556.6 0.7 68.8
OSK-W-18-1631 76.0 81.1 5.1 4.50 infill Caribou
OSK-W-18-1632 322.0 324.5 2.5 3.28 infill Zone 27
OSK-W-18-1634 169.0 172.9 3.9 6.29 infill Caribou
including 169.0 169.3 0.3 32.1
and 170.5 170.9 0.4 23.3
and 172.6 172.9 0.3 14.3
OSK-W-18-1638 515.0 517.0 2.0 198 97.4 infill Lynx
including 516.0 517.0 1.0 302 100
  538.6 540.6 2.0 14.6 infill Lynx
including 538.6 539.6 1.0 29.1
OSK-W-18-1639 452.0 455.5 3.5 3.27 infill Lynx
  475.8 481.0 5.2 510 19.8 infill Lynx
including 476.8 477.7 0.9 2930 100
  502.0 504.0 2.0 4.87 infill Lynx
including 502.0 502.7 0.7 13.8
OSK-W-18-1640 106.7 109.0 2.3 6.27 infill Caribou
including 108.2 108.6 0.4 31.7
  121.2 124.2 3.0 50.0 43.6 infill Caribou
including 122.4 124.2 1.8 80.6 69.9
OSK-W-18-1642 127.9 131.7 3.8 12.8 infill Caribou
  372.0 374.3 2.3 5.95 infill Zone 27
including 372.0 372.3 0.3 23.6
OSK-W-18-1643 155.0 157.7 2.7 5.99 infill Bobcat
including 156.8 157.7 0.9 17.8
OSK-W-18-1644 197.0 199.6 2.6 3.32 infill Caribou
  322.5 325.8 3.3 41.1 infill Zone 27
OSK-W-18-1645 560.0 562.0 2.0 5.39 infill Lynx
including 560.8 561.5 0.7 15.2
OSK-W-18-1646 152.8 155.2 2.4 7.51 infill Caribou
  254.3 257.0 2.7 6.28 infill Zone 27
OSK-W-18-1647 496.3 498.3 2.0 17.4 infill Lynx
OSK-W-18-1648 50.0 52.0 2.0 3.74 infill Caribou
  330.0 334.4 4.4 9.19 infill Zone 27
OSK-W-18-1649 66.8 68.8 2.0 4.61 infill Caribou
  266.0 268.0 2.0 48.4 45.0  infill

 

Caribou

 

including 266.4 267.3 0.9 108 100
  334.9 337.0 2.1 14.9   infill Zone 27
including 334.9 335.2 0.3 88.6
OSK-W-18-1650 265.9 270.0 4.1 6.11 infill Zone 27
including 269.0 270.0 1.0 16.1
  295.0 298.2 3.2 4.22 infill Zone 27
OSK-W-18-1651 226.9 229.1 2.2 4.01 infill Caribou
  305.0 307.0 2.0 3.68 infill Caribou
  320.0 322.0 2.0 7.39 infill Zone 27
including 321.0 322.0 1.0 14.3
  337.3 342.0 4.7 3.45 infill Zone 27
OSK-W-18-1653 285.4 288.0 2.6 4.15 infill Zone 27
OSK-W-18-1654 259.0 261.0 2.0 9.10 infill Zone 27
OSK-W-18-1655 318.8 321.1 2.3 4.99 infill Zone 27
  343.6 363.0 19.4 21.6 19.9 infill Zone 27
including 343.6 344.6 1.0 60.5  
including 351.0 353.6 2.6 62.2 56.7
including 360.0 360.9 0.9 122 100
  365.8 368.1 2.3 11.1 infill Zone 27
including 367.6 368.1 0.5 50.3
OSK-W-18-1656 550.9 556.7 5.8 8.28  infill

 

Lynx

 

including 553.3 554.3 1.0 28.6
OSK-W-18-1657 391.0 393.3 2.3 5.00 infill Lynx
  447.0 449.1 2.1 8.41   Lynx
OSK-W-18-1659 260.3 267.1 6.8 4.09 infill Zone 27
  274.3 279.5 5.2 5.88  

 infill

Zone 27

 

including 275.4 275.8 0.4 27.1
OSK-W-18-1660 51.2 53.4 2.2 7.19  

 infill

Caribou

 

including 51.8 52.6 0.8 18.3
OSK-W-18-1661 347.2 349.3 2.1 9.28 infill Zone 27
OSK-W-18-1662 257.9 261.5 3.6 4.08 infill Zone 27
  269.0 278.0 9.0 14.8 12.2 infill Zone 27
including 270.9 271.8 0.9 126 100
OSK-W-18-1665 341.2 343.9 2.7 4.65 infill Zone 27
OSK-W-18-1669 323.6 327.0 3.4 4.75 infill Zone 27
including 325.2 326.0 0.8 12.8
OSK-W-18-1671 248.0 250.3 2.3 12.7 infill Zone 27
including 249.0 249.3 0.3 95.0
  253.9 257.8 3.9 5.64 infill Zone 27
including 256.8 257.4 0.6 22.3
  287.9 290.4 2.5 24.1 infill Zone 27
including 289.8 290.4 0.6 85.5
  294.5 296.8 2.3 3.52 infill Zone 27

 

Note:    VNCR = Crustiform veins. True widths are estimated at 65 – 80% of the reported core length interval.  See “Quality Control and Reporting Protocols” below.

 

 

Hole Number Azimuth (°) Dip (°) Length (m) UTM E UTM N Section
OSK-W-17-907 134 -51 1317 453219 5435340 3575
OSK-W-17-1070 141 -49 66 452024 5434701 2200
OSK-W-17-1119 331 -55 609 452540 5434453 2550
OSK-W-17-1143 331 -46 159 453253 5435003 3425
OSK-W-17-1158 331 -59 696 453046 5434870 3175
OSK-W-17-1186 331 -54 984 452417 5434558 2475
OSK-W-17-1313 331 -51 876 452280 5434572 2375
OSK-W-17-936-W2 332 -56 819 452773 5434547 2775
OSK-W-17-958 143 -55 1212 453359 5435437 3725
OSK-W-18-1440 329 -57 870 452418 5434448 2425
OSK-W-18-1518 330 -54 393 452266 5434569 2350
OSK-W-18-1530 329 -46 141 453258 5434988 3425
OSK-W-18-1552 332 -52 366 452308 5434640 2425
OSK-W-18-1559 331 -53 330 452299 5434661 2425
OSK-W-18-1561 334 -52 302 453403 5434957 3550
OSK-W-18-1564 324 -47 366 452429 5434680 2550
OSK-W-18-1589 138 -48 123 452235 5434944 2500
OSK-W-18-1594 140 -50 270 452212 5434966 2500
OSK-W-18-1598 145 -51 525 453345 5435474 3750
OSK-W-18-1613 141 -52 381 453199 5435178 3475
OSK-W-18-1618 326 -45 255 452312 5434665 2450
OSK-W-18-1622 139 -48 303 452159 5434944 2450
OSK-W-18-1623 332 -45 279 452292 5434648 2425
OSK-W-18-1624 330 -47 333 452311 5434665 2450
OSK-W-18-1627 141 -51 513 453228 5435374 3600
OSK-W-18-1628 145 -48 579 453286 5435494 3700
OSK-W-18-1631 330 -45 315 452356 5434670 2475
OSK-W-18-1632 329 -47 390 452341 5434666 2475
OSK-W-18-1634 330 -46 354 452304 5434658 2425
OSK-W-18-1638 147 -49 555 453297 5435476 3700
OSK-W-18-1639 142 -53 519 453266 5435395 3625
OSK-W-18-1640 318 -59 407 452289 5434578 2375
OSK-W-18-1642 331 -55 473 452331 5434629 2450
OSK-W-18-1643 139 -45 377 452868 5435083 3125
OSK-W-18-1644 352 -45 342 452070 5434450 2125
OSK-W-18-1645 141 -50 618 453308 5435500 3725
OSK-W-18-1646 2 -53 330 452014 5434504 2100
OSK-W-18-1647 142 -53 534 453266 5435395 3625
OSK-W-18-1648 343 -47 342 452056 5434462 2125
OSK-W-18-1649 357 -46 369 452070 5434450 2125
OSK-W-18-1650 360 -56 306 452014 5434504 2100
OSK-W-18-1651 2 -45 378 452070 5434450 2125
OSK-W-18-1653 341 -45 336 452056 5434462 2125
OSK-W-18-1654 355 -52 282 452014 5434504 2100
OSK-W-18-1655 351 -45 375 452087 5434442 2150
OSK-W-18-1656 144 -45 573 453260 5435472 3675
OSK-W-18-1657 146 -51 504 453277 5435392 3650
OSK-W-18-1659 4 -55 315 452014 5434504 2100
OSK-W-18-1660 359 -45 387 452056 5434462 2125
OSK-W-18-1661 353 -45 393 452103 5434436 2150
OSK-W-18-1662 6 -52 303 452014 5434504 2100
OSK-W-18-1665 347 -46 375 452103 5434436 2150
OSK-W-18-1669 3 -47 405 452056 5434462 2125
OSK-W-18-1671 359 -52 309 452014 5434504 2100

 

 

OSK-W-17-907 intersected 7.56 g/t Au over 4.9 metres related to a crustiform vein in Lynx.  Mineralization consists of local visible gold, up to 5% pyrite, and 1% molybdenite and sphalerite in quartz-carbonate crustiform veins injected in a gabbro.

 

OSK-W-17-936-W2 intersected 16.7 g/t Au over 2.4 metres in Caribou. Mineralization consists of 5% clustered pyrite and trace pyrite-tourmaline stringers in pervasive silica flooding within a strongly silicified porphyritic felsic dike.

 

OSK-W-17-958 intersected 36.5 g/t Au over 2.1 metres in Lynx. Mineralization consists of up to 5% pyrite-tourmaline stringers and disseminated pyrite in a gabbro with silica and fuchsite alteration.

 

OSK-W-18-1070 intersected 8.12 g/t Au over 2.8 metres in Zone 27. Mineralization consists of trace disseminated pyrite and a centimetre-scale quartz-carbonate vein in a sericitized rhyolite.

 

OSK-W-17-1119 intersected 5.63 g/t Au over 2.9 metres in Caribou.  Interval contains up to 10% pyrite stringers in a strongly chloritized gabbro with weak sericitization and silicification.

 

OSK-W-17-1143 intersected 20.4 g/t Au over 2.0 metres in Lynx. Mineralization contains local visible gold and 5% pyrite with pervasive silica flooding zone in a sericitized fragmental felsic unit.

 

OSK-W-17-1158 intersected 71.4 g/t Au over 2.0 metres in Bobcat. Mineralization consists of trace disseminated pyrite, trace quartz-carbonate veins in a chloritized and sericitized fragmental dike.

 

OSK-W-17-1186 intersected 18.0 g/t Au over 2.0 metres in Underdog. Mineralization consists of 25% pyrite with intense pervasive silica flooding hosted in a porphyritic felsic dike with moderate sericite alteration.

 

OSK-W-17-1313 intersected 25.7 g/t Au over 8.9 metres in Zone 27. Mineralization consists of up to 25% pyrite with intense silica flooding and trace sphalerite clusters at the silicified and sericitized contact between a porphyritic felsic dike and an andesite.

 

OSK-W-18-1440 intersected 6.61 g/t Au over 2.4 metres in Caribou. Mineralization contains 7% disseminated pyrite and trace pyrite stringers in an andesite with moderate chlorite and carbonate alteration and weak silica and sericite alteration.

 

OSK-W-18-1518 intersected 3.74 g/t Au over 3.0 metres in Caribou. Mineralization consists of 5% pyrite with pervasive silica flooding in a sericitized rhyolite.

 

OSK-W-18-1530 intersected 11.4 g/t Au over 2.0 metres in Lynx. Mineralization contains trace fragmental pyrite and trace pyrite stringers in a sericite, chlorite and silica altered fragmental felsic dike.

 

OSK-W-18-1552 intersected a vein returning 3.70 g/t Au over 2.0 metres in Lynx. Mineralization contains up to 20% pyrite stringers at the sericitized contact between a porphyritic felsic dike and an andesite.

 

OSK-W-18-1559 intersected 4.47 g/t Au over 2.0 metres in Zone 27. Mineralization consists of trace pyrite stringers and pyrite-quartz clusters in a chloritized andesite.

 

OSK-W-18-1561 intersected 7.33 g/t Au over 2.2 metres in Lynx. Mineralization consists of trace disseminated pyrite and 90% quartz clusters over 40 cm in a strongly silicified rhyolite with light sericite and carbonate alteration.

 

OSK-W-18-1564 intersected 4.49 g/t Au over 2.0 metres and 4.71 g/t Au over 2.0 metres in Caribou. Mineralization consists of 2% disseminated pyrite and stringers hosted in a bleached and sericitized porphyritic dike or a chloritized andesite with carbonate and hematite alteration.

 

OSK-W-18-1589 intersected 742 g/t Au over 2.2 metres in Zone 27. Mineralization consists of local visible gold clusters within a pyrite-tourmaline stringer hosted in a moderately sericitized rhyolite.

 

OSK-W-18-1594 intersected 10.4 g/t Au over 2.6 metres in Zone 27. Mineralization consists of 10% to locally 60% pyrite stringers in a silicified and sericitized fragmental rhyolite.

 

OSK-W-18-1598 intersected 5.47 g/t Au over 2.2 metres in Lynx. Mineralization consists of 2% pyrite with quartz-carbonate ± tourmaline crustiform veins and 1% pyrite stringers in a bleached and fuchsite altered gabbro.

 

OSK-W-18-1613 intersected 8.12 g/t Au over 2.3 metres in Lynx. Mineralization consists of up to 5% pyrite with pervasive silica flooding in a moderately silica altered porphyritic felsic dike.

 

OSK-W-18-1618 intersected 3.00 g/t Au over 2.5 metres in Caribou. Mineralization consists of trace pyrite clusters in a moderately sericite altered rhyolite.

 

OSK-W-18-1622 intersected 16.0 g/t Au over 2.1 metres with in Zone 27. Mineralization consists of up 25% pyrite in stockwork in a chlorite-rich matrix and a local centimetre band of pyrite massive, hosted in a bleached andesite.

 

OSK-W-18-1623 intersected 6.51 g/t Au over 2.3 metres in Caribou. Mineralization consists of local visible gold and 25% pyrite-tourmaline stringers within a strongly silicified and moderately sericitized rhyolite.

 

OSK-W-18-1624 intersected 6.01 g/t Au over 2.9 metres and 7.97 g/t Au over 2.4 metres  in Caribou and  4.30 g/t Au over 4.8 metres in Zone 27. The first and second intervals contain 1% pyrite stringers and trace pyrite in quartz or quartz-tourmaline veins and locally 5% pyrite infilling fractures within a moderately sericitized and silicified rhyolite. The third interval contains 5% pyrite stringers, 1% disseminated pyrite and trace chalcopyrite in a strongly bleached andesite.

 

OSK-W-18-1627 intersected a crustiform vein returning 9.25 g/t Au over 2.4 metres. Mineralization consists of 2% pyrite stringers in a metre-scale crustiform vein composed of quartz-carbonate with 1% ptygmatic tourmaline veinlets hosted in a lightly fuchsite altered gabbro.

 

OSK-W-18-1628 intersected 57.5 g/t Au over 2.6 metres and 23.0 g/t Au over 2.1 metres in Lynx. Both intervals contain local visible gold and up to 7% disseminated pyrite and stringers in a strongly sericite, locally silica and fuchsite altered gabbro.

 

OSK-W-18-1631 intersected 4.50 g/t Au over 5.1 metres in Caribou. Mineralization consists of 10% pyrite stringers hosted in a porphyritic felsic dike and gabbroic unit.

 

OSK-W-18-1632 intersected 3.28 g/t Au over 2.5 metres in Zone 27. Mineralization consists of 10% pyrite stockwork and 3% disseminated pyrite in a sericitized andesite.

 

OSK-W-18-1634 intersected 6.29 g/t Au over 3.9 metres in Caribou. Mineralization consists of up to 25% pyrite clusters with local patches of silica flooding, quartz-carbonate veins and ptygmatic tourmaline veinlets in a moderately sericitized rhyolite.

 

OSK-W-18-1638 intersected  198 g/t Au over 2.0 metres and 14.6 g/t Au over 2.0 metres in Lynx. The first interval is composed of 6% pyrite stringers and clusters, 1% pyrite in two 30-centimetre scale quartz-carbonate crustiform veins, 1% pyrite in ptygmatic tourmaline veinlets hosted in bleached and fuchsite altered gabbro. The second interval contains local visible gold with 3% pyrite stringers and trace pyrite in ptygmatic tourmaline veins hosted in a silicified and fuchsite altered gabbro.

 

OSK-W-18-1639 intersected three intervals: 3.27 g/t Au over 3.5 metres, 510 g/t Au over 5.2 metres and 4.87 g/t Au over 2.0 metres in Lynx. The first interval contains 1% pyrite stringers with 70% quartz clusters in a chlorite and carbonate altered gabbro. The second interval contains local visible gold in veinlets and as disseminated grains and 5% pyrite stringers in a crustiform vein hosted in a sericite and fuchsite altered gabbro. The third interval contains local visible gold and 3% pyrite stringers in a sericitized and weakly fuchsite altered gabbro.

 

OSK-W-18-1640 intersected two intervals: 6.27 g/t Au over 2.3 metres and 50.0 g/t Au over 3.0 metres in Caribou. The first interval contains 8% pyrite stockwork with pervasive silica flooding, 1% sphalerite and trace chalcopyrite hosted in a moderately bleached and sericitized felsic porphyritic dike. The second interval contains 35% semi-massive pyrite within a bleached, moderately to strongly sericite and silica-altered andesite and felsic porphyritic dike.

 

OSK-W-18-1642 intersected 12.8 g/t Au over 3.8 metres in Caribou and 5.95 g/t Au over 2.3 metres in Zone 27. The first interval contains 20% (to locally 60%) pyrite ± tourmaline stringers with trace sphalerite hosted in a strongly silicified and sericitized rhyolite and strongly sericitized andesite injected locally by quartz-carbonate-tourmaline veins. The second interval contains up to 15% disseminated pyrite, stringers or clusters with quartz-carbonate veins and quartz tourmaline breccia in a bleached and sericitized and chloritized gabbro.

 

OSK-W-18-1643 intersected 5.99 g/t Au over 2.7 metres in Bobcat. Mineralization consists of 3% pyrite-tourmaline stringers at the margins of quartz-carbonate veins hosted in a weakly sericitized rhyolite.

 

OSK-W-18-1644 intersected two intervals: 3.32 g/t Au over 2.6 metres in Caribou and 41.1 g/t Au over 3.3 metres in Zone 27. The first interval contains 5% pyrite with quartz-carbonate veins, 8% pyrite stockwork with pervasive silica flooding, 1% sphalerite and trace chalcopyrite hosted in a moderately bleached and sericitized felsic porphyritic intrusion. The second interval contains local visible gold, up to 30% disseminated, stringer, or cluster pyrite with trace chalcopyrite with silica patches and trace ptygmatic tourmaline veinlets hosted in a bleached and moderately to strongly sericite altered andesite.

 

OSK-W-18-1645 intersected 5.39 g/t Au over 2.0 metres in Lynx. Mineralization consists of 5% pyrite and 1% sphalerite with pervasive silica flooding in a gabbro.

 

OSK-W-18-1646 intersected two intervals: 7.51 g/t Au over 2.4 metres in Caribou and 6.28 g/t Au over 2.7 metres in Zone 27. The first interval contains 5% pyrite in ptygmatic tourmaline veins in a moderately sericite, chlorite and fuchsite altered porphyritic felsic dike. The second interval contains 3% disseminated and cluster pyrite in chloritized and silicified andesite alternating with sericitized porphyritic felsic dike.

 

OSK-W-18-1647 intersected 17.4 g/t Au over 2.0 metres in Lynx. Mineralization consists of trace pyrite in ptygmatic tourmaline veinlets in a crustiform carbonate vein overprinted by silica and fuchsite alteration hosted in a gabbro.

 

OSK-W-18-1648 intersected two intervals: 3.74 g/t Au over 2.3 metres in Caribou and 9.19 g/t Au over 4.4 metres in Zone 27. The first interval contains 7% pyrite with quartz-carbonates veins in a weakly sericitized porphyritic felsic dike. The second interval contains 1% pyrite stringers and 2% disseminated pyrite in a moderately sericite and fuchsite altered porphyritic felsic dike at the contact with Red Dog intrusion.

 

OSK-W-18-1649 intersected three intervals: 4.61 g/t Au over 2.0 metres and 48.4 g/t Au over 2.0 metres in Caribou and 14.9 g/t Au over 2.1 metres in Zone 27. The first interval contains 3% pyrite stringers, 2% sphalerite stringers and 3% disseminated pyrite in a sericite and silica altered porphyritic felsic dike. The second interval contains 3% disseminated pyrite and clusters with 2% ptygmatic tourmaline veins in a chloritized and sericitized porphyritic felsic dike. The third interval contains local visible gold, 7% pyrite with silica flooding, 2% pyrite stringers, 2% pyrite-tourmaline stringers and 3% disseminated pyrite in sericitized and silicified fragmental porphyritic felsic dike.

 

OSK-W-18-1650 intersected two intervals: 6.11 g/t Au over 4.1 metres and 4.22 g/t Au over 3.2 metres in Zone 27. Mineralization consists of 5% pyrite-tourmaline stringers and 2% pyrite with silica flooding in a moderately sericitized and bleached porphyritic felsic dike.

 

OSK-W-18-1651 intersected fourth intervals: 4.01 g/t Au over 2.2 metres and 3.68 g/t Au over 2.0 metres in Caribou, and 7.39 g/t Au over 2.0 metres and 3.45 g/t Au over 4.7 metres in Zone 27.  The first and second intervals contain 15% semi-massive pyrite, 3% pyrite stringers and clusters and 3% disseminated pyrite within a sericitized and silicified rhyolite or porphyritic felsic dike. The third interval contains 5% pyrite stringers and 5% disseminated pyrite in a bleached and moderately silicified and sericitized andesite with weak fuchsite alteration. The fourth interval contains up to 40% semi-massive pyrite, 10% pyrite stringers, 10% clustered or disseminated pyrite, 2% pyrite in smoky quartz veins or ptygmatic tourmaline veinlets and trace chalcopyrite hosted in sericitized, silicified and bleached porphyritic dike and sericitized andesite.

 

OSK-W-18-1653 intersected 4.15 g/t Au over 2.6 metres in Zone 27. Mineralization is composed of 5% pyrite-tourmaline clusters, 1% disseminated pyrite, trace pyrite with quartz-tourmaline veins and up to 10% pyrite with pervasive silica flooding. Host rocks are a sericitized rhyolite and a sericitized porphyritic felsic dike.

 

OSK-W-18-1654 intersected 9.10 g/t Au over 2.0 metres in Zone 27. Mineralization consists of up to 5% pyrite stringers with local tourmaline, 1% pyrite in quartz-tourmaline veins and trace chalcopyrite in a silicified and sericitized porphyritic felsic dike.

 

OSK-W-18-1655 intersected three intervals: 4.99 g/t Au over 2.3 metres, 21.6 g/t Au over 19.4 metres and 11.1 g/t Au over 2.3 metres in Zone 27. The first interval contains 5% pyrite with pervasive silica flooding, 2% pyrite stringers and 1% disseminated pyrite in a sericitized and silicified rhyolite at the contact with a porphyric felsic dike. The second interval contains local visible gold, up to 20% pyrite stockwork, 10% disseminated pyrite, up to 5% disseminated sphalerite and 1% disseminated chalcopyrite. Host is a bleached, silica and sericite altered porphyric felsic intrusion. The third interval contains 3% pyrite with quartz-tourmaline veins and 7% disseminated pyrite in a faulted zone at contact between a porphyritic felsic dike and an andesite.

 

OSK-W-18-1656 intersected 8.28 g/t Au over 5.8 metres in Lynx. Mineralization consists of 2% pyrite stringers in quartz-tourmaline-carbonate veins hosted in a chloritized gabbro.

 

OSK-W-18-1657 intersected 5.00 g/t Au over 2.3 metres and 8.41 g/t Au over 2.1 metres in Lynx. The first interval contains up to 7% disseminated pyrite in a strongly silica altered rhyolite. The second interval contains 10% disseminated pyrite and pyrite-tourmaline stringers in a strongly sericitized, chloritized and bleached gabbro with local silica-fuchsite alteration.

 

OSK-W-18-1659 intersected 4.09 g/t Au over 6.8 metres and 5.88 g/t Au over 5.2 metres in Zone 27. The first interval contains 7% pyrite stringers and up to 40% semi-massive pyrite (over 1.5 metres) with silica alteration in a sericitized andesite and porphyritic felsic dike. The second interval contains local visible gold with locally 30% massive pyrite and 10% pyrite stringers in a strongly sericitized andesite and porphyritic felsic intrusion.

 

OSK-W-18-1660 intersected 7.19 g/t Au over 2.2 metres in Caribou. Mineralization consists of up to 6% disseminated and stringer pyrite and 1% sphalerite in quartz veins hosted in a strongly silicified porphyritic felsic dike.

 

OSK-W-18-1661 intersected 9.28 g/t Au over 2.1 metres in Zone 27. Mineralization consists of up to 20% disseminated pyrite, 10% pyrite stringers, 3% disseminated sphalerite, trace of pyrite-tourmaline stringers and trace disseminated chalcopyrite in a bleached, sericitized and locally silicified porphyritic felsic intrusion.

 

OSK-W-18-1662 intersected two intervals: 4.08 g/t Au over 3.6 metres and 14.8 g/t Au over 9.0 metres in Zone 27.  The first interval contains 2% pyrite stringers, 3% disseminated pyrite, 2% pyrite in quartz vein in a strongly sericitized porphyritic felsic dike at contact with a sericitized andesite. The second interval contains local visible gold, up to 5% pyrite stringers in a strongly sericitized and weakly silicified porphyritic felsic dike.

 

OSK-W-18-1665 intersected 4.65 g/t Au over 2.7 metres in Zone 27.  Mineralization is composed of 30% pyrite-tourmaline stringers with local patchy silica alteration hosted in a sericitized porphyritic felsic dike and a sericitized rhyolite.

 

OSK-W-18-1669 intersected 4.75 g/t Au over 3.4 metres in Zone 27. Mineralization consists of up to 10% pyrite stringers and clusters, 6% disseminated pyrite in a breccia tourmaline quartz zone. Host rocks are a sericitized porphyritic felsic dike and a bleached and sericitized fragmental andesite.

 

OSK-W-18-1671 intersected four intervals: 12.7 g/t Au over 2.3 metres, 5.64 g/t Au over 3.9 metres, 24.1 g/t Au over 2.5 metres and 3.52 g/t Au over 2.3 metres in Zone 27. The first interval contains 12% pyrite stringers and clusters with local silica flooding in moderately sericitized and bleached andesite. The second, third and fourth intervals contain 30 to 70% pyrite-tourmaline stringers and local quartz veins hosted in a sericitized and bleached andesite and a porphyritic felsic dike with moderate fuchsite, and weak silica-sericite and chlorite alteration.

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

True width determination is currently unknown but is estimated at 65-80% 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. 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, 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 Lake Gold Deposit

The Windfall Lake 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 Windfall Lake Technical Report (as defined below), comprises 2,382,000 tonnes at 7.85 g/t Au (601,000 ounces) in the indicated mineral resource category and 10,605,000 tonnes at 6.70 g/t Au (2,284,000 ounces) in the inferred mineral resource category. For details regarding the key assumptions, parameters and methods used to estimate the mineral resources presented in respect of the Windfall Lake gold project, please see the technical report entitled “Technical Report and Mineral Resource Estimate for the Windfall Lake Project, Windfall Lake and Urban-Barry Properties” and dated June 12, 2018 (effective date of May 14, 2018), which has been prepared by InnovExplo Inc. from Val-d’Or, Québec (the “Windfall Lake Technical Report”). The Windfall Lake Technical Report is available on Osisko’s website at www.osiskomining.com and on SEDAR under Osisko’s issuer profile at www.sedar.com). The Windfall Lake gold deposit is currently one of the highest grade resource-stage gold projects in Canada. Mineralization occurs in four principal zones: Lynx, Zone 27, Caribou and Underdog. All zones comprise sub-vertical lenses following intrusive porphyry contacts plunging to the northeast. The deposit is well defined from surface to a depth of 900 metres and remains open along strike and at depth. Mineralization has been identified only 30 metres from surface in some areas and as deep as 1,200 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 precious metal resource properties in Canada. Osisko holds a 100% interest in the high-grade Windfall Lake 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 Quevillon area (over 3,300 square kilometres), a 100% interest in the Marban project located in the heart of Québec’s prolific Abitibi gold mining district, and properties in the Larder Lake Mining Division in northeast Ontario, including the Jonpol and Garrcon deposits on the Garrison property, the Buffonta past producing mine and the Gold Pike mine property. The Corporation also holds interests and options in a number of additional properties in northern Québec and Ontario.

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. The information in this news release about the Windfall Lake gold deposit being one of the highest grade resource-stage gold projects in Canada; the Windfall Lake gold deposit being a world-class gold system; the significance of new results from the ongoing deep-hole drill/exploration program at the Windfall Lake gold project; the significance of assay results presented in this news release; potential depth extensions of the Lynx and Underdog mineralized zones; the potential, if any of the Deep Underdog and Deep Lynx zones; the type and extend of drilling on the Deep Underdog and Deep Lynx zones, including planned wedge holes; the success of Osisko’s deep-hole drill/exploration program at the Windfall Lake gold project, if any; the down-plunge projection of the gold mineralized structures; the current 800,000 metre drill program; the type of drilling included in the drill program; potential mineralization; the potential to extend mineralization up and down-plunge and at depth at the Windfall Lake gold deposit; the ability to realize upon any mineralization in a manner that is economic; the ability to complete any proposed exploration activities and the results of such activities, including the continuity or extension of any mineralization; and any other information herein that is not a historical fact may be “forward-looking information”. Any statement that involves discussions with respect to 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”, “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 forward-looking information is based on reasonable assumptions and estimates of management of the Corporation at the time such assumptions and estimates were made, and involves known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of Osisko to be materially different from any future results, performance or achievements expressed or implied by such forward-looking information. 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 interests in the Windfall Lake gold project; the ability of the Corporation to obtain required approvals and complete transactions on terms announced; 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.

 

For further information please contact:

John Burzynski
President and Chief Executive Officer

Telephone: (416) 363-8653