Osisko Intersects 86.7 g/t Au Over 4.3 Metres at Windfall

TORONTO, ONTARIO--(Marketwired - Jan 18, 2018) - Osisko Mining Inc. (TSX:OSK) ("Osisko" or the "Corporation") is pleased to provide new results from the ongoing drill 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 combines definition, expansion and exploration drilling in and around the main Windfall gold deposit and the adjacent Lynx deposit (located immediately NE of Windfall).

Significant new analytical results from 148 intercepts in 84 drill holes and 5 wedges focused on infill and expansion drilling in the Main Windfall lake deposit are presented below.

• New Underdog Zone discovered to SW
• New mineralization discovered between the Mallard Zone and Zone 27.
• New mineralization discovered near surface west of the main deposit.

Highlights from the new results include: 86.7 g/t Au over 4.3 metres in OSK-W-17-1345; 74.0 g/t Au over 2.5 metres and 29.6 g/t Au over 2.9 metres in OSK-W-17-1334; 48.6 g/t over 2.0 metres in OSK-OBM-15-565; 32.7 g/t Au over 2.8 metres in OSK-W-17-1233; 41.5 g/t Au over 2.0 metres and 24.8 g/t Au over 2.4 metres in OSK-OBM-16-678; 10.0 g/t Au over 8.1 metres in OSK-W-17-1317; 11.1 g/t Au over 6.9 metres in OSK-W-17-1125-W1; 29.2 g/t Au over 2.2 metres in OSK-W-17-1273; 11.6 g/t Au over 5.4 metres in OSK-W-17-1308; 25.2 g/t Au over 2.0 metres in OSK-W-17-1313; and 20.5 g/t Au over 2.3 metres in OSK-W-17-1225. Maps showing hole locations and full analytical results are available at www.osiskomining.com.

Notes:

1. True widths are estimated at 65 - 80% of the reported core length interval. See "Quality Control" below.
2. Definitions: HW = Hanging Wall, FW = footwall, VNCR = Crustiform Vein, TBD = To be determined, Ext = extension.

OSK-OBM-15-565 intersected 48.6 g/t Au over 2.0 metres. This interval is located between Mallard and Zone 27 corridors. Mineralization is composed of 1% pyrite stringers, and trace disseminated pyrite in a sericitized andesite.

OSK-OBM-16-678 intersected 24.8 g/t Au over 2.4 metres, and 41.5 g/t au over 2.0 metres in Zone 27. The first interval is composed of a 30 centimetres massive pyrite vein hosted in a sericitized rhyolite. The second interval is composed of up to 4% pyrite stringers at the contact between a bleached andesite and a sericitized porphyritic felsic dike.

OSK-W-17-937-W1 intersected 3.21 g/t Au over 2.2 metres. The interval is in Wolf 2 and is composed of up to 8% pyrite stringers and disseminated pyrite in andesite and porphyritic felsic units.

OSK-W-17-937-W2 intersected 16.8 g/t Au over 2.5 metres and 9.01 g/t Au over 2.0 metres in the Caribou Corridor. The first interval is in the Wolf HW and composed of 1% pyrite stringers and disseminated pyrite in a chloritized and slightly sericitized andesite. The second interval is in Wolf 2 hosted inandesite and silicified felsic intrusions with 5% pyrite in pervasive silica flooding and 7% pyrite stringers.

OSK-W-17-978 intersected 3.04 g/t Au over 2.8 metres in Caribou Extension. Mineralization is at the contact between a carbonate and chlorite altered andesite with 1% pyrite stringers, 10% quartz-tourmaline veins, and a porphyritic felsic dike with carbonate and hematite alteration with disseminated pyrite and local pervasive silica flooding.

OSK-W-17-989-W2 intersected 6.29 g/t Au over 3.0 metres in CS1 in the Caribou Corridor. Mineralization is within a sericitized andesite and composed of 5% pyrite stringers, and 2% disseminated pyrite.

OSK-W-17-1002 intersected Zone 27 returning 5.07 g/t Au over 2.0 metres. Mineralization is hosted in a sericitized porphyritic felsic dike and composed of 25% pyrite-tourmaline stringers.

OSK-W-17-1014 intersected Zone 27 returning 6.27 g/t Au over 3.4 metres. Mineralization is composed of 9% pyrite-tourmaline stringers hosted in a sericitized rhyolite.

OSK-W-17-1051 intersected 3.94 g/t Au over 2.4 metres in a crustiform vein within the F-17 area. Mineralization is composed of a 30 centimetres scale crustiform vein with traces of pyrite stringers in a strongly silicified porphyritic felsic dike.

OSK-W-17-1052 intersected 3.81 g/t Au over 2.3 metres related to Zone 27. Mineralization is composed of 10% pyrite stringers and 1% disseminated pyrite in a strongly sericitized and weakly chloritized gabbro.

OSK-W-17-1053 intersected 5.06 g/t Au over 5.1 metres in Zone 27. Mineralization is composed of trace of pyrite stringers and quartz-tourmaline veinlets at a sericitized contact between a felsic porphyritic dike and a rhyolite.

OSK-W-17-1073 intersected 3.11 g/t Au over 4.2 metres in a crustiform vein. Mineralization is composed of up 5% pyrite-tourmaline stringers with a 1.3 metres crustiform vein with pyrite hosted in a porphyritic felsic dike with local sericite alteration.

OSK-W-17-1125-W1 intersected 4.01 g/t Au over 2.1 metres, 7.57 g/t Au over 2.0 metres and 11.1 g/t Au over 6.9 metres within the Caribou corridor. The first interval, in CS3, is composed of sericitized rhyolite containing up to 25% pyrite stringers. The second interval, in Caribou FW, is composed of chloritized zone in a felsic porphyritic dike with trace disseminated pyrite close to the contact with the andesite. The third interval, in Wolf HW, is composed of 2% pyrite stringers and pyrite-tourmaline stringers with local visible gold, chalcopyrite and sphalerite hosted in a sericitized porphyritic felsic dike.

OSK-W-17-1125-W3 intersected 18.1 g/t Au over 2.0 metres and 10.2 g/t au over 2.0 metres in Caribou and Wolf, respectively. The first interval is in an altered gabbro with chlorite and carbonates containing traces of disseminated pyrite. The second interval is a sericitized felsic dike with 5% pyrite clusters and 5% chalcopyrite in quartz clusters.

OSK-W-17-1134 intersected 16.0 g/t Au over 2.3 metres in a crustiform vein within the Mallard Corridor. Mineralization is composed of 2% pyrite in crustiform veins representing 20% of the interval land 2% pyrite stringers hosted in a sericitized andesite.

OSK-W-17-1135 intersected 3.33 g/t Au over 2.4 metres in Zone 27. Mineralization is composed of 1% pyrite clusters with intense silica flooding in a sericitized rhyolite.

OSK-W-17-1139 intersected 4.06 g/t au over 2.0 metres in the Caribou Corridor. Mineralization is hosted in a shear zone with moderate sericite and chlorite alteration, weak silicification, and traces of disseminated pyrite.

OSK-W-17-1140 intersected 3.94 g/t Au over 2.4 metres in the Caribou Corridor. Mineralization is within a chloritized andesite with weak silica and sericite alteration and is composed of traces of disseminated pyrite.

OSK-W-17-1141 intersected Zone 27 returning 4.00 g/t Au over 4.1 metres. Mineralization is composed of traces of pyrite stringers in a chloritized and sericitized rhyolite.

OSK-W-17-1145 intersected 4.01 g/t Au over 3.2 metres in Zone 27 FW. Mineralization is composed of 5% pyrite stringers and 2% pyrite clusters in a sericitized and strongly silicified rhyolite.

OSK-W-17-1159 intersected 4.99 g/t Au over 2.0 metres in Caribou Extension. Mineralization is composed of traces of pyrite-tourmaline stringers with 5% quartz-tourmaline veins and ptygmatic tourmaline veins hosted in a foliated, chloritized and sericitized felsic dike.

OSK-W-17-1163 intersected 9.60 g/t Au over 2.0 metres in a new area 200 metres north east of Mallard. Mineralization is within a chlorite and carbonate altered andesite and composed of 2% disseminated pyrite.

OSK-W-17-1164 intersected 3.37 g/t Au over 2.3 metres in Zone 27. Mineralization is composed 5% pyrite, in stringers and clusters, at a silicified and sericitized contact between two porphyritic felsic dikes.

OSK-W-17-1184 intersected 4.21 g/t Au over 2.0 metres and 4.64 g/t Au over 2.6 metres in the Zone 27 Corridor. The first interval is in Z27 HW and composed of 50% semi-massive pyrite over 50 centimetres, 1% pyrite with ptygmatic tourmaline veins within a sericitized felsic porphyritic dike. The second interval is in Zone 27 and composed of a chloritized rhyolite with traces of disseminated pyrite.

OSK-W-17-1186 intersected 12.3 g/t Au over 3.0 metres in the Caribou Corridor and 3.49 g/t Au over 2.5 metres in Zone 27 HW. Both intervals are composed of traces of disseminated and fragmental pyrite in a strongly chloritized andesite.

OSK-W-17-1188 infilled Zone 27 with 16.8 g/t Au over 2.6 metres. Mineralization is composed of 2% disseminated pyrite within a chloritized mafic volcanic unit.

OSK-W-17-1191 intersected 13.9 g/t Au over 2.8 metres and 7.46 g/t Au over 2.1 metres in Zone 27. The first interval is composed of a sericitized rhyolite with traces of pyrite, disseminated or stringers. The second interval is composed of 1% pyrite stringers within a sericitized felsic porphyritic unit.

OSK-W-17-1194 intersected 3.12 over 5.9 metres in a new zone north of the Mallard Corridor. The mineralization is composed of 4% pyrite, stringers and clusters, in a bleached andesite moderately sericitized.

OSK-W-17-1196 intersected 15.7 g/t Au over 2.0 metres in Zone 27 FW. Mineralization is composed of 3% pyrite-tourmaline stringers and 1% pyrite in tourmaline ptygmatic veins within a sericitized andesite.

OSK-W-17-1198 infilled Zone 27 with 3.47 g/t Au over 7.5 metres. Mineralization is composed of 6% pyrite stringers associated with ptygmatic tourmaline veinlets hosted in a sericitized felsic porphyritic dike.

OSK-W-17-1200 intersected 3.00 g/t Au over 2.9 metres in a new zone in the Caribou Corridor. The mineralization is composed of 2% pyrite clusters within a moderately chloritized and weakly sericitized contact between an andesite and a porphyritic felsic dike.

OSK-W-17-1202 intersected 8.71 g/t au over 2.2 metres in Caribou Extension. Mineralization is composed of 15% pyrite stringers within a strongly silicified and weakly fuchsitized felsic dike.

OSK-W-17-1203 intersected Mallard returning 6.76 g/t Au over 3.0 metres. Mineralization is composed of 10% disseminated, stringer, and fragmented pyrite, locally semi-massive, hosted in a weakly sericitized and silicified felsic porphyritic dike.

OSK-W-17-1207 intersected 5.94 g/t Au over 2.3 metres and 3.35 g/t Au over 2.3 metres in Mallard corridor. The first interval, in Drake, is composed of a hydrothermal breccia with weak to moderate sericite and silica alteration containing 20% pyrite hosted in a rhyolite. The second interval, in Mallard, is composed of 5% pyrite stringers and traces of disseminated pyrite within a chloritized and weakly sericitized andesite.

OSK-W-17-1215 intersected 4.11 g/t Au over 2.0 metres. Mineralization is composed of a stockwork of semi-massive to massive pyrite (10-80%) and chalcopyrite (1-5%). Sulphides are within a hydrothermal breccia with polymithic fragments (different felsic porphyritic dike types, fuchsite altered gabbro and sericitized rhyolite). This is a new potential zone within the Underdog Corridor, 700 metres South-West of the Main deposit.

OSK-W-17-1217 intersected a new zone between the Mallard and the Zone 27 corridor returning 5.47 g/t Au over 2.2 metres. Mineralization is composed of 1% pyrite stringers and disseminated pyrite within a weakly sericitized rhyolite.

OSK-W-17-1225 intersected 5.77 g/t Au over 3.3 metres, 9.58 g/t Au over 2.3 metres and 20.5 g/t Au over 2.3 metres. The first interval is within a chloritized gabbro and composed of 3% pyrite stringers and 1% disseminated pyrite. It is a new zone and geometry is not yet determined. The second interval is in Mallard HW and composed of 4% pyrite clusters, 3% pyrite stringers within a chloritized and sericitized andesite. The third interval is in Mallard and composed of a sericitized porphyric felsic dike with traces of disseminated pyrite.

OSK-W-17-1227 intersected Wolf Extension returning 6.56 g/t Au over 3.4 metres, 10.5 g/t Au over 2.0 metres and 4.93 g/t Au over 2.0 metres. The first interval is composed of 2% sphalerite stringers, 3% pyrite stringers and 2% disseminated pyrite hosted in a bleached porphyritic felsic dike. The second interval is composed of 2% disseminated pyrite and 2% pyrite stringers hosted in a moderately sericitized andesite. The third interval is composed of 4% pyrite stringers, 3% disseminated pyrite and 2% quartz-tourmaline veins hosted in a moderately sericitized andesite.

OSK-W-17-1233 intersected 32.7 g/t Au over 2.8 metres in a new zone between the Mallard and Zone 27 corridors. Mineralization is at the contact between a rhyolite and a gabbro and composed of 3% disseminated pyrite and 10% quartz veins with strong fuchsite alteration.

OSK-W-17-1239 intersected 4.11 g/t Au over 2.0 metres and 10.4 g/t au over 2.8 metres in the Caribou Corridor. Mineralization is composed of up to 3% pyrite clusters and stringers within a strongly sericitized felsic porphyritic dikes.

OSK-W-17-1247 returned 3.00 g/t Au over 3.0 metres in a new potential area within the Underdog Corridor. Mineralization is composed of 1% disseminated pyrite associated with chlorite veins within a felsic dike. The interval is 700 metres south-west of the main deposit.

OSK-W-17-1256 intersected 3.11 over 2.2 metres in Mallard. Mineralization is composed of 1% disseminated or stringer pyrite hosted within a chloritized and weakly sericitized andesite.

OSK-W-17-1264 intersected 6.33 g/t Au over 3.4 metres and 6.88 g/t Au over 2.5 metres in the Zone 27 Corridor. The first interval, in Zone 27 HW, is composed of 20% pervasive pyrite-silica flooding, 2% pyrite-tourmaline stringers within a sericitized rhyolite. The second interval, in Zone 27, is composed of 30% pyrite-silica flooding within a sericitized rhyolite.

OSK-W-17-1265 intersected 5.34 g/t Au over 2.3 metres in Caribou extension and 13.0 g/t Au over 2.0 metres in Zone 27. The first interval is composed of 10% massive pyrite and 2% pyrite stringers within a silicified porphyritic felsic dike. The second interval is composed of up to 4% pyrite stringers and 45% quartz veins in an silicified andesite.

OSK-W-17-1267 intersect 3.04 g/t Au over 2.4 metres in the Caribou Corridor. Mineralization is composed of 3% pyrite clusters, 1% pyrite stringers within a sericitized porphyritic felsic dike.

OSK-W-17-1268 intersected 5.51 g/t Au over 2.0 metres and 9.39 g/t Au over 2.0 metres in the Mallard Corridor and 8.17 g/t Au over 3.0 metres and 4.84 g/t Au over 2.1 metres in the Zone 27 Corridor. The first interval, related to a new zone, is composed of 1% pyrite-silica flooding stringer within a sericitized and silicified rhyolite. The second interval, in Drake, is composed of trace disseminated and stringer pyrite in a felsic porphyritic dike with weak carbonatization and sericitization. The third interval, in Zone 27 FW, is composed of 5% pyrite-tourmaline stringers and 5% pyrite clusters in a sericitized and silicified rhyolite. The fourth interval, in Zone 27, is composed of up to 30% pyrite within a felsic porphyritic dike.

OSK-W-17-1269 intersected five intervals in the Zone 27 Corridor; 3.10 g/t Au over 2.5 metres, 3.69 g/t au over 4.5 metres, 3.09 g/t Au over 3.0 metres, 3.47 g/t Au over 2.4 metres and 3.33 g/t Au over 2.7 metres. The first two intervals are in the Zone 27 FW. Mineralization is composed of up to 30% pyrite stringers and up to 2% disseminated pyrite hosted in a porphyritic felsic dike and a strongly sericitized andesite. The last three intervals are in Zone 27. Mineralization is composed of up to 4% pyrite stringers within a sericitized and silicified porphyritic felsic dike or an andesite.

OSK-W-17-1270 intersected 3.07 g/t Au over 7.8 metres and 7.14 g/t Au over 2.9 metres in the Caribou Corridor. The first interval is in Caribou Extension and composed of up to 4% pyrite stringers, 2% disseminated pyrite with locally 5% pyrite and 1% sphalerite hosted in a pervasively silica flooded, sericitized rhyolite. The second interval is composed of 3% quartz clusters in weakly sericitized and bleached andesite.

OSK-W-17-1273 intersected three intervals from the Zone 27 Corridor: 6.72 g/t Au over 2.1 metres, 16.4 g/t Au over 2.5 metres and 29.2 g/t Au over 2.2 metres. The first interval is composed of 20% pyrite stringers and 1% disseminated pyrite. The second interval is composed of up to 15 % semi-massive pyrite and up to 5% pyrite stringers. The third interval is composed of up to 5% pyrite stringers and 1% disseminated pyrite. All the mineralized intervals are within a strongly sericitized rhyolite.

OSK-W-17-1275 intersected 12.4 g/t Au over 2.6 metres in Caribou. Mineralization is composed of up to 1% pyrite stringers within a strongly silicified rhyolite.

OSK-W-17-1276 intersected two intervals within the Mallard zone: 12.6 g/t Au over 2.8 metres and 13.3 g/t Au over 2.0 metres. The first interval is at the contact between a felsic dike and an andesite. The second interval is related to a quartz-tourmaline vein. Mineralization is composed of 3% pyrite stringers, 1% disseminated pyrite and trace of ptygmatic quartz-tourmaline veins. Local visible gold is associated with the quartz-tourmaline vein.

OSK-W-17-1279 intersected 4.56 g/t over 2.2 metres in Zone 27. The mineralization is composed of 10% disseminated pyrite and 10% pyrite stringers in a silicified felsic dike.

OSK-W-17-1281 intersected three intervals: 3.24 g/t Au over 2.2 metres in the Caribou Corridor, 3.25 g/t Au over 3.0 metres and 3.37 g/t Au over 4.0 metres in Zone 27. The first interval is composed of 1% pyrite stringers in strongly sericitized rhyolite. The second and third intervals are composed of up to 15% pyrite in stockworksin a porphyritic felsic dike and a strongly fuchsitized andesite, respectively.

OSK-W-17-1282 intersected Zone 27 footwall returning 8.06 g/t au over 3.1 metres. The mineralization is composed of up to 45% pyrite associated to pyrite-silica flooding and low core angle quartz veins hosted in a moderately sericitized rhyolite.

OSK-W-17-1288 intersected 3.44 g/t Au over 2.6 metres Caribou Extension. The mineralization is composed of 3% pyrite stringers and 1% disseminated pyrite in a sericitized andesite.

OSK-W-17-1289 intersected three intervals: 5.76 g/t Au over 2.6 metres in Zone 27 FW, 5.05 g/t Au over 2.6 metres and 3.22 g/t Au over 2.5 metres in Mallard. The first interval is composed of 20% pyrite stringers and up to 3% disseminated pyrite at the contact between a gabbro and a rhyolite. The Mallard intervals are composed of up to 8% pyrite stingers and up to 10% coarse grained pyrite hosted in a sericitized andesite.

OSK-W-17-1291 intersected 3.65 g/t over 2.0 metres and 11.4 g/t Au over 2.0 metres in Caribou Extension. Both intervals are composed of local pyrite stringers in a weakly sericitized rhyolite.

OSK-W-17-1292 intersected Wolf returning 7.91 g/t Au over 3.1 metres. Mineralization is composed of up to 20% pyrite stringers, locally semi-massive pyrite hosted in a strongly silicified porphyritic felsic intrusion.

OSK-W-17-1293 intersected three intervals in the Caribou Corridor. The first interval returned 3.1 g/t Au over 5.3 metres, the second interval returned 3.58 g/t Au over 6.5 metres and the third interval returned 3.63 g/t Au over 2.5 metres. The three intervals are in felsic dikes crosscutting strongly a sericitized andesite. Mineralization is composed of up to 5% pyrite stringers and 3% disseminated pyrite.

OSK-W-17-1296 intersected 5.82 g/t Au over 2.4 metres in Zone 27. Mineralization is composed of 3% pyrite stringers in a strongly sericitized rhyolite.

OSK-W-17-1303 intersected 3.74 g/t Au over 2.3 metres in Caribou Extension. Mineralization is composed of 3% pyrite stringers within a porphyritic felsic dike.

OSK-W-17-1305 intersected 7.65 g/t Au over 2.5 metres in CS1. Mineralization is composed of up to 25% pyrite stringers within a strongly sericitized andesite at the contact with a felsic dike.

OSK-W-17-1306 intersected 14.7 g/t Au over 2.6 metres in the Caribou Corridor. Mineralization is composed of up to 15% pyrite stringers and 3% disseminated pyrite hosted in a moderately bleached and fuchsite altered andesite. The interval is 150 metres East of OSK-W-17-1147-W1 (7.52 g/t Au over 2.0 metres, reported October 18, 2017).

OSK-W-17-1308 intersected 11.6 g/t Au over 5.4 metres in the Caribou Corridor. Mineralization is composed of up to 3% disseminated pyrite, 2% pyrite stringers, local visible gold and smoky quartz vein. The mineralization is hosted in a porphyritic felsic intrusion.

OSK-W-17-1312 intersected 7.56 g/t Au over 3.5 metres related to Zone 27 HW. Mineralization is composed of 5% pyrite stringers and 3% pyrite-tourmaline hosted in a sericitized and silicified porphyritic dike.

OSK-W-17-1313 intersected 3.34 g/t Au over 2.1 metres and 5.29 g/t Au over 3.0 metres in Caribou, 11.3 g/t Au over 2.0 metres in Zone 27 HW, and 25.2 g/t Au over 2.0 metres in a vein within the Red Dog dike. The first and second intervals are composed of up to 30% pyrite stringers within a sericitized felsic porphyritic dike. The third interval is composed of up to 7% pyrite stingers associated to silica flooding and hosted in a silicified rhyolite. The fourth interval is composed of local visible gold and traces pyrite of clusters.

OSK-W-17-1317 intersected Zone 27 returning 10.0 g/t au over 8.1 metres. Mineralization is composed of up 25% pyrite stringers within a sericitized porphyritic felsic intrusive.

OSK-W-17-1319 intersected Zone 27 returning 7.42 g/t au over 2.0 metres. Mineralization is composed of local visible gold, 6% pyrite stringers and traces of pyrite-tourmaline stringers hosted in a moderately sericitized and patchy silica altered rhyolite near the andesite contact.

OSK-W-17-1320 intersected Caribou extension returning 11.9 g/t Au over 2.0 metres, 5.16 g/t Au over 5.2 metres and 6.04 g/t Au over 2.0 metres. The first interval is within a sericitized and weakly silicified rhyolite and composed of traces of disseminated pyrite clusters. The second interval is composed of 25% semi-massive pyrite, 2% pyrite clusters, 5% pyrite-silica flooding, 3% interstitial sphalerite and 2% disseminated pyrite at the contact between a strongly silicified rhyolite and moderately sericitized felsic dike. The third interval is composed of a chloritized felsic dike with 1% pyrite stringers and traces of disseminated pyrite.

OSK-W-17-1323 intersected 5.48 g/t Au over 2.2 metres in the Caribou Corridor. Mineralization is composed of a smoky quartz-carbonate-chlorite vein within a sericitized porphyritic felsic dike with 5% disseminated pyrite and traces of pyrite cluster.

OSK-W-17-1326 intersected Zone 27 returning 8.32 g/t Au over 2.0 metres and 6.13 g/t au over 3.3 metres. The first interval is composed of 10% pyrite stringers and 3% ptygmatic tourmaline veins within a chloritized porphyritic felsic dike. The second interval is composed of 4% pyrite stringers and 3% disseminated pyrite within a sericitized and weakly silicified porphyritic felsic dike.

OSK-W-17-1332 intersected 8.27 g/t Au over 2.0 metres in a new zone between Mallard and Zone 27 corridors. Mineralization is composed of 4% pyrite and pyrite-tourmaline stringers within a sericitized porphyritic felsic dike.

OSK-W-17-1333 intersected Caribou Extension returning 18.4 g/t Au over 3.5 metres, 4.85 g/t Au over 2.4 metres and 5.89 g/t Au over 2.4 metres. The first interval is composed of 10% pyrite-tourmaline stringers associated with strong pervasive silica flooding and hosted in a sericitized porphyritic felsic dike. Mineralization is at the contact with a sericitized and silicified rhyolite. The second interval is composed of 10% interstitial pyrite and 2% sphalerite within a fragmental rhyolite with strong pervasive silica flooding. The third interval is composed of 2% disseminated pyrite, 1% pyrite stringers, 2% pyrite clusters and a five decimetres quartz-tourmaline vein with strong fuchsite, sericite and bleaching in an andesite.

OSK-W-17-1334 intersected 3.31 g/t Au over 2.5 metres, 74.0 g/t Au over 2.5 metres, 12.8 g/t Au over 2.2 metres and 3.73 g/t Au over 3.5 metres in Caribou extension and 29.6 g/t Au over 2.9 metres in Zone 27. The first interval is composed of 5% pyrite-silica flooding within a sericitized and strongly silicified rhyolite. The second interval is composed of 30% crustiform veins with local visible gold hosted in a sericitized, silicified and chloritized gabbro. The third interval is composed of 2% pyrite in tourmaline ptygmatic vein, hosted in a sericitized porphyritic felsic dike with fuchsite. The fourth interval is composed of 5% pyrite stringers, 1% tourmaline ptygmatic veins within a fuchsitized, sericitized, silicified and chloritized porphyritic felsic dike. The fifth interval is composed of 10% pyrite stringers within a sericitized, chloritized and bleached gabbro.

OSK-W-17-1335 intersected Mallard returning 5.66 g/t Au over 2.1 metres. Mineralization is composed of 10% pervasive pyrite-silica flooding and 3% pyrite in tourmaline ptygmatic veins within a sericitized and chloritized rhyolite at the contact with a chloritized andesite.

OSK-W-17-1337 intersected the Drake Zone in the Mallard Corridor returning 3.58 g/t Au over 2.1 metres. Mineralization is composed of up 50% pyrite and pyrite-tourmaline stringers within a sericitized and weakly silicified andesite.

OSK-W-17-1341 intersected 3.43 g/t Au over 2.0 metres, 17.0 g/t Au over 2.3 metres, 7.79 g/t Au over 2.9 metres, 4.52 g/t Au over 5.1 metres and 5.23 g/t Au over 2.3 metres. The first interval, in Caribou, is composed of 15% pyrite and pyrite-tourmaline stringers within a sericitized and weakly silicified rhyolite. The second interval, in Zone 27 HW, is composed of 10% pyrite in pervasive silica flooding within a sericitized and silicified porphyritic felsic dike. The third interval, in Zone 27, is composed of 7% disseminated pyrite, 2% pyrite in quartz-tourmaline veins within a sericitized porphyritic felsic dike. The fourth interval, in Zone 27, is composed of 4% disseminated pyrite within a sericitized and chloritized andesite. The fifth interval, in Zone 27, is composed of 7% pyrite stringers within a sericitized and weakly silicified andesite.

OSK-W-17-1342 intersected Mallard returning 3.30 g/t Au over 2.0 metres. Mineralization is composed of up to 10% pyrite stringers and pyrite clusters within a sericitized and chloritized andesite.

OSK-W-17-1344 intersected 9.54 g/t Au over 2.4 metres in Caribou Corridor. Mineralization is composed of 3% pyrite-tourmaline stringers and 1% pyrite quartz-tourmaline veins within a sericitized and silicified porphyritic felsic dike.

OSK-W-17-1345 intersected 7.40 g/t Au over 2.5 metres and 86.7 g/t Au over 4.3 metres in Caribou Corridor. The first interval, in Caribou Extension, is composed of up to 90% pyrite in a pervasive silica flooding, hosted in a silica and sericite altered rhyolite. The second interval is in Wolf: high grade mineralization is composed of one gold stringer with 8% pyrite, 5% chalcopyrite and 3% sphalerite over a 40 centimetres zone of pervasive silica flooding hosted in a silicified felsic intrusive.

OSK-W-17-1348 intersected Caribou Extension returning 4.25 g/t Au over 2.0 metres. Mineralization is composed of traces of disseminated pyrite within a silicified, sericitized and chloritized porphyritic dike. The fragmental felsic unit is 20% injected of quartz-tourmaline veins.

OSK-W-17-1350 intersected four intervals related to Caribou Extension; 9.37 g/t Au over 2.0 metres, 4.45 g/t Au over 2.0 metres, 6.33 g/t Au over 2.0 metres and 6.88 g/t Au over 3.4 metres. The first interval is composed of a crustiform vein with quartz-carbonate-tourmaline, and 7% pyrite hosted in a strongly sericitized rhyolite. The second interval is composed of 3% pyrite-tourmaline stringers and local visible gold associated with quartz-tourmaline veins. The porphyritic felsic dike is strongly silica, sericite, and chlorite altered. The third interval is composed of 5% disseminated pyrite clusters and disseminated chalcopyrite within a sericitized and weakly chloritized porphyritic felsic dike. The fourth interval is composed of local visible gold, 7% disseminated pyrite, and 2% ptygmatic tourmaline veins at the contact between a sericitized porphyritic felsic dyke and an andesite.

OSK-W-17-1351 intersected 6.14 g/t Au over 2.2 metres, 3.65 g/t Au over 2.2 metres and 3.64 g/t Au over 2.3 metres in the Caribou Corridor. The first interval is composed of 10% pyrite-silica flooding, 3% pyrite stringers within a sericitized and strongly silicified porphyritic felsic dike. The second interval, in Caribou Extension, is composed of 5% pyrite stringers within a sericitized andesite. The third interval, in Caribou Extension, is composed of up to 3% pyrite stringers and quartz-tourmaline veins in a silicified andesite.

OSK-W-17-1359 intersected 5.06 g/t Au over 2.6 metres, 5.37 g/t Au over 2.3 metres, 3.87 g/t Au over 2.1 metres in Caribou Corridor and 4.98 g/t Au over 2.2 metres in Zone 27 Corridor. The first interval is composed of 60% semi-massive pyrite with sphalerite in pervasive silica flooding and 1% pyrite in ptygmatic tourmaline veins hosted in a silicified rhyolite. The second interval is composed of 3% pyrite-tourmaline stockwork, 5% pyrite in quartz-tourmaline veins and 40% semi-massive pyrite with tourmaline, all hosted in a strongly silicified rhyolite. The third interval is composed of 2% pyrite-silica flooding and 2% quartz-tourmaline veins within a sericitized and strongly silicified rhyolite. The fourth interval is composed of 6% pyrite-tourmaline stringers, tourmaline ptygmatic veinlets and 1% disseminated pyrite within a sericitized porphyritic dike.

OSK-W-17-1368 intersected 8.71 g/t Au over 2.0 metres in Caribou Extension. Mineralization is composed of 5% pyrite-tourmaline stringers hosted in a silicified and sericitized felsic dike.

OSK-W-17-1369 intersected 14.8 g/t Au over 2.0 metres in Zone 27. Mineralization is hosted in a sericite altered felsic porphyritic intrusion and composed of 5% pyrite in smoky quartz veins.
OSK-W-17-1371 intersected 5.63 g/t Au over 2.6 metres in the Caribou Corridor. Mineralization is composed of 8% disseminated pyrite, 3% pyrite stringers and 2% pyrite-tourmaline veins associated with pervasive silica flooding and hosted in a felsic dike.
OSK-W-17-1381 intersected 7.60 g/t Au over 3.2 metres in the Caribou Extension corridor.Mineralization is composed of 3% pyrite stringers and 10% pyrite in a 30 centimetres quartz vein hosted in a sericitized felsic porphyritic dike.

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 the 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 widths determinations are estimated at 65-80% of the reported core length intervals for most of the zones. 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 ALS Laboratories in Val d'Or, Québec, Thunder Bay and Sudbury, Ontario or Vancouver, British Colombia or 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 the previous operator comprises 2,762,000 tonnes at 8.42 g/t Au (748.000 ounces) in the indicated category and 3,512,000 tonnes at 7.62 g/t Au (860,000 ounces) in the inferred category (sourced from a technical report dated June 10, 2015 entitled "Preliminary Economic Assessment of the Windfall Lake Gold Property, Québec, Canada" with an effective date of April 28, 2015, prepared in accordance with NI 43-101). The Windfall Lake gold deposit is currently one of the highest grade resource-stage gold projects in Canada. The bulk of the mineralization occurs in the Main Zone, a southwest/northeast trending zone of stacked mineralized lenses, measuring approximately 600 metres wide and at least 1.400 metres long. The deposit is well defined from surface to a depth of 500 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 870 metres in others, with significant potential to extend mineralization up and 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% 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 Quebec and Ontario. Osisko continues to be well financed with approximately $190 million in cash and investments.

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 current 800,000 metre drill program; the significance of new results from the ongoing drill program at the Windfall Lake gold project; the significance of assay results presented in this press release; the type of drilling included in the drill program (definition drilling, expansion drilling to the NE of the main deposit and adjacent Lynx deposit, and exploration drilling on the greater deposit and Urban-Barry project area); 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 it was made, 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.

Contact

John Burzynski
President and Chief Executive Officer
(416) 363-8653