Osisko Intersects 265 g/t Au Over 2.4 Metres at Windfall

TORONTO, ONTARIO--(Marketwired - March 2, 2018) - Osisko Mining Inc. (OSK:TSX) ("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 61 intercepts in 34 drill holes and 5 wedges focused on infill and expansion drilling in the Main Windfall lake deposit are presented below.

Highlights from the new results include: 265 g/t Au over 2.4 metres in OSK-W-17-1168; 191 g/t Au over 2.6 metres in OSK-W-17-1087; 198 g/t Au over 2.3 metres and 116 g/t Au over 2.1 metres in OSK-EAG-12-333; 173 g/t Au over 2.3 metres in OSK-W-17-1383; 47.7 g/t Au over 2.2 metres in OSK-W-17-1402, 42.7 g/t Au over 2.0 metres in OSK-W-17-1391 and 9.53 g/t over 8.9 metres in OSK-W-18-823-W2. Maps showing hole locations and full analytical results are available at www.osiskomining.com.

Hole Number	From (m)	To (m)	Interval (m)	Au (g/t) uncut	Au (g/t) cut to 100 g/t	Zone	Corridor
OSK-EAG-12-333	818.2	823.0	4.8	3.07		FW3	Underdog
including	822.7	823.0	0.3	23.1
	848.1	850.2	2.1	116	59.4	FW3	Underdog
including	849.2	850.2	1.0	219	100
	934.0	936.3	2.3	198	21.8	FW3U	Underdog
including	935.2	935.7	0.5	910	100
OSK-EAG-12-427	1110.0	1112.2	2.2	4.29		VNCR	Underdog
OSK-EAG-13-480	522.3	524.3	2.0	37.1	20.6	Vein
including	524.0	524.3	0.3	210	100
	692.0	694.0	2.0	6.68		FW1 FW	Underdog
including	692.0	693.0	1.0	12.4
OSK-W-16-762	1158.0	1160.5	2.5	6.59		FW3	Underdog
including	1158.0	1158.8	0.8	17.8
OSK-W-17-795	1110.3	1113.7	3.4	5.53		FW1	Underdog
including	1110.3	1110.9	0.6	23.1
OSK-W-17-866-W2	933.3	935.5	2.2	4.92		FW0	Underdog
	1221.0	1223.0	2.0	7.59		FW3	Underdog
including	1221.7	1222.3	0.6	23.7
OSK-W-17-901	675.5	678.0	2.5	8.27		FW3U	Underdog
including	676.6	676.9	0.3	65.9
OSK-W-17-903-W2	556.0	560.9	4.9	3.72		Z27	Zone 27
including	556.0	557.1	1.1	8.88
including	560.0	560.9	0.9	8.94
	593.0	595.0	2.0	8.52		Z27 FW	Zone 27
including	593.0	594.0	1.0	16.7
OSK-W-17-937-W1	756.2	758.6	2.4	26.6		Wolf 2	Wolf
including	757.0	758.6	1.6	39.0
OSK-W-17-943	491.0	493.0	2.0	3.00		CS1	Caribou
including	492.0	493.0	1.0	5.57
	614.0	616.0	2.0	4.51		Wolf HW	Wolf
	688.0	690.0	2.0	4.96		Wolf	Wolf
including	688.0	689.0	1.0	9.64
OSK-W-17-1025	690.0	692.3	2.3	3.13		FW0	Underdog
OSK-W-17-1051	954.0	956.4	2.4	7.60		FW3	Underdog
OSK-W-17-1087	354.0	356.6	2.6	191	19.6	Mallard	Mallard
including	354.0	354.5	0.5	991	100
OSK-W-17-1168	503.6	506.0	2.4	265	13.3	VNCR	Caribou
including	504.3	504.6	0.3	2110	100
OSK-W-17-1221	771.0	773.0	2.0	4.61		Vein	Wolf
including	771.0	771.8	0.8	11.5
OSK-W-17-1226	662.0	664.0	2.0	11.5		Caribou Ext.	Caribou
including	662.6	663.5	0.9	24.4
	673.0	675.0	2.0	10.4		Caribou Ext.	Caribou
including	673.0	674.0	1.0	20.3
	823.8	826.0	2.2	6.57		Caribou Ext.	Caribou
including	823.8	825.0	1.2	12.0
OSK-W-17-1232	331.0	333.0	2.0	4.70		Vein	Caribou
OSK-W-17-1275	553.1	556.1	3.0	4.49		Z27	Zone 27
including	554.1	555.0	0.9	11.5
OSK-W-17-1293	802.7	805.0	2.3	6.54		Vein
including	803.7	804.0	0.3	49.7
OSK-W-17-1295	387.0	389.0	2.0	3.36		FW3	Underdog
OSK-W-17-1310	54.0	57.0	3.0	3.61		Caribou	Caribou
	354.0	357.0	3.0	3.37		Vein	Mallard
OSK-W-17-1319	162.0	165.0	3.0	5.80		Z27	Zone 27
including	162.0	163.5	1.5	11.4
OSK-W-17-1320	557.5	560.8	3.3	3.46		Caribou Ext.	Caribou
OSK-W-17-1334	86.0	88.0	2.0	4.05		Bobcat	Bobcat
OSK-W-17-1336	277.4	279.5	2.1	4.16		Vein
	810.0	813.0	3.0	17.0		FW0	Underdog
	972.0	974.0	2.0	4.10		FW2	Underdog
OSK-W-17-1337	19.0	21.5	2.5	3.39		Mallard	Mallard
including	20.0	20.4	0.4	13.7
OSK-W-17-1342	211.9	214.0	2.1	8.19		Mallard HW	Mallard
including	211.9	231.0	1.1	15.4
OSK-W-17-1347	164.0	166.0	2.0	4.64		Vein
including	165.2	166.0	0.8	11.5
	249.4	252.2	2.8	11.1		Mallard FW	Mallard
including	250.4	251.3	0.9	27.3
OSK-W-17-1350	724.0	726.0	2.0	4.16		Caribou Ext.	Caribou
OSK-W-17-1376	198.7	201.0	2.3	10.2		Vein
including	198.7	199.0	0.3	72.7
	816.5	818.6	2.1	33.6		FW2	Underdog
including	816.5	817.3	0.8	73.3
OSK-W-17-1383	38.1	40.4	2.3	173	18.2	Bobcat	Bobcat
including	39.0	39.4	0.4	990	100
OSK-W-17-1391	453.0	455.0	2.0	42.7	33	Caribou Ext.	Caribou
including	454.0	454.6	0.6	133	100
OSK-W-17-1399	684.5	686.5	2.0	3.72		Caribou Ext.	Caribou
OSK-W-17-1402	462.2	464.5	2.3	3.39		Caribou	Caribou
	820.1	822.3	2.2	47.7	18.4	FW1	Underdog
including	822.0	822.3	0.3	315	100
	863.6	865.6	2.0	3.48		FW1 FW	Underdog
including	864.1	864.9	0.8	7.60
	873.5	876.3	2.8	3.35		FW1 FW	Underdog
	938.2	940.2	2.0	4.27		FW2	Underdog
OSK-W-18-823-W2	510.6	519.5	8.9	9.53		CS1	Caribou
including	510.6	513.5	2.9	18.0
	526.0	528.0	2.0	5.22		CS1	Caribou
OSK-W-18-1402-W1	804.2	806.5	2.3	5.79		FW0	Underdog
including	805.0	805.5	0.5	23.5
OSK-W-18-1418	660.0	665.0	5.0	4.78		Caribou Ext.	Caribou
	710.0	717.0	7.0	5.95		Caribou Ext.	Caribou
including	710.7	712.6	1.9	11.9
	930.0	932.0	2.0	5.85		Caribou Ext.	Caribou
OSK-W-18-1421	231.0	233.9	2.9	17.7		CW2	Caribou
OSK-W-18-1423	521.2	523.5	2.3	6.04		Caribou Ext.	Caribou
	556.0	559.0	3.0	3.97		Caribou Ext.	Caribou

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, Ext = extension.

Hole Number	Azimuth  (°)	Dip  (°)	Length  (m)	UTM E	UTM N	Section
OSK-EAG-12-333	333	-58	983	452459	5434565	2525
OSK-EAG-12-427	330	51	1215	452701	5434438	2675
OSK-EAG-13-480	331	-57	991	452400	5434486	2450
OSK-W-16-762	332	-56	1311	452730	5434409	2675
OSK-W-17-795	333	-65	1428	452646	5434421	2625
OSK-W-17-866-W2	332	-57	1332	452633	5434280	2525
OSK-W-17-901	328	-55	810	452391	5434638	2500
OSK-W-17-903-W2	329	-56	795	452539	5434692	2650
OSK-W-17-937-W1	333	-57	945	452897	5434430	2850
OSK-W-17-943	331	-55	744	452660	5434495	2675
OSK-W-17-1025	330	-58	990	452486	5434439	2475
OSK-W-17-1051	138	-68	1248	452313	5435323	2775
OSK-W-17-1087	328	-61	381	452255	5434830	2475
OSK-W-17-1168	329	-57	717	453464	5435090	3650
OSK-W-17-1221	335	-51	1079	453082	5434544	3050
OSK-W-17-1226	331	-51	934	453371	5434726	3400
OSK-W-17-1232	154	-47	351	452025	5434834	2275
OSK-W-17-1275	331	-55	912	452499	5434592	2575
OSK-W-17-1293	329	-70	828	452904	5434849	3050
OSK-W-17-1295	334	57	801	451559	5434288	1600
OSK-W-17-1310	312	-45	375	452209	5434617	2325
OSK-W-17-1319	310	-50	291	452222	5434607	2325
OSK-W-17-1320	328	-76	852	452904	5434849	3050
OSK-W-17-1334	334	-70	657	452839	5434895	3025
OSK-W-17-1336	335	-61	1149	452616	5434449	2600
OSK-W-17-1337	140	-57	360	452053	5434963	2350
OSK-W-17-1342	333	-50	282	452086	5434761	2300
OSK-W-17-1347	151	-61	489	452160	5435159	2550
OSK-W-17-1350	328	-55	843	452993	5434557	2975
OSK-W-17-1376	330	-50	1125	452426	5434380	2400
OSK-W-17-1383	331	-63	597	452767	5434864	2925
OSK-W-17-1391	327	-62	663	452981	5434900	3150
OSK-W-17-1399	332	-61	1053	453411	5434870	3500
OSK-W-17-1402	330	-59	1122	452616	5434449	2600
OSK-W-18-823-W2	330	-56	918	452565	5434414	2550
OSK-W-18-1402-W1	330	-59	1224	452616	5434449	2600
OSK-W-18-1418	334	-45	1077	453288	5434531	3225
OSK-W-18-1421	340	-47	918	452216	5434360	2200
OSK-W-18-1423	327	-61	792	453025	5434853	3150

OSK-EAG-12-333 intersected FW3 returning 3.07 g/t au over 4.8 metres and 116 g/t Au over 2.1 metres, and FW3U with 198 g /t Au over 2.3 metres in Underdog Corridor. The first interval is composed of up to 10% pyrite within pervasive silica flooding and 1% disseminated pyrite hosted in a porphyritic felsic dike with moderate chlorite, silica and sericite alteration. The second interval contains up to 20% pyrite and local visible gold within intense silica alteration. The third interval is composed of 3% pyrite stringers and local visible gold within a strongly sericitized and silicified felsic porphyritic dike.

OSK-EAG-12-427 intersected crustiform veins in FW4 returning 4.29 g/t Au over 2.2 metres in the Underdog Corridor. Mineralization is composed of 30% pyrite and 1% chalcopyrite in quartz-tourmaline-sericite veins.

OSK-EAG-13-480 intersected a vein in the Red Dog intrusion returning 37.1 g/t Au over 2.0 metres and FW1 FW with 6.68 g/t au over 2.0 metres. The first interval is composed of local visible gold in a quartz-carbonate vein with up to 3% pyrite and 1 % chalcopyrite. The second interval is composed of 1% pyrite stringers within porphyritic felsic dikes with moderate sericite, chlorite and fuchsite alteration.

OSK-W-17-762 intersected FW3 with 6.59 g/t Au over 2.5 metres in Underdog. Mineralization is composed of local visible gold within 10 centimetre silica flooding bands and 10% pyrite hosted in a porphyritic felsic intrusion.

OSK-W-17-795 intersected FW1 with 5.53 g/t Au over 3.4 metres in Underdog. Mineralization is composed of up to 10% pyrite stringers in silica flooding alteration hosted in a sericite altered felsic porphyritic dike.

OSK-W-17-866-W2 intersected FW0 with 4.92 g/t Au over 2.2 metres and FW3 with 7.59 g/t Au over 2.0 metres in Underdog Corridor. Mineralization from FW0 corresponds with 70% massive pyrite over 30 centimetres hosted within a felsic porphyritic dike with strong sericitization. The second interval is composed of up to 15% pyrite stringers and 1% disseminated pyrite hosted in a porphyritic felsic dike with moderate silica and sericite alteration.

OSK-W-17-901 intersected 8.27 g/t Au over 2.5 metres in FW3U. Mineralization is composed of a 10 centimetres silica flooding zone with 55% pyrite, 1% pyrite stringers and 7% disseminated pyrite in a bleached andesite.

OSK-W-17-903-W2 intersected 3.72 g/t Au over 4.9 metres in Zone 27 and 8.52 g/t Au over 2.0 metres in Z27 FW. The first interval is composed of disseminated and stringer pyrite at the contact between a silicified and weakly sericitized porphyritic dike and a weak chlorite, sericite altered andesite. The second interval is composed of pyrite traces hosted in an andesite with strong chlorite and carbonates alteration.

OSK-W-17-937-W1 intersected 26.6 g/t Au over 2.4 metres in Wolf 2. Mineralization is composed of up to 9% disseminated pyrite and 5% tourmaline-pyrite stringers at the contact between a bleached and strongly sericitized andesite and a small sericitized porphyritic felsic dike.

OSK-W-17-943 intersected 3.00 g/t Au over 2.0 metres in Caribou, and 4.51 g/t Au over 2.0 metres and 4.96 g/t Au over 2.0 metres in Wolf. The first interval is composed of up to 10% pyrite stringers and 2% disseminated pyrite hosted in a sericitized rhyolite and a sericitized porphyritic felsic dike. The second interval is composed of 3% pyrite stringers within a sericitized and chloritized porphyritic felsic dike. The third interval is composed of disseminated pyrite within an andesite with chlorite and carbonate alteration.

OSK-W-17-1025 intersected FW0 with 3.13 g/t Au over 2.3 metres. Mineralization is composed of 3% pyrite in silica flooding and 1% pyrite stringers in weakly sericitized porphyritic felsic dike.

OSK-W-17-1051 intersected FW3 with 7.6 g/t Au over 2.4 metres in Underdog Corridor. Mineralization is composed of up to 1% pyrite clusters and disseminated pyrite within a weak sericite and silica altered felsic porphyritic dike.

OSK-W-17-1087 intersected Mallard with 191 g/t Au over 2.6 metres. Mineralization is composed of 5% pyrite stringers and 1% disseminated pyrite within a sericite altered andesite.

OSK-W-17-1168 intersected 265 g/t Au over 2.4 metres in Caribou Corridor. Mineralization is composed of a crustiform vein with local visible gold and 1% pyrite clusters with tourmaline and fuchsite hosted in a gabbro with moderate chlorite alteration. The interval is 150 metres East of OSK-W-17-787 (7.21 g/t Au over 6.5 metres previously reported March 21, 2017).

OSK-W-17-1221 intersected 4.61 g /t Au over 2.0 metres in Wolf corridor. Mineralization is composed of a centimetre scale quartz carbonate vein in a chloritized and slightly silicified porphyritic felsic dike with traces of pyrite stringer.

OSK-W-17-1226 intersected 11.5 g/t Au over 2.0 metres, 10.4 g/t Au over 2.0 metres and 6.57 g/t Au over 2.2 metres in Caribou Extension. First and second intervals are composed of up to 10% pyrite-tourmaline stringers and disseminated pyrite in a sericitized rhyolite. The third interval is composed of 1% pyrite stringers hosted in porphyritic felsic dike with sericite alteration.

OSK-W-17-1232 intersected a vein returning 4.70 g/t Au over 2.0 metres in Caribou Corridor. Mineralization is composed of 3% disseminated pyrite and 7% ptygmatic tourmaline veins within a weak sericite altered rhyolite.

OSK-W-17-1275 intersected 4.49 g/t Au over 3.0 metres in Zone 27. Mineralization is composed of traces of pyrite stringers within a sericitized porphyritic felsic dike.

OSK-W-17-1293 intersected 6.54 g/t Au over 2.3 metres. Mineralization is composed of 1% pyrite and 1% chalcopyrite in quartz veins within a silicified, chloritized and carbonate altered monzonite (Red Dog intrusion).

OSK-W-17-1295 intersected FW3 with 3.36 g/t Au over 2.0 metres in Underdog. Mineralization is composed of 2% pyrite clusters in a sericitized and weakly silicified porphyritic felsic dike.

OSK-W-17-1310 intersected 3.61 g/t Au over 3.0 metres in Caribou and 3.37 g/t Au over 3.0 metres in Drake. The first interval is composed of 1% pyrite stingers within a chloritized and sericitized rhyolite. The second interval is composed of chloritized and sericitized andesite with 5% quartz-carbonate veins.

OSK-W-17-1319 intersected 5.80 g/t Au over 3.0 metres in Zone 27. Mineralization is composed of traces of disseminated pyrite within a sericitized porphyritic felsic dike.

OSK-W-17-1320 intersected 3.46 g/t Au over 3.3 metres in Caribou Extension. Mineralization is composed of disseminated pyrite and quartz-pyrite clusters in a chloritized, sericitized and silicified andesite.

OSK-W-17-1334 intersected 4.05 g/t Au over 2.0 metres in Bobcat. Mineralization is composed of disseminated pyrite and crustiform quartz-carbonate veins in a chloritized, silicified and carbonate altered gabbro.

OSK-W-17-1336 intersected three intervals: 4.16 g/t Au over 2.05 metres in a vein, 17.0 g/t Au over 3.0 metres in FW0 and 4.10 g/t Au over 2.0 metres in FW2, Underdog Corridor. The first interval is composed of 1% disseminated pyrite in a quartz vein within a strongly chloritized gabbro. The second interval is composed of up to 2% disseminated pyrite and 1% pyrite stringers in a sericitized porphyritic felsic dike. The third interval is composed of 1% pyrite stringers and 1% pyrite in quartz-carbonate veins within a moderate sericite and silica altered felsic porphyritic dike.

OSK-W-17-1337 intersected 3.39 g/t Au over 2.5 metres in Mallard. Mineralization is composed of up to 20% pyrite stringers within a sericitized, silicified and bleached andesite.

OSK-W-17-1342 intersected Mallard HW with 8.19 g/t Au over 2.1 metres. Mineralization is composed of traces of disseminated and clustered pyrite within a chloritized andesite.

OSK-W-17-1347 intersected 4.64 g/t Au over 2.0 metres in a vein and 11.1 g/t Au over 2.8 metres in Mallard FW. The first interval is composed of a five centimetre quartz vein with 15% pyrite clusters hosted in a chloritized, silicified and weakly sericitized andesite. The second interval is at the contact between a strongly chlorite, fuchsite altered andesite and a porphyritic felsic dike. Mineralization is composed of 10% pyrite clusters and 3% pyrite stringers. The vein is located 100 metres north-west of Mallard corridor and is not related to any known zones.

OSK-W-17-1350 intersected Caribou Extension with 4.16 g/t Au over 2.0 metres. The mineralization is composed of up to 2% pyrite stringers within a sericitized, chloritized and carbonate altered large quartz eyes felsic porphyritic dike.

OSK-W-17-1376 intersected a vein returning 10.2 g/t Au over 2.3 metres and FW2 with 33.6 g/t Au over 2.1 metres. The first interval is composed of 5-10% quartz-carbonate veining with 5% disseminated pyrite in an andesite with chlorite, carbonate, sericite and silica alteration. Mineralization in FW2 is composed of a silica and sericite altered porphyritic dike with up to 5%, locally 80%, pyrite-tourmaline stringers.

OSK-W-17-1383 intersected 173 g/t Au over 2.3 metres in Bobcat. Mineralization is composed of local visible gold, 3% pyrite stringers with pervasive silica flooding within a gabbro with silica, carbonate and sericite alteration.

OSK-W-17-1391 intersected 42.7 g/t Au over 2.0 metres in Caribou Extension. Mineralization is composed of up to 10% pyrite stringers and 1% chalcopyrite, local visible gold, tourmaline ptygmatic veins, quartz-tourmaline veins and crustiform veins hosted in a silicified and bleached andesite.

OSK-W-17-1399 intersected 3.72 g/t Au over 2.0 metres in Caribou Extension. Mineralization is composed of up to 10% pyrite-tourmaline stringers within a strongly silicified rhyolite.

OSK-W-17-1402 intersected Caribou with 3.39 g/t Au over 2.3 metres and multiples intervals in Underdog corridor: FW1 with 47.7 g/t Au over 2.2 metres, FW1 FW with 3.48 g/t Au over 2.0 metres and 3.35 g/t Au over 2.8 metres, and FW2 with 4.27 g/t au over 2.0 metres. The first interval is composed of 3% pyrite stringers, 5% pyrite clusters within a sericitized andesite with weak silica and fuchsite alteration. The second interval is composed of local visible gold, 2% disseminated pyrite and 1% pyrite clusters, hosted in a moderately sericitized porphyritic dike. The third and fourth intervals are composed of 3% pyrite stringers and 1% disseminated pyrite in pervasive silica flooding within a sericitized porphyritic felsic dike. The last interval is composed of 2% pyrite stringers and 1% pyrite-silica flooding within a sericite, silica and fuchsite altered felsic porphyritic dike.

OSK-W-18-823-W2 intersected CS1 with 9.53 g/t Au over 8.9 metres and 5.22 g/t Au over 2.0 metres in Caribou. Mineralization is composed of 10% semi-massive pyrite bands, 10% pyrite stringers, up to 10% disseminated pyrite and up to 2% ptygmatic tourmaline veinlets hosted in a sericitized, chloritized and bleached andesite.

OSK-W-18-1402-W1 intersected 5.79 g/t Au over 2.3 metres in FW0. The mineralization is composed of 3% pyrite in a ptygmatic tourmaline vein at low core angle within a silicified and sericitized fragmental felsic intrusion.

OSK-W-18-1418 intersected 4.78 g/t Au over 5.0 metres, 5.95 g/t Au over 7.0 metres and 5.85 g/t Au over 2.0 metres in Caribou Extension. The first interval is composed of up to 5% pyrite stringers within a silicified and sericitized felsic porphyritic dike. The second interval is composed of up to 15% pyrite-tourmaline stringers hosted in a silicified and sericitized rhyolite. The third interval is composed of up to 10% pyrite-silica flooding within a silica altered andesite.

OSK-W-18-1421 intersected CW2 with 17.7 g/t Au over 2.9 metres in Caribou Corridor. Mineralization is composed of up to 8% pyrite stringers, 1% chalcopyrite, 1% sphalerite, ptygmatic tourmaline veins and local visible gold within a strongly silica altered rhyolite.

OSK-W-18-1423 intersected 6.04 g/t Au over 2.3 metres and 3.97 g/t Au over 3.0 metres in Caribou Extension. The first interval is composed of 7% disseminated pyrite within a bleached andesite. The second interval is composed of 4% disseminated pyrite, 2% pyrite stringers at a bleached andesite contact with a 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 as of December 31, 2017.

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.