Osisko Windfall Drilling Continues to Intercept High-Grade Across the Windfall Deposit

 

576 g/t Au over 2.7 metres in Triple Lynx

93.1 g/t Au over 3.0 metres in Caribou

22.3 g/t Au over 4.4 metres in Underdog

TORONTO, Dec. 02, 2021 (GLOBE NEWSWIRE) -- Osisko Mining Inc. (OSK:TSX. "Osisko" or the "Corporation") is pleased to provide new analytical results from the ongoing drill program at its 100% owned Windfall gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec.

Significant new analytical results presented below include 135 intercepts in 37 drill holes (18 from surface, 19 from underground) and 22 wedges. The infill intercepts are located inside defined February 2021 mineral resource estimate (“MRE”) blocks (see Osisko news release dated February 17, 2021). The expansion intercepts are located outside the February 2021 MRE blocks and either expand resource wireframes or are in a defined zone or corridor but do not yet correlate to a specific wireframe.

Osisko Chief Executive Officer John Burzynski commented: “Though the main infill drill campaign at Windfall has been successfully completed in support of the upcoming mineral resource estimate update, we continue with targeted infill and expansion drilling. Today’s results are part of this continuing program and clearly demonstrate Windfall’s growth upside, especially the expansion results.”

Selected high-grade intercepts include: 576 g/t Au over 2.7 metres, 17.6 g/t Au over 10.6 metres and 15.7 g/t Au over 8.1 metres in OSK-W-21-2587; 221 g/t Au over 2.0 metres in WST-21-0877; 127 g/t Au over 2.6 metres in OSK-W-21-2537-W3; 93.1 g/t Au over 3.0 metres in OSK-W-21-2606; 28.6 g/t Au over 4.9 metres in OSK-W-21-2540-W4; 34.7 g/t Au over 3.8 metres in OSK-W-21-1963-W8; 37.4 g/t Au over 3.0 metres in OSK-W-21-1963-W7, 15.4 g/t Au over 6.8 metres in WST-21-0857A and 22.3 g/t Au over 4.4 metres in OSK-W-21-2532-W3. Maps showing hole locations and full analytical results are available at www.osiskomining.com.

Infill Drilling

Hole No.	From (m)	To (m)	Interval (m)	Au (g/t) uncut	Au (g/t) cut to 100 g/t	Zone	Corridor
OSK-W-21-1949-W11	1047.2	1049.6	2.4	3.57		LX4_3430	Lynx 4
	1053.6	1059.0	5.4	5.31		LX4_3434	Lynx 4
OSK-W-21-1963-W7	1331.6	1334.6	3.0	37.4		LX4_3449	Lynx 4
including	1331.6	1332.3	0.7	99.1
	1345.0	1347.0	2.0	4.96		LX4_3445	Lynx 4
including	1345.6	1346.2	0.6	13.1
	1374.0	1376.0	2.0	19.8		LX4_3445	Lynx 4
including	1374.7	1375.4	0.7	38.8
	1378.8	1382.5	3.7	6.39		LX4_3445	Lynx 4
OSK-W-21-1963-W8	1340.7	1344.5	3.8	34.7	26.1	LX4_3449	Lynx 4
including	1341.6	1342.1	0.5	166	100
OSK-W-21-2287-W7	1138.0	1140.2	2.2	4.78		LX4_3453	Lynx 4
including	1139.6	1140.2	0.6	16.5
	1219.8	1222.0	2.2	6.56		LX4_3449	Lynx 4
including	1220.3	1221.0	0.7	19.7
OSK-W-21-2287-W9	1237.2	1239.4	2.2	6.50		LX4_3449	Lynx 4
OSK-W-21-2400-W1	672.0	674.0	2.0	3.63		CA1	Caribou
including	672.4	672.7	0.3	23.1
	762.0	764.0	2.0	4.43		CA2_2208	Caribou
	820.0	822.3	2.3	4.03		CA2_2218	Caribou
OSK-W-21-2416-W7	939.9	944.0	4.1	9.01		TLX_3161	Triple Lynx
including	940.3	941.0	0.7	24.2
	966.6	969.0	2.4	9.84		TLX_3163	Triple Lynx
	985.0	987.1	2.1	8.85		TLX_3163	Triple Lynx
including	986.0	986.3	0.3	36.3
	1006.0	1008.1	2.1	6.21		TLX_3164	Triple Lynx
including	1007.8	1008.1	0.3	35.5
	1051.5	1053.5	2.0	20.2		TLX_3170	Triple Lynx
	1086.0	1089.0	3.0	4.33		TLX_3172	Triple Lynx
	1096.0	1098.2	2.2	7.08		TLX_3193	Triple Lynx
including	1097.1	1097.6	0.5	21.4
OSK-W-21-2479-W10	464.0	466.0	2.0	4.52		Z27_1203	Zone 27
including	464.7	465.2	0.5	13.2
	694.1	696.4	2.3	6.32		UDD_4100	Underdog
OSK-W-21-2479-W11	709.7	712.0	2.3	9.08		UDD_4102	Underdog
including	709.7	710.0	0.3	22.5
and	710.3	710.7	0.4	33.3
OSK-W-21-2531-W3	635.0	637.6	2.6	5.99		CA2_2206	Caribou
including	636.7	637.6	0.9	13.9
OSK-W-21-2531-W4	870.6	872.6	2.0	4.42		UDD_4100	Underdog
	1043.5	1045.7	2.2	3.56		UDD_4915	Underdog
	1075.7	1077.7	2.0	3.50		UDD_4501	Underdog
including	1075.7	1076.0	0.3	16.1
OSK-W-21-2532-W3	909.0	911.0	2.0	7.17		UDD_4106	Underdog
	1036.0	1038.0	2.0	4.23		UDD_4911	Underdog
	1081.6	1086.0	4.4	22.3	20.6	UDD_4513	Underdog
including	1084.7	1085.4	0.7	111	100
	1139.0	1141.0	2.0	6.04		UDD_4512	Underdog
OSK-W-21-2537-W3	908.0	910.6	2.6	127	61.2	TLX_3161	Triple Lynx
including	909.1	910.0	0.9	276	100
OSK-W-21-2551-W4	834.6	836.8	2.2	15.9		LX4_3424	Lynx 4
including	836.3	836.8	0.5	67.7
	887.6	889.9	2.3	28.9		LX4_3414	Lynx 4
including	889.4	889.9	0.5	90.1
	900.0	902.0	2.0	3.75		LX4_3437	Lynx 4
	911.0	913.0	2.0	7.13		LX4_3437	Lynx 4
OSK-W-21-2578	156.0	158.0	2.0	14.6		CA1_2505	Caribou
including	157.0	158.0	1.0	28.8
	165.9	168.0	2.1	9.77		CA1_2505	Caribou
	178.0	180.0	2.0	6.42		CA1_2505	Caribou
OSK-W-21-2578-W2	606.0	608.0	2.0	3.60		UDD_4100	Underdog
OSK-W-21-2587	1042.5	1046.0	3.5	7.33		TLX_3164	Triple Lynx
	1073.0	1077.0	4.0	21.3		TLX_3162	Triple Lynx
including	1075.8	1077.0	1.2	42.9
	1098.4	1101.1	2.7	576	20.0	TLX_3170	Triple Lynx
including	1100.7	1101.1	0.4	3850	100
	1104.1	1112.2	8.1	15.7		TLX_3170	Triple Lynx
including	1107.7	1108.1	0.4	63.1
OSK-W-21-2589-W2	736.2	738.5	2.3	34.9		TLX_3171	Triple Lynx
including	737.1	738.0	0.9	88.1
OSK-W-21-2600	650.3	652.5	2.2	6.14		UDD_4914	Underdog
including	650.3	650.6	0.3	14.2
OSK-W-21-2606	699.0	702.0	3.0	93.1	63.0	CA2_2208	Caribou
including	700.0	701.0	1.0	191	100
OSK-W-21-2609	638.0	640.0	2.0	6.33		CA2_2237	Caribou
including	638.9	639.5	0.6	16.0
OSK-W-21-2612	377.0	383.0	6.0	4.71		Z27_1102	Zone 27
OSK-W-21-2615	193.7	195.7	2.0	4.01		WFN_7009	Windfall North
OSK-W-21-2618	207.0	209.0	2.0	5.86		WFN_7009	Windfall North
OSK-W-21-2620	701.0	703.0	2.0	4.59		CAE_2547	Caribou
OSK-W-21-2622	191.4	193.4	2.0	7.29		WFN_7010	Windfall North
including	192.8	193.4	0.6	24.1
OSK-W-21-2627	57.0	59.0	2.0	20.6		WFN_7003	Windfall North
including	57.6	58.6	1.0	39.9
WST-21-0649	541.0	543.0	2.0	21.8	16.7	LX4_3450	Lynx 4
including	541.7	542.0	0.3	134	100
WST-21-0784	265.0	267.1	2.1	3.52		TLX_3161	Triple Lynx
including	266.3	266.8	0.5	14.0
WST-21-0855B	562.7	566.6	3.9	14.0		LX4_3440	Lynx 4
including	566.3	566.6	0.3	58.7
WST-21-0859	277.3	280.2	2.9	17.5		LSW_3508	Lynx SW
including	278.3	278.7	0.4	66.7
	347.0	349.0	2.0	29.6	19.5	TLX_3166	Triple Lynx
including	347.9	348.2	0.3	167	100
WST-21-0868A	196.0	198.1	2.1	44.6		TLX_3161	Triple Lynx
	302.0	305.0	3.0	6.14		TLX_3182	Triple Lynx
	336.0	338.0	2.0	5.50		TLX_3131	Triple Lynx
WST-21-0877	79.6	81.6	2.0	4.51		LXM_3339	Lynx
including	80.9	81.6	0.7	12.6
WST-21-0879	669.5	671.5	2.0	19.6		LX4_3412	Lynx 4
including	669.5	670.5	1.0	39.1
WST-21-0899C	213.1	215.3	2.2	5.80		LSW_3507	Lynx SW
	313.1	315.4	2.3	6.04		LSW_3556	Lynx SW
WST-21-0901	313.0	315.0	2.0	7.51		LHW_3215	Lynx HW
WST-21-0906A	357.5	359.7	2.2	4.42		LSW_3556	Lynx SW
WST-21-0910A	396.3	399.0	2.7	11.1		LSW_3556	Lynx SW
including	397.9	398.6	0.7	30.1

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See "Quality Control and Reporting Protocols" below. CA1 and CA2 = Caribou, LX4 = Lynx 4, LHW = Lynx Hanging Wall, LXM = Lynx Main, LSW = Lynx Southwest, TLX = Triple Lynx, UDD = Underdog, WNF = Windfall North and Z27 = Zone 27.

Expansion Drilling

Hole No.	From (m)	To (m)	Interval (m)	Au (g/t) uncut	Au (g/t) cut to 100 g/t	Zone	Corridor
OSK-W-21-1871-W1	844.0	846.0	2.0	5.55		UDD	Underdog
OSK-W-21-1949-W11	1028.1	1030.2	2.1	17.6		LX4	Lynx 4
including	1029.2	1029.6	0.4	72.0
	1068.0	1071.4	3.4	3.66		LX4	Lynx 4
	1101.7	1103.8	2.1	4.73		LX4	Lynx 4
including	1102.4	1102.7	0.3	22.9
OSK-W-21-2287-W9	943.6	945.6	2.0	4.57		LX4	Lynx 4
including	943.6	944.1	0.5	18.2
OSK-W-21-2416-W6	986.0	988.3	2.3	9.75		TLX	Triple Lynx
OSK-W-21-2479-W11	470.7	472.8	2.1	8.28		Z27	Zone 27
including	470.7	471.1	0.4	27.5
	773.0	775.2	2.2	5.95		UDD	Underdog
	879.7	882.0	2.3	6.37		UDD	Underdog
including	879.7	880.4	0.7	20.5
OSK-W-21-2522-W4	754.0	756.2	2.2	6.14		Lynx	Lynx
OSK-W-21-2532-W3	691.9	694.0	2.1	12.6		UDD	Underdog
including	691.9	692.8	0.9	28.7
	1089.0	1091.0	2.0	15.0		UDD	Underdog
including	1089.4	1090.0	0.6	37.7
OSK-W-21-2540-W4	978.7	983.6	4.9	28.6		TLX	Triple Lynx
including	983.0	983.6	0.6	74.9
OSK-W-21-2540-W5	936.0	940.8	4.8	11.0		TLX	Triple Lynx
OSK-W-21-2540-W6	931.0	933.2	2.2	9.62		TLX	Triple Lynx
OSK-W-21-2548	235.5	238.5	3.0	3.70		BCT	Bobcat
	252.3	254.5	2.2	3.64		BCT	Bobcat
	358.0	360.1	2.1	4.19		BCT	Bobcat
OSK-W-21-2578	376.8	380.3	3.5	10.6		Z27	Zone 27
	691.1	693.2	2.1	10.8		UDD	Underdog
including	692.6	692.9	0.3	67.0
OSK-W-21-2578-W2	590.0	592.0	2.0	7.84		UDD	Underdog
including	590.0	590.8	0.8	19.0
	706.0	709.2	3.2	6.00		UDD	Underdog
	917.9	920.1	2.2	4.10		UDD	Underdog
including	919.3	919.6	0.3	27.8
OSK-W-21-2587	978.4	989.0	10.6	17.6	17.6	TLX	Triple Lynx
including	982.3	983.0	0.7	101	100
and	983.0	983.7	0.7	77.2
	1054.0	1056.0	2.0	5.53		TLX	Triple Lynx
	1060.0	1062.0	2.0	9.86		TLX	Triple Lynx
including	1061.0	1062.0	1.0	18.3
OSK-W-21-2593	696.4	698.5	2.1	7.44		LX4	Lynx 4
including	696.4	697.0	0.6	17.9
OSK-W-21-2595	343.7	346.3	2.6	12.0		CAE	Caribou
including	345.9	346.3	0.4	52.1
	456.0	458.0	2.0	5.39		CAE	Caribou
including	457.2	457.6	0.4	26.4
	527.7	530.1	2.4	8.50		CAE	Caribou
including	528.1	528.7	0.6	24.9
	559.0	561.0	2.0	5.68		CAE	Caribou
including	559.3	559.9	0.6	16.2
	568.8	571.3	2.5	7.32		CAE	Caribou
including	570.9	571.3	0.4	17.5
	646.5	648.5	2.0	9.53		CAE	Caribou
including	646.5	647.0	0.5	36.0
	651.0	653.2	2.2	24.7		CAE	Caribou
including	652.7	653.2	0.5	98.5
OSK-W-21-2606	581.0	583.7	2.7	5.99		CAE	Caribou
including	583.1	583.7	0.6	26.8
OSK-W-21-2609	646.3	648.4	2.1	25.6		CA2	Caribou
including	646.8	647.4	0.6	84.3
OSK-W-21-2610	534.7	536.7	2.0	4.57		CAE	Caribou
OSK-W-21-2612	301.7	303.8	2.1	13.2		Z27	Zone 27
	309.0	311.0	2.0	7.35		Z27	Zone 27
OSK-W-21-2616	208.3	210.3	2.0	4.01		WFN	Windfall North
OSK-W-21-2623	170.0	172.0	2.0	5.36		WFN	Windfall North
	195.0	197.5	2.5	4.86		WFN	Windfall North
including	196.7	197.5	0.8	13.8
OSK-W-21-2624	18.0	20.0	2.0	10.8		WFN	Windfall North
WST-21-0771C	285.2	287.6	2.4	4.46		LSW	Lynx SW
WST-21-0855B	505.5	507.8	2.3	13.0		LX4	Lynx 4
including	505.5	506.2	0.7	30.8
WST-21-0857A	38.0	40.4	2.4	18.4		LXM	Lynx
including	39.4	40.0	0.6	66.3
	363.2	370.0	6.8	15.4	14.8	TLX	Triple Lynx
including	363.9	364.6	0.7	106	100
	463.2	465.3	2.1	4.46		TLX	Triple Lynx
including	464.4	465.3	0.9	8.32
WST-21-0860	245.9	248.1	2.2	5.87		TLX	Triple Lynx
including	246.5	247.0	0.5	24.4
WST-21-0863	388.0	390.0	2.0	8.66		TLX	Triple Lynx
WST-21-0868A	228.0	231.0	3.0	4.31		TLX	Triple Lynx
	234.0	236.5	2.5	5.34		TLX	Triple Lynx
	241.5	243.5	2.0	5.85		TLX	Triple Lynx
	373.6	375.9	2.3	5.88		TLX	Triple Lynx
	559.2	561.5	2.3	7.11		LX4	Lynx 4
WST-21-0877	307.7	309.7	2.0	221	15.1	LSW	Lynx SW
including	309.1	309.4	0.3	1475	100
WST-21-0885B	148.5	150.5	2.0	6.49		LSW	Lynx SW
including	149.5	150.5	1.0	13.0
	296.5	300.5	4.0	12.8		LSW	Lynx SW
WST-21-0886	100.6	102.7	2.1	11.8		BCT	Bobcat
including	101.7	102.4	0.7	30.5
WST-21-0898	391.7	394.7	3.0	28.2		TLX	Triple Lynx
including	392.8	394.0	1.2	61.9
WST-21-0899B	164.9	167.0	2.1	6.35		LSW	Lynx SW
	220.2	225.3	5.1	10.2		LSW	Lynx SW
including	220.2	221.0	0.8	25.8
WST-21-0899C	372.0	374.0	2.0	8.81		LSW	Lynx SW
including	373.2	373.6	0.4	43.7
WST-21-0910A	97.2	99.3	2.1	4.04		BCT	Bobcat
including	98.1	98.7	0.6	13.9
	169.5	171.5	2.0	10.3		LSW	Lynx SW
including	171.0	171.5	0.5	39.0
	290.0	292.0	2.0	21.2		LSW	Lynx SW
including	290.3	291.0	0.7	55.9

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See "Quality Control and Reporting Protocols" below. BCT = Bobcat, CAE and CA2 = Caribou, LSW = Lynx Southwest, LXM = Lynx Main, LX4 = Lynx 4, TLX = Triple Lynx, UDD = Underdog, WFN = Windfall North and Z27 = Zone 27.

Drill hole location

Hole Number	Azimuth (°)	Dip (°)	Length (m)	UTM E	UTM N	Elevation	Section
OSK-W-21-1871-W1	331	-56	1119	452496	5434397	402	2475
OSK-W-21-1949-W11	105	-57	1314	453440	5435479	401	3825
OSK-W-21-1963-W7	123	-58	1431	453761	5435816	401	4275
OSK-W-21-1963-W8	123	-58	1452	453761	5435816	401	4275
OSK-W-21-2287-W7	116	-53	1320	453607	5435714	404	4075
OSK-W-21-2287-W9	116	-53	1329	453607	5435714	404	4075
OSK-W-21-2400-W1	336	-53	861	452878	5434419	401	2825
OSK-W-21-2416-W6	123	-54	990	453169	5435624	412	3650
OSK-W-21-2416-W7	123	-54	1104	453169	5435624	412	3650
OSK-W-21-2479-W10	344	-55	807	452315	5434420	399	2325
OSK-W-21-2479-W11	344	-55	1005	452315	5434420	399	2325
OSK-W-21-2522-W4	128	-54	1208	453450	5435592	411	3900
OSK-W-21-2531-W3	344	-62	1329	452566	5434415	403	2550
OSK-W-21-2531-W4	344	-62	1203	452566	5434415	403	2550
OSK-W-21-2532-W3	341	-60	1191	452478	5434430	401	2475
OSK-W-21-2537-W3	114	-54	1024	452981	5435549	420	3450
OSK-W-21-2540-W4	117	-60	1297	453465	5435640	410	3925
OSK-W-21-2540-W5	117	-60	1311	453465	5435640	410	3925
OSK-W-21-2540-W6	117	-60	1541	453465	5435640	410	3925
OSK-W-21-2548	331	-57	774	452832	5434545	398	2850
OSK-W-21-2551-W4	120	-55	1026	453622	5435635	405	4050
OSK-W-21-2578	350	-53	942	452178	5434397	399	2200
OSK-W-21-2578-W2	350	-53	924	452178	5434397	399	2200
OSK-W-21-2587	127	-59	1278	453350	5435673	418	3850
OSK-W-21-2589-W2	130	-49	969	452960	5435539	420	3425
OSK-W-21-2593	18	-76	833	454135	5435058	397	4225
OSK-W-21-2595	150	-60	742	452830	5435324	414	3225
OSK-W-21-2600	329	-50	789	452470	5434626	403	2550
OSK-W-21-2606	325	-61	774	452786	5434526	398	2800
OSK-W-21-2609	338	-62	711	452683	5434351	402	2625
OSK-W-21-2610	153	-62	684	452831	5435324	414	3225
OSK-W-21-2612	333	-51	717	452391	5434638	402	2500
OSK-W-21-2615	338	-60	258	452248	5435150	412	2625
OSK-W-21-2616	341	-56	264	452279	5435163	411	2650
OSK-W-21-2618	330	-56	248	452279	5435162	411	2650
OSK-W-21-2620	145	-59	723	452769	5435312	406	3150
OSK-W-21-2622	328	-63	249	452247	5435150	412	2625
OSK-W-21-2623	336	-50	279	452278	5435162	411	2650
OSK-W-21-2624	351	-47	93	452186	5435122	405	2550
OSK-W-21-2627	155	-45	105	452196	5435179	405	2600
WST-21-0649	136	-47	790	453258	5435211	98	3525
WST-21-0771C	127	-52	357	452954	5435003	252	3175
WST-21-0784	132	-66	361	453507	5435327	-7	3800
WST-21-0855B	118	-45	751	453507	5435333	-48	3800
WST-21-0857A	141	-51	592	453322	5435236	54	3600
WST-21-0859	133	-66	499	453105	5435067	231	3325
WST-21-0860	126	-60	304	453508	5435328	-7	3800
WST-21-0863	135	-64	403	453508	5435327	-7	3800
WST-21-0868A	130	-44	922	453374	5435296	-26	3675
WST-21-0877	158	-60	490	453105	5435065	231	3325
WST-21-0879	139	-44	724	453258	5435209	96	3525
WST-21-0885B	145	-53	377	452954	5435003	253	3175
WST-21-0886	128	-51	375	452954	5435004	253	3175
WST-21-0898	141	-61	402	453508	5435327	-7	3800
WST-21-0899B	134	-60	287	452955	5435004	253	3175
WST-21-0899C	139	-58	434	452955	5435004	252	3175
WST-21-0901	116	-18	340	453462	5435327	32	3775
WST-21-0906A	133	-58	381	453105	5435066	231	3325
WST-21-0910A	143	-63	438	452954	5435004	252	3175

Bobcat
Mineralization most commonly occurs in gold-bearing quartz-pyrite veins controlled by northeast trending faults and shears and to a lesser extent in minor crustiform quartz-tourmaline-ankerite-pyrite veins and pyrite replacement zones and stockwork. Mineralization is hosted in sheared mafic volcanics, rhyolites near faults, or at the contact with felsic porphyritic intrusions.

Caribou Zone
Mineralization most commonly occurs in gold-bearing pyrite stockworks as well as semi-massive pyrite replacement zones associated with phyllic alteration (sericite-pyrite ± silica) with sulphides, pyrite dominated with minor chalcopyrite and sphalerite ranging from trace to up to 20%, and local visible gold. Mineralization is hosted in rhyolites or mafic-intermediate volcanics frequently at or near faults or the contact with felsic porphyritic intrusions.

Lynx Zone
Mineralization occurs as grey to translucent quartz-carbonate-pyrite-tourmaline veins and pyrite replacement zones and stockworks. Vein-type mineralization is associated with haloes of pervasive sericite-pyrite ± silica alteration and contain sulphides (predominantly pyrite with minor amounts of chalcopyrite, sphalerite, galena, arsenopyrite, and pyrrhotite) and local visible gold. Replacement mineralization is associated with strong pervasive silica-sericite-ankerite ± tourmaline alteration and contains disseminated pyrite from trace to 80% with local visible gold. Pyrite stockworks can form envelopes that reach several tens of metres thick. Fuchsite alteration is common and is spatially constrained to near the gabbros. Mineralization occurs at or near geological contacts between felsic porphyritic or fragmental intrusions and the host rhyolites or gabbros and locally can be hosted along the gabbro-rhyolite contact.

Underdog
Mineralization most commonly occurs in gold-bearing quartz-pyrite (± tourmaline) veins and as disseminated, stringer, semi-massive to massive pyrite with minor sphalerite, chalcopyrite and molybdenite associated with strong sericite and silica alteration. Mineralization is hosted along the intrusive contacts of a three-phase composite felsic porphyritic unit which cross-cuts felsic and mafic volcanic sequences.

Zone 27
Mineralization most commonly occurs as replacement-type characterized by 5% to 50% disseminated, stringer, semi-massive or stockwork pyrite, ptygmatic tourmaline veins, quartz-tourmaline crustiform veins, local quartz-carbonate veins, and local visible gold. Mineralization is associated with moderate to strong sericite, weak to strong silica, weak chlorite and carbonate and locally weak fuchsite and is hosted in strongly altered andesites, in or at the contact of the rhyolite, or along the contacts with felsic porphyritic intrusions.

Windfall North
Mineralization is hosted in sheared andesites and most commonly occurs in gold-bearing quartz veins with trace to 10% pyrite, traces of sphalerite and chalcopyrite, and local visible gold. Mineralization is hosted in a silica-carbonate-sericite alteration envelope and is constrained within shear zones with pervasive sericite-carbonate ± fuchsite ± silica 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), Director of Exploration for Osisko's Windfall gold project, who is a "qualified person" as defined by National Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101").

Quality Control and Reporting Protocols
True width determination is estimated at 55-80% 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 3.5 g/t Au diluted over core lengths of at least 2.0 metres. NQ core assays were obtained by either 1-kilogram screen fire assay or standard 50-gram fire-assaying-AA finish or gravimetric finish at (i) ALS Laboratories in Val d'Or, Québec, Vancouver, British Colombia, Lima, Peru or Vientiane, Laos (ii) Bureau Veritas in Timmins, Ontario. The 1-kilogram screen assay method is selected by the geologist when samples contain coarse gold or present a higher percentage of pyrite than surrounding intervals. Selected samples are also analyzed for multi-elements, including silver, using a Four Acid Digestion-ICP-MS method at ALS Laboratories. Drill program design, Quality Assurance/Quality Control ("QA/QC") and interpretation of results is performed by qualified persons employing a QA/QC program consistent with NI 43-101 and industry best practices. Standards and blanks are included with every 20 samples for QA/QC purposes by the Corporation as well as the lab. Approximately 5% of sample pulps are sent to secondary laboratories for check assay.

About the Windfall Gold Deposit
The Windfall gold deposit is located between Val-d'Or and Chibougamau in the Abitibi region of Québec, Canada. The Mineral Resource Estimate (“MRE“) defined by Osisko, as disclosed in the news release dated February 17, 2021 is supported by the technical report entitled “Preliminary Economic Assessment Update for the Windfall Project” dated April 26, 2021 (that includes Windfall Mineral Resource Estimate with an effective date  of November 30, 2020), and assuming a cut-off grade of 3.50 g/t Au, comprises 521,000 tonnes at 11.3 g/t Au (189,000 ounces) in the measured mineral resource category, 5,502,000 tonnes at 9.4 g/t Au (1,668,000 ounces) in the indicated mineral resource category and 16,401,000 tonnes at 8.0 g/t Au (4,244,000 ounces) in the inferred mineral resource category. The key assumptions, parameters and methods used to estimate the mineral resource estimate disclosed in the February 17, 2021 news release are further described in the full technical report prepared by BBA Inc. in accordance with NI 43-101 and is available on SEDAR (www.sedar.com) under the Corporation's issuer profile. The Windfall gold deposit is currently one of the highest-grade resource-stage gold projects in Canada and has world-class scale. Mineralization occurs in three principal zones: Lynx, Main Zone, and Underdog. Mineralization is generally comprised of sub-vertical zones following intrusive porphyry contacts plunging to the northeast. The resources are defined from surface to a depth of 1,600 metres as it now includes the Triple 8 (T8) zone. The resources excluding T8 are defined from surface to a depth of 1,200 metres. The deposit remains open along strike and at depth. Mineralization has been identified at surface in some areas and as deep as 2,625 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 gold resource properties in Canada. Osisko holds a 100% interest in the high-grade Windfall 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 Quévillon area (over 2,700 square kilometres).

Cautionary Note Regarding Forward-Looking Information
This news release contains "forward-looking information" within the meaning of the applicable Canadian securities legislation that is based on expectations, estimates, projections and interpretations as at the date of this news release. Any statement that involves predictions, expectations, interpretations, beliefs, plans, projections, objectives, assumptions, future events or performance (often, but not always, using phrases such as "expects", or "does not expect", "is expected", "interpreted", "management's view", "anticipates" or "does not anticipate", "plans", "budget", "scheduled", "forecasts", "estimates", "potential", "feasibility", "believes" or "intends" or variations of such words and phrases or stating that certain actions, events or results "may" or "could", "would", "might" or "will" be taken to occur or be achieved) are not statements of historical fact and may be forward-looking information and are intended to identify forward-looking information. This news release contains the forward-looking information pertaining to, among other things: the Windfall gold deposit being one of the highest-grade resource-stage gold projects in Canada and having world-class scale; the key assumptions, parameters and methods used to estimate the mineral resource estimate disclosed in this news release; the prospects, if any, of the Windfall gold deposit; timing and ability of Osisko to file a technical report for the mineral resource estimate disclosed in this news release; the timing and ability of Osisko, if at all, to publish a feasibility study for the Windfall gold deposit; the amount and type of drilling to be completed and the timing to complete such drilling; the focus of the remaining infill drilling; the trend of grade increase; the Lynx zone remaining open to expansion down plunge; upgrading a inferred mineral resource to a measured mineral resource or indicated mineral resource category; future drilling at the Windfall gold deposit; the significance of historic exploration activities and results. Such factors include, among others, risks relating to the ability of exploration activities (including drill results) to accurately predict mineralization; errors in management's geological modelling; the ability of Osisko to complete further exploration activities, including (infill) drilling; property and royalty interests in the Windfall gold deposit; the ability of the Corporation to obtain required approvals; the results of exploration activities; risks relating to mining activities; the global economic climate; metal prices; dilution; environmental risks; and community and non-governmental actions. Although the forward-looking information contained in this news release is based upon what management believes, or believed at the time, to be reasonable assumptions, Osisko cannot assure shareholders and prospective purchasers of securities of the Corporation that actual results will be consistent with such forward-looking information, as there may be other factors that cause results not to be as anticipated, estimated or intended, and neither Osisko nor any other person assumes responsibility for the accuracy and completeness of any such forward-looking information. Osisko does not undertake, and assumes no obligation, to update or revise any such forward-looking statements or forward-looking information contained herein to reflect new events or circumstances, except as may be required by law.

CONTACT INFORMATION:
John Burzynski
Chief Executive Officer
Telephone (416) 363-8653