Osisko Drilling Returns High Grade at Lynx

369 g/t Au Over 3.5 Metres in Lynx

155 g/t Au Over 3.0 Metres in Triple Lynx

TORONTO, April 08, 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 78 intercepts in 46 drill holes (12 from surface, 22 from underground) and 12 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 mineral resource estimate (“MRE”) and either expand resource wireframes or are located in a defined zone or corridor but do not yet correlate to a specific wireframe.

Osisko Chief Executive Officer John Burzynski commented: “Once again the drilling in the Lynx area delivers both inside and outside of the February 2021 MRE blocks. Further, expansion drilling in the Triple Lynx corridor continues to provide strong targets for growth as demonstrated by Hole OSK-W-20-2371-W1, one of our top results today. As we noted in our April 7, 2021 PEA update, ongoing drilling is showing great potential to see further increases in the already strong economic base case of the Windfall deposit.”

Selected high-grade intercepts include: 369 g/t Au over 3.5 metres in OSK-W-21-2369-W3; 155 g/t Au over 3.0 metres and 45.7 g/t Au over 2.1 metres in WST-21-0670; 129 g/t Au over 3.2 metres in OSK-W-20-2252-W11, 144 g/t Au over 2.5 metres in WST-21-0657; 123 g/t Au over 2.4 metres in OSK-W-20-2371-W1, 78.4 g/t Au over 3.1 metres in OSK-W-21-2480, 70.0 g/t Au over 2.6 metres in WST-20-0568, 76.4 g/t Au over 2.2 metres in WST-20-0578, and 52.6 g/t Au over 2.3 metres in OSK-W-20-2420. 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-20-2416	1019.1	1021.1	2.0	7.61		TLX_3162	Triple Lynx
including	1019.4	1020.0	0.6	21.6
OSK-W-20-2426	346.0	348.0	2.0	5.84		TLX_3178	Triple Lynx
including	347.0	347.3	0.3	34.2
OSK-W-20-2428	720.0	722.4	2.4	25.0		Lynx_3304	Lynx
including	721.1	721.9	0.8	61.0
OSK-W-20-2431	759.0	761.0	2.0	3.86		TLX_3129	Triple Lynx
including	760.0	760.7	0.7	10.9
	806.0	808.1	2.1	6.53		TLX_3195	Triple Lynx
including	807.6	808.1	0.5	25.9
OSK-W-21-2363-W4	748.2	750.8	2.6	16.3		TLX_3171	Triple Lynx
including	750.0	750.5	0.5	33.7
OSK-W-21-2369-W3	672.8	676.3	3.5	369	100	LXM_3304	Lynx
Including	672.8	673.5	0.7	127	100
and	673.5	674.2	0.7	545	100
and	674.2	674.6	0.4	192	100
and	674.6	675.0	0.4	155	100
and	675.0	675.6	0.6	557	100
and	675.6	676.3	0.7	500	100
OSK-W-21-2394-W4	668.7	671.0	2.3	40.9		TLX_3184	Triple Lynx
including	669.1	670.0	0.9	99.7
	882.0	884.0	2.0	3.11		TLX_3130	Triple Lynx
OSK-W-21-2394-W5	652.5	655.4	2.9	3.86		TLX_3171	Triple Lynx
including	654.5	655.4	0.9	7.79
OSK-W-21-2416-W2	927.5	929.7	2.2	7.16		TLX_3161	Triple Lynx
including	928.2	928.8	0.6	22.5
	936.9	944.0	7.1	5.15		TLX_3161	Triple Lynx
including	937.5	938.2	0.7	15.8
OSK-W-21-2436-W1	698.2	703.0	4.8	4.28		LX4_3424	Lynx 4
including	698.2	699.0	0.8	11.2
OSK-W-21-2443	1062.9	1065.0	2.1	6.51		Triple Lynx	Triple Lynx
including	1064.3	1065.0	0.7	16.6
OSK-W-21-2452	714.0	716.6	2.6	13.5		TLX_3198	Triple Lynx
	747.0	749.2	2.2	4.46		TLX_3129	Triple Lynx
including	747.0	747.7	0.7	10.2
OSK-W-21-2457	773.7	776.0	2.3	33.4	18.6	Lynx_3437	Lynx
including	774.8	775.2	0.4	185	100
OSK-W-21-2464	720.8	731.5	10.7	7.23		Lynx_3304	Lynx
including	725.8	726.8	1.0	17.2
OSK-W-21-2480	741.4	744.5	3.1	78.4	31.5	LXM_3304	Lynx
including	742.8	743.5	0.7	308	100
WST-20-0573	336.1	338.3	2.2	4.76		LXSW_3556	Lynx
including	336.1	336.8	0.7	12.3
WST-20-0605A	461.0	463.0	2.0	9.11		LXSW_3502	Lynx
including	461.7	462.3	0.6	30.2
WST-21-0614	308.0	310.0	2.0	3.74		TLX_3169	Triple Lynx
	313.0	315.3	2.3	8.89		TLX_3169	Triple Lynx
including	314.9	315.3	0.4	17.8
WST-21-0620A	274.0	276.0	2.0	4.97		TLX_3164	Triple Lynx
WST-21-0636	114.0	116.0	2.0	4.42		LXM_3334	Lynx
WST-21-0637	323.0	327.0	4.0	7.64		TLX_3167	Triple Lynx
including	326.0	327.0	1.0	15.4
	475.5	478.0	2.5	3.47		Lynx 4	Lynx
	507.0	509.0	2.0	9.77		LX4_3450	Lynx 4
including	507.3	507.6	0.3	60.5
WST-21-0647	311.0	313.0	2.0	5.83		TLX_3166	Triple Lynx
including	312.3	313.0	0.7	14.9
WST-21-0648B	59.0	61.4	2.4	4.28		Lynx_3339	Lynx
WST-21-0656	284.0	286.2	2.2	3.16		TLX_3164	Triple Lynx
WST-21-0657	219.5	222.0	2.5	144	55.3	TLX_3161	Triple Lynx
including	220.8	221.3	0.5	543	100
WST-21-0659	360.9	364.0	3.1	6.83		TLX_3131	Triple Lynx
WST-21-0670	364.3	367.3	3.0	155	64.8	TLX_3166	Triple Lynx
including	364.3	365.3	1.0	369	100
	369.3	371.4	2.1	45.7	23.8	TLX_3166	Triple Lynx
including	369.9	370.4	0.5	191	100
	409.5	412.0	2.5	6.63		TLX_3165	Triple Lynx
including	410.0	410.4	0.4	30.6
WST-21-0690	274.5	276.9	2.4	7.31		TLX_3164	Triple Lynx

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See "Quality Control and Reporting Protocols" below. LXM = Lynx Main, LX4 = Lynx 4, TLX = Triple Lynx and LXSW = Lynx Southwest.

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-20-2252-W11	944.0	946.0	2.0	4.53		Triple Lynx	Triple Lynx
	961.1	963.5	2.4	19.1	15.2	Triple Lynx	Triple Lynx
including	961.4	961.7	0.3	131	100
	965.8	969.0	3.2	129	21.2	Triple Lynx	Triple Lynx
including	967.8	968.1	0.3	1250	100
	975.0	977.0	2.0	4.58		Triple Lynx	Triple Lynx
OSK-W-20-2313-W10	1009.0	1011.0	2.0	3.49		Triple Lynx	Triple Lynx
	1052.0	1054.0	2.0	22.4		Triple Lynx	Triple Lynx
including	1052.0	1053.0	1.0	44.6
OSK-W-20-2363-W3	957.0	961.7	4.7	6.61		Triple Lynx	Triple Lynx
including	957.0	957.6	0.6	18.4
OSK-W-20-2371-W1	1007.3	1009.7	2.4	123	27.2	Triple Lynx	Triple Lynx
including	1007.3	1007.9	0.6	483	100
OSK-W-20-2397-W1	652.0	654.0	2.0	13.4		LXM_3304	Lynx
including	652.3	653.1	0.8	33.1
OSK-W-20-2416	946.0	948.0	2.0	7.01		Triple Lynx	Triple Lynx
	967.0	976.4	9.4	10.0		Triple Lynx	Triple Lynx
including	971.0	972.0	1.0	29.5
OSK-W-20-2420	744.0	746.3	2.3	52.6	51.3	Lynx	Lynx
including	744.5	745.5	1.0	103	100
	983.0	985.1	2.1	4.06		Triple Lynx	Triple Lynx
including	983.0	984.0	1.0	8.45
OSK-W-20-2426	634.0	636.0	2.0	17.6		Triple Lynx	Triple Lynx
including	635.0	636.0	1.0	32.4
	751.0	753.0	2.0	11.7		Triple Lynx	Triple Lynx
OSK-W-20-2428	665.0	667.3	2.3	19.3		Lynx	Lynx
including	665.0	666.3	1.3	34.1
	686.5	690.3	3.8	4.58		Lynx	Lynx
including	686.5	687.0	0.5	12.2
OSK-W-20-2431	759.0	761.0	2.0	3.86		Triple Lynx	Triple Lynx
including	760.0	760.7	0.7	10.9
	806.0	808.1	2.1	6.53		TLX_3195	Triple Lynx
including	807.6	808.1	0.5	25.9
OSK-W-21-2363-W4	806.6	809.0	2.4	11.5		Triple Lynx	Triple Lynx
including	806.6	806.9	0.3	91.9
	812.5	816.0	3.5	15.5		Triple Lynx	Triple Lynx
including	812.5	813.4	0.9	33.9
OSK-W-21-2394-W5	600.0	602.0	2.0	6.49		Triple Lynx	Triple Lynx
OSK-W-21-2443	1062.9	1065.0	2.1	6.51		Triple Lynx	Triple Lynx
including	1064.3	1065.0	0.7	16.6
OSK-W-21-2445	590.4	593.0	2.6	3.28		Triple Lynx	Triple Lynx
including	590.4	590.8	0.4	19.7
	852.0	854.1	2.1	3.56		Triple Lynx	Triple Lynx
OSK-W-21-2445-W1	596.2	598.5	2.3	4.04		Triple Lynx	Triple Lynx
	618.0	620.0	2.0	3.69		Triple Lynx	Triple Lynx
including	618.0	619.0	1.0	7.22
OSK-W-21-2459	705.6	707.9	2.3	4.49		Triple Lynx	Triple Lynx
WST-20-0568	273.6	276.2	2.6	70.0	13.6	Lynx SW	Lynx SW
including	275.9	276.2	0.3	589	100
WST-20-0570	290.7	292.9	2.2	3.46		Lynx SW	Lynx SW
including	291.1	291.9	0.8	9.09
WST-20-0578	151.5	153.7	2.2	76.4	14.4	Lynx	Lynx
including	152.4	152.7	0.3	555	100
WST-20-0605A	258.0	260.0	2.0	3.58		Lynx SW	Lynx SW
including	258.0	259.0	1.0	7.12
WST-20-0613	376.0	385.0	9.0	7.47		Triple Lynx	Triple Lynx
including	380.4	380.8	0.4	16.5
and	381.1	382.0	0.9	27.6
and	383.4	384.0	0.6	15.5
WST-20-0613	396.0	398.0	2.0	5.05		Triple Lynx	Triple Lynx
	241.8	244.0	2.2	4.37		Lynx SW	Lynx SW
	377.9	380.0	2.1	8.67		Lynx SW	Lynx SW
including	377.9	378.4	0.5	36.2
WST-21-0637	172.0	174.0	2.0	5.30		Triple Lynx	Triple Lynx
including	172.0	172.5	0.5	18.1
WST-21-0662	212.0	214.0	2.0	12.7		Lynx SW	Lynx SW
including	212.5	213.0	0.5	34.1
WST-21-0678	48.0	50.0	2.0	4.30		Lynx	Lynx
including	48.0	48.5	0.5	11.7
WST-21-0689A	389.0	391.2	2.2	8.67		Triple Lynx	Triple Lynx
WST-21-0683	538.6	540.7	2.1	7.03		Lynx 4	Lynx

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

Drill hole location

Hole Number	Azimuth (°)	Dip (°)	Length (m)	UTM E	UTM N	Elevation	Section
OSK-W-20-2252-W11	129	-54	1191	453241	5435694	415	3750
OSK-W-20-2313-W10	134	-52	1059	452965	5435583	420	3450
OSK-W-20-2363-W3	139	-52	1185	452930	5435548	419	3425
OSK-W-20-2371-W1	123	-53	1032	452996	5435363	412	3375
OSK-W-20-2397-W1	131	-58	1200	453451	5435594	412	3900
OSK-W-20-2416	123	-54	1128	453169	5435624	412	3650
OSK-W-20-2420	124	-59	1185	453397	5435557	413	3825
OSK-W-20-2426	134	-56	1035	453008	5435388	413	3400
OSK-W-20-2428	127	-53	1257	453412	5435633	412	3875
OSK-W-20-2431	136	-57	849	453008	5435388	412	3400
OSK-W-21-2363-W4	139	-52	1270	452930	5435548	419	3425
OSK-W-21-2369-W3	130	-56	1415	453424	5435566	410	3850
OSK-W-21-2394-W4	138	-52	920	452923	5435467	414	3375
OSK-W-21-2394-W5	138	-52	915	452923	5435467	414	3375
OSK-W-21-2416-W2	123	-54	1266	453169	5435624	412	3650
OSK-W-21-2436-W1	130	-57	744	453709	5435618	400	4125
OSK-W-21-2443	127	-56	1164	453304	5435639	415	3775
OSK-W-21-2445	141	-50	945	452906	5435434	415	3325
OSK-W-21-2445-W1	141	-50	909	452906	5435434	415	3325
OSK-W-21-2452	137	-56	891	453008	5435388	412	3400
OSK-W-21-2457	15	-77	957	454135	5435058	397	4225
OSK-W-21-2459	132	-52	1227	452997	5435607	425	3500
OSK-W-21-2464	120	-53	1031	453412	5435633	412	3875
OSK-W-21-2480	121	-55	1230	453412	5435633	412	3875
WST-20-0568	157	-58	493	453104	5435065	231	3325
WST-20-0570	159	-51	454	453104	5435065	231	3325
WST-20-0573	148	-59	436	452955	5435003	253	3175
WST-20-0578	154	-47	802	453418	5435305	69	3725
WST-20-0605A	148	-61	532	453105	5435065	231	3325
WST-20-0613	123	-55	442	453358	5435273	16	3650
WST-20-0616	179	-61	459	453228	5435126	135	3475
WST-21-0614	131	-59	427	453357	5435273	16	3650
WST-21-0620A	174	-57	300	453507	5435327	-7	3800
WST-21-0636	133	-36	178	453322	5435235	55	3600
WST-21-0637	151	-47	550	453321	5435235	54	3600
WST-21-0647	150	-59	345	453228	5435126	135	3475
WST-21-0648B	166	-59	345	453228	5435126	135	3475
WST-21-0656	139	-61	322	453357	5435272	16	3650
WST-21-0657	141	-56	448	453357	5435272	16	3650
WST-21-0659	126	-45	397	453357	5435272	16	3650
WST-21-0662	149	-50	220	452955	5435003	253	3175
WST-21-0670	142	-43	471	453257	5435209	96	3525
WST-21-0678	153	-50	574	453321	5435235	55	3600
WST-21-0683	146	-40	636	453257	5435210	95	3525
WST-21-0689A	161	-64	397	453356	5435272	16	3650
WST-21-0690	150	-63	307	453356	5435272	16	3650

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.

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 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 3.0 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 defined by Osisko, as disclosed in the news release dated February 17, 2021 and supported by the technical report entitled “Mineral Resource Estimate Update for the Windfall Project, Eeyou Istchee James Bay, Québec, Canada” dated March 8, 2021 (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 [phone]