Osisko Windfall Infill and Expansion Drilling Continues to add High-Grade

 

75.4 g/t Au Over 3.2 Metres in Triple Lynx

103 g/t Au Over 2.3 Metres and 105 g/t Au Over 2.0 Metres in Lynx

TORONTO, July 07, 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 60 intercepts in 20 drill holes (5 from surface, 15 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 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: “Infill and expansion drilling from across the Windfall deposit continues to progress well. In particular, the focused infill drilling in all the Lynx zones consistently returns well distributed high-grade and expansion drilling is adding ounces. WST-21-0810 and OSK-W-21-2123-W5 both extended Triple Lynx wireframes, 25 metres and 40 meters at depth, respectively.”

Selected high-grade intercepts include: 75.4 g/t Au over 3.2 metres and 86.9 g/t Au over 2.4 metres in OSK-W-21-2470-W4; 103 g/t Au over 2.3 metres in WST-21-0722; 105 g/t Au over 2.0 metres in WST-21-0716; 29.5 g/t Au over 6.0 metres in OSK-W-21-2067-W8; 87.1 g/t Au over 2.0 metres in OSK-W-21-2067-W7; 42.3 g/t Au over 3.0 metres in OSK-W-21-1882-W3; 60.6 g/t Au over 2.0 metres in WST-21-0721 and 30.7 g/t Au over 3.9 metres in WST-21-0682B. 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-21-1882-W3	829.3	832.3	3.0	42.3		UDD_4102	Underdog
including	831.3	832.3	1.0	85.2
	936.0	938.0	2.0	4.12		UDD_4511	Underdog
including	936.0	936.5	0.5	16.3
OSK-W-21-2067-W7	1136.0	1138.0	2.0	87.1	20.1	TLX_3172	Triple Lynx
including	1136.8	1137.2	0.4	435	100
OSK-W-21-2067-W8	1112.0	1118.0	6.0	29.5	20.1	TLX_3170	Triple Lynx
including	1115.4	1116.1	0.7	181	100
OSK-W-21-2275-W7	675.0	677.0	2.0	4.70		TLX_3196	Triple Lynx
including	675.4	676.0	0.6	14.6
OSK-W-21-2470-W4	956.0	958.0	2.0	3.85		TLX_3163	Triple Lynx
	961.6	964.0	2.4	86.9	35.3	TLX_3163	Triple Lynx
including	962.0	962.8	0.8	255	100
	987.8	991.0	3.2	75.4	45.6	TLX_3164	Triple Lynx
including	987.8	988.5	0.7	236	100
OSK-W-21-2478-W5	860.0	862.1	2.1	16.7		TLX_3184	Triple Lynx
including	860.7	861.7	1.0	34.1
OSK-W-21-2479-W4	651.3	653.3	2.0	41.5	40.3	UDD_4100	Underdog
including	653.0	653.3	0.3	108	100
OSK-W-21-2503-W1	1022.8	1024.8	2.0	9.75		TLX_3164	Triple Lynx
including	1024.2	1024.8	0.6	25.6
OSK-W-21-2520	639.0	643.2	4.2	9.87		CA2_2206	Caribou
including	639.0	639.3	0.3	64.6
and	642.5	643.2	0.7	26.3
OSK-W-21-2522-W1	655.2	657.3	2.1	10.0		LXM_3304	Lynx
including	656.2	656.6	0.4	41.6
	747.1	749.4	2.3	4.58		LXM_3345	Lynx
including	747.8	748.4	0.6	17.1
OSK-W-21-2523	503.5	507.7	4.2	4.27		CA2_2247	Caribou
including	503.5	504.0	0.5	13.1
	511.0	513.1	2.1	3.61		CA2_2241	Caribou
	522.7	529.0	6.3	8.53		CA2_2233	Caribou
including	528.4	529.0	0.6	39.7
OSK-W-21-2532	452.0	454.0	2.0	24.7		Caribou_2232	Caribou
including	453.0	454.0	1.0	49.0
OSK-W-21-2534	558.4	560.6	2.2	9.81		Caribou_2247	Caribou
WST-21-0682A	89.8	92.0	2.2	19.8		LXM_3339	Lynx
including	90.1	91.0	0.9	47.7
WST-21-0682B	105.5	107.6	2.1	6.82		LXM_3311	Lynx
including	106.9	107.3	0.4	25.7
	349.0	352.0	3.0	32.7	29.9	TLX_3166	Triple Lynx
including	349.0	349.3	0.3	128	100
	357.6	361.5	3.9	30.7		TLX_3166	Triple Lynx
including	358.0	358.6	0.6	68.0
and	360.8	361.5	0.7	78.0
	363.5	365.7	2.2	5.78		TLX_3166	Triple Lynx
	456.0	458.0	2.0	24.5		TLX_3130	Triple Lynx
including	456.0	456.6	0.6	74.6
WST-21-0716	26.5	28.5	2.0	22.1		LXM_3303	Lynx
including	27.1	28.0	0.9	47.4
	81.0	83.0	2.0	105	33.1	LXM_3304	Lynx
including	81.4	82.0	0.6	339	100
	87.0	89.0	2.0	17.7		LXM_3304	Lynx
including	87.0	87.7	0.7	50.4
WST-21-0720	80.2	82.5	2.3	8.25		LXM_3336	Lynx
including	80.8	81.3	0.5	35.9
	92.3	94.7	2.4	8.99		LXM_3304	Lynx
WST-21-0721	92.0	94.0	2.0	60.6	60.2	LXM_3304	Lynx
including	92.4	93.6	1.2	101	100
WST-21-0722	25.3	27.6	2.3	103	25.2	LXM_3303	Lynx
including	26.5	27.0	0.5	459	100
WST-21-0759	325.1	327.2	2.1	3.96		TLX_3131	Triple Lynx
WST-21-0778	313.4	315.7	2.3	5.23		TLX_3131	Triple Lynx
including	314.4	315.0	0.6	18.0
	511.0	513.0	2.0	28.3		LX4_3429	Lynx 4
including	512.0	513.0	1.0	51.5
WST-21-0789B	325.6	327.9	2.3	8.20		TLX_3166	Triple Lynx
including	325.9	326.8	0.9	17.0
WST-21-0801	306.5	308.6	2.1	11.5		LSW_3556	Lynx Southwest
including	307.0	307.7	0.7	33.7
WST-21-0810	344.0	346.0	2.0	4.77		TLX_3131	Triple Lynx
	373.0	376.0	3.0	5.08		TLX_3167	Triple Lynx
	531.0	533.0	2.0	33.8	25.2	LX4_3450	Lynx 4
including	532.1	532.6	0.5	135	100
	736.8	738.9	2.1	22.2		LX4_3412	Lynx 4
including	737.6	737.9	0.3	78.9
WST-21-0815	81.0	83.0	2.0	4.09		Z27_1102	Zone 27
WST-21-0819A	79.0	81.0	2.0	3.89		Z27_1115	Zone 27
including	80.1	81.0	0.9	8.45
WST-21-0820	92.5	95.0	2.5	3.56		Z27_1102	Zone 27
WST-21-0827	247.7	250.0	2.3	13.4		TLX_3161	Triple Lynx

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See "Quality Control and Reporting Protocols" below. Z27 = Zone 27, CA2 = Caribou 2, LSW = Lynx Southwest, LXM = Lynx Main, LX4 = Lynx 4, TLX = Triple Lynx, and UDD = Underdog.

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-21-2123-W5	1154.6	1159.0	4.4	16.6		Triple Lynx	Lynx
including	1154.6	1155.0	0.4	42.9
and	1156.0	1156.4	0.4	61.4
and	1157.6	1158.0	0.4	41.9
	1203.0	1205.0	2.0	5.59		Triple Lynx	Lynx
including	1203.8	1204.1	0.3	13.3
	1209.0	1211.0	2.0	4.32		Triple Lynx	Lynx
OSK-W-21-2470-W3	956.8	958.8	2.0	45.7	30.6	Triple Lynx	Lynx
including	957.3	957.9	0.6	151	100
	989.8	991.8	2.0	16.2		Triple Lynx	Lynx
including	991.2	991.5	0.3	80.1
OSK-W-21-2479-W4	426.0	428.0	2.0	19.2		Zone 27	Main Zone
including	427.3	428.0	0.7	49.9
OSK-W-21-2480-W3	731.5	733.5	2.0	26.4		Lynx	Lynx
including	732.5	733.5	1.0	51.8
OSK-W-21-2523	409.5	412.0	2.5	7.42		Caribou	Main Zone
including	409.5	410.3	0.8	16.2
OSK-W-21-2540	824.5	826.5	2.0	4.94		Lynx Main	Lynx
including	825.9	826.5	0.6	15.8
WST-21-0682B	375.0	377.0	2.0	4.08		Lynx SW	Lynx
	384.0	386.1	2.1	5.90		Lynx SW	Lynx
including	385.6	386.1	0.5	24.2
WST-21-0759	29.7	32.0	2.3	6.83		Lynx Main	Lynx
WST-21-0778	323.0	325.0	2.0	10.7		Triple Lynx	Lynx
including	323.3	323.6	0.3	69.0
WST-21-0789B	371.0	373.0	2.0	4.42		Triple Lynx	Lynx
including	372.6	373.0	0.4	19.3
WST-21-0810	450.2	453.0	2.8	25.2		Triple Lynx	Lynx
including	452.5	453.0	0.5	96.7

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

Drill hole location

Hole Number	Azimuth (°)	Dip (°)	Length (m)	UTM E	UTM N	Elevation	Section
OSK-W-21-1882-W3	328	-58	1004	452469	5434405	400	2450
OSK-W-21-2067-W7	123	-53	1166	453241	5435697	416	3750
OSK-W-21-2067-W8	123	-53	1191	453241	5435697	416	3750
OSK-W-21-2123-W5	126	-57	1332	453235	5435774	409	3800
OSK-W-21-2275-W7	127	-49	1182	452888	5435583	409	3400
OSK-W-21-2470-W3	132	-59	1209	453304	5435639	415	3775
OSK-W-21-2470-W4	132	-59	1155	453304	5435639	415	3775
OSK-W-21-2478-W5	128	-54	1166	452997	5435607	425	3500
OSK-W-21-2479-W4	344	-55	761	452315	5434419	399	2325
OSK-W-21-2480-W3	121	-55	810	453412	5435633	412	3875
OSK-W-21-2503-W1	126	-58	1161	453333	5435641	413	3800
OSK-W-21-2520	337	-56	1140	452596	5434392	401	2550
OSK-W-21-2522-W1	128	-54	1116	453451	5435594	411	3900
OSK-W-21-2523	340	-58	1107	452480	5434428	402	2475
OSK-W-21-2532	341	-60	1107	452480	5434428	401	2475
OSK-W-21-2534	343	-59	1203	452549	5434363	401	2500
OSK-W-21-2540	117	-60	1025	453465	5435640	410	3925
WST-21-0682A	133	-66	139	453106	5435066	231	3325
WST-21-0682B	129	-64	472	453106	5435066	231	3325
WST-21-0716	160	-3	97	453359	5435194	83	3625
WST-21-0720	162	2	103	453359	5435194	84	3625
WST-21-0721	166	-1	103	453359	5435194	83	3625
WST-21-0722	166	1	106	453359	5435194	84	3625
WST-21-0759	141	-43	680	453321	5435235	54	3600
WST-21-0778	145	-31	534	453374	5435296	-26	3675
WST-21-0789B	125	-55	381	453106	5435066	231	3325
WST-21-0801	139	-54	418	452954	5435003	253	3175
WST-21-0810	138	-47	765	453257	5435209	96	3525
WST-21-0815	159	0	99	451960	5434734	250	2175
WST-21-0819A	173	-2	100	451957	5434735	250	2175
WST-21-0820	179	18	115	451957	5434735	250	2175
WST-21-0827	145	-66	313	453507	5435327	-7	3800

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.

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.

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.

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), 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