Osisko Windfall Infill Drilling Returns More of the Same

395 g/t Au Over 2.3 Metres and 61.5 g/t Au Over 9.2 Metres

TORONTO, Nov. 05, 2020 (GLOBE NEWSWIRE) — Osisko Mining Inc. (OSK:TSX. “Osisko” or the “Corporation”) is pleased to provide new analytical results from the ongoing expansion and definition drill program at its 100% owned Windfall gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec.

Drilling is currently focused on the Lynx deposit. Osisko Chief Executive Officer John Burzynski commented: “Infill drilling at Windfall, and in particular Lynx, continues to progress well. Predictably, and with a familiar consistency, once again Lynx delivered on high-grade with our headline intercept of 395 g/t Au over 2.3 metres, and also on width with the very nice intercept of 61.5 g/t Au over 9.2 metres.”

The table below contains resource definition infill intercepts located inside the February 2020 mineral resource estimate wireframes (

see Osisko news release dated February 19, 2020

). Significant new analytical results are presented below and include 33 intercepts in 16 drill holes and 7 wedges.

Selected high-grade intercepts from the new results include:

395


g/t Au over


2.3


metres

OSK-W-20-2292-W1;

61.5


g/t Au over


9.2


metres

and

37.0 g/t Au over 3.0 metres

in OSK-W-20-2256-W4;

55.5 g/t Au over 2.5 metres

in WST-20-0350 and

40.1 g/t Au over 2.8 metres

in WST-20-0013. Maps showing hole locations and full analytical results are available at

www.osiskomining.com

.


Hole No.

From



(m)

To

(m)

Interval



(m)

Au (g/t)



uncut

Au (g/


t)



cut


to

100 g/t

Zone

Corridor

OSK-W-20-2139-W12

905.3

907.9

2.6

28.5


Lynx_371


Triple Lynx


including
906.2 906.8 0.6 88.3

OSK-W-20-2139-W9

886.7

893.0

6.3

15.4


Lynx_371

Triple Lynx

OSK-W-20-2252-W3

865.7

867.7

2.0

11.7


Lynx_371


Triple Lynx


including
865.7 866.0 0.3 58.6

OSK-W-20-2256-W4

862.0

871.2

9.2

61.5

32.6

Lynx_361


Triple Lynx


including
863.0 864.0 1.0 281 100

and
870.0 871.2 1.2 171 100


881.0

884.0

3.0

37


.0


Lynx_361


Triple Lynx


including
882.0 883.0 1.0 86.2

OSK-W-20-2275-W2

628.9

631.0

2.1

8.18


Lynx_365


Triple Lynx


including
628.9 629.8 0.9 18.5


800.0

802.3

2.3

3.65


Lynx_376


Triple Lynx


including
800.0 800.6 0.6 10.9

OSK-W-20-2283

935.0

937.0

2.0

18.5


Triple Lynx


Triple Lynx


including
936.0 936.7 0.7 49.6

OSK-W-20-2292-W1

1040.7

1043.0

2.3

395

15.4

Lynx_374


Triple Lynx


including
1041.3 1041.6 0.3 3010 100

OSK-W-20-2292-W2

909.3

913.0

3.7

3.64


Lynx_375

Triple Lynx

OSK-W-20-2322

1090.3

1094.1

3.8

28.9

Lynx_334


Lynx


including
1090.3 1091.3 1.0 81.9

WST-20-0011

74.3

76.4

2.1

4.68

Lynx_311

Lynx

WST-20-0012D

81.0

83.0

2.0

3.14


Lynx_311


Lynx


including
82.5 83.0 0.5 8.68

WST-20-0013

140.0

142.8

2.8

40.1

31.5

Lynx_304


Lynx


including
140.7 141.5 0.8 130 100

WST-20-0014A

100.2

102.2

2.0

5.4


0


Lynx_304

Lynx

WST-20-0350

128.5

131.0

2.5

55.5


Lynx_359


Lynx


including
129.2 129.9 0.7 98.8

WST-20-0352

32.3

36.0

3.7

16.2


Lynx_325


Lynx


including
35.0 36.0 1.0 46.8


97.0

99.0

2.0

5.95


Lynx_304

Lynx

WST-20-0394

35.1

37.3

2.2

11.7


Lynx_325

Lynx

70.8

72.8

2.0

4.15

Lynx_311

Lynx

107.0

109.3

2.3

24.2

23.2

Lynx_304


Lynx


including
107.0 107.7 0.7 78.9 75.7

WST-20-0395

50.0

52.0

2.0

6.45


Lynx_303

Lynx

WST-20-0420

79.4

81.7

2.3

4.11


Lynx_323


Lynx


including
81.4 81.7 0.3 29.1


150.0

152.1

2.1

19


.0


Lynx_321


Lynx


including
151.2 152.1 0.9 43.5

WST-20-0422

160

162

2.0

5.90

Lynx_328

Lynx

WST-20-0482

87.9

90.0

2.1

6.00

Lynx_323

Lynx

WST-20-0484

43.1

45.5

2.4

4.8


0


Lynx_325


Lynx


including
43.7 44.0 0.3 33.1


94.2

96.3

2.1

13.5


Lynx_304


Lynx


including
94.8 95.2 0.4 31.0

WST-20-0485

106.3

108.3

2.0

5.55


Lynx_323


Lynx


including
107.9 108.3 0.4 27.2


119.3

122.0

2.7

12.6


Lynx_304


Lynx


including
119.3 119.7 0.4 60.5


143.2

145.3

2.1

16.3


Lynx_359


Lynx


including
144.3 145.0 0.7 48.4

WST-20-0486

44.9

47.3

2.


4

11.2

Lynx_325


Lynx


Including
46.8 47.3 0.5 34.8

51.5

54.5

3.0

14.9

Lynx_303

Lynx
Notes: True widths are estimated at 55 – 80% of the reported core length interval. See

“Quality Control and Reporting Protocols”

below.



Drill hole location


Hole


Number

Azimuth


(°)

Dip


(°)

Length


(m)

UTM E

UTM N

Elevation

Section

OSK-W-20-2139-W12
115 -52 1038 452980 5435549 420 3450

OSK-W-20-2139-W9
115 -52 1152 452980 5435549 420 3450

OSK-W-20-2252-W3
129 -53 1062 453241 5435694 415 3750

OSK-W-20-2256-W4
125 -51 1122 453160 5435686 414 3675

OSK-W-20-2275-W2
127 -49 1035 452886 5435584 409 3400

OSK-W-20-2283
135 -50 1151 452997 5435607 425 3500

OSK-W-20-2292-W1
125 -54 1149 453037 5435563 420 3525

OSK-W-20-2292-W2
125 -54 1002 453037 5435563 420 3525

OSK-W-20-2322
130 -54 1191 453608 5435713 404 4075

WST-20-0011
157 -54 451 453105 5435065 231 3325

WST-20-0012D
174 -62 465 453226 5435126 134 3475

WST-20-0013
171 -42 169 453357 5435208 154 3625

WST-20-0014A
137 1 124 453359 5435209 155 3625

WST-20-0350
142 -31 175 453359 5435209 154 3625

WST-20-0352
140 -10 177 453359 5435209 155 3625

WST-20-0394
152 -26 172 453358 5435208 154 3625

WST-20-0395
153 -16 169 453358 5435208 155 3625

WST-20-0420
155 -10 166 453450 5435264 116 3725

WST-20-0422
171 -26 177 453449 5435264 117 3725

WST-20-0482
165 -9 181 453449 5435264 117 3725

WST-20-0484
138 -26 160 453359 5435209 154 3625

WST-20-0485
148 -44 181 453359 5435209 154 3625

WST-20-0486
130 -37 162 453359 5435209 154 3625


Lynx Zone


Mineralization occurs as grey to translucent quartz-carbonate-pyrite-tourmaline veins and pyrite replacement zones and stockworks. The vein-type 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.


Triple Lynx


Mineralization in the Triple Lynx zone is vein-type, quartz-carbonate-pyrite-tourmaline veins, associated with pervasive sericite-pyrite ± silica alteration and contain sulphides similar to the main Lynx Zone, pyrite dominated with minor other sulphides, ranging from trace to up to 70% locally, and local visible gold. Locally fuchsite is present when proximal to the gabbros. Mineralization is hosted in or at the contacts of felsic porphyritic dikes with rhyolites (locally bleached) or gabbros.


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. 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 (


i


) ALS Laboratories in Val d’Or, Québec, Thunder Bay, Ontario, Sudbury, Ontario or Vancouver, British


Colombia, or (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 acids digestion





MS61


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 i


n


Eeyou Istchee James Bay


,


Québec, Canada. The mineral resource defined by Osisko, as disclosed in


the


news release


dated February 19, 2020


and supported by


the technical report entitled “An updated mineral resource estimate for the Windfall Lake Project, Located in the Abitibi Greenstone Belt, Urban Township, Eeyou Istchee James Bay, Québec, Canada” and dated April 3, 2020 (with an effective date of January 3, 2020)


,


and assuming a cut-off grade of 3.5 g/t, comprises 4,127,000 tonnes at 9.1 g/t Au (1,20


6


,000 ounces) in the indicated mineral resource category and 14,532,000 tonnes at 8.40 g/t Au (3,93


8


,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 19,2020 news


release


are


further described in the full technical report


prepared by Micon International Limited (“Micon”) and BBA Inc (“BBA”)


,


in accordance with NI 43-101


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


deformed


sub-vertical


zones


plunging to the northeast


.


V


ein-type or pyrite replacement-type styles of mineralization


crosscut


syn





volcanic


host rocks and syn-deformation


felsic porphyry intrusions


and are spatially associated with


the contacts of the


intrusi


ons.


The


deposit


is


well


defined


from


surface


to


a


depth


of


1,200


metres


and


remains


open along


strike


and


at


depth.


Mineralization


has


been


identified


30


metres


from


surface


in


some


areas


and


as


deep


as


2,000


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 precious metal 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; the prospects, if any, of the Windfall gold deposit; the timing and ability of Osisko, if at all, to publish a feasibility study for the Windfall gold deposit; the projected capital expenditures of mining activities at the Windfall gold deposit; upgrading a


n


inferred mineral resource to a measured mineral resource or indicated mineral resource category; future drilling at the Windfall gold deposit; the deposit remaining open along strike to the northeast and at depth; significant high-grade zones (Lynx 4, Triple Lynx) remaining open down plunge; the plunge potential of the Lynx and Underdog zones; 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 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


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