Osisko Windfall Infill Drilling: Insert Superlative Here

NOT FOR DISTRIBUTION TO U.S. NEWS WIRE SERVICES




OR FOR DISSEMINATION IN THE UNITED STATES

TORONTO, Jan. 26, 2021 (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 continues with more good results with respect to grade and width, particularly in the Lynx zones. Both underground and surface drills continue to infill our resources and explore open down plunge areas.”

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 63 intercepts in 38 drill holes and 7 wedges.

Selected high-grade intercepts from the new results include:

108 g/t Au over 10.5 metres

in OSK-W-20-2256-W7;

21.7 g/t Au over 11.3 metres

in OSK-W-20-2271-W3;

76.7 g/t Au over 3.0 metres

in OSK-W-20-2377;

30.9 g/t Au over 4.5 metres

in OSK-W-20-2292-W4;

35.1 g/ t Au over 2.8 metres

in OSK-W-20-2325; and

36.5 g/t Au over 2.1 metres

in OSK-W-20-2283-W3. Maps showing hole locations and full analytical results are available at

www.osiskomining.com

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

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 occurs as quartz-carbonate-pyrite-tourmaline vein-type 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.

Zone 27


Mineralization is typically characterized by 5% to 50% disseminated, stringer, semi-massive or stockwork pyrite, ptygmatic tourmaline veins, quartz-tourmaline crustiform veins, and local quartz-carbonate veins. Local visible gold is observed as small specks or clusters with quartz veins. Alteration consists of moderate to strong sericite, weak to strong silica, weak chlorite and carbonate and locally weak fuchsite. Mineralization is hosted in strongly altered andesites or in or at the contact of the rhyolite.

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.

F-Zone


Mineralization is hosted in sheared andesites with carbonate replacement or quartz veining and occurs as quartz ± ankerite veinlets or in shear zones as replacement, characterised by trace to 10% pyrite with local visible gold. Alteration is dominated by sericite-fuchsite-tourmaline-pyrite.

Mallard


Mineralization is hosted in sheared mafic volcanics with felsic porphyritic intrusions and occurs as veins associated with sericite-pyrite ± silica ± chlorite alteration and contains pyrite ranging from trace to 30% and local visible gold.

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. Local visible gold is associated with carbonate ± silica ± chlorite alteration. Mineralization is hosted in sheared mafic volcanics, rhyolites near faults, or at the contact with felsic porphyritic intrusions.

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 in 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 (1,206,000 ounces) in the indicated mineral resource category and 14,532,000 tonnes at 8.40 g/t Au (3,938,000 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. Vein-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


intrusions.


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 an 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