Osisko Windfall Infill Drilling: Very Good

TORONTO, Dec. 01, 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.

Infill drilling at Lynx has returned the highest-grade result at Windfall to date of

13


,


634 g/t Au over 2.0 metr


e


s


including



90,700 g/t Au over 0.3 metres


in hole WST-20-0543. This infill hole from the definition program is located 70 metres down plunge from WST-20-0310 (

376 g/t Au over 2.0 metres


,


see Osisko news release dated June 23, 2020

) and confirms the continuity of the Lynx 323 wireframe.

Osisko Chief Executive Officer John Burzynski commented: “Today’s spectacular result, certainly one the highest gold grades in terms of metal factor (grade x width) ever reported, continues to demonstrate the exceptional high-grade characteristics of Lynx. Our infill drilling program continues to show the strength of our deposit, and is confirming both the continuity and high-grade nature of Windfall. We encourage people to go to our social media page or website and view some of the recent photos of the spectacular visible gold in this sample and other recent drill core coming from the ongoing work at Windfall.”

Drill hole location

WST-20-0543

intersected

13


,


634 g/t Au over 2.0 metres

. Mineralization consists of up to 15% local visible gold and up to 5% disseminated pyrite hosted in an intensely silica flooded, sericitized, and strongly fuchsite altered gabbro.

Lynx Zone


Mineralization typically 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 occasional 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. 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


,


present a higher percentage of pyrite than surrounding intervals


or any samples exceeding 10 g/t Au.


A 1-kilogram split is passed through a 75-um stainless steel screen to separate the oversize fraction. Any +75-


μ


m material remaining on the screen is retained and analyzed in its entirety by fire assay with gravimetric finish and reported as the Au (+) fraction results. The 75μm fraction is homogenized and two 50


–


g


ram


sub-samples are analyzed by fire assay with Atomic a


b


sorption finish. The average of the two atomic a


b


sorption finish is taken and reported as the Au (-) fraction result. As of August 7, 2019, the -75μm fractions have been analyzed using gravimetric finish. All three values are used in calculating the combined gold content of the plus and minus fractions.


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. 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 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