Osisko Infill and Expansion Drilling Hits More High-Grade

Toronto, Ontario, CANADA


124 g/t Au Over 2.7 Metres in Triple Lynx

78.7 g/t Au over 2.0 metres in Lynx SW

TORONTO, May 04, 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 52 intercepts in 35 drill holes (9 from surface, 15 from underground) and 11 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 located in a defined zone or corridor but do not yet correlate to a specific wireframe.

Osisko Chief Executive Officer John Burzynski commented: “Today’s highlighted intercepts in the Lynx and Triple Lynx zones, as seen on the accompanying long sections available on our website, demonstrate the continued distribution of high-grade intersected throughout these areas in both infill and expansion drilling.”

Selected high-grade intercepts include: 124 g/t Au over 2.7 metres in WST-21-0729; 78.7 g/t Au over 2.0 metres and 39.3 g/t Au over 2.2 metres in WST-21-0703, 34.6 g/t Au over 3.6 metres in OSK-W-21-2465, 41.6 g/t Au over 2.9 metres in WST-21-0696, 41.9 g/t Au over 2.1 metres in WST-21-0652, 31.5 g/t Au over 2.4 metres in OSK-W-21-2472 and 37.1 g/t Au over 2.0 metres in WST-21-0749. 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) uncutAu (g/t)        cut to 100 g/tZoneCorridor
OSK-W-20-2252-W11851.0853.02.03.99 TLX_3189Triple Lynx
OSK-W-20-2283-W2789.6791.82.24.14 TLX_3171
Triple Lynx
including790.9791.20.318.5 
OSK-W-21-2394-W4643.2646.23.09.31 TLX_3171
Triple Lynx
including643.2643.60.418.8 
OSK-W-21-2394-W6674.6676.72.110.7 TLX_3171
Triple Lynx
including675.1676.00.921.7 
 694.0696.02.04.57 TLX_3184Triple Lynx
OSK-W-21-2436-W3805.0807.02.021.420.4LX4_3437
Lynx 4
including806.6807.00.4105100
OSK-W-21-2445-W3601.6605.13.53.68 TLX_3171Triple Lynx
OSK-W-21-2470976.0978.02.04.62 TLX_3163Triple Lynx
OSK-W-21-2478887.0889.22.28.94 TLX_3184
Triple Lynx
including887.8888.20.444.7 
OSK-W-21-2492775.0777.52.517.2 LX4_3414
Lynx 4
including776.9777.50.642.9 
 783.9786.22.322.420.9LX4_3414
Lynx 4
including784.8785.20.4109100
OSK-W-21-2495659.0661.02.03.65 LXM_3304
Lynx
including659.4659.70.320.9 
WST-21-0652336.0338.12.141.922.1LXSW_3556
Lynx
including337.7338.10.4204100
WST-21-0658185.0187.12.115.7 TLX_3161
Triple Lynx
including185.0185.60.651.3 
WST-21-0671A171.0173.02.025.0 LXM_3304
Lynx
including171.0172.01.043.6 
WST-21-0675159.2161.42.214.2 LXM_3304
Lynx
including159.2159.90.739.4 
WST-21-0676152.7155.12.43.93 LXM_3304
Lynx
including152.7153.30.610.4 
WST-21-0677399.0401.02.08.52 TLX_3165Triple Lynx
 409.5411.52.011.4 TLX_3165
Triple Lynx
including410.5411.00.528.8 
WST-21-0692334.2336.42.25.34 TLX_3131Triple Lynx
WST-21-0698138.3140.32.010.3 LXM_3334Lynx
WST-21-0703252.0256.24.211.6 LXSW_3506
Lynx
including255.1255.50.466.5 
 463.7465.92.239.328.1LXSW_3502
Lynx
including464.7465.30.6141100
WST-21-0729304.9307.62.712423.5TLX_3166
Triple Lynx
including305.9306.30.4780100
WST-21-0739128.2130.22.023.5 LXM_3304
Lynx
including129.0129.70.763.8 
WST-21-0749144.9146.92.037.1 LXM_3304Lynx

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) uncutAu (g/t)        cut to 100 g/tZoneCorridor
OSK-W-21-2394-W6914.0916.02.05.70 TLX_3195
Triple Lynx
including914.8915.20.427.2 
OSK-W-21-2436-W2614.2617.02.87.16 Lynx 4Lynx
OSK-W-21-2445-W1878.0880.02.04.68 Triple LynxTriple Lynx
OSK-W-21-2445-W2618.2620.62.44.22 Triple LynxTriple Lynx
OSK-W-21-2445-W4918.5920.52.016.9 Triple Lynx
Triple Lynx
including918.5919.51.032.0 
OSK-W-21-2465919.0921.02.08.88 Lynx 4Lynx
 951.4955.03.634.6 Lynx 4
Lynx
including952.0954.02.054.3 
OSK-W-21-2465962.5964.62.112.4 Lynx 4Lynx
OSK-W-21-24701020.91023.02.16.37 Triple Lynx
Triple Lynx
including1021.81022.10.339.1 
 1178.01180.12.15.63 Triple Lynx
Triple Lynx
including1179.21180.10.912.9 
OSK-W-21-2470-W1963.0968.05.010.8 Triple Lynx
Triple Lynx
including963.0964.01.041.4 
 987.0989.02.027.727.6Triple Lynx
Triple Lynx
including987.3987.70.4101100
OSK-W-21-2472731.8734.22.431.5 LX4_3437
Lynx 4
including733.4734.20.878.3 
 781.1783.92.811.2 Lynx 4
Lynx
including783.1783.90.831.8 
OSK-W-21-2473625.6630.04.410.0 Lynx
Lynx
including625.6626.20.649.1 
OSK-W-21-24781117.01119.02.07.22 Triple LynxTriple Lynx
OSK-W-21-2482782.0784.02.011.7 Triple Lynx
Triple Lynx
including782.0782.90.926.0 
OSK-W-21-24891005.01007.02.08.26 Triple LynxTriple Lynx
WST-21-0652216.0218.02.04.15 Lynx SWLynx SW
 448.0450.02.04.35 Lynx SW
Lynx SW
including448.7449.20.515.6 
WST-21-0657442.3444.32.04.26 Triple LynxTriple Lynx
WST-21-0696370.7373.62.941.636.7Triple Lynx
Triple Lynx
including371.8372.70.9116100
 464.0466.02.05.62 Lynx 4Lynx
WST-21-070343.245.22.078.737.1Lynx SW
Lynx SW
including43.544.20.7219100
WST-21-0706314.5316.92.414.1 Lynx SW
Lynx SW
including315.3315.90.654.1 
WST-21-0729174.3177.63.38.95 LynxLynx

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

Drill hole location

Hole NumberAzimuth (°)Dip (°)Length (m)UTM EUTM NElevationSection
OSK-W-20-2252-W11129-54119145324154356944153750
OSK-W-20-2283-W2135-50101145299754356074253500
OSK-W-21-2394-W4138-5292045292354354674143375
OSK-W-21-2394-W6138-5297845292354354674143375
OSK-W-21-2436-W2130-5778945370954356184004125
OSK-W-21-2436-W3130-5787945370954356184004125
OSK-W-21-2445-W1141-5090945290654354334153325
OSK-W-21-2445-W2141-5082245290654354334153325
OSK-W-21-2445-W3141-5075345290654354334153325
OSK-W-21-2445-W4141-5094445290654354334153325
OSK-W-21-2465123-61125345339754355574133825
OSK-W-21-2470132-59123045330454356394153775
OSK-W-21-2470-W1132-59122745330454356394153775
OSK-W-21-247212-7290045413554350583974225
OSK-W-21-2473123-56127245342054356104133875
OSK-W-21-2478128-54125745299754356074253500
OSK-W-21-2482131-5793945300954353874133400
OSK-W-21-2489133-54114045312154355094193550
OSK-W-21-2492122-5387045368754356764014125
OSK-W-21-2495123-54125745342654355654103850
WST-21-0652128-6048145295554350032533175
WST-21-0657141-564484533575435272163650
WST-21-0658137-492554533575435272163650
WST-21-0671A142-513724535075435327-73800
WST-21-0675133-403364535085435327-73800
WST-21-0676129-323184535085435327-73800
WST-21-0677144-426524532575435209963525
WST-21-0692157-545414533565435272163650
WST-21-0696137-4949245322954351271343475
WST-21-0698167-401604533565435272163650
WST-21-0703146-6048945310454350652313325
WST-21-0706165-5441745310454350652313325
WST-21-0729132-4951045322954351271353475
WST-21-0739164-371954535075435326-73800
WST-21-0749136-301964533575435272163650

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 3.0 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 (416) 363-8653