Mr. John Burzynski reports

OSISKO LYNX BULK SAMPLE RETURNS 17.8 G/T AU RECONCILED HEAD GRADE

Osisko Mining Inc. has provided new results from the continuing exploration program at its 100-per-cent-owned Windfall Lake gold project located in the Abitibi greenstone belt, Urban township, Eeyou Istchee James Bay, Quebec. Results from processing 5,716 tonnes mined from Lynx have exceeded expectations, returning an average grade of 17.8 grams per tonne (g/t) gold (Au). The bulk sample average grade is 89 per cent higher than the 9.40 g/t Au predicted by infill drilling on the Lynx zone 311 resource block model wireframe. Mining of the bulk sample successfully confirmed the presence of mineralization predicted in the resource model and the analytical results have confirmed the visual mineralization encountered along the stope. Highlights and full results are presented in the attached tables.

Highlights:

• Average grade of 17.8 g/t Au for the bulk sample is 89 per cent higher than predicted in the 12.5-metre infill drilling block model;
• Higher-than-anticipated average Au recovery of 97.2 per cent achieved;
• 66.7 per cent of the gold was recovered in the gravity concentrate;
• The sample contained 3,271 ounces Au and 2,176 ounces of silver (Ag).

President and chief executive officer John Burzynski commented: "We are highly encouraged with the excellent results from this second bulk sample completed from the Windfall deposit. The average grade greatly exceeded our expectations based on the infill drilling, returning 89 per cent higher grade than anticipated. The significant grade increase from the block model appears to correspond well with the very regular visible gold observed in Lynx drilling. The bulk sampling work is greatly helping to build our confidence in the continuity, grade, recoveries and the predictability of the mineralized zones at Windfall."

Geology

The Lynx zone 311 bulk sample is characterized by an east-northeast subvertical silica altered corridor with an average width of approximately 2.5 metres. Banded grey quartz veins contain 3 per cent to 15 per cent disseminated pyrite and local visible gold, crosscutting foliated rhyolite and granodiorite with strong sericite and local fuchsite alteration. The continuous vein system was mapped along sills over three levels.

Processing

A total of 5,716 tonnes were processed in November, 2019. The bulk sample test was performed at the Northern Sun Redstone concentrator. Processing produced gravity and flotation concentrates. Ore transportation trucks were sampled for moisture and weighed on a calibrated weight scale. The sample material was crushed and milled to a particle size favourable to the flotation recovery process. Gravity and flotation concentrates produced will be sent to a local smelter for sale. Day and night shift daily composite samples of streams for the reconciliation process were prepared and analyzed by an external independent lab. Concentrate production tonnage and assays were used to reconcile the bulk sample mass balance process in the concentrator. The reconciliation was performed by an external independent consultant using Bilmat (a reconciliation software) on a dry-tonne basis.

The reconciled head grade obtained from the processed sample is 17.8 g/t Au and 11.8 g/t Ag. The sample contained 3,271 oz Au and 2,176 oz Ag, with a total of 3,181 oz Au and 2,052 oz Ag recovered. Reconciled recoveries are 97.2 per cent for gold and 94.3 per cent for silver. The preliminary economic assessment (PEA) metallurgical testwork considered a communition, gravity and carbon-in-leach process flowsheet, giving an average recovery of 93.8 per cent for Lynx zone. Test mill availability dictated the use of a mill with a communition, gravity and flotation flowsheet. The reconciled results from the processing of the bulk sample material are presented in one of the attached tables.

                                     LYNX BULK SAMPLE RECONCILED RESULTS

Tonnes           Head     Contained            Gravity            Flotation              Overall      Recovered
(dry)           grade        ounces        concentrate          concentrate             recovery         ounces
         Au        Ag     Au     Ag   Tonnes    Au rec.     Tonnes   Au rec.   Au rec.    Ag rec.     Au     Ag
       (g/t)     (g/t)                              (%)       (dry)      (%)       (%)        (%)  

5,716	 17.8	     11.8	 3,271 	2,176	     9.7	     66.7      	284.4	    91.7	     97.2	      94.3	  3,181	 2,052

Mill feed tonnages used in the sample processing reconciliation were provided by Northern Sun. Day and night shift daily composite samples collected during the processing of the bulk sample were assayed by external independent laboratories. Bulk sample results were reconciled by Soutex Inc., an external independent consultant using Bilmat.

Block model

The area mined was located in mineralization wireframe 311 from the Windfall Lynx updated resources block model. The area was prepared for mining with infill drilling at 12.5-metre spacing. The same parameters used in the November, 2018, mineral resource estimation (see Osisko news release dated Nov. 28, 2018) were used for an internal update of the resource block model in the bulk sample area. The infill drilling block model predicted 5,717 tonnes at 9.40 g/t Au, containing 1,736 ounces of gold inside the excavated area.

        INFILL RESOURCE BLOCK MODEL PREDICTIONS VERSUS ACTUAL PROCESSED
 
            Predicted from block model                   Actual processed material
            (12.5-metre infill spacing)
Tonnes         Au (g/t)      Au ounces        Tonnes       Au (g/t)      Au ounces 

5,717             9.40           1,736         5,716          17.8           3,271   

Concentrates

Both the gravity concentrate and flotation concentrate produced from the sample are considered high grade. The gravity concentrate averaged 7,020 g/t Au (225.7 ounces per ton (oz/t) Au), while the flotation concentrate averaged 110.6 g/t Au (3.6 oz/t Au), or, respectively, $381,464 per tonne and $6,010 per tonne. Further work will be conducted on the process flowsheet prior to feasibility in light of these high-value numbers.

Mining and grade control

The Lynx bulk sample was mined in wireframe 311 with the long-hole mining method proposed in the PEA. Two development drifts were mined conventionally at 20-metre vertical intervals between 210 and 230 metres below surface. A third development drift was mined 20 metres above the stope at 190 metres below surface to confirm grade and continuity of the Lynx 311 wireframe. While mining the development drifts, split blasts of the face were completed to test the width and grade of the mineralization. A V30 borehole was used in the slot raise and 2.5-inch production holes were drilled down and blasted. The blasted ore was retrieved with remote scoop tram equipment and trucked to the mill with muck samples taken.

Qualified person

The scientific and technical content of this news release has been reviewed, prepared and approved by Kim-Quyen Nguyen, master of business administration, professional engineer (OIQ 146014), project manager of Windfall gold project technical studies, who is a qualified person as defined by National Instrument 43-101 (Standards of Disclosure for Mineral Projects). The infill block model in the bulk sample area from the Lynx 311 zone of the Windfall Lake deposit, with an effective date of June 10, 2019, was prepared by Judith St-Laurent, professional geoscientist (OGQ No. 1023), bachelor of science, of Osisko Mining, who is a qualified person within the meaning of NI 43-101. The scientific and technical content in this press release has been reviewed and approved by Mathieu Savard, professional geoscientist (OGQ No. 510), senior vice-president exploration of Osisko Mining, who is a qualified person within the meaning of NI 43-101.

Technical info, quality control and reporting protocols

Process reconciliation was performed using Bilmat software and validated by Soutex Inc., an external consultant. Day and night shift daily and global reconciliations were performed. Day and night shift daily mill throughput was estimated using the load cell on the Redstone primary ball mill feed conveyor. Day and night shift daily composite samples were taken on streams required for reconciliation. Global mill throughput was estimated based on the Redstone mill truck scale which is calibrated once per year. Global flotation concentrate was weighed on the same truck scale and samples were taken from each bucket used to load the concentrate trucks. Global gravity concentrate was weighed on a scale and each bag was drill sampled. All samples were sent out to an external independant lab for preparation and assaying. They were all assayed for gold, silver, iron, sulphur and moisture. Gold assay from all streams was obtained by screened metallics fire assay.

About the Windfall Lake gold deposit

The Windfall gold deposit is located between Val d'Or and Chibougamau in the Abitibi region of Quebec, Canada. The mineral resource defined by Osisko, as disclosed in the Windfall Lake technical report and Nov. 27, 2018, Lynx resource update, comprises 2,874,000 tonnes at 8.17 g/t Au (754,000 ounces) in the indicated mineral resource category and 10,352,000 tonnes at 7.11 g/t Au (2,366,000 ounces) in the inferred mineral resource category.

The Windfall Lake gold deposit is currently one of the highest-grade resource-stage gold projects in Canada. Mineralization occurs in four principal zones: Lynx, Zone 27, Caribou and Underdog. All zones comprise subvertical lenses following intrusive porphyry contacts plunging to the northeast. The deposit is well defined from surface to a depth of 900 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 downplunge 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-per-cent interest in the high-grade Windfall gold deposit located between Val d'Or and Chibougamau in Quebec and holds a 100-per-cent undivided interest in a large area of claims in the surrounding the Urban Barry area and nearby Quevillon area (over 2,700 square kilometres).

We seek Safe Harbor.