Osisko Development Corp. announced drilling and underground chip sampling results from new development areas as part of its ongoing exploration program at its 100%-owned Trixie test mine (Trixie), within the company's wider Tintic Project, located in the historic East Tintic Mining District in central Utah, U.S.A. Underground Chip Sample Assay Highlights: Assay highlights include underground chip samples from 114 new development faces at Trixie. A length-weighted composite for each face Site ID is presented in Table 1 and individual higher-grade samples are also identified within the composites.

Samples are collected in feet ("ft.") and assays are reported in grams per tonne ("g/t") and troy ounce per short ton ("oz/t") gold ("Au") and silver ("Ag"). Conversions to metric and imperial measurements are rounded to two decimal places. Selected assay highlights include: 503.78 g/t Au and 2,586.22 g/t Ag over 3.35 meters ("m") (14.69 oz/t Au and 75.43 oz/t Ag over 11.00 ft.) including 1,375.03 g/t Au and 6,994.86 g/t Ag over 1.22 m (40.11 oz/t Au and 204.02 oz/t Ag over 4.00 ft.); 1,237.85 g/t Au and 95.44 g/t Ag over 0.98 m (36.10 oz/t Au and 2.78 oz/t Ag over 3.20 ft.) including 2,637.71 g/t Au and 185.16 g/t Ag over 0.46 m (76.93 oz/t Au and 5.40 oz/t Ag over 1.50 ft.); 1,700.62 g/t Au and 131.19 g/t Ag over 0.76 m (49.60 oz/t Au and 3.83 oz/t Ag over 2.50 ft.) including 3,539.06 g/t Au and 265.43 g/t Ag over 0.37 m (103.22 oz/t Au and 7.74 oz/t Ag over 1.20 ft.); 3,901.32 g/t Au and 78.71 g/t Ag over 0.91 m (113.79 oz/t Au and 2.30 oz/t Ag over 3.00 ft.) including 7,765.62 g/t Au and 124.89 g/t Ag over 0.46 m (226.50 oz/t Au and 3.64 oz/t Ag over 1.50 ft.); 1,468.70 g/t Au and 280.94 g/t Ag over 0.61 m (42.84 oz/t Au and 8.19 oz/t Ag over 2.00 ft.); 352.65 g/t Au and 446.22 g/t Ag over 4.57 m (10.29 oz/t Au and 13.01 oz/t Ag over 15.00 ft.); 335.08 g/t Au and 333.77 g/t Ag over 3.66 m (9.77 oz/t Au and 9.74 oz/t Ag over 12.00 ft.); 1,042.03 g/t Au and 498.82 g/t Ag over 2.87 m (30.39 oz/t Au and 14.55 oz/t Ag over 9.40 ft.) including 3,419.93 g/t Au and 1,587.57 g/t Ag over 0.82 m (99.75 oz/t Au and 46.30 oz/t Ag over 2.70 ft.); 531.46 g/t Au and 648.34 g/t Ag over 2.59 m (15.50 oz/t Au and 18.91 oz/t Ag over 8.50 ft.) including 1,888.17 g/t Au and 2,942.92 g/t Ag over 0.46 m (55.07 oz/t Au and 85.84 oz/t Ag over 1.50 ft.); 473.14 g/t Au and 1,371.28 g/t Ag over 2.90 m (13.80 oz/t Au and 40.00 oz/t Ag over 9.50 ft.) including 1,753.17 g/t Au and 5,095.23 g/t Ag over 0.76 m (51.13 oz/t Au and 148.61 oz/t Ag over 2.50 ft.); 288.82 g/t Au and 249.84 g/t Ag over 6.10 m (8.42 oz/t Au and 7.29 oz/t Ag over 20.00 ft.); 1,470.35 g/t Au and 1,222.90 g/t Ag over 0.61 m (42.89 oz/t Au and 35.67 oz/t Ag over 2.00 ft.); 697.81 g/t Au and 731.43 g/t Ag over 2.74 m (20.35 oz/t Au and 21.33 oz/t Ag over 9.00 ft.) including 1,721.84 g/t Au and 1,816.49 g/t Ag over 0.91 m (50.22 oz/t Au and 52.98 oz/t Ag over 3.00 ft.); 2,311.18 g/t Au and 1,146.46 g/t Ag over 2.29 m (67.41 oz/t Au and 33.44 oz/t Ag over 7.50 ft.) including 5,524.28 g/t Au and 2,673.83 g/t Ag over 0.91 m (161.12 oz/t Au and 77.99 oz/t Ag over 3.00 ft.); 557.17 g/t Au and 370.45 g/t Ag over 2.68 m (16.25 oz/t Au and 10.80 oz/t Ag over 8.80 ft.) including 1,865.07 g/t Au and 1,366.68 g/t Ag over 0.61 m (54.40 oz/t Au and 39.86 oz/t Ag over 2.00 ft.); 1,633.69 g/t Au and 1615.74 g/t Ag over 2.13 m (47.65 oz/t Au and 47.13 oz/t Ag over 7.00 ft.) including 5,012.31 g/t Au and 3,441.76 g/t Ag over 0.61 m (146.19 oz/t Au and 100.38 oz/t Ag over 2.00 ft.) Drill Assay Highlights: In 2022, the company completed 28 surface reverse circulation ("RC") drill holes near Trixie totaling approximately 8,442 m (27,700 ft.) and 62 underground diamond drill holes ("DD") in the 625 level at Trixie totaling approximately 3,232 m (10,060 ft.).

To date, assays have been received for 8 RC drill holes and 14 DD holes, which are summarized in Table. The Company currently has two underground diamond drill rigs in operation at Trixie and has greatly improved on core recovery and drill production challenges faced early in the 2022 program. Select assay highlights include: 25.95 g/t Au and 21.48 g/t Ag over 3.81 m in hole TUG-625-029 (0.76 oz/t Au and 0.63 oz/t Ag over 12.50 ft.) including 43.00 g/t Au and 41.80 g/t Ag over 1.52 m (1.25 oz/t Au and 1.22 oz/t Ag over 5.00 ft.) located 15 m (49 ft.) up dip in the T2 structure; 14.97 g/t Au and 113.85 g/t Ag over 2.47 m in hole TUG-625-050 (0.44 oz/t Au and 3.32 oz/t Ag over 8.10 ft.) including 25.50 g/t Au and 90.00 g/t Ag over 1.07 m (0.74 oz/t Au and 2.63 oz/t Ag over 3.50 ft.) located at the contact of the Tintic quartzite and the Ophir shale; 12.58 g/t Au and 439.26 g/t Ag over 5.33 m in hole TUG-625-060 (0.37 oz/t Au and 12.81 oz/t Ag over 17.50 ft.) within the T4 mineralized zone; 264.00 g/t Au and 511.00 g/t Ag over 1.22 m in hole TUG-625-065 (7.70 oz/t Au and 14.90 oz/t Ag over 4.00 ft.) 55 m (180 ft.) down dip of the 625 L in the T2 structure; 65.50 g/t Au and 84.30 g/t Ag over 1.22 m in hole TUG-625-069 (1.91 oz/t Au and 2.46 oz/t Ag over 4.00 ft.) including 231.00 g/t Au and 246.00 g/t Ag over 0.30 m (6.74 oz/t Au and 7.18 oz/t Ag over 1.00 ft.) 38 m (125 ft.) down dip of the 625 L in the T2 structure.