Osisko Development Intercepts 57.29 g/t Gold Over 3.05 Meters, 625.95 g/t Gold Over 0.5 Meters and 15.26 g/t Gold Over 4.4 Meters in Lowhee Infill Drilling at Cariboo Gold Project

Executive Summary

• Osisko Development released assay results from ≈ 6,471 m of underground infill diamond drilling and ≈ 398 m of chip/rock‑saw channel sampling in the Lowhee Zone.
• Multiple high‑grade intercepts were identified, including a spectacular 625.95 g/t Au over 0.5 m (hole BMU‑25‑040) and several >50 g/t Au intervals across numerous holes.
• The company announced that a 13,000‑m systematic infill drill program is already underway to further define mineral reserves, inferred resources and potential extensions at depth.

Key Details

• Assay Highlights – Diamond Drill (68 holes):
• BMU‑25‑040: 625.95 g/t Au over 0.5 m.
• BMU‑25‑032: 57.29 g/t Au over 3.05 m (including 238.20 g/t Au over 0.5 m).
• BMU‑25‑004: 15.26 g/t Au over 4.4 m (including 83.40 g/t Au over 0.5 m).
• BMU‑25‑025: 55.96 g/t Au over 0.8 m; 29.45 g/t Au over 0.55 m.
• BMU‑25‑034: 55.74 g/t Au over 1.0 m (including 57.15 g/t Au and 54.34 g/t Au over 0.5 m).
• BMU‑25‑014: 8.37 g/t Au over 5.9 m (including 50.24 g/t Au over 0.5 m).
• BMU‑25‑026: 7.06 g/t Au over 6.4 m (including 75.61 g/t Au over 0.5 m).
• BMU‑25‑017: 12.44 g/t Au over 3.45 m (including 79.17 g/t Au over 0.5 m).
• BMU‑25‑019: 7.23 g/t Au over 5.75 m (including 61.18 g/t Au over 0.5 m).

• BMU‑25‑045: 28.55 g/t Au over 1.45 m (including 80.20 g/t Au over 0.5 m).

• Assay Highlights – Underground Chip/Channel Sampling (89 samples):

• UGCH00189: 22.01 g/t Au over 3.8 m (including 104.37 g/t Au over 0.8 m).
• UGCH00183: 12.23 g/t Au over 4.6 m (including 69.95 g/t Au over 0.8 m).
• UGCH00176: 3.61 g/t Au over 0.5 m (including 22.20 g/t Au over 0.7 m).

• UGCH00192: 3.30 g/t Au over 4.5 m (including 14.59 g/t Au over 1.0 m).

• Program Summary:

• Total of 68 underground DD holes (≈ 6,471 m) drilled Nov 2024 – Aug 2025; assays received through 16 Aug 2025.
• 14 NQ (47.6‑mm) holes (42–48 m depth) infilling a 25 m ore‑drive section.
• 4 deeper NQ holes (~290 m) exploring adjacent zones.
• 22 NQ holes (≈ 90 m) systematic grid infill of reserve and inferred blocks.

• 8 NQ holes (≈ 118 m) infilling existing reserves/resources.

• Next Steps:

• Ongoing 13,000‑m systematic grid infill program targeting mineral reserve blocks, inferred resources and non‑DSO resources across a ~100 m swath of the Lowhee Zone at 10 m spacing from the 1,260 m elevation development level.
• Data will feed resource modeling, mine planning, stope design and future infill drill spacing decisions.
• Structural modelling indicates the sandstone host remains open well beyond current depths, suggesting potential for deeper extensions of reserves/resources.

Notable Quotes

• Chris Lodder, President: “We’re highly encouraged that underground exploration drilling…continues to indicate that veins remain open at depth, highlighting the strong potential for future resource expansion through additional exploration programs leveraging existing underground infrastructure.”