Osisko Development Corp. Announces Positive Results from an Ore Sorting Testing Program Conducted on A Bulk Tonnage Sample of Mineralized Material Extracted from its Permitted, 100%-Owned Cariboo Gold Project, Located in Central British Columbia, Canada

Published: 2025-07-07 09:36:40 ET ODV.V

Published on 07/07/2025 at 09:36

Osisko Development announced positive results for the Cariboo Gold Project. X-ray transmission (XRT) ore sorter testwork of a ~80 tonne sample taken from the Cariboo underground achieved positive results consistent with 2025 FS parameters. 42-55% waste rejection with 84-89% gold recovery achieved by sorting mid-size and oversize sample material including 10-30 mm and 30-70 mm size fractions, respectively.

Encouraging results from testing the previously unassessed 6-10 mm size fraction, made possible by recent advancements in AI, demonstrated 59% waste rejection and 95% gold recovery, highlighting a potential opportunity for future optimization. 2.0-2.1 upgrade ratio consistent with 2025 FS assumption of 1.95. New testwork represents a significantly larger data set, with previous sorting totaling ~5 tonnes and completed largely on material sourced from drill core.

76% of the contained gold in the test sample estimated to report to the fines fraction (50% of area is sulphide), high sulphide (greater than 20% area), medium sulphide (between 10% and 20% area), and low sulphide (between 5% and 10% area). The first pass targeted the most x-ray responsive material, yielding the highest gold grade, but with lower overall recovery. Opportunities & Next Steps.

Testing on a subsample of the fines material consisting of 8 tonnes of the 6-10 mm size fraction. Testing on a subsample the fines material consisting of 8 tons of the 6-10 mm length, enabled by recent advancements in AI software, showed promising results including 95% gold recovery with a 41% mass pull. This size fraction was previously untested for ore sorting and may represent a material opportunity for future flowsheet optimization.