Intercepts From Underground Drilling At The Trixie, Tintic Project

MONTREAL - Osisko Development Corp. reported on underground infill and exploration diamond drilling (DD) for the ongoing 2023 exploration program at the Trixie test mine, within the wider Tintic Project, located in the historic East Tintic Mining District in central Utah.

Chris Lodder, President, said, "We are excited to announce the results of the most-recent phase of our Trixie exploration program, highlighting areas outside of our initial resource area, and the start of our porphyry drilling campaign with an initial hole from underground at Trixie. Based on our surface and underground geological and geochemical compilation, we have identified this as a high priority target as a potential magmatic source to known high-grade gold and silver epithermal systems and the surrounding anomalous copper in structures and hydrothermally altered host rocks. This target is one of several porphyry targets we will be testing in the coming year, with the target being a non-outcropping Bingham style porphyry copper-gold system."

In 2023, the Company has drilled 72 holes for a total of 6,125 m (20,095 ft.) at Trixie. To date, assays have been received for 51 DD holes, with assays pending for the remaining holes. This portion of the 2023 exploration drill program is now complete. Approximately 25% of the drilling to date consists of delineation of domains within the area of the current Trixie MRE (as defined herein) and 75% is exploration drilling adjacent to the area of the Trixie MRE, including step outs down dip, down plunge and along strike testing for mineralized structures. The focus of these recent holes was to test for mineralization along one of the priority target areas south on strike from the known T2 domain, towards the Sioux Ajax fault. A highlight from this area includes 54.95 g/t Au and 1,143.21 g/t Ag over 2.59 m in hole TRXU-DD-23-045 (1.60 oz/t Au and 33.34 oz/t Ag over 8.50 ft.). A down dip highlight in the T1 domain includes 7.66 g/t Au and 4.00 g/t Ag over 7.32 m in TRXU-DD-23-035 (0.22 oz/t Au and 0.12 oz/t Ag over 24.00 ft.). This intercept is approximately 25 m (75 ft.) from the known Trixie MRE deposit boundary.

The 75-85 domain consists of a discrete, north-south striking, moderate to steeply west-dipping structure in the footwall of the T4domain that was historically mined prior to the discovery of the T2 domain. See Figure 3 for domain geometry and relationships. The T1 domain consists of Tintic quartzite-hosted disseminated mineralization interpreted as a halo to the T2 domain. These drilling results will provide valuable infill data to improve our understanding and the confidence level of the mineralized zones defined in the area of the Trixie MRE and to support a an updated mineral resource estimate ("MRE") in the future. The exploration results will assist with understanding the extent of mineralized structures and support future underground exploration.

In addition the Company is pleased to announce that drilling of the Trixie West high-priority copper-gold-molybdenum potential porphyry target from underground at Trixie commenced. The objective of the drill program is to test a new area below the Trixie deposit for a potential porphyry style copper-gold-molybdenum mineral system that may have been the source of the significant high-grade gold and silver epithermal mineralization and past producing carbonate silver-lead-zinc replacement deposits. Two large lithocaps, presented as anomalous surface geochemical footprints, a type of high heat signature indicative of significant potential subsurface volcanic activity, have been identified within the Company's Tintic Project property (Figure 5), namely in the Big Hill and Silver Pass areas. Drilling in these areas is expected to commence in Q4 2023 subject to permits.