Osisko Gold Confirms High-Grade Proserpine Mineralization With Open Pit Potential

• Osisko Gold Group confirmed new high-grade gold mineralized system at its Proserpine target, located 7 km from the permitted Cariboo Gold Project in British Columbia.
• Initial diamond drilling results include 95.93 g/t gold intercepts over 4.60 meters, suggesting potential for open-pit mining methods alongside underground operations.
• The discovery has expanded the known mineralized footprint to approximately 1.0 km by 0.5 km, prompting resumption of exploration drilling with three active rigs.
• Analysts view the scale of the discovery as a key driver for future valuation, despite the stock's recent surge following the announcement.

Osisko Gold Group Inc. has announced initial diamond drilling results from its surface exploration program at the Proserpine regional greenfield target. The program completed 6,463 meters across 14 drill holes, confirming the presence of an emerging gold mineralized system. The results highlight high-grade structures similar to those at the Cariboo deposit, alongside broader zones of lower-grade mineralization. This combination suggests potential for bulk mining methods, specifically open pit mining. Key intercepts included 95.93 g/t Au over 4.60 m and 5.46 g/t Au over 8.60 m. Drilling has expanded the known mineralized footprint at Proserpine to roughly 1.0 km along strike by 0.5 km in width, with gold encountered from near surface to depths beyond 400 meters.

Chris Lodder, President of Osisko Gold, noted that the results encourage the company's view of a significant new gold system of scale. With all holes that reached target depth intersecting mineralization, the company has resumed drilling operations with three rigs. An additional 26,500 meters of drilling is planned to increase drill density at Proserpine Southeast and begin first-pass drilling at Proserpine Northwest. This exploration campaign aims to identify additional deposits and expand the resource base for the Cariboo Gold Project.

What Do the Drilling Results Indicate About Open Pit Potential?

The initial drilling results from the Proserpine target have revealed a mineralized system that supports both high-grade underground and lower-grade bulk mining methods. The high-grade intercepts, such as the 95.93 g/t Au over 4.60 m, indicate the presence of significant gold concentrations. These grades are comparable to those found at the Cariboo deposit, which is a permitted underground operation. However, the broader zones of lower-grade mineralization suggest that open-pit mining could be a viable method for extracting gold from the Proserpine target.

The technical data supporting these results is consistent with the 2025 feasibility study for the Cariboo Gold Project. The study projects a 10-year life producing approximately 1.89 million ounces of gold over a 10-year life, with an after-tax net present value of $943 million based on a $2,400 per ounce gold price. The Proserpine target's mineralization style resembles that of the Cariboo Gold deposit, characterized by high-grade gold intercepts associated with quartz-pyrite to polymetallic quartz veins. This similarity reinforces the potential for Proserpine to serve as a complementary source of gold to the main Cariboo operation.

The discovery at Proserpine is located within the broader Cariboo Gold Project property boundary, which spans approximately 186,740 hectares. The project received Mines Act and Environmental Management Act permits in late 2024, solidifying its shovel-ready status. The proximity of Proserpine to the permitted Cariboo Gold Project allows for potential synergies in infrastructure and processing. The company is currently focusing its drilling efforts on the central southeast limits to expand upon preliminary results from previous campaigns.

How Will Additional Drilling Expand the Known Footprint?

Osisko Gold has resumed drilling operations with three rigs following a seasonal hiatus, with plans to complete an additional 26,500 meters of drilling. This expanded campaign aims to increase drill density at Proserpine Southeast and initiate first-pass drilling at previously untested targets at Proserpine Northwest. The company intends to define the scale of this new gold system, which could significantly complement the underground operation planned for the Cariboo project.

National Bank Financial analyst Don DeMarco noted that while the grades are exceptional, the critical factor is the scale. Drilling has defined mineralization over a small portion of a larger target that remains open in all directions. The current drill campaign has tested an area of 1.0 km by 0.5 km within a larger 6.0 km by 1.0 km anomaly. This suggests that the known mineralized footprint is just the beginning of a much larger system. The company plans to continue testing the exploration potential within the broader Cariboo property boundary.

The siliceous sandstone unit, believed to be a favorable host for mineralization, was also confirmed within the target area. This geological context supports the company's strategy of targeting similar structures to those found at Cariboo. The results have expanded the known mineralization footprint, with gold encountered from near surface to vertical depths exceeding 400 meters. This depth potential indicates that the system is not only extensive laterally but also vertically.

Osisko Gold's stock rose 12.2% following the news, valuing the company at approximately $1.2 billion. The market reaction reflects investor interest in the potential for open-pit mining at Proserpine, which could provide a scalable source of gold production. The company continues to evaluate the structural controls and geology of the deep mineralization to guide future exploration efforts. The results demonstrate the continuity of mineralization at significant depths, potentially expanding the mineable resource base.

The company cautions that these results are preliminary and based on incomplete data. Inferred mineral resources have a greater degree of uncertainty than indicated resources, and additional drilling may result in materially different results. The full technical report is available on SEDAR+ and EDGAR, providing transparency for investors and stakeholders. The resumption of drilling with three rigs signals the company's confidence in the Proserpine target's potential.

The Proserpine discovery adds to Osisko Gold's portfolio of high-potential assets in British Columbia. The Cariboo Gold Project itself is a 100%-owned, permitted feasibility-stage asset with significant indicated and inferred mineral resources. The addition of Proserpine as a potential open-pit mining target enhances the long-term resource growth prospects for the company. Investors will be watching the upcoming drilling results to assess the scale and economic viability of the new mineralized system.