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

• Osisko Gold Group confirmed a new high-grade gold system at the Proserpine target, expanding the known mineralized footprint near its Cariboo project in British Columbia.
• Initial drilling results revealed intercepts including 95.93 grams per tonne gold, signaling potential for open-pit mining alongside existing underground operations.
• The discovery has prompted Osisko to resume drilling with three rigs and plan an additional 26,500 meters to define the scale of the emerging system.

Osisko Gold Group Inc. announced initial diamond drilling results from its Proserpine regional greenfield target, located approximately seven kilometers southeast of the Cariboo Gold deposit in central British Columbia. The exploration program, which completed 6,463 meters across 14 drill holes between February and May 2026, has confirmed the presence of a significant new gold mineralized system. The results highlight high-grade structures that exhibit similarities to the nearby Cariboo Gold deposit, providing a strong proof-of-concept for future resource growth.

Drilling has expanded the known mineralized footprint at Proserpine to roughly one kilometer along strike by half a kilometer in width. Gold was encountered from near surface to depths beyond 400 meters, with mineralization remaining open in all directions. All holes that reached their intended target depths intersected mineralization, validating the geological model and suggesting that the system is far from fully defined. This expansive footprint underscores the prospect of a sizeable new gold system close to the permitted Cariboo project.

Key findings highlight exceptional high-grade structures within the broader target area. Notable intercepts include 95.93 grams per tonne gold over 4.60 meters at 71 meters vertical depth, which included a high-grade interval of 873.00 grams per tonne gold over 0.50 meters. Other significant intersections include 5.46 grams per tonne gold over 8.60 meters at 77 meters vertical depth and 2.17 grams per tonne gold over 14.45 meters at 431 meters vertical depth. These results demonstrate the presence of both high-grade veins and broader zones of mineralization.

What Does the Proserpine Discovery Mean for Cariboo's Mining Strategy?

The discovery at Proserpine is significant not only for its grades but also for its potential to alter the mining method at the Cariboo project. Osisko Gold's management notes that while high-grade structures were identified, the presence of broader zones with lower-grade mineralization may indicate potential for bulk mining methods. This suggests that Proserpine could support open-pit mining operations alongside the planned underground operation at Cariboo.

President Chris Lodder emphasized that the drilling has broadly tested an area measuring approximately 1.0 kilometer by 0.5 kilometers within a larger target defined by gold-in-soil and rock anomalies spanning 6.0 kilometers by 1.0 kilometer. The combination of high-grade intercepts and broader lower-grade zones validates the potential for diverse mining approaches. This duality enhances the strategic value of the Cariboo project, offering flexibility in resource development and potential for extended mine life.

The Cariboo Gold Project is the company's primary 100%-owned asset, targeting both high-grade underground-style mineralization and potential open-pit, bulk mining opportunities. The Proserpine discovery represents a significant step in de-risking the project's long-term potential beyond the existing defined deposits. It complements the main development project, which has a 2025 feasibility study projecting 1.89 million ounces of gold over 10 years with a $943 million net present value.

How Will Osisko Gold Expand Its Drilling Program at Proserpine?

Following these initial results, Osisko Gold has resumed drilling with three rigs to aggressively test the system's full scale. The company plans a further 26,500 meters of drilling to increase drill density at Proserpine Southeast and begin first-pass drilling at Proserpine Northwest. This expansion aims to further define the scale and continuity of the Proserpine target relative to the existing Cariboo Gold operations.

Analysts note that while the exceptional grades are noteworthy, the scale of the target, which remains open in all directions, is the more significant takeaway for future resource growth. National Bank Financial mining analyst Don DeMarco highlighted that the intercepts provide an encouraging proof-of-concept that Proserpine could become a meaningful contributor to future resource growth. He emphasized that the scale of the target is more important than the grades alone, as drilling has only tested a small portion of a much larger target.

Proserpine is one of several regional targets being tested as part of an exploration campaign aimed at identifying additional deposits. The aggressive drilling program underscores the company's confidence in the geological potential of the area. By expanding the known mineralized footprint and testing the system's continuity, Osisko Gold aims to unlock significant value from the Cariboo region. The stock jumped approximately 9-12% following the announcement, reflecting investor interest in the discovery's potential.

The Proserpine discovery complements Osisko's main development project by offering a pathway to expand the resource base through regional greenfield targets. The company's ability to identify high-grade mineralization near its permitted operations enhances its strategic position in the gold sector. As drilling continues, the focus will remain on defining the extent of the mineralized system and assessing its economic viability for large-scale extraction.