Osisko Gold Confirms High-Grade Gold Discovery Near Cariboo With Open-Pit Potential

• Osisko Gold Group confirmed high-grade gold structures at its Proserpine target, outlining a new mineralized system with open-pit mining potential.
• The discovery expands the known footprint near the Cariboo project, potentially extending the mine life and resource base of the permitted underground operation.
• Analysts highlight the scale of the Proserpine system as a critical driver for future resource growth, with the stock rising 12.2% following the announcement.
• The company plans 26,500 meters of additional drilling to define the system and assess its viability for bulk mining methods.

Osisko Gold Group Inc. has reported initial diamond drilling results from its Proserpine regional greenfield target, located approximately seven kilometers southeast of its permitted Cariboo Gold deposit in central British Columbia. The exploration program, which was conducted between February and May 2026, involved drilling 6,463 meters across 14 holes. These results have confirmed the presence of high-grade gold structures alongside broader zones of lower-grade mineralization, suggesting the potential for open-pit mining operations to complement the planned underground mine at Cariboo. The findings validate the strategic logic of expanding the project's resource base through regional greenfield exploration.

Drilling efforts have significantly expanded the known mineralized footprint at Proserpine to roughly one kilometer along strike by half a kilometer in width. Gold mineralization was encountered from near surface to depths beyond 400 meters, with the system remaining open in all directions. Notably, every hole that reached its intended target depth intersected mineralization. Standout results include hole PSP-26-004, which cut 4.6 meters grading 95.93 grams per tonne gold from 110 meters depth, including a high-grade interval of 873 grams gold over 50 centimeters. Another significant intercept was found in hole PSP-26-001, which intersected 8.6 meters grading 5.46 grams gold from 97 meters depth.

National Bank Financial mining analyst Don DeMarco noted that while the exceptional grades are noteworthy, the scale of the discovery is the more important takeaway. The drilling has defined mineralization over only a small portion of a much larger target that remains open in all directions. Osisko Gold plans to resume drilling with three rigs and has outlined a program to drill an additional 26,500 meters. This next phase aims to increase drill density at Proserpine Southeast and begin first-pass drilling at Proserpine Northwest, underscoring the prospect of a sizeable new gold system close to the permitted Cariboo infrastructure.

The Cariboo Gold Project is Osisko’s main development asset, featuring a permitted underground mine and processing complex located in the historic Wells-Barkerville mining camp. A 2025 feasibility study envisions a scalable underground operation expected to produce about 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 assumption. The project currently hosts approximately 17.4 million measured and indicated tonnes grading 2.88 grams gold for contained metal of 1.61 million ounces.

How Does the Proserpine Discovery Impact Cariboo's Long-Term Viability?

The Proserpine target is part of a broader exploration campaign aimed at identifying additional deposits to expand the resource base and extend mine life. Recent deep drilling at Cariboo has also extended mineralization beyond 700 meters vertical depth, reinforcing the project's long-term growth potential. The Proserpine results provide a proof-of-concept that the area could become a meaningful contributor to future resource growth. By identifying a new mineralized system capable of supporting future open-pit mining, Osisko is positioning the Cariboo project to potentially transition from a purely underground operation to one that integrates bulk mining methods.

The company recently changed its name from Osisko Development to Osisko Gold Group, reflecting its focus on advancing its 100%-owned Cariboo Gold Project. The stock responded positively to the news, jumping 12.2% to $3.83 in Toronto, valuing the company at approximately $1.2 billion. This market reaction underscores investor interest in the scale and continuity of the mineralization at Proserpine.

What Are the Next Steps for Drilling and Resource Definition?

Osisko plans to drill an additional 26,500 meters at Proserpine using three rigs to further define the scale and continuity of the mineralization. The company aims to assess the viability of the system for open-pit development, which could significantly lower processing costs compared to underground mining. The drilling program will initially focus on increasing drill density at Proserpine Southeast, where the mineralized footprint is already well-defined, and then move to first-pass drilling at Proserpine Northwest.

The Proserpine target is one of several regional targets being tested to identify additional deposits. The company is leveraging historical data and modern 3D modeling to prioritize exploration efforts. The expansion of the known mineralization to 1 km along strike by 500 meters in width represents a significant step out from previously defined zones. This expansion drilling is critical for adding to reserves and resources by the end of the year, providing a more robust foundation for the project's long-term development plan.

The integration of Proserpine into the broader Cariboo project strategy highlights Osisko's commitment to maximizing the value of its assets in the British Columbia mining camp. By combining high-grade underground targets with potential open-pit opportunities, the company aims to create a diversified and resilient production profile. The successful definition of the Proserpine system could unlock significant value, extending the mine life beyond the initial 10-year plan and potentially increasing the total contained metal of the project.