Osisko Gold Confirms High-Grade Proserpine Discovery Near Cariboo

• Osisko Gold Group confirmed high-grade gold mineralization at the Proserpine target, expanding the known footprint near its permitted Cariboo project in British Columbia.
• Initial drilling intersected exceptional grades over significant widths, prompting a 26,500-metre follow-up program to test for bulk mining potential.
• Analysts view the discovery as a proof-of-concept for resource growth, as the system remains open in all directions beyond tested areas.
• The results support the strategic expansion of the Cariboo project, which includes a permitted underground mine and a 2025 feasibility study outlining a 10-year production plan.

Osisko Gold Group reported initial diamond drilling results from its Proserpine regional greenfield target, located seven kilometres southeast of Cariboo. The program completed 6,463 metres in 14 holes between February and May 2026, confirming high-grade gold structures and broader lower-grade zones. These results suggest the potential for open-pit mining operations alongside the company's permitted Cariboo underground operation .

Drilling has expanded the known mineralized footprint at Proserpine to roughly one kilometre along strike by half a kilometre in width. Gold was encountered from near surface to depths beyond 400 metres, with mineralization remaining open in all directions. All holes that reached target depth intersected mineralization, prompting Osisko to resume drilling with three rigs. The company plans a further 26,500 metres to increase drill density at Proserpine Southeast and begin first-pass drilling at Proserpine Northwest .

What Are the Key Drilling Results at Proserpine?

Standout intercepts highlight the exceptional quality of the mineralization at Proserpine. Hole PSP-26-004 cut 4.6 metres grading 95.93 grams per tonne gold from 110 metres depth, including a 50-centimetre interval of 873 grams gold . Another hole, PSP-26-001, cut 8.6 metres grading 5.46 grams gold from 97 metres depth. Additional highlights include hole PSP-26-009, which cut 5.5 metres of 3.17 grams gold from 408 metres downhole, and PSP-26-003, which intersected 12.4 metres of 1.46 grams gold from 367 metres depth .

These results demonstrate the presence of high-grade gold structures extending to significant depths . The discovery outlines a new mineralized system that could support future open-pit mining alongside a planned underground operation . Osisko is actively pursuing regional greenfield targets to expand its resource base and extend mine life within the broader Cariboo Gold Project property .

Why Does This Discovery Matter for Cariboo?

Proserpine is one of several regional targets being tested as part of an exploration campaign aimed at identifying additional deposits . National Bank Financial mining analyst Don DeMarco described the intercepts as an encouraging proof-of-concept that Proserpine could become a meaningful contributor to future resource growth . He emphasized that while grades are exceptional, the scale is the more important takeaway, as drilling has defined mineralization over only a small portion of a much larger target .

The discovery underscores the prospect of a sizeable new gold system close to Osisko's permitted Cariboo project . Cariboo is Osisko's main development project, hosting about 17.4 million measured and indicated tonnes grading 2.88 grams gold . A 2025 feasibility study envisions a scalable underground operation expected to produce about 1.89 million ounces of gold over a 10-year life . The project has an after-tax net present value of $943 million based on a 5% discount rate and a US$2,400 per ounce gold price .

Osisko Gold jumped 12.2% to $3.83 in Toronto, valuing the company at about $1.2 billion . This market reaction reflects investor interest in the potential for resource growth and the extension of mine life through regional exploration . The company recently changed its name from Osisko Development, signaling a shift in focus toward advancing its primary assets .

How Is Osisko Advancing Regional Exploration?

Osisko has resumed drilling with three rigs at Proserpine, planning a further 26,500 metres to increase drill density . The follow-up program aims to test new areas near its permitted Cariboo project and define the full extent of the mineralized system . Recent deep drilling at Cariboo has extended mineralization below 700 metres, reinforcing long-term growth potential.

The Lowhee Zone infill drill program at Cariboo has also been completed, supporting continued use of existing geological and mine-planning assumptions. This confirmation is critical for maintaining the reliability of the reserve base and operational planning for the permitted underground project . Osisko is also advancing its regional exploration at Proserpine to identify additional deposits that could support future open-pit mining operations alongside the main underground complex .

Osisko Gold Group is a Canadian gold mining and exploration company listed on the NYSE and TSXV . Its primary focus is advancing its 100%-owned, permitted Cariboo Gold Project in central British Columbia . The company targets both high-grade underground-style mineralization and potential open pit, bulk mining opportunities . The Proserpine discovery represents a significant step in this strategy, offering the prospect of a sizeable new gold system near Cariboo .