Osisko Gold Confirms High-Grade Mineralized System at Proserpine Target

• Osisko Gold Group confirmed high-grade gold structures and broader lower-grade zones at its Proserpine target, located 7 km from the permitted Cariboo deposit in British Columbia .
• Initial diamond drilling of 6,463 meters across 14 holes revealed an emerging mineralized system that supports potential open-pit or bulk mining methods .
• Appian Capital Advisory provided a US$450 million senior secured project loan to fund the development of the Cariboo Gold Project .
• The combination of exceptional grades and vast scale at Proserpine underscores the district-level exploration potential of the Cariboo region .
• Osisko plans to resume drilling with three rigs, targeting an additional 26,500 meters to expand the known footprint of the system .

Osisko Gold Group Inc. has released the first set of diamond drilling results from its surface exploration program at the Proserpine regional greenfield target . Located within the broader Cariboo Gold Project property boundary in central British Columbia, Proserpine sits approximately seven kilometres southeast of the Company’s permitted, 100%-owned Cariboo Gold Project . The program, which completed 6,463 metres in 14 holes between February and May 2026, confirmed high-grade gold structures and broader lower-grade zones that together suggest potential for open-pit mining .

Key highlights from the drilling campaign include an intercept of 95.93 g/t Au over 4.60 m at 71 m vertical depth, which included a high-grade core of 873.00 g/t Au over 0.50 m . Other significant intercepts included 5.46 g/t Au over 8.60 m and 2.17 g/t Au over 14.45 m . Mineralization was encountered from near surface to depths exceeding 400 meters, with the footprint expanded to approximately 1.0 km along strike by 0.5 km in width .

President Chris Lodder noted that the combination of high-grade structures and broader lower-grade mineralization may indicate potential for open-pit or bulk mining methods . The siliceous sandstone unit, identified as a favorable host rock, was confirmed within the target area . Drilling has resumed with three active rigs, with a planned program of 26,500 meters to further expand the mineralized footprint and test previously untargeted areas .

How Will Proserpine Alter Cariboo’s Resource Outlook?

The discovery at Proserpine represents a significant new gold mineralized system of scale . For context, the currently defined Cariboo Gold deposit extends approximately 4.0 km along strike by 0.5 km in width . The Proserpine results underscore significant remaining exploration potential within the broader property . Drilling confirmed the presence of a prospective siliceous sandstone unit, believed to be a favorable host for mineralization .

The Cariboo project itself is a permitted underground operation with a 2025 feasibility study envisioning a 10-year life producing 1.89 million oz of gold . The project holds 17.4 million tonnes of measured and indicated resources grading 2.88 grams gold, with an after-tax net present value of $943 million at a US$2,400/oz gold price . The findings have expanded the known footprint of mineralization and reinforced the project's long-term growth potential .

National Bank Financial analyst Don DeMarco noted that while the grades are exceptional, the scale of the target is the more significant factor . Drilling has only tested a small portion of a larger system, with the target area measuring roughly 6.0 km x 1.0 km in gold-in-soil and rock anomaly . Osisko plans to drill 26,500 metres at Proserpine using three rigs to increase drill density .

This activity underscores the prospect of a sizeable new gold system close to its permitted Cariboo project . The potential for bulk mining methods could significantly alter the resource outlook by enabling larger-scale extraction alongside the planned underground mine .

What Does the Appian Capital Loan Facility Enable?

Appian Capital Advisory has entered into a credit agreement with Osisko Gold Group Inc. for a senior secured project loan facility of up to US$450 million . The proceeds are designated for the development and construction of the Cariboo Gold Project in British Columbia, Canada . Osisko Gold, formerly Osisko Development Corp., is a continental North American gold development company focused on past-producing mining camps in mining-friendly jurisdictions .

The financing structure includes a US$100 million initial draw, which enables Osisko to accelerate pre-construction activities and materially de-risk the project ahead of a final investment decision . An additional US$350 million in subsequent draws is available upon final investment decision, subject to customary project milestones and conditions precedent . The initial draw will support an infill drilling campaign, detailed engineering, procurement, underground development, and operational readiness planning .

This transaction also strengthens the diversification of Appian’s portfolio, complementing current exposure to base metals and critical minerals while benefiting from gold’s typically uncorrelated return profile . The financing supports the company's objective to become an intermediate gold producer by advancing its flagship 100%-owned Cariboo Gold Project .

With the initial phase of Proserpine drilling complete, the resumption of activity with three rigs marks a critical step in delineating the system . The company plans a further 26,500 metres to increase drill density at Proserpine Southeast and begin first-pass drilling at Proserpine Northwest . This activity underscores the prospect of a sizeable new gold system close to its permitted Cariboo project .

The results validate the district-scale exploration potential of the Cariboo Gold Project . The combination of high-grade structures and broader lower-grade zones suggests a versatile mining opportunity . Osisko Gold's strategic financing and aggressive drilling program position the company to capitalize on this emerging system .