Osisko drilling extends Cariboo gold zones deeper

New drilling by Osisko Development (TSXV, NYSE: ODV) has extended high-grade gold zones at the Cariboo gold project in central British Columbia below the current resource envelope. Shares rose.

Hole IM-26-003 at Cariboo cut about 5 metres of 6.61 grams gold per tonne from 425 metres downhole, Osisko said Thursday in a statement. It also cut about 7 metres grading 6.17 grams gold from 517 metres and 50 cm of 73.10 grams gold from 843 metres.

Results “confirm high-grade mineralization below the current Cariboo deposit, reinforcing sight lines for a potential step change in mineralized volume, currently not reflected in the mine plan or valuation,” National Bank financial mining analyst Don DeMarco said in a note. Osisko’s “resource growth story gains momentum,” he added.

With measured and indicated reserves estimated at about 1.61 million oz., Cariboo is a key property for Montreal-based Osisko, which is focusing on reviving past-producing mining camps across North America.

Cariboo’s potential “is not unlike select generational Canadian operating mines,” DeMarco said.

Osisko shares rose 3.6% to $3.50 Thursday afternoon in Toronto, valuing the company at about $1.1 billion (US$775 million). The stock has traded between $2.95 and $6.63 in the past 12 months.

Deep extensions

All 11 holes whose results were released Thursday encountered assay composites of at least 1.8 grams gold, Osisko said.

The holes, covering 8,971 metres, were completed between December 2025 and April 2026. Crews targeted deep extensions of known vein corridors and gaps between existing deposits. About two-thirds of drilling transected areas outside the Cariboo deposit.

Other drilling highlights include hole CM-26-002, which cut 7.6 metres of 3.26 grams gold from about 76 metres depth; hole CM-25-002, which returned about 5 metres of 4.41 grams gold from 192 metres; and hole IM-26-001, which cut 6.3 metres of 6.40 grams gold from 326 metres depth.

Results to date “confirm the presence of high-grade mineralization at depth and reinforce the strong potential for upside within under-tested gap zones and below the current Cariboo’s deposit footprint,” which extends to an average depth of about 350 metres, Osisko said.

Five rigs continue drilling from surface, systematically testing targets down-dip of the current resource to a maximum vertical depth of up to 800 metres, Osisko said.

Underground mine

Cariboo is projected to be a traditional underground operation, employing mechanized long-hole open stoping to extract ore from gold-bearing vein corridors.

Saleable gold doré would be produced at the mine site complex, and the flotation concentrate would be transported by truck to the Port of Vancouver and sold to a smelting partner. 

Cariboo’s after-tax net present value stands at $943 million, according to an April 2025 feasibility study. Projected capital expenditures are pegged at $1.41 billion.

Over an estimated 10-year mine life, annual gold output would average about 190,000 oz., Osisko has said. This includes 202,000 oz. annually in the first five years.

Cariboo benefits from year-round access and existing infrastructure, as well as support from the provincial government and First Nations. The land package at Cariboo alone exceeds the entire footprint of Quebec’s prolific Val-d’Or mining camp.