Stillwater Critical Minerals (TSXV: PGE; US-OTC: PGEZF) has established its first indicated resource and more than tripled inferred tonnage at its Stillwater West project in Montana, sharply expanding its inventory of nickel, copper and platinum group metals.

The Glencore (LSE: GLEN)-backed explorer said Thursday that the new indicated resource totals 29.4 million tonnes grading 0.18% nickel, 0.09% copper and 0.02% cobalt, containing 119 million lb. nickel, 59 million lb. copper and 11 million lb. cobalt.

"The establishment of our first indicated mineral resource and the continued refinement of our geological model significantly enhance our understanding of this large and evolving mineral system," CEO Michael Rowley said in a release. "The 2026 resource estimate provides a stronger technical foundation for advancing metallurgical studies, engineering and future economic evaluation."

Inferred resource triples

Compared with the January 2023 resource, the new inferred estimate now contains 3 billion lb. of nickel, 1.5 billion lb. of copper and 283 million lb. of cobalt within 805.1 million tonnes — almost tripling the nickel and more than tripling the copper and cobalt over the previous estimate. Contained platinum and palladium total 2.8 million oz. and 3.9 million oz., respectively, more than doubling their previous amounts, while gold more than doubles to 864,000 oz.

The project sits beside Sibanye-Stillwater's (JSE: SSW; NYSE: SBSW) platinum group metals (PGM) mines and processing facilities, the only primary PGM complex in the United States. Glencore holds a 13% stake in Stillwater and provides technical support, and the explorer has applied for Department of Defense funding. Nickel, cobalt and platinum group metals all appear on the U.S. government's critical minerals list, and the United States relies on imports for much of its nickel and PGM supply — the policy backdrop for federal programs that have channelled funding toward domestic critical minerals projects.

Indicated resource

In the indicated category, other metals include platinum at 0.12 gram per tonne, palladium at 0.22 gram, gold at 0.043 gram and rhodium at 0.016 gram, amounting to a combined 359,000 oz. of platinum, palladium, gold and rhodium.

In the inferred category, platinum grades 0.09 gram per tonne, palladium 0.16 gram, gold 0.034 gram and rhodium 0.012 gram, containing a combined 7.4 million oz. of the four metals. Both categories use a 0.2% nickel-equivalent cut-off.

The previous 2023 resource of 254.8 million inferred tonnes contained 1.05 billion lb. nickel, 499 million lb. copper, 91 million lb. cobalt, 1.26 million oz. platinum, 2.05 million oz. palladium, 395,000 oz. gold and 115,000 oz. rhodium.

Stillwater also more than doubled its inferred chromium inventory to 6.6 billion lb. from 2023. Chromium is not included in the nickel-equivalent calculation, and the company has made no recovery or economic assumptions for the metal.

The new estimate incorporates 14 holes totalling 5,781 metres drilled during the 2023 and 2025 campaigns, along with historical holes added following a quality-control review. Mine Technical Services prepared the resource, which assumes open-pit mining.

Mine studies next

Most of the resource remains in the lower-confidence inferred category, and Stillwater has yet to complete an economic study. Under National Instrument 43-101 reporting standards, indicated resources carry a higher level of confidence than inferred tonnage, which is generally considered too speculative to anchor economic analysis without additional drilling. The new grade-block model is intended to support metallurgical testing, mine planning and development scenarios, including examining whether higher-grade zones could be mined earlier.

The resource covers about 10 km of Stillwater's 32-km property across the Stillwater Igneous Complex, one of the small number of layered intrusions mined for platinum group metals at scale worldwide, alongside South Africa's Bushveld Complex. The company's 2026 drilling campaign is focused on extending mineralization at Chrome Mountain and joining the CZ-Central deposits with HGR at Iron Mountain.

Shares rise

Stillwater shares gained 13% on Thursday to 45¢ in Toronto, giving the company a market value of about $139 million. The shares have traded between 23¢ and 67¢ over the past year.

Vancouver-based Couloir Capital identified resource expansion as a key valuation driver ahead of Thursday's update. The firm raised its target price on Stillwater to 93¢ from 45¢ in October while maintaining a buy recommendation, saying it expected the 2025 drilling program to support a larger resource. Couloir's target predates the new estimate, and its Stillwater research is commissioned by the company.