Stillwater Critical Minerals (TSXV: PGE; US-OTC: PGEZF) is using new rhodium assays and a defined chromium inventory to press the Stillwater West multi-metal project in Montana as an important future U.S. source of critical minerals.
The company on Thursday reported narrow rhodium assays from eight holes in last year’s 3,472-metre expansion campaign – four at Chrome Mountain and four in the Iron Mountain area, including the promising CZ and HGR zones. The results are to feed into an updated resource estimate expected next month, ahead of starting work on a first preliminary economic assessment (PEA) later this year.
“This is a project that can be accelerated,” CEO Michael Rowley told The Northern Miner Thursday by phone. “All we’re doing is bringing Platreef mine models to similar rocks in Montana,” he added, referring to the Ivanhoe Mines’ (TSX: IVN) property that is one of the world’s largest precious metals deposits under development.
Stillwater West hosts 10 critical minerals, including the U.S.’s largest rhodium and chromium resources. The property is home to one of the world’s five largest layered mafic-ultramafic systems, Rowley said, with the high-grade J-M Reef like that found at the Stillwater and East Boulder mines long supporting the only historical primary platinum-group metal (PGM) mines in the U.S.
Map showing how closely linked Stillwater’s Stillwater West and Sibanye-Stillwater’s assets are to each other. Credit: Stillwater Critical Minerals (Click image to enlarge)
Policy fillip
Management is pitching the asset to Washington and investors as a project that should move faster than many early-stage projects, given the rising U.S. interest in securing domestic critical minerals supplies. The White House moved in March last year to speed up domestic mine output and soon after added Sibanye-Stillwater’s (JSE: SSW, NYSE: SBSW) neighbouring Stillwater mine to the federal permitting dashboard under the FAST-41 transparency project.
Stillwater West doesn’t have that status, but the move shows Washington already sees the district as strategically important to U.S. critical-mineral supply.
Stillwater’s TSXV-listed shares traded lower on Friday at 32.5¢ apiece after booking a 13% gain on Thursday. It has a market capitalization of $105.7 million (US$76.7 million).
Rhodium results
Rhodium is used in automotive catalytic converters as well as specialty industrial equipment such as mirrors. It’s also used to electroplate jewelery.
Stillwater West is located in a proven district beside Sibanye’s operating mines and about 60 km from its Columbus smelter-refinery complex. Montana has a pro-mining stance, evidenced in Sibanye’s ongoing work there since acquiring the assets in 2017 – signs Rowley says shows the district can support another large project.
Swiss-based bulk trader Glencore (LSE: GLEN) in May 2024 acquired a 15% stake in Stillwater and has since actively backed more than 40,000 metres of drilling, Rowley said.
At Stillwater West’s Chrome Mountain deposit, Thursday’s highlight new rhodium assays include hole CM2025-01 returning 1.22 metres grading 0.167 gram per tonne from 358 metres downhole. Another interval cut 1.22 metres grading 0.107 gram from 388 metres.
About 7 km east at Iron Mountain, hole IM2025-01 returned 1.22 metres grading 0.148 gram rhodium from 272 metres.
Stillwater’s 2023 inferred resource totals 255 million tonnes at a 0.2% nickel-equivalent cut-off, containing 1.64 billion lb. nickel, copper and cobalt and 3.81 million oz. palladium, platinum, rhodium and gold. The resource includes a 115,000-oz. rhodium component and 2.3 billion lb. of contained chromium.
Rhodium ranks highest among U.S. critical minerals by potential for economic disruption, Rowley said, while the U.S. is dependent on chromium imports used in steel, industrial manufacturing and defence applications.
Montana ‘elephants’
Stillwater West targets Platreef-style mineralization in a geological setting the company says matches South Africa’s Bushveld Igneous Complex, host to the world’s largest PGM deposits. The style of mineralization tends to support larger, polymetallic bulk mine plans like Platreef or Valterra Platinum’s (JSE: VAL) Mogalakwena mines targeting platinum, palladium, rhodium, nickel and copper.
The Stillwater West multi-metal project in Montana. Credit: Stillwater Critical Minerals
Next door in Montana, Sibanye-Stillwater’s J-M Reef is comparable to South Africa’s Merensky Reef, famous for its grade and continuity.
Sibanye’s J-M Reef is interesting for its sheer scale. A December-dated proven and probable reserve statement for Stillwater and East Boulder counts 45 million tonnes combined grading 13.4 grams platinum and palladium (2E) per tonne for 11.4 million oz. of contained 2E. East Boulder hosts another 21.6 million tonnes at 11.4 grams 2E for 19.4 million oz. of metal.
Their respective mine plans run through 2049 and 2059, together producing 284,000 oz. 2E last year at all-in sustaining cost of US$1,203 per ounce.
Elephant in the room
Observers see strong logic for some future tie-up between the explorer and Sibanye, even if no official relationship exists now, Rowley said. Sibanye already mines, smelts and refines metals in the district, while Stillwater West brings a heavier nickel-copper-cobalt mix to a camp best known for palladium and platinum.
“We’re open for business,” Rowley said, though he added there is “no corporate connection” with Sibanye now and suggested any toll-processing deal, joint work or corporate move would come only after Stillwater “puts more value on the table.”
Connecting dots
For now, Stillwater works to systematically connect and grow the five Stillwater West deposits as a single development story, Rowley said.
The CZ and Central deposits already touch in surface projection at Iron Mountain and that HGR zone sits only about 700 metres away. Last year’s drilling at CZ and HGR points the same way, with the resource estimate likely to show both areas link up with the HGR deposit into a larger block at Iron Mountain.
Stillwater has the money to keep pushing. It raised $17 million in December and says it is fully funded for its biggest drill program yet, although details remain in planning pending the resource update.
Narrative gap
Rowley says the diverse endowment of base, precious and bulk minerals complicates selling the narrative to retail investors. His job now is to show that a broad metal mix is a strength, not a discount.
“Being polymetallic is hard because the retail public wants you to be one flavour,” Rowley said. “The biggest and best mines in the world, the longest-lasting mines, they’re at least porphyry copper-gold, or like Platreef and Mogalakwena that we aspire to. There’s a lot to be said for being polymetallic.”
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