Stillwater Critical Minerals (TSXV: PGE; US-OTC: PGEZF) is “rewriting the book” on the Lower Stillwater Igneous Complex in Montana, says president and CEO, Michael Rowley.
The company’s evaluation of the flagship Stillwater West project continues to confirm more parallels to South Africa’s Bushveld Igneous Complex, and positions the company as the second-largest landholder in the Stillwater Complex, with a 100%-owned position next to Sibanye-Stillwater’s (JSE: SSW; NYSE: SBSW) PGE mines in south-central Montana.
“Given global geopolitical tension on several fronts, the world is increasingly looking towards North America and other first-world jurisdictions to supply the critical minerals such as PGMs, nickel, cobalt, copper and gold the modern economy requires,” Rowley said in an interview with The Northern Miner.
“With Stillwater West, we’re at a remarkable sweet spot. It’s got a lot of data, a supportive U.S. Geological Survey backing, but it’s, remarkably, not well understood,” Rowley said. “We’re rewriting the book on the Lower Stillwater Complex, quite literally. And there’s a lot of potential there. It’s a big and well-mineralized system.”
Since acquiring the project in 2017, Stillwater Critical, then known as Group 10 Metals, has focused on the potential for Stillwater West to host large-scale Platreef-style nickel and copper sulphide deposits, enriched in palladium, platinum, rhodium, gold and cobalt.
The company’s work to date has confirmed Stillwater West’s location in the Stillwater Igneous Complex relative to Sibanye-Stillwater’s productive J-M Reef deposits as comparable to Ivanhoe Mines’ (TSX: IVN; US-OTC: IVPAF) Platreef deposit and Anglo American’s (LSE: AAL) PGE-nickel-copper Mogalakwena mine in a similar geologic setting in the U.S.
Stillwater’s most important milestone yet was the release in October 2021 of an initial inferred resource estimate encompassing five Platreef-style deposits totalling 1.1 billion lb. of nickel, copper and cobalt, and 2.4 million ounces of palladium, platinum, rhodium and gold. The constrained model totals 157 million inferred tonnes averaging 0.45% total nickel-equivalent (or 1.2 grams palladium-equivalent per tonne), using a 0.2% nickel-equivalent cut-off.
Since then, Stillwater Critical has reported several wide, high-grade battery and precious metal intercepts in wide step-outs from known mineralization in expansion drilling.
Notable comparables
The strength of those results, and the larger potential shown by the full 32-km length of the Stillwater West project, enabled the company to attract Danie Grobler and Albie Brits, two of the world’s top geologists with a combined 40 years of high-level experience advancing world-class mines in the Platreef district in South Africa.
In collaboration with the existing Stillwater team and the U.S. Geological Survey, Grobler is leading a comprehensive review of the substantial project database that is expected to be transformative in guiding further expansion and drill campaigns.
The Stillwater Igneous Complex is well-known analogue to South Africa’s Bushveld Igneous Complex, and Grobler says their geologic similarities have aided exploration in the Stillwater. For example, Sibanye-Stillwater’s high-grade J-M Reef deposit was discovered by the direct application of geologic models developed during the discovery of the high-grade Merensky reef deposit in the Bushveld.
“More recent developments on the Bushveld have focused on the Platreef deposits in the northern limb of the Bushveld, which departs from the conventional narrow reef-type mines that dominate global PGM mining. These occurrences of thick mineralized horizons that support bulk mining techniques also include a much higher battery metal content,” said Grobler from his office in South Africa.
The mines of the Platreef are among the largest and most profitable in the world, and their mix of commodities offers an attractive internally hedged suite of in-demand critical minerals that are globally very rare. Starting with Anglo’s PGE-nickel-copper Mogalakwena mines in 1993 and continuing today with Ivanhoe’s underground Platreef mine, these mines have demonstrated the world-class nature of these bulk-tonnage, critical mineral systems within the Bushveld complex, notes Grobler.
To get a better sense of the enormity of the discovery potential, it’s worth noting these two deposits’ established resource endowments. According to Anglo’s 2021 ore reserves report, Mogalakwena held measured and indicated resources of 1.7 billion tonnes grading 2.18 grams palladium, platinum, rhodium and gold (4E) per tonne for 153.7 million oz. of metal.
Ivanhoe reports Platreef’s indicated resources alone to contain an estimated 41.9 million oz. 4E, plus 2.4 billion lb. of nickel and 1.2 billion lb. copper, at a 2 grams per tonne cut-off. It has a further 52.8 million oz. 4E and 3.4 billion lb. of nickel and 1.78 billion lb. of copper at the same cut-off.
A further plus for the project in today’s heightened market sensitivity to environmental issues is that Platreef-style deposits contain nickel sulphide mineralization. The style of mineralization can produce nickel metal with a much smaller footprint than that recovered from laterite deposits, which currently represent most of the global supply.
Additional environmental benefits are possible through a reaction of atmospheric carbon dioxide with certain ultramafic rocks present in Platreef-style deposits. Test work is underway to evaluate the potential for commercial-scale carbon sequestration as part of a possible mining operation at Stillwater West.
North American focus
So far this year, Stillwater Critical has completed a channel sampling program in the D.R. deposit area and the Bald Hills target area of the Chrome Mountain resource area. The work was meant to expand drill-defined mineralization while also allowing a detailed study of surface geology in conjunction with expanded geologic mapping.
The company has also completed surface sampling across the mineralized shear zone at the high-grade Pine target, which will help underpin a formal resource for this area.
Meanwhile, a gravity geophysical survey is planned in the near term, based on the success of this technique in targeting mineralization in a similar geologic setting on the Platreef deposits of the Bushveld.
Grobler said completing the comprehensive review and update of existing project data and the deposit model is a critical catalyst to move the needle forward on Stillwater West, including an
upcoming resource update later this year. The update will incorporate the results of a successful 14-hole 2021 drill campaign, which returned many wide and high-grade battery and precious metal intercepts in wide step-outs from known mineralization at the three most advanced deposit areas within the 12-km core of the project.
The company expects the drilling will significantly expand and enhance the existing resource.
Rowley underlines that Stillwater is aiming to become a world-class source of low-carbon, sulphide-hosted nickel, copper, and cobalt, critical to electrification, as well as platinum, palladium and rhodium, used in catalytic converters, fuel cells, and the production of green hydrogen.
He said the company had attracted the attention of several major PGM companies from the outset, which has translated into several nondisclosure agreements. “We gave several asset tours this summer that were very positive. They’re there, looking.
“And I guess the key point about mergers and acquisitions is that these big players really cannot find projects of scale and potential in jurisdictions that they like. The world has gotten smaller. The focus on North America is remarkable,” says Rowley.
At 15.5¢ per share, Stillwater Critical’s Toronto-quoted equity is down about 50% over the past 12 months, giving it a market cap of $26.8 million.
I worked on that drill program last fall.