Stillwater West PGE-Ni-Cu (Montana)


  • Vast, brownfields project in Montana’s Stillwater District; one of the world’s largest and highest-grade PGE-Ni-Cu regions
  • Adjacent to Sibanye-Stillwater’s PGE Mines with 80 million ounces of Pd+Pt at over 16 grams per tonne*
  • The Stillwater District has a rich mining history for PGEs, Ni, Cu, Cr, and other commodities
  • The project features an extensive database –– including almost 12,000 m of core –– to which Group Ten is applying modern geological models developed in South Africa at Ivanhoe’s Platreef and Anglo American’s Mogalakwena mines
  • Compilation and analysis by Group Ten shows the potential for much larger mineralized systems than have been previously recognized
  • Existing road access and power infrastructure with three operating mines



The Stillwater West PGE-Ni-Cu Project consists of 14 multi-kilometer-scale target areas along a 25 km strike length adjoining and adjacent to Sibanye-Stillwater’s high-grade Stillwater (Stillwater, East Boulder, and Blitz) mines in the Stillwater Igneous Complex of Montana, USA. With more than 41 million ounces of past production² and current M&I resources¹, plus another 49 million ounces of inferred resources¹, the Stillwater Complex is recognized as one of the top regions in the world for PGE-Ni-Cu mineralization, alongside the Bushveld Complex and Great Dyke in southern Africa. In June 2017, one month after South African producer Sibanye announced the completed takeover of Stillwater Mining company for USD 2.2 billion, Group Ten Metals announced the closure of the Stillwater West project acquisition deal, which positions the Company as the second largest landholder in the district. In addition to the land package, the Stillwater West acquisition included an extensive historic database of soil and rock geochemistry, geophysical surveys, geologic mapping, and historic drilling with over 11,000 metres of preserved core.


The Stillwater Complex is a 2.7 billion-year-old layered intrusive mafic-ultramafic complex with geology similar to South Africa’s Bushveld Complex. Mining in the Stillwater District currently occurs along the J-M Reef, a PGE-enriched sulphide horizon that shares many similarities with the highly-prolific Merensky and UG2 Reefs in the Bushveld Complex, particularly very high PGE grades along narrow seams. At an average grade above 16 grams per tonne, the Stillwater mines are the highest-grade PGE operations in the world and among the very few significant producers outside of Africa or Russia –– which produce over 70% of platinum group metals –– globally. 

In addition to these narrower “reef-type” deposits, the Bushveld also hosts much larger-scale disseminated and high-sulphide PGE-nickel-copper-type deposits, including Anglo American’s world-leading Mogalakwena Mine (265 Moz Pt+Pd) and Ivanhoe’s developing Platreef Mine (112 Moz Pt+Pd). Similarly, the lower part of the Stillwater Complex, which hosts the majority of Group Ten’s 54 km² holdings, also shows the potential for these broadly-disseminated deposits that can range well beyond 100 metres in thickness. 

A total of 14 target areas ranging from 3 to 8 km in length and defined by major high-level electro-magnetic conductors with broad coincident soil geochemical anomalies have been identified on the Stillwater West property. Each of these are further divided into eight ‘Platreef-style’ bulk tonnage PGE-Ni-Cu sulphide target areas and six ‘Reef-type’ higher-grade PGE target areas. While Group Ten’s Stillwater West property hosts both styles (the “reef-type” Picket Pin in the upper portion of the Complex and the larger “Platreef-type” deposit located in the lower portion), the Company has prioritized exploration of the lower Stillwater Complex where work to date demonstrates strong potential for very large, world-class mineralized systems. Each of the major conductor targets on the main claim is as large as Ivanhoe’s Platreef deposit and drilling data from the 1960s, 1970s, and 2000s confirms the presence of significant intervals of platinum group elements (PGE) and cobalt with nickel and copper sulphides associated with at least six (6) of the 15 identified geophysical targets. 

The eight ‘Platreef-style’ bulk tonnage PGE-Ni-Cu target areas occur within the ultramafic and basal part of the Stillwater Complex and are highlighted by strong electro-magnetic conductive signatures that are characteristic of large bodies of massive to extensively disseminated sulphides. These geophysical targets have overlapping highly elevated palladium, platinum, gold, nickel, copper, and chromium values in soils and rock sampling. Individual target areas have from a few drill holes to as many as 30 wide-spaced holes that have intercepted significant levels of platinum, palladium, and gold along with nickel, copper, cobalt, rhodium, vanadium, and chromium.



  • Systematic release of results from each target area moving from west to east
  • Reassay of select intervals within the core inventory and release of results
  • Entry of all core data into the first property-wide 3D geologic database for modeling and target refinement
  • Development of a predictive geologic model to drive future exploration efforts and follow-up drilling (ongoing); and prioritization of all targets along the 25-km-long strike length of the Project 


  • Mobilize exploration and drill crews to site to begin priority drill testing of identified targets (August)
  • Release rolling results from surface and drill work as they become available










Report on Montana Platinum Group Metal Mineral Assets of Sibanye-Stillwater, November 2017, Measured and Indicated Resources of 57.2 million tonnes grading 17.0 g/t Pt+Pd containing 31.3 million ounces and 92.5 million tonnes grading 16.6 g/t containing 49.4 million ounces.

Public production records from Stillwater Mining Company from 1992 to present.

Magmatic Ore Deposits in Layered Intrusions—Descriptive Model for Reef-Type PGE and Contact-Type Cu-Ni-PGE Deposits, Michael Zientek, USGS Open-File Report 201

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