Stillwater West PGE-Ni-Cu (Montana)

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The Stillwater West PGE-Ni-Cu project, consists of 40 square kilometres adjacent to, and contiguous with, Sibanye-Stillwater’s high-grade Platinum PGE mining operations, which include the Stillwater, East Boulder and Blitz mines in Montana, USA.  Group Ten’s acquisition of the highly-prospective Stillwater West project positions the Company as the second-largest land holder in the Stillwater ultramafic complex. Prior work on the project generated significant geological and exploration data which will be instrumental in Group Ten’s advancement of the project and is currently under review by the Company’s technical team.

The Sibanye-Stillwater mines occur along the J-M Reef within the Stillwater Complex; one of the largest and richest PGE deposits in the world. These mines have produced over 12 million ounces of palladium and platinum to date1, and host a Measured and Indicated resource of 31.3 million ounces at a grade of 17.0 grams/tonne (g/t) Pt+Pd and an additional 49.4 million ounces at 16.6 g/t Pt+Pd in Inferred resources2. Group Ten’s Stillwater West project covers approximately 40 square kilometres in two claim groups with each parcel including over 17 kilometers of strike length parallel to the J-M Reef within the Stillwater layered ultramafic complex.

The Stillwater Complex is recognized as one of the top regions in the world for PGE-nickel-copper mineralization, alongside the Bushveld Complex and Great Dyke in southern Africa, which are similar layered intrusions. The J-M Reef, and other PGE-enriched sulphide horizons in the Stillwater Complex, share many similarities with the highly prolific Merensky and UG2 Reefs in the Bushveld Complex, while the lower part of the Stillwater Complex also shows the potential for much larger scale disseminated and high-sulphide PGE-nickel-copper type deposits, possibly similar to Platreef in the Bushveld Complex3. The Stillwater West property covers the lower part of the Stillwater Complex along with the Picket Pin PGE Reef-type deposit in the upper portion.

The first discoveries in the Stillwater district were high-grade nickel and copper sulphides, and later chromite, within the lower part of the Stillwater Complex in the 1880s.  Exploration and mining of these metals continued intermittently from the lower sequence up to the 1970s. The PGE potential of the Stillwater Complex was first recognized in the 1930s and ultimately led to the discovery of the high-grade J-M Reef deposit in the 1970s within the lower-middle part of the Stillwater Complex, along with at least six other PGE-enriched sulphide horizons (including the Picket Pin PGE horizon situated above the J-M Reef, now owned by Group Ten), and additional high-sulphide PGE-rich occurrences in the lower part of the Stillwater Complex, now within the expanded Group Ten holdings4.Past work on the Stillwater West project includes broad soil and rock geochemical sampling, geologic mapping and some initial drilling. Results of these programs demonstrate the occurrence of multi-kilometric scale areas of highly anomalous palladium, platinum, gold, copper and nickel values in soil and rock samples and resulted in the identification of multiple targets with a primary focus on high-grade PGE and gold deposits.


  1. Public production records from 1992 to present.
  2. 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.
  3. 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 2012–1010.
  4. A Geologic and Mineral Exploration Spatial Database for the Stillwater Complex, Montana, Michael Zientek and Heather Parks, USGS Scientific Investigations Report 2014–5183.
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