Rustenburgite
Rustenburgite is an IMA-recognized mineral species in the native element class, with the chemical formula Pt₃Sn.
It crystallizes in the cubic crystal system (space group Fm3m). It is a member of the Perovskite, Auricupride structural group.
Key properties: specific gravity 15.08; Metallic. Anisotropism: Slight, due to strain. R1 –R2: (480) 56.2, (546) 59.8, (589) 60.4, (656) 61.65 luster.
IMA symbol Rsb, IMA status: approved, named in 1974.
Occurs as very sparse grains in concentrates (Merensky Reef, South Africa).
It is found associated with Atokite, unspecified platinum tellurides (Merensky Reef, South Africa); moncheite, pyrrhotite, pentlandite (Stillwater complex, Montana, USA).
The name refers to its occurrence in the Rustenburg mine, South Africa.