Sperrylite is a very rare platinum arsenide mineral (PtAs2). Very few localities on Earth have been reported to have sperrylite. The two classic localities for this mineral are Sudbury, Ontario, Canada and the Norilsk Mining District in northern Siberia.
Sperrylite has a metallic luster, a bright silvery color, a dark gray to black streak, is fairly hard (H = 6 to 7), and is quite heavy for its size. It forms crystals in the isometric system, resulting in octahedrons and octahedrons truncated by cubic forms.
Sperrylite (silver) in platinum-copper ore (field of view 2.2 cm across) with chalcopyrite (dark brassy gold - CuFeS2) & magnetite (black - Fe3O4).
Geology & Age: massive Fe-Cu sulfide hosted in gabbrodolerite, lower series of differentiated layered igneous intrusion associated with hotspot-generated Siberian Traps Flood Basalts, Permian-Triassic boundary time, 251 my.
Locality: apparently from the Oktyabersky Mine, ~12 km NW of Talnakh, Norilsk Mining District, Putoran Plateau, Krasnoyarsk Territory, northern Siberia, Russia.
Sperrylite (silvery crystals at far left) & chalcopyrite (brassy gold areas + peacock-colored tarnished area at lower right) & magnetite (small black crystals at far left). Same specimen as above (field of view 2.75 cm across).
Sperrylite (silvery) & chalcopyrite (brassy gold) & magnetite (black) - flip side of specimen shown above (5.7 cm across).
Acquired through the generosity of Lee & Mary Ellen St. John.