Wiktionary
cooperite
n. (context mineral English) A grey mineral consisting mostly of platinum sulfide (PtS).
Wikipedia
Cooperite
Cooperite is a grey mineral consisting of platinum sulfide (PtS), generally in combinations with sulfides of other elements such as palladium and nickel (PdS and NiS). Its general formula is (Pt,Pd,Ni)S. It is a dimorph of braggite.
It is mined as an ore of platinum and platinum group metals such as palladium. It occurs in South Africa in minable quantities and a small old mine near Mount Washington on Vancouver Island.
It was first described in 1928 for occurrences in the Bushveld Igneous Complex and named after South African metallurgist Richard A. Cooper who first characterized it.