cooperite

Cooperite is a rare platinum sulfide mineral with the chemical formula PtS. It is a member of the platinum-group minerals and occurs in sulfide-rich ore deposits, commonly in association with other platinum-bearing minerals such as sperrylite (PtAs2) and platarsite (PtAsS). It forms in magmatic sulfide deposits and in hydrothermal veins related to ultramafic rocks; it can occur as fine-grained intermixed masses within nickel-iron sulfide assemblages.

In terms of appearance, cooperite has a metallic luster and a steel-gray to brass-gray color; it is opaque and has a relatively high specific gravity. Crystals, when present, are typically small and not well formed, often occurring as grains and intergrowths with other platinum-group minerals.

From a scientific perspective, cooperite is important as part of the study of platinum-group mineral paragenesis and ore genesis. It is a binary platinum sulfide and can form under reducing conditions in nickel-copper sulfide systems.

Occurrence and locality are global, with cooperite reported in ultramafic intrusions and related hydrothermal deposits. It is usually found in association with other platinum-group minerals, reflecting its role in the mineralogical suite of platinum-bearing ore bodies.