Cooperite (mineral)
Cooperite is a platinum sulfide mineral with the chemical formula PtS. It is a relatively rare mineral and is an important ore of platinum.
Occurrence and Formation:
Cooperite is primarily found in ultramafic igneous rocks, particularly those associated with layered intrusions such as the Bushveld Igneous Complex in South Africa and the Stillwater Complex in Montana, USA. It typically occurs in association with other platinum group minerals (PGMs) like braggite and sperrylite, as well as base metal sulfides such as pyrrhotite, pentlandite, and chalcopyrite.
The formation of cooperite is believed to be the result of magmatic segregation, where PGMs and sulfides separate from a silicate melt during the cooling and crystallization of the magma. Subsequent hydrothermal alteration can also play a role in the redistribution and concentration of cooperite.
Properties:
- Chemical Formula: PtS
- Crystal System: Tetragonal
- Color: Tin-white to steel-gray
- Luster: Metallic
- Streak: Gray-black
- Hardness: 4 - 4.5 (Mohs scale)
- Density: 9.5 g/cm³
- Cleavage: Distinct on {001}
- Fracture: Uneven
- Tenacity: Brittle
Cooperite is opaque and non-magnetic. It can sometimes exhibit a slight tarnish. It is difficult to distinguish from other PGMs without detailed laboratory analysis.
Uses:
The primary use of cooperite is as an ore of platinum. Platinum is a valuable metal used in a wide range of applications, including:
- Catalytic converters in automobiles
- Electronics
- Jewelry
- Chemical industry
- Medical implants
Etymology and History:
Cooperite was first described in 1928 from the Bushveld Igneous Complex in South Africa. It was named in honor of Robert Allan Cooper, a South African metallurgist who studied the platinum group elements.