Mineral Species: Carrollite

Chemical Formula: Cu(Co,Ni)2S4

Chemical Name: Copper Cobalt Nickel Sulphide

Mineral Class: Sulphide

Mineral Notes: Carrollite is a rare sulphide which forms in nickel-rich hydrothermal sulphide veins. It is a member of the Thiospinel Group. The mineral is named after the type locality in Carroll County, Maryland, USA. It tends to form excellent octahedral crystals, some of which can grow very large.

Description: A well-formed octahedral crystal of Carrollite on the side of a Quartz matrix. Numerous other, smaller, crystals are also present on the surface. The mineral has an attractive dark grey colour and a highly metallic luster. The surface of the largest crystal shows triangular growth zones and striations. 

Location: Kamboue, Shaba Province, Dem Rep of Congo.