Cobaltite

Cobaltite is a cobalt arsenide sulfide mineral with the chemical formula CoAsS. It is part of the sulfosalt group and forms in hydrothermal ore veins and related metamorphic environments.

The mineral typically appears as metallic, steel-gray to black crystals and aggregates with a bright metallic luster. The streak is gray, and it is opaque and brittle. Crystals can be prismatic and may show well-developed faces; habit ranges from solitary crystals to finer-grained masses.

In terms of composition and associations, cobaltite contains cobalt, arsenic, and sulfur. It commonly occurs with other sulfide minerals such as pyrite, arsenopyrite, sphalerite, and chalcopyrite, and it is found in a variety of ore-bearing environments worldwide.

Economically, cobaltite is a cobalt-bearing mineral and can contribute to cobalt ore reserves in some deposits, but it is not usually the dominant cobalt source compared with other cobalt minerals. Consequently, it is of particular interest to mineral collectors and researchers, with its mining significance depending on local ore assemblages.

The mineral was named for its cobalt content and has been described in mineral literature since the 19th century. It is related to other cobalt- and nickel-containing sulfarsenide minerals and occurs in complex ore assemblages within hydrothermal and contact metasomatic settings.