Cobaltite on Chalcopyrite

An approximately 1 x 1 x 1 cm, well-formed metallic silver Cobaltite crystal sits partly embedded in a matrix of characteristic Chalcopyrite from the Tunaberg copper-cobalt ore field at Tunaberg, Nyköping, in Södermanland County, Sweden. This is a skarn-hosted disseminated sulphide ore body which was first worked as early as 1420 when it was mined just for copper. The Cobaltite, a cobalt-arsenic sulphide, forms a blocky, slightly stepped crystal with a brilliant lustre. Examples of Cobaltite are becoming increasingly hard to find nowadays and are only available via older collections. This excellent example is accompanied with a well-known British collector’s label.