Tetrahedrite

Formula: Cu6(Cu4C2+2)Sb4S12S  where C2+ = Fe2+, Zn, Cd, Hg and/or other species

Colour: Steel- to iron-gray

Lustre: Metallic

Hardness: 3½ – 4

Specific Gravity: 4.97

Crystal System: Isometric

Member of: Tetrahedrite Group

Name: Renamed in 1845 by Wilhelm Karl von Haidinger because of the common tetrahedral form of its crystals. Originally called argentum rude album by Georgius Agricola (Georg Bauer) in 1546 because it contained silver, although it may not have necessarily been silver-dominant as a related mineral, freibergite, is.

First Recorded Locality: Copiapó, Copiapó Province, Atacama – Chile

Although considered a series, there are presently three IMA-recognized end-members (tetrahedrite-(Fe), tetrahedrite-(Zn) and tetrahedrite-(Hg)), and the existence of suspected additional members has been reported, although these have not yet been IMA approved. Hence, to accommodate these likely future recognitions, the “tetrahedrite series” is here treated as the “Tetrahedrite Subgroup” of the Tetrahedrite Group.