tetraedride

Tetraedride, commonly known in mineralogy as tetrahedrite, is a copper antimony sulfide mineral with the ideal formula Cu12Sb4S13. It belongs to the tetrahedrite group of sulfosalt minerals and represents the antimony-rich end-member of a solid solution with the arsenic-rich analogue tennantite (Cu12As4S13). In natural samples, arsenic can substitute for antimony, and iron, zinc, and other metals can partially substitute for copper or occupy related sites, giving a range of compositions expressible as Cu12(As,Sb)4S13.

Tetraedride forms through hydrothermal processes in copper- and silver-bearing ore deposits and in metamorphosed rocks where sulfosalts crystallize. It is widespread globally and occurs most commonly in veins and replacement zones, often alongside quartz, calcite, sphalerite, galena, and other sulfide minerals.

In hand specimens, tetraedride has a metallic luster and a gray to black color, frequently forming prismatic crystals or massive aggregates. It is relatively soft for a sulfide, with a Mohs hardness of about 3.5–4, and a high specific gravity around 4.6–5.0, contributing to its dense, metallic appearance.

Tetraedride is of economic importance as a copper ore in deposits where tetrahedrite-tennantite minerals are abundant. It is also of interest to mineral collectors for its role in the tetrahedrite-tennantite solid-solution series and its characteristic crystal habits.