Polyedrit

Polyedrit is a mineral belonging to the tetrahedrite group. These minerals are complex sulfosalts with the general formula (Cu,Fe)12Sb4S13. In polyedrit, iron is a significant component, replacing copper in the crystal structure. Its chemical formula is often represented as (Cu,Fe)10Zn2Sb4S13, highlighting the presence of zinc alongside copper and iron. Polyedrit typically forms in hydrothermal veins and is associated with other copper, silver, and lead minerals. It can also be found in some metamorphic rocks. The mineral commonly occurs as small, granular masses, sometimes forming well-developed tetrahedral or dodecahedral crystals. Its color ranges from steel-gray to black, and it possesses a metallic luster. Polyedrit is relatively soft, with a Mohs hardness of around 3 to 3.5, and has a high specific gravity. It is not a commercially important ore mineral itself, but its presence can indicate the potential for associated valuable metals like copper and silver. Variations in the proportions of copper, iron, and zinc lead to a series of related minerals within the tetrahedrite group.