andorite

Andorite is a mineral belonging to the acanthite group, with the chemical formula PbAgAsS3. It is a rare sulfosalt mineral found in hydrothermal veins. Andorite typically occurs as small, prismatic, or tabular crystals, often exhibiting distinct striations. Its color ranges from grayish-black to steel-gray.

The mineral was first described in 1873 and named after the Austrian mineralogist F. Andor. Significant occurrences of andorite have been reported in various locations worldwide, including Bohemia, Sweden, Chile, and Mexico. It is often associated with other sulfosalt minerals such as tetrahedrite, freibergite, and bournonite.

Andorite is relatively soft, with a Mohs hardness of about 3 to 3.5. It has a high specific gravity, typically around 5.7. The mineral is opaque and has a metallic to submetallic luster. In thin sections, it can appear translucent with a reddish internal reflection.

While not economically significant for its lead or silver content, andorite is of interest to mineral collectors and researchers studying the complex geochemistry of hydrothermal ore deposits. Its presence can indicate specific temperature and pressure conditions during mineral formation.