Mineral Species: Berthierite

Chemical Formula: FeSb2S4

Chemical Name: Iron Antimony Sulfide

Mineral Class: Sulfide

Mineral Notes: Berthierite forms in low-temperature hydrothermal antimony veins, in areas deficient in sulfur. It is named after Pierre Berthier (1782–1861) a French chemist. Berthierite is easily confused with the closely related mineral Stibnite. However the chemistry of Berthierite differs from Stibnite by having an additional sulphur and one iron ion. Physically Berthierite differs from Stibnite by being found more frequently as acicular to fibrous clusters, having a brown streak and non flexible crystals. 

Description: A thick vein of crystalline Berthierite in a matrix of white Quartz. The mineral is very lustrous and has an attractive silvery colour. Thin, elongated crystals, characteristic of this mineral, can be seen in several places on the side of the specimen.

Location: Vlastejovice, Czech Republic