Formula: FeSb₂S₄

Species: Sulfates

Colour: Dark steel-grey, often with iridescent tarnish.

Lustre: Metallic

Hardness: 2 – 3

Specific Gravity: 4.64

Crystal System: Orthorhombic

Member of: Berthierite Group (Clerite and Garavellite)

Name: Named in 1827 by Wilhelm Karl von Haidinger in honor of Pierre Berthier, French chemist and mineralogist at the Ecole des Mines, and also Inspector of Mines during his career. He named a number of species including chamosite, franklinite, halloysite, and nontronite. He is well-known for his study of bauxite. The mineral berthierine is also named after him.

Type Locality: Chazelles, Brioude, Haute-Loire, Auvergne-Rhône-Alpes – France