Class : Silicates
    Subclass : Inosilicates
    Crystal system : Orthorhombic
    Chemistry : FeSiO₃
    Rarity : Common

Ferrosilite belongs to the group of orthorhombic pyroxenes (orthopyroxenes). It forms a series with enstatite (magnesian) and hypersthene. It is a constituent of basic and ultrabasic rocks (especially gabbros and norites) as well as BIFs. It is also present but rarer in high grade metamorphic rocks (granulites and charnockites), contact deposits (hornfel), and volcanic rocks. Its name comes from its chemical composition : iron + silicon. Clear crystals are rare and only known in gabbroic pegmatites : they are then flattened prisms. Ferrosilite generally occurs in fibrous, lamellar, grainy or compact masses, greenish black to brownish black, sometimes dark green or dark brown. It changes into amphibole (uralitization). It is exceptionally used as a gem.

Main photo : Ferrosilite from Caspar quarry, Ettringen, Germany © Volker Betz

No twins known for this mineral species.

No fakes recorded for this mineral species.