Chamosite

Chamosite is the Feend member of the chlorite group. A hydrous aluminium silicate of iron, which is produced in an environment of low to moderate grade of metamorphosed iron deposits, as gray or black crystals in oolitic iron ore. Like other chlorites, it is a product of the hydrothermal alteration of pyroxenes, amphiboles and biotite in igneous rock. The composition of chlorite is often related to that of the original igneous mineral so that more fe-rich chlorites are commonly found as replacements of the fe-rich ferromagnesian minerals (Deer et al., 1992).