Chlorite group

group of phyllosilicate minerals

Chamosite is the Fe2+ end member of the chlorite group. A hydrous aluminium silicate of iron, which is produced in an environment of low-to-moderate-grade metamorphosed iron deposits, as grey 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).

Cookeite is a mineral species of the silicate group and the phyllosilicate subgroup, part of the chlorite family, with the formula LiAl4(Si3Al)O10(OH)8. This soft, low-density mineral of variable color has a crystalline structure made up of alternating layers LiAl2(OH)6 and Al2O4(OH)2Si8O12 having several polytypes. Cookeite is often found as a product of hydrothermal alteration of silicates in pegmatites. It forms at relatively low temperatures (below 200°C) and variable pressures.

Thuringite is a variety of the chlorite mineral chamosite, a hydrous iron and aluminium silicate mineral. It is usually found as small green scales deposited on other minerals, particularly to which it is closely related.

Sudoite is a mineral from the chlorite group. It was named after Toshio Sudo (1911–2000), professor of mineralogy at the University of Tokyo, in Japan, and a pioneer of clay science. The mineral tosudite also bears his name. It was approved as a valid species by the International Mineralogical Association in 1966.

Delessite is a mineral variety, a magnesium-rich form of chamosite which is a member of the chlorite group. Delessite has the chemical formula .