Chlorite

The chlorites are a group of phyllosilicate minerals, commonly found in igneous rocks as an alteration product of mafic minerals. Within ultramafic rocks, metamorphism can also produce predominantly clinochlore chlorite in association with talc.

Chlorite is a common mineral associated with hydrothermal ore deposits. In this environment chlorite may be a retrograde metamorphic alteration mineral of existing ferromagnesian minerals, or it may be present as a metasomatism product via addition of iron, magnesium, or other compounds into the rock mass.

Chlorite is also a common metamorphic mineral, usually indicative of low-grade metamorphism. It is the diagnostic species of the zeolite facies and of lower greenschist facies. It occurs in the quartz, albite, sericite, chlorite, garnet assemblage of pelitic schist.