chlorite group

The chlorites are the group of phyllosilicate minerals common in low-grade metamorphic rocks and in altered igneous rocks.

Chlorite minerals do not contain the element chlorine. The name chlorite is from the Greek chloros (χλωρός), meaning "green", in reference to its color. Greenschist, formed by metamorphism of basalt or other low-silica volcanic rock, typically contains significant amounts of chlorite mineral (but not the chlorite ion, nor chlorine in any other form).