Actinolite is an amphibole silicate mineral with the chemical formula Ca₂(Mg_4.5-2.5Fe²⁺_0.5-2.5)Si₈O₂₂(OH)₂.

Etymology

The name actinolite is derived from the Greek word aktis ?????, meaning "beam" or "ray", because of the mineral's fibrous nature.

Mineralogy

Actinolite is an intermediate member in a solid-solution