Actinolite

Actinolite is a green mineral from the amphibole group, typically found in metamorphic rocks and known for its fibrous to columnar crystal structure. Its color varies from pale to dark green, influenced by its iron content, and it displays a glassy to silky luster. Actinolite forms as long, slender crystals or needle-like fibers, often producing a fibrous or radial pattern within the host rock. Chemically, it is a calcium magnesium iron silicate with the formula Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂.