The Crystal Cave

Actinolite

Ca₂(Mg,Fe²⁺)₅[OH|Si₄O₁₁]₂

Silicates (inosilicates, amfibole group) hydrous calcium magnesium iron silicate.
Appearance: Elongated and prismatic crystals, Can be in lamellar and columnar aggregates, also radiating even massive, fibrous or granular habits. The color is light to dark green.
Hardness: 5-6
SG: 3,0-3,4
Transparant or nearly opaque with vitreous luster.
Crystal system: Monoclinc.
Environment: Forms in schists and amfibolates, commonly from metamorphism of basic igneous rocks.