Actinolite - Tremolite

Chemical Formula : Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂
Hardness : 6
Cleavage : Two, perfect
Luster : Vitreous
Color : White (tremolite), Green (actinolite)
Streak : White
Density : 2.98-3.46
Diagnostic Features and Trivia : Actinolite and tremolite are members of the amphibole group. Tremolite is commonly found in aggregates of almost bladed crystals, and is easily identified by its prefect cleavage, and whtie color. Actinolite is less likely to fom long crystals, but its perfect cleacage and deep green color help identification.
Crystal System and Habit : Monoclinic, Crystals common, but more likely developing aggregates of long prisms, also fibrous and asbestiform.
Twinning : None
Polymorphs : None
Index of Refraction : alpha=1.601-1.670; beta=1.617-1.688; gamma=1.628-1.693;