
General Information:

Chemical Formula:
Ca2(Mg,Fe++)5Si8O22(OH)2

Composition:
(Molecular Weight = 875.45 gm)
Calcium 9.16 %
CaMagnesium 8.33 %
MgIron 12.76 %
FeSilicon 25.66 %
SiHydrogen 0.23 %
H Oxygen 43.86 %
O 
Empirical Formula:
Ca2Mg3Si8O22(OH)2Fe2+2

Environment:
Metamorphic rocks.

IMA Status:
Approved IMA 1978

Locality:
Common world wide.

Name Origin:
From the Greek, aktinos, meaning "ray" in allusion to actinolite's fibrous nature.
Physical Properties:

Cleavage:
[110] Perfect, [110] Perfect

Color:
green, green black, gray green, or black.

Density:
2.98 - 3.1, Average = 3.04

Diaphaniety:
Translucent to transparent

Habits:
Bladed - Aggregates of thin lath-like crystals (e.g. kyanite)., Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite), Fibrous - Crystals made up of fibers.

Hardness:
5.5 - Knife Blade

Luminescence:
Non-fluorescent.

Luster:
Vitreous (Glassy)

Streak:
white
More details...
ACTINOLITE. ATTINOLITE