Actinolite
Mineral Ca2(Mg,Fe)5Si8O22(OH)2
Also called Byssolite and Smaragdite
Take care.
- Can shed asbestos fibres: Keep it in a closed box, and never break, saw, sand, or scrape it.
About it
Bright to dark green blades and radiating needles in greenschist and talc; fibrous forms are asbestos. Fine sprays come from Chester, Vermont, and Austria's Zillertal.
- Type
- Mineral
- Group
- Silicate (inosilicate), amphibole group
- Formula
- Ca2(Mg,Fe)5Si8O22(OH)2
- Hardness (Mohs)
- 5–6
- Specific gravity
- 3.03–3.24
- Streak
- white
- Lustre
- vitreous (glassy), silky
- Crystal system
- Monoclinic
- Colours
- green, dark green, greyish green, black
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect in two directions at about 56° and 124°
Typical values: real specimens vary. For more, see mindat.org.