Mineral · Amphibole group
Actinolite
Ca2(Mg,Fe2+)5Si8O22(OH)2
Actinolite is the green calcium magnesium iron amphibole of greenschists, forming bladed and fibrous crystals in Alpine clefts, Pakistan and Zillertal (Austria), and the green needles in 'actinolite in quartz'. Nephrite jade is fine-grained actinolite–tremolite. Fibrous (asbestiform) actinolite is a regulated asbestos mineral.
| Formula | Ca2(Mg,Fe2+)5Si8O22(OH)2 |
|---|---|
| IMA status | approved |
| Crystal system | Monoclinic |
| Mohs hardness | 5–6 |
| Group | Amphibole group |
| Type locality | None |
| Streak | White |
| Specific gravity | 3.0 |
| Reference list | IMA List of Minerals (RRUFF) — verify formula and status against the current list |
Handling and safety
Asbestiform actinolite is asbestos; do not crush or breathe dust from fibrous specimens.
Elsewhere
Cite this article
Stratum Study. "Actinolite" (Mineral). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/minerals/actinolite. Accessed 2026-09-20.
@misc{stratum-actinolite,
title = {Actinolite},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/minerals/actinolite}},
year = {2026},
note = {Mineral article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, wikidata, commons. Accessed 2026-09-20.}
} Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.