actinolite

 
Pronunciation: /akˈtɪnəlʌɪt/

noun

[mass noun]
  • a green mineral of the amphibole group containing calcium, magnesium, and iron and occurring chiefly in metamorphic rocks and as a form of asbestos.

Origin:

late 18th century: from Greek aktis, aktin- 'ray' + lithos 'stone' (because of the ray-like crystals)