actinolite

noun

ac·​tin·​o·​lite ak-ˈti-nə-ˌlīt 

: a bright green or grayish-green mineral of the amphibole group that is a silicate of calcium, magnesium, and iron occurring in fibrous, radiate, or columnar forms

Word History

Etymology

actino- + -lite; translation of German Strahlstein, Strahlschörl (earlier New Latin actinotus in the terminology of the naturalist J. F. Gmelin)

First Known Use

1794, in the meaning defined above