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Actinolite

/ækˈtɪnəlaɪt/noun

A green amphibole mineral that grows in slender radiating crystals, one of the forms of asbestos.

The Greek roots

ἀκτίς
aktís
ray, beam of light
+
λίθος
líthos
stone

Literally: ray stone

The story of the word

Richard Kirwan named it in 1794 for the way its needles fan out from a point, like spokes or beams. The same ἀκτίς gives actinium, the element named for its rays, and the actinic light that burns photographic film. Actinolite has a quieter twin in this batch: nephrite jade is a compact felted mass of actinolite and tremolite fibres, which is why jade is so hard to break.

How it travelled
Ancient Greek → scientific coinage → English
First recorded
1794

Same family

actiniumactinicmonolithlithography

In a sentence

Under the lens the actinolite showed as a spray of green needles across the rock face.

Built on the same root

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