Definition of actinolite in English:



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.

    • ‘Calcic amphiboles, including hornblende and actinolite are abundant, and probably are alteration products, which also include albite, orthoclase and rare pyrite.’
    • ‘They have a mineralogical association of quartz, diopside, actinolite, plagioclase and K-feldspar.’
    • ‘Kyanite, microcline, zircon, monazite and opaque minerals are variably present with epidote, actinolite and chlorite being present as secondary alteration minerals.’
    • ‘The presence of several amphibole minerals, such as tremolite, actinolite, anthophyllite, was confirmed.’
    • ‘Amosite, fibrous anthophyllite, fibrous tremolite, fibrous actinolite, and crocidolite are amphiboles, double-chain silicates, which observed microscopically look like sharp needles.’


Late 18th century: from Greek aktis, aktin- ‘ray’ + lithos ‘stone’ (because of the raylike crystals).