• synonyms


[ak-tin-l-ahyt, ak-tuh-nl-]
noun Mineralogy.
  1. a variety of amphibole, occurring in greenish bladed crystals or in masses.
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Origin of actinolite

First recorded in 1825–35; actino- + -lite
Related formsac·tin·o·lit·ic [ak-tin-l-it-ik, ak-tuh-nl-] /ækˌtɪn lˈɪt ɪk, ˌæk tə nl-/, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for actinolite

Historical Examples

  • The actinolite slate is dark green, and formed by an almost insensible gradation from the mica slate.

    In the Arctic Seas

    Francis Leopold McClintock

  • Byssolite, bis′o-līt, n. an olive-green variety of actinolite, in long crystals.

  • Actinolite is a green silicate of lime, magnesia, and iron 322 especially common in certain metamorphic rocks.


    William J. Miller

  • It is entirely composed of a slaty rock, traversed by numerous veins of Actinolite.

British Dictionary definitions for actinolite


  1. a green mineral of the amphibole group consisting of calcium magnesium iron silicate. Formula: Ca 2 (Mg,Fe) 5 Si 8 O 22 (OH) 2
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Word Origin

C19: from actino- (from the radiating crystals in some forms) + -lite
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

actinolite in Science


  1. A greenish variety of amphibole. Actinolite is a monoclinic mineral, and occurs in long, slender, green needlelike crystals, or in fibrous, radiated forms in metamorphic rocks. Chemical formula: Ca2(Mg,Fe)5Si8O22OH2.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.