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[ak-tin-l-ahyt, ak-tuh-nl-] /ækˈtɪn lˌaɪt, ˈæk tə nl-/
noun, Mineralogy
a variety of amphibole, occurring in greenish bladed crystals or in masses.
Origin of actinolite
1825-35; actino- + -lite
Related forms
[ak-tin-l-it-ik, ak-tuh-nl-] /ækˌtɪn lˈɪt ɪk, ˌæk tə nl-/ (Show IPA),
adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for actinolite
  • Anthophyllite can be distinguished from actinolite and tremolite by its nearly parallel extinction.
  • Retrograde alteration to actinolite, chlorite, and clays may be present.
British Dictionary definitions for actinolite


a green mineral of the amphibole group consisting of calcium magnesium iron silicate. Formula: Ca2(Mg,Fe)5Si8O22(OH)2
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
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actinolite in Science
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.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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