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A lustrous yellow, green, or black mineral, Ca2(Al, Fe)3(SiO4)3OH, commonly found in metamorphic rock.
[French épidote, from Greek epididonai, to give in addition, increase (from the greater length of its crystals compared with those of related minerals) : epi-, epi- + didonai, to give; see dō- in Indo-European roots.]
ep′i·dot′ic (-dŏt′ĭk) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Minerals) a green mineral consisting of hydrated calcium iron aluminium silicate in monoclinic crystalline form: common in metamorphic rocks. Formula: Ca2(Al,Fe)3(SiO4)3(OH)
[C19: from French épidote, ultimately from Greek epididonai to increase, from didonai to give; so called because two sides of its crystal are longer than the other two sides]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
a mineral, hydrous calcium aluminum iron silicate, Ca2(Al, Fe)3Si3O12(OH), occurring in green prismatic crystals or in masses.
[1800–10; < French épidote < Greek *epidotós given besides, increased]
ep`i•dot′ic (-ˈdɒt ɪk) adj.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.