a dark-colored, soft
, monoclinic mica, K(Mg,Fe)3
, found in igneous, metamorphic, and sedimentary
Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'biotite'
: so named after J. B. Biot
(1774-1862), Fr physicist + -it