[ bahy-uh-tahyt ]

  1. a very common mineral of the mica group, occurring in black, dark-brown, or dark-green sheets and flakes: an important constituent of igneous and metamorphic rocks.

Origin of biotite

1860–65; named after J. B. Biot (1774–1862), French mineralogist and mathematician; see -ite1

Other words from biotite

  • bi·o·tit·ic [bahy-uh-tit-ik], /ˌbaɪ əˈtɪt ɪk/, adjective

Words Nearby biotite Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use biotite in a sentence

British Dictionary definitions for biotite


/ (ˈbaɪəˌtaɪt) /

  1. a black or dark green mineral of the mica group, found in igneous and metamorphic rocks. Composition: hydrous magnesium iron potassium aluminium silicate. Formula: K(Mg,Fe) 3 (Al,Fe)Si 3 O 10 (OH) 2 . Crystal structure: monoclinic

Derived forms of biotite

  • biotitic (ˌbaɪəˈtɪtɪk), adjective

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

Scientific definitions for biotite


[ ə-tīt′ ]

  1. A dark-brown or dark-green to black mica. Biotite is monoclinic and is found in igneous, metamorphic, and sedimentary rocks. Chemical formula: K(Mg,Fe)3(Al,Fe)Si3O10(OH)2.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.