biotite

American

[bahy-uh-tahyt] / ˈbaɪ əˌtaɪt /

noun

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.

biotite British

/ ˈbaɪəˌtaɪt, ˌbaɪəˈtɪtɪk /

noun

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

"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

biotite Scientific

/ bī′ə-tīt′ /

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)Si ₃ O ₁₀ (OH) ₂ .

Other Word Forms

Derived Forms

biotitic

adjective

Etymology

Origin of biotite

1860–65; named after J. B. Biot (1774–1862), French mineralogist and mathematician; see -ite ¹

Vocabulary lists containing biotite

Rocks and Minerals - Middle School and High School

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Biotite mica has more iron and magnesium and is considered a ferromagnesian silicate mineral.

From Textbooks • Jan. 1, 2017

Biotite and hornblende are also commonly used for K-Ar dating.

From Textbooks • Jan. 1, 2015

Biotite is, however, readily distinguished by its darker colour, strong pleochroism, and small optic axial angle.

From Encyclopaedia Britannica, 11th Edition, Volume 3, Slice 7 "Bible" to "Bisectrix" by Various

Biotite, containing haloes, 223; pleochroism of, 235; intensified pleochroism in halo, 235.

From The Birth-Time of the World and Other Scientific Essays by Joly, John

Biotite granites, which take a good polish and are used for monuments and for decoration, are quarried in Oglethorpe and Elbert counties.

From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 7 "Geoponici" to "Germany" by Various

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023