biotite

American  

[bahy-uh-tahyt] / ˈbaɪ əˌtaɪt /

noun

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.

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biotite British  

/ ˈbaɪəˌtaɪt, ˌbaɪəˈtɪtɪk /

noun

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

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biotite Scientific  

/ bī′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)Si ₃ O ₁₀ (OH) ₂ .

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Other Word Forms

• biotitic adjective

Etymology

Origin of biotite

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

Example Sentences

Geochemical fingerprinting of the widespread Toba tephra using biotite compositions.

From Nature • Mar. 11, 2018

Diorite is identifiable by it’s Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar.

From Textbooks • Jan. 1, 2017

Chlorite, muscovite, biotite, garnet, and staurolite are index minerals representing a respective sequence of low-to-high grade rock.

From Textbooks • Jan. 1, 2017

To be more specific, felsic rocks typically have biotite and/or amphibole; intermediate rocks have amphibole and, in some cases, pyroxene; and mafic rocks have pyroxene and, in some cases, olivine.

From Textbooks • Jan. 1, 2015

Their essential minerals are those of basalt, viz. olivine, augite and plagioclase felspar, while hornblende, ilmenite, apatite and biotite are their commonest accessory ingredients.

From Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 6 "Dodwell" to "Drama" by Various