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

Derived Forms

• biotitic
  adjective

Etymology

Origin of biotite

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

Example Sentences

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, 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

The mica in recent volcanic rocks, gabbros, and diorites is usually Biotite, while that so common in metamorphic limestones is usually, if not always, Phlogopite.

From The Student's Elements of Geology by Lyell, Charles, Sir