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.

---

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

---

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 .

---

Other Word 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

Geochemical fingerprinting of the widespread Toba tephra using biotite compositions.

From Nature • Mar. 11, 2018

Rearrange the following minerals in order of increasing metamorphic grade: biotite, garnet, sillimanite, chlorite.

From Textbooks • Jan. 1, 2015

During the ore-forming process, some of the original minerals in these rocks are altered to potassium feldspar, biotite, epidote, and various clay minerals.

From Textbooks • Jan. 1, 2015

Commonly even very felsic rocks will not have biotite or muscovite because they may not have enough aluminum or enough hydrogen to make the OH complexes that are necessary for mica minerals.

From Textbooks • Jan. 1, 2015

Each mineral may also enclose particles of the others; in the quartz, for example, small crystals of graphite, biotite, iron oxides, sillimanite or felspar may appear in great numbers.

From Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 6 "Home, Daniel" to "Hortensius, Quintus" by Various