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 /

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

See Examples For:

biotite

Geochemical fingerprinting of the widespread Toba tephra using biotite compositions.

From Nature ● Mar. 11, 2018

In some cases, hornfels has visible crystals of minerals like biotite or andalusite.

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

Figure 5.10 A granitic rock containing biotite and amphibole which have been altered near to the rock’s surface to limonite, which is a mixture of iron oxide minerals.

From Textbooks ● Jan. 1, 2015

Often they enclose dark crystals of biotite and hornblende, arranged zonally.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3 "Gordon, Lord George" to "Grasses" by Various