from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A dark-brown or dark-green to black mica, K(Mg,Fe)3(Al,Fe)Si3O10(OH)2, found in igneous and metamorphic rocks.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A dark brown mica; it is a mixed aluminosilicate and fluoride of potassium, magnesium and iron.

from the GNU version of the Collaborative International Dictionary of English

  • n. Mica containing iron and magnesia, generally of a black or dark green color; -- a common constituent of crystalline rocks. See mica.

from The Century Dictionary and Cyclopedia

  • n. An important member of the mica group of minerals. See mica.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. dark brown to black mica found in igneous and metamorphic rock


from The American Heritage® Dictionary of the English Language, 4th Edition

After Jean Baptiste Biot (1774-1862), French physicist.

from Wiktionary, Creative Commons Attribution/Share-Alike License

Biot +‎ -ite, named by J.F.L. Hausmann in 1847 in honour of the French physicist Jean-Baptiste Biot, who, in 1816, researched the optical properties of mica, discovering many unique properties.


  • In certain minerals, notably the brown variety of mica known as biotite, the microscope reveals minute circular marks occurring here and there, quite irregularly.

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  • Furthermore, their model included a second mineral called biotite, surrounding a zircon core.

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  • And micas such as biotite have been found in regions containing evidence of the earliest life-forms, which are believed to have existed about 3.8 million years ago.

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  • Cape Maclear at the north end is rocky, predominantly biotite-granite.

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  • He also put a challenge to geologists to to synthesize "a hand-sized specimen of a typical biotite-bearing granite" as a test and was dismissed, G.

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  • Vermiculite is formed by the alteration and/or weathering of the minerals biotite and phlogopite.


  • Black biotite contains potassium, iron, and magnesium.


  • The mica group of minerals includes: biotite, muscovite, lepidolite, and phlogopite.


  • The breakdown of biotite and phlogopite creates vermiculite.


  • Most significant is the presence of the Sinharaja Basic Zone, consisting of hornblende, pyriclasts, basic charnokites, pyroxene amphibolites and scapolite-bearing calc-granulites and blended with small amounts of quartzites, garnet-biotite gneisses and intermediate charnokites.

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