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1
Biotite under microscope
Biotite under microscope
::2013/01/14::
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2
Biotite thin section
Biotite thin section
::2008/11/16::
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3
Biotite
Biotite
::2012/09/20::
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4
Biotite Distortion from Moriae Handmade Pedals
Biotite Distortion from Moriae Handmade Pedals
::2012/11/21::
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5
Moriae Biotite Distortion Demo Colin Smith Alright Reviews
Moriae Biotite Distortion Demo Colin Smith Alright Reviews
::2013/01/11::
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6
Biotite
Biotite
::2013/05/01::
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7
Biotite Exhibiting Pleochroism
Biotite Exhibiting Pleochroism
::2013/02/07::
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8
Optical Mineralogy birds-eye extinction muscovite biotite
Optical Mineralogy birds-eye extinction muscovite biotite
::2009/10/29::
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9
Petrology - H - Biotite Gneiss cross polarised
Petrology - H - Biotite Gneiss cross polarised
::2008/06/13::
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10
Biotite
Biotite
::2013/05/01::
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11
Charles Swara   Biotite Original Mix
Charles Swara Biotite Original Mix
::2014/10/06::
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12
Biotite in PPL
Biotite in PPL
::2010/09/20::
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13
Biotite muscovite schist (XP)
Biotite muscovite schist (XP)
::2014/01/28::
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14
Biotite.mp4
Biotite.mp4
::2010/07/17::
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15
How to Pronounce Biotite
How to Pronounce Biotite
::2013/02/02::
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16
Tekkit #2: "Quartz, Feldspar, Biotite
Tekkit #2: "Quartz, Feldspar, Biotite
::2014/10/09::
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17
Biotite muscovite schist (PPL)
Biotite muscovite schist (PPL)
::2014/01/28::
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18
Garnet biotite muscovite schist (PPL)
Garnet biotite muscovite schist (PPL)
::2014/01/28::
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19
Optical Mineralogy pleochroic halo biotite
Optical Mineralogy pleochroic halo biotite
::2009/10/29::
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20
Garnet biotite muscovite schist (XP)
Garnet biotite muscovite schist (XP)
::2014/01/28::
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21
Biotite Figure
Biotite Figure
::2013/03/10::
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22
Optical Mineralogy pleochroic halo extinction biotite
Optical Mineralogy pleochroic halo extinction biotite
::2009/10/29::
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23
9.7" Big Dark Black Book of BIOTITE MICA Crystals Bear Lake Ontario for sale
9.7" Big Dark Black Book of BIOTITE MICA Crystals Bear Lake Ontario for sale
::2014/01/14::
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24
9.7"XL Classic Book of  BIOTITE MICA Black/white- Canada
9.7"XL Classic Book of BIOTITE MICA Black/white- Canada
::2011/01/19::
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25
Shake shake shake,shake your biotite
Shake shake shake,shake your biotite
::2014/10/08::
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26
8.4" Big Book of Dark Black BIOTITE MICA Crystals Bear Lake Ontario for sale
8.4" Big Book of Dark Black BIOTITE MICA Crystals Bear Lake Ontario for sale
::2013/11/05::
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27
13.5" Big Old Book of DarkBlack BIOTITE MICA Crystals Bear Lake Ontario for sale
13.5" Big Old Book of DarkBlack BIOTITE MICA Crystals Bear Lake Ontario for sale
::2013/07/01::
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28
BIOTITE - H&PARAGON
BIOTITE - H&PARAGON
::2010/10/20::
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29
Biotite first fire
Biotite first fire
::2012/06/16::
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30
biotite granite
biotite granite
::2014/04/26::
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31
biotite hornblende schist
biotite hornblende schist
::2014/04/07::
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32
Biotite after Sinus Elevation Technique&GBR on right side sinus
Biotite after Sinus Elevation Technique&GBR on right side sinus
::2013/11/14::
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33
9.5" Large Black Book of Large BIOTITE MICA Crystals Bear Lake Ontario for sale
9.5" Large Black Book of Large BIOTITE MICA Crystals Bear Lake Ontario for sale
::2014/02/17::
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34
garnet biotite schist
garnet biotite schist
::2014/04/07::
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35
Biotite 2
Biotite 2
::2012/12/15::
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36
Tootsie biotite
Tootsie biotite
::2013/08/20::
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37
biotite 0001
biotite 0001
::2012/12/16::
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38
Biotite 1
Biotite 1
::2012/12/15::
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39
pyroxexe biotite schist
pyroxexe biotite schist
::2014/04/07::
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40
Lily does 100 biotite crunchers
Lily does 100 biotite crunchers
::2013/09/22::
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41
What is Adya Clarity
What is Adya Clarity
::2013/11/22::
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42
Creation Geology Part 7, Polonium Halos
Creation Geology Part 7, Polonium Halos
::2012/09/14::
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43
CRYSTAL HOTTIE CHALLENGE - DAY 2
CRYSTAL HOTTIE CHALLENGE - DAY 2
::2012/11/08::
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44
FUKUSHIMA RADIATION REMEDIATION: MICAROX - The Natural, Powerful Solution
FUKUSHIMA RADIATION REMEDIATION: MICAROX - The Natural, Powerful Solution
::2011/10/28::
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45
PEDRAS PARIDEIRAS - PORTUGAL
PEDRAS PARIDEIRAS - PORTUGAL
::2011/10/03::
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46
Vermiculite
Vermiculite
::2014/08/22::
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47
How did Polonium Haloes form in old rocks?
How did Polonium Haloes form in old rocks?
::2010/01/10::
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48
Sillimanite garnet mica schist (PPL)
Sillimanite garnet mica schist (PPL)
::2014/01/28::
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49
Kyanite garnet mica schist (XP)
Kyanite garnet mica schist (XP)
::2014/01/28::
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50
Optical Mineralogy Andalusite chiastolite
Optical Mineralogy Andalusite chiastolite
::2009/11/11::
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RESULTS [51 .. 101]
From Wikipedia, the free encyclopedia
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Biotite
Biotite aggregate - Ochtendung, Eifel, Germany.jpg
Thin tabular biotite aggregate
(Image width: 2.5 mm)
General
Category Dark mica series
Formula
(repeating unit)
K(Mg,Fe)
3
(AlSi
3
O
10
)(F,OH)
2
Identification
Formula mass 433.53 g
Color Dark brown, greenish-brown, blackish-brown, yellow, white
Crystal habit Massive to platy
Crystal system Monoclinic (2/m)
Space Group: C 2/m
Twinning Common on the [310],
less common on the {001}
Cleavage Perfect on the {001}
Fracture Micaceous
Tenacity Brittle to flexible, elastic
Mohs scale hardness 2.5–3.0
Luster Vitreous to pearly
Streak White
Diaphaneity Transparent to translucent to opaque
Specific gravity 2.7–3.1
Density 2.8–3.4
Optical properties Biaxial (-)
Refractive index nα = 1.565–1.625
nβ = 1.605–1.675
nγ = 1.605–1.675
Birefringence δ = 0.03–0.07
Pleochroism Strong
Dispersion r < v (Fe rich);
r > v weak (Mg rich)
Ultraviolet fluorescence None
References [1][2][3]

Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula K(Mg,Fe)
3
AlSi
3
O
10
(F,OH)
2
. More generally, it refers to the dark mica series, primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more aluminous endmembers include siderophyllite. Biotite was 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.[4]

Biotite is a sheet silicate. Iron, magnesium, aluminium, silicon, oxygen, and hydrogen form sheets that are weakly bound together by potassium ions. It is sometimes called "iron mica" because it is more iron-rich than phlogopite. It is also sometimes called "black mica" as opposed to "white mica" (muscovite) – both form in some rocks, in some instances side-by-side.

Properties[edit]

Like other mica minerals, biotite has a highly perfect basal cleavage, and consists of flexible sheets, or lamellae, which easily flake off. It has a monoclinic crystal system, with tabular to prismatic crystals with an obvious pinacoid termination. It has four prism faces and two pinacoid faces to form a pseudohexagonal crystal. Although not easily seen because of the cleavage and sheets, fracture is uneven. It appears greenish to brown or black, and even yellow when weathered. It can be transparent to opaque, has a vitreous to pearly luster, and a grey-white streak. When biotite is found in large chunks, they are called “books” because it resembles a book with pages of many sheets.

Under cross-polarized light biotite can generally be identified by the gnarled bird's eye extinction.

Occurrence[edit]

Biotite is found in a wide variety of igneous and metamorphic rocks. For instance, biotite occurs in the lava of Mount Vesuvius and in the Monzoni intrusive complex of the western Dolomites. It is an essential phenocryst in some varieties of lamprophyre. Biotite is occasionally found in large cleavable crystals, especially in pegmatite veins, as in New England, Virginia and North Carolina. Other notable occurrences include Bancroft and Sudbury, Ontario. It is an essential constituent of many metamorphic schists, and it forms in suitable compositions over a wide range of pressure and temperature.

The largest documented single crystals of biotite were approximately 7 m2 (75 sq ft) sheets found in Iveland, Norway.[5]

Uses[edit]

biotite: Topotype deposit

Biotite is used extensively to constrain ages of rocks, by either potassium-argon dating or argon-argon dating. Because argon escapes readily from the biotite crystal structure at high temperatures, these methods may provide only minimum ages for many rocks. Biotite is also useful in assessing temperature histories of metamorphic rocks, because the partitioning of iron and magnesium between biotite and garnet is sensitive to temperature.

References[edit]

  1. ^ Biotite mineral information and data Mindat
  2. ^ Biotite Mineral Data Webmineral
  3. ^ Handbook of Mineralogy
  4. ^ Johann Friedrich Ludwig Hausmann (1828). Handbuch der Mineralogie. Vandenhoeck und Ruprecht. p. 674.  "Zur Bezeichnung des sogenannten einachsigen Glimmers ist hier der Name Biotit gewählt worden, um daran zu erinnern, daß Biot es war, der zuerst auf die optische Verschiedenheit der Glimmerarten aufmerksam machte." (For the designation of so-called uniaxial mica, the name "biotite" has been chosen in order to recall that it was Biot who first called attention to the optical differences between types of mica.)
  5. ^ P. C. Rickwood (1981). "The largest crystals". American Mineralogist 66: 885–907. 
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