Biotite Mineral Data + Say BIOTITE

General Biotite Information
Help on Chemical Formula: Chemical Formula: K(Mg,Fe++)3[AlSi3O10(OH,F)2
Help on Composition: Composition: Molecular Weight = 433.53 gm
   Potassium   9.02 %  K    10.86 % K2O
   Magnesium  14.02 %  Mg   23.24 % MgO
   Aluminum    6.22 %  Al   11.76 % Al2O3
   Iron        6.44 %  Fe    8.29 % FeO
   Silicon    19.44 %  Si   41.58 % SiO2
   Hydrogen    0.41 %  H     3.64 % H2O
   Oxygen     43.36 %  O
   Fluorine    1.10 %  F     1.10 % F
                -   %  F    -0.46 % -O=F2
             ______        ______ 
             100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: KMg2.5Fe2+0.5AlSi3O10(OH)1.75F0.25
Help on Environment: Environment: Granitic rocks. Forms a series with phlogopite. Has several polytypes (1M, 3T, 2M1). Biotite is now a group name for phlogopite, siderophyllite and eastonite.
Help on IMA Status: IMA Status: Not Approved IMA 1998
Help on Locality: Locality: Common world wide. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named in 1847 after the French physicist, Jean Baptiste Biot (1774 - 1862), who studied the optical properties of the micas.
Help on Synonym: Synonym: Iron Mica
  Lepidomelane (Fe)
  Manganophyllite (Mn)
  Micaceous Iron Ore
 

Biotite Image

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Biotite

Comments: Brown book of pseudohexagonal biotite crystals in matrix.
Location: Sattleberg, Laacher See, Rhineland-Palatinate, Germany. Scale: Size Not Given.
© Lou Perloff / Photo Atlas of Minerals
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Biotite

Comments: Sharp hexagonal plates of dark brown biotite to 2.5 cm. across, with white albite.
Location: Brazil. Scale: 6.9x5.5x3 cm.
© Richard Dale / Dale Minerals
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Biotite   Anthophyllite

Comments: Fibrous mass of anthophyllite as a shell around biotite.
Location: Hermanov, Severocesky, Czech Republic. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species
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Biotite   Wohlerite

Comments: Prismatic wohlerite crystals with lepidomelane (Fe-rich biotite).
Location: Langevannet, Tvedalen, Telemark, Norway. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Biotite Crystallography
Help on Axial Ratios: Axial Ratios: a:b:c =0.5771:1:1.1046
Help on Cell Dimensions: Cell Dimensions: a = 5.343, b = 9.258, c = 10.227, Z = 2; beta = 100.26° V = 497.79 Den(Calc)= 2.89
Help on Crystal System: Crystal System: Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 3.37(1), 10.1(1), 2.66(0.8),
Help on Forms: Forms:

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Forms: [ 1 1 2] [ 2 2 1] [ 0 1 0] [ 0 0 1]

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Hendricks S B , Jefferson M E , American Mineralogist , 24 (1939) p.729-771, Polymorphism of the micas with optical measurements

View Additional jPOWD Structure files for Biotite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [2] [20] [21] [22] [23] [24] [25] [26] [27] [28] [3] [4] [5] [6] [7] [8] [9]
 

Physical Properties of Biotite

Help on Cleavage: Cleavage: [001] Perfect
Help on Color: Color: Dark brown, Greenish brown, Blackish brown, Yellow, White.
Help on Density: Density: 2.8 - 3.4, Average = 3.09
Help on Diaphaniety: Diaphaniety: Transparent to translucent to opaque
Help on Fracture: Fracture: Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Help on Habit: Habit: Lamellar - Thin laminae producing a lamellar structure.
Help on Habit: Habit: Micaceous - Platy texture with "flexible" plates.
Help on Habit: Habit: Pseudo Hexagonal - Crystals show a hexagonal outline.
Help on Hardness: Hardness: 2.5-3 - Finger Nail-Calcite
Help on Luminescence: Luminescence: None.
Help on Luster: Luster: Vitreous - Pearly
Help on Streak: Streak: gray
 

Optical Properties of Biotite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.026 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.044 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2163,KPDmeas= 0.2016,KC= 0.2071
Help on Optical Data: Optical Data: Biaxial (-), a=1.565-1.625, b=1.605-1.675, g=1.605-1.675, bire=0.0400-0.0500, 2V(Calc)=0, 2V(Meas)=0-25. Dispersion r > v or r < v.
Help on Pleochroism (x): Pleochroism (x): yellow, buff, light brown, pale greenish brown, or pale greenish brown.
Help on Pleochroism (y): Pleochroism (y): reddish brown, brown, greenish brown, bluish green, or opaque.
Help on Pleochroism (z): Pleochroism (z): reddish brown, golden yellow brown, dark brown, green, or opaque.
 

Calculated Properties of Biotite

Help on Electron Density: Electron Density:

relectron=3.07 gm/cc
note: rBiotite =3.10 gm/cc.
Help on Fermion Index Fermion Index Fermion Index = 0.02467
Boson Index = 0.97533
Help on Photoelectric: Photoelectric:

PEBiotite = 4.04 barns/electron
U=PEBiotite x relectron= 12.42 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 129.08 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Biotite - barely detectable

 

Biotite Classification
Help on Dana Class: Dana Class: 71.2.2b.2 (71)Phyllosilicate Sheets of Six-Membered Rings
  (71.2)with 2:1 Layers
  (71.2.2b)Mica Group (Biotite subgroup)
 
71.2.2b.1 Phlogopite KMg3(Si3Al)O10(F,OH)2 C 2/m 2/m
 
71.2.2b.1a Tetra-ferriphlogopite! KMg3FeSi3O10(OH)2 2/m
 
71.2.2b.1b Shirozulite! KMn3(AlSi3)O10(OH,F)2 C 2/m 2/m
 
71.2.2b.2 Biotite * K(Mg,Fe)3[AlSi3O10(OH,F)2 C 2/m 2/m
 
71.2.2b.3 Annite KFe3AlSi3O10(OH,F)2 C 2/m 2/m
 
71.2.2b.3a Fluorannite! KFe3AlSi3O10F2 C 2/m 2/m
 
71.2.2b.4 Tetra-ferri-annite K(Fe,Mg)3(Fe,Al)Si3O10(OH)2 C 2/m 2/m
 
71.2.2b.5 Siderophyllite KFe2Al(Al2Si2)O10(F,OH)2 C 2/m 2/m
 
71.2.2b.5a Eastonite! KMg2Al[Al2Si2O10](OH)2 2/m
 
71.2.2b.6 Hendricksite K(Zn,Mg,Mn)3Si3AlO10(OH)2 C 2/m 2/m
 
71.2.2b.7 Lepidolite K(Li,Al)3(Si,Al)4O10(F,OH)2 C 2/m,Cm Mono
 
71.2.2b.8 Polylithionite KLi2AlSi4O10(F,OH)2 C 2/m 2/m
 
71.2.2b.8a Trilithionite! KLi1.5Al1.5AlSi3O10F2 C 2/m 2/m
 
71.2.2b.8b Sokolovaite! CsLi2AlSi4O10F2 C 2/m, C 2 or Cm Mono
 
71.2.2b.9 Tainiolite KLiMg2Si4O10F2 C 2/m 2/m
 
71.2.2b.10 Zinnwaldite KLiFeAl(AlSi3)O10(F,OH)2 C 2/m 2/m
 
71.2.2b.11 Norrishite K(Mn2Li)Si4O10(O)2 C 2/m 2/m
 
71.2.2b.12 Masutomilite K(Li,Al,Mn)3[(Si,Al)4O10](F,OH)2 C 2/m 2/m
 
71.2.2b.13 Aspidolite NaMg3AlSi3O10(OH)2 C 2/m 2/m
 
71.2.2b.14 Wonesite (Na,K).5(Mg,Fe,Al)3(Si,Al)4O10(OH,F)2 C 2/m 2/m
 
71.2.2b.15 Preiswerkite NaMg2Al3Si2O10(OH)2 C 2/m 2/m
 
71.2.2b.16 Ephesite NaLiAl2(Al2Si2)O10(OH)2 C 2/c 2/m
 
71.2.2b.17 IMA2004-049! NaMg3(AlSi3)O10(OH)2 C 2/m 2/m
Help on Strunz Class: Strunz Class: VIII/H.11-00 VIII - Silicates
  VIII/H - Phyllosilicates (layered) Mica like layered silicates with [Si4O10]4- and related groups
  VIII/H.11 - Mica group, Biotite series
 

Other Biotite Information
Help on References: References: NAME( Dana) PHYS. PROP.(Dana8) OPTIC PROP.(Heinrich65)
Help on See Also: See Also: Links to other databases for Biotite :
1 - Alkali-Nuts(English) 2 - Alkali-Nuts(Francais) 3 -Am. Min. Crystal Structure Database 4 - Amethyst Galleries' Mineral Gallery 5 - Applied Mineralogy 6 -Athena 7 - Crocoite.com Mineral Locations 8 - EUROmin Project 9 - Franklin Minerals(Dunn) 10 - Franklin Minerals(Palache) 11 - Glendale Community College 12 -Google Images 13 -Google Scholar 14 -Handbook of Mineralogy (MinSocAm) 15 -Handbook of Mineralogy (UofA) 16 -MinDAT 17 -MinMax(Deutsch) 18 -MinMax(English) 19 -Mineralienatlas (Deutsch) 20 - Minerals in Thin Section-University of North Carolina 21 -Minerals in Thin Sections-Humboldt State 22 - Minerals of Wisconsin 23 -QUT Mineral Atlas 24 - Scandinavian mineral gallery 25 - Thin Sections - Brock University 26 - UCLA - Petrography Thin-Sections 27 -University of Minnesota 28 - WWW-MINCRYST 29 -École des Mines de Paris

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Biotite

K(Mg,Fe++)3[AlSi3O10(OH,F)2
Dana No: 71.2.2b.2 Strunz No: VIII/H.11-00
Locality:

 

Notes:

 
 
   
 
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