Mineralogy Database

Biotite Mineral Data

Search Webmineral :
  
Advertisment

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 - Bitote is now the group name
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 Name Pronunciation: Name Pronunciation: Biotite Say BIOTITE
Help on Synonym: Synonym: Iron Mica
  Lepidomelane (Fe)
  Manganophyllite (Mn)
  Micaceous Iron Ore
  Oxybiotite
 

Biotite Image

Click Here for Larger   Image in a New Browser Window Images:
Click Here for Larger   Image

  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

Click Here for Larger   Image in a New Browser Window Images:
Click Here for Larger   Image

  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

Click Here for Larger   Image in a New Browser Window Images:
Click Here for Larger   Image

  Anthophyllite   Biotite

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

Click Here for Larger   Image in a New Browser Window Images:
Click Here for Larger   Image

  Wohlerite   Biotite

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 - Prismatic H-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:

Mouse
Dbl Clk - Start-Stop Rotation
RMB - Cycle Display Modes
Drag1 - Manipulate Crystal
Drag2 - Resize

Keyboard
S - Stereo
I - Indicies
<space> - Start-Stop Rotation
F - Fit to Screen
M - Menu

Help on Above

Forms: ( 1 1 2) ( 2 2 1) ( 0 1 0) ( 0 0 1)

Warning: this java applet does not work in some browsers because of security restrictions.

 

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 Diaphaneity: Diaphaneity: 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: Non-fluorescent.
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
Ncalc = 1.58 - 1.7
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.
 

Calculated Properties of Biotite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.07 gm/cc
note: Specific Gravity of Biotite =3.10 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.02
Boson Index = 0.98
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)
Concentration of Biotite per GRapi unit = 0.77 (%)

Estimated Radioactivity from Biotite - barely detectable

 

Biotite Classification

Help on  Dana Class: Dana Class: 71.02.02b.02 (71)Phyllosilicate Sheets of Six-Membered Rings
  (71.02)with 2:1 Layers
  (71.02.02b)Mica Group (Biotite subgroup)
 
71.02.02b.01 Phlogopite KMg3(Si3Al)O10(F,OH)2 C 2/m 2/m
 
71.02.02b.01a Tetraferriphlogopite! KMg3FeSi3O10(OH)2 2/m
 
71.02.02b.01b Shirozulite! KMn3(AlSi3)O10(OH,F)2 C 2/m 2/m
 
71.02.02b.01c Fluorophlogopite! KMg3(AlSi3)O10F2 C 2/m 2/m
 
71.02.02b.02 Biotite* K(Mg,Fe)3[AlSi3O10(OH,F)2 C 2/m 2/m
 
71.02.02b.03 Annite KFe3AlSi3O10(OH,F)2 C 2/m 2/m
 
71.02.02b.03a Fluorannite! KFe3AlSi3O10F2 C 2/m 2/m
 
71.02.02b.04 Tetraferriannite K(Fe,Mg)3(Fe,Al)Si3O10(OH)2 C 2/m 2/m
 
71.02.02b.05 Siderophyllite KFe2Al(Al2Si2)O10(F,OH)2 C 2/m 2/m
 
71.02.02b.05a Eastonite! KMg2Al[Al2Si2O10](OH)2 2/m
 
71.02.02b.06 Hendricksite K(Zn,Mg,Mn)3Si3AlO10(OH)2 C 2/m 2/m
 
71.02.02b.07 Lepidolite K(Li,Al)3(Si,Al)4O10(F,OH)2 C 2/m,Cm Mono
 
71.02.02b.08 Polylithionite KLi2AlSi4O10(F,OH)2 C 2/m 2/m
 
71.02.02b.08a Trilithionite! KLi1.5Al1.5AlSi3O10F2 C 2/m 2/m
 
71.02.02b.08b Sokolovaite! CsLi2AlSi4O10F2 C 2/m, C 2 or Cm Mono
 
71.02.02b.09 Tainiolite KLiMg2Si4O10F2 C 2/m 2/m
 
71.02.02b.10 Zinnwaldite KLiFeAl(AlSi3)O10(F,OH)2 C 2/m 2/m
 
71.02.02b.11 Norrishite K(Mn2Li)Si4O10(O)2 C 2/m 2/m
 
71.02.02b.12 Masutomilite K(Li,Al,Mn)3[(Si,Al)4O10](F,OH)2 C 2/m 2/m
 
71.02.02b.13 Aspidolite NaMg3AlSi3O10(OH)2 C 2/m 2/m
 
71.02.02b.14 Wonesite (Na,K).5(Mg,Fe,Al)3(Si,Al)4O10(OH,F)2 C 2/m 2/m
 
71.02.02b.15 Preiswerkite NaMg2Al3Si2O10(OH)2 C 2/m 2/m
 
71.02.02b.16 Ephesite NaLiAl2(Al2Si2)O10(OH)2 C 2/c 2/m
 
71.02.02b.18 Suhailite! (NH4)Fe3(Si3Al)O10(OH)2 C 2/m? 2/m
Help on  Strunz Class: Strunz Class: 09.EC.20 09 - SILICATES (Germanates)
  09.E - Phyllosilicates
  09.EC -Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets
 
09.EC.20 Annite KFe3AlSi3O10(OH,F)2 C 2/m 2/m
 
09.EC.20 Biotite* K(Mg,Fe)3[AlSi3O10(OH,F)2 C 2/m 2/m
 
09.EC.20 Hendricksite K(Zn,Mg,Mn)3Si3AlO10(OH)2 C 2/m 2/m
 
09.EC.20 Ephesite NaLiAl2(Al2Si2)O10(OH)2 C 2/c 2/m
 
09.EC.20 Aspidolite NaMg3AlSi3O10(OH)2 C 2/m 2/m
 
09.EC.20 Lepidolite K(Li,Al)3(Si,Al)4O10(F,OH)2 C 2/m,Cm Mono
 
09.EC.20 Preiswerkite NaMg2Al3Si2O10(OH)2 C 2/m 2/m
 
09.EC.20 Masutomilite K(Li,Al,Mn)3[(Si,Al)4O10](F,OH)2 C 2/m 2/m
 
09.EC.20 Wonesite (Na,K).5(Mg,Fe,Al)3(Si,Al)4O10(OH,F)2 C 2/m 2/m
 
09.EC.20 Polylithionite KLi2AlSi4O10(F,OH)2 C 2/m 2/m
 
09.EC.20 Phlogopite KMg3(Si3Al)O10(F,OH)2 C 2/m 2/m
 
09.EC.20 Norrishite K(Mn2Li)Si4O10(O)2 C 2/m 2/m
 
09.EC.20 Siderophyllite KFe2Al(Al2Si2)O10(F,OH)2 C 2/m 2/m
 
09.EC.20 Fluorannite! KFe3AlSi3O10F2 C 2/m 2/m
 
09.EC.20 Shirokshinite! K(NaMg2)Si4O10F2 C 2/m 2/m
 
09.EC.20 Zinnwaldite KLiFeAl(AlSi3)O10(F,OH)2 C 2/m 2/m
 
09.EC.20 Eastonite! KMg2Al[Al2Si2O10](OH)2 2/m
 
09.EC.20 Tetraferriannite K(Fe,Mg)3(Fe,Al)Si3O10(OH)2 C 2/m 2/m
 
09.EC.20 Tetraferriphlogopite! KMg3FeSi3O10(OH)2 2/m
 
09.EC.20 Trilithionite! KLi1.5Al1.5AlSi3O10F2 C 2/m 2/m
 
09.EC.20 Sokolovaite! CsLi2AlSi4O10F2 C 2/m, C 2 or Cm Mono
 
09.EC.20 Shirozulite! KMn3(AlSi3)O10(OH,F)2 C 2/m 2/m
 
09.EC.20 Suhailite! (NH4)Fe3(Si3Al)O10(OH)2 C 2/m? 2/m
 
09.EC.20 Fluorophlogopite! KMg3(AlSi3)O10F2 C 2/m 2/m
 

Other Biotite Information

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 - Athena
6 - EUROmin Project
7 - Ecole des Mines de Paris
8 - Franklin Minerals(Dunn)
9 - Franklin Minerals(Palache)
10 - GeoScienceWorld
11 - Glendale Community College
12 - Google Images
13 - Google Scholar
14 - Handbook of Mineralogy (MinSocAm)
15 - Handbook of Mineralogy (UofA)
16 - MinDAT
17 - Mineral and Gemstone Kingdom
18 - Mineralienatlas (Deutsch)
19 - Minerals in Thin Section-University of North Carolina
20 - Minerals in Thin Sections-Humboldt State
21 - Online Mineral Museum
22 - QUT Mineral Atlas
23 - Ruff.Info
24 - Scandinavian mineral gallery
25 - UCLA - Petrography Thin-Sections
26 - WWW-MINCRYST

Search for Biotite using:

Google
 
Web webmineral.com
[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Biotite :

Ask about Biotite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Espaņol

Print or Cut-and-Paste your Biotite Specimen Label here :

Biotite

K(Mg,Fe++)3[AlSi3O10(OH,F)2
Dana No: 71.02.02b.02 Strunz No: 09.EC.20
Locality:

 

Notes:

 

 


Dakota Matrix
Excalibur Minerals
Exceptional Minerals
Hudson Insitute
John Betts Fine Minerals
Mc Dougall Minerals
Mineral News
Rock and Mineral Shows
Weinrich Minerals, Inc.