Mineralogy Database

Illite Mineral Data

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General Illite Information

Help on Chemical  Formula: Chemical Formula: (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)]
Help on Composition: Composition: Molecular Weight = 389.34 gm
   Potassium   6.03 %  K     7.26 % K2O
   Magnesium   1.87 %  Mg    3.11 % MgO
   Aluminum    9.01 %  Al   17.02 % Al2O3
   Iron        1.43 %  Fe    1.85 % FeO
   Silicon    25.25 %  Si   54.01 % SiO2
   Hydrogen    1.35 %  H    12.03 % H2O
   Oxygen     55.06 %  O
             ______        ______ 
             100.00 %       95.27 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: K0.6(H3O)0.4Al1.3Mg0.3Fe2+0.1Si3.5O10(OH)2�(H2O)
Help on Environment: Environment: Weathering or hydrothermal alteration of muscovite-phengite. Also authigenic alteration of K-spar or recrystallization of smectites in marine sediments. Group name for dioctahedral interlayer-deficient clays.
Help on IMA Status: IMA Status: Not Approved IMA 1998
Help on Locality: Locality: Maquoketa shale, Gilead, Calhoun County, Illinois, USA. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named in 1937 for the state of Illinois where the mineral was first described.
Help on Name Pronunciation: Name Pronunciation: Illite Say ILLITE
Help on Synonym: Synonym: Gumbelite
  Hydromica
  Hydromuscovite
 

Illite Image

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  Illite

Comments: Wispy, authigenic illite crystals lining a pore space in sandstone. SEM image from a core sample.
Location: Unknown. Scale: Picture size 33 µ-m.
© OMNI Laboratories, Inc

Illite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.5768:1:1.1492
Help on Cell Dimensions: Cell Dimensions: a = 5.18, b = 8.98, c = 10.32, Z = 2; beta = 101.83° V = 469.85 Den(Calc)= 2.75
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): 4.43(1), 2.56(0.85), 3.66(0.4),
 

Physical Properties of Illite

Help on Cleavage: Cleavage: {001} Perfect
Help on Color: Color: White.
Help on Density: Density: 2.6 - 2.9, Average = 2.75
Help on Diaphaneity: Diaphaneity: Translucent
Help on Habit: Habit: Aggregates - Made of numerous individual crystals or clusters.
Help on Hardness: Hardness: 1-2 - Between Talc and Gypsum
Help on Luster: Luster: Earthy (Dull)
Help on Streak: Streak: white
 

Optical Properties of Illite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.021 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.021 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2079,KPDmeas= 0.2079,KC= 0.2124
Ncalc = 1.55 - 1.62
Help on Optical Data: Optical Data: Biaxial (-), a=1.535-1.57, b=1.555-1.6, g=1.565-1.605, bire=0.0300-0.0350, 2V(Calc)=42-68, 2V(Meas)=5-25. Dispersion none.
Help on Pleochroism (x): Pleochroism (x): colorless.
Help on Pleochroism (y): Pleochroism (y): colorless.
Help on Pleochroism (z): Pleochroism (z): colorless.
 

Calculated Properties of Illite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.77 gm/cc
note: Specific Gravity of Illite =2.75 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PEIllite = 2.33 barns/electron
U=PEIllite x relectron= 6.45 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 87.50 (Gamma Ray American Petroleum Institute Units)
Concentration of Illite per GRapi unit = 1.14 (%)

Estimated Radioactivity from Illite - barely detectable

 

Illite Classification

Help on  Dana Class: Dana Class: 71.02.02d.02 (71)Phyllosilicate Sheets of Six-Membered Rings
  (71.02)with 2:1 Layers
  (71.02.02d)Mica Group (Hydromica subgroup)
 
71.02.02d.01 Hydrobiotite [K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2]•[(Mg,Fe,Al)3(Si,Al)4O10(OH)2•4(H2O)] C 2/m 2/m
 
71.02.02d.02 Illite* (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/m 2/m
 
71.02.02d.03 Vermiculite (Mg,Fe,Al)3(Al,Si)4O10(OH)2•4(H2O) C 2/m 2/m
 
71.02.02d.04 Brammallite* (Na,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/c 2/m
Help on  Strunz Class: Strunz Class: 09.EC.60 09 - SILICATES (Germanates)
  09.E - Phyllosilicates
  09.EC -Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets
 
09.EC.60 Aliettite [Mg3Si4O10(OH)2](Ca0.5,Na)0.33(Al,Mg,Fe)2-3(Si,Al)4O10(OH)2•n(H2O) Unk Mono
 
09.EC.60 Dozyite (Mg7Al2)(Si4Al2)O15(OH)12 Cm m
 
09.EC.60 Corrensite (Ca,Na,K)(Mg,Fe,Al)9(Si,Al)8O20(OH)10•n(H2O) Unk Ortho
 
09.EC.60 Kulkeite Na0.35Mg8AlSi7O20(OH)10 Unk Mono
 
09.EC.60 Karpinskite (Mg,Ni)2Si2O5(OH)2(?) Unk Mono
 
09.EC.60 Illite* (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/m 2/m
 
09.EC.60 Hydrobiotite [K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2]•[(Mg,Fe,Al)3(Si,Al)4O10(OH)2•4(H2O)] C 2/m 2/m
 
09.EC.60 Lunijianlaite LiAl6(Si7Al)O20(OH)10 Unk Mono
 
09.EC.60 Rectorite (Na,Ca)Al4(Si,Al)8O20(OH)4•2(H2O) Unk Mono
 
09.EC.60 Saliotite Na0.5Li0.5Al3AlSi3O10(OH)5 C 2/m 2/m
 
09.EC.60 Tosudite Na0,5(Al,Mg)6(Si,Al)8O18(OH)12•5(H2O) Unk Ortho
 
09.EC.60 Brinrobertsite! (Na,K,Ca)x(Al,Fe,Mg)4(Si,Al)8O20(OH)4•3.54(H2O)[x=0.35,n=3.54] pseudo 2/m 2/m
 

Other Illite Information

Help on References: References: NAME( Dana8) PHYS. PROP.(Eur. J. Min.,Vol.9,p821-827,1997) OPTIC PROP.(Heinrich65)
Help on See Also: See Also: Links to other databases for Illite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Franklin Minerals(Dunn)
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - MinDAT
10 - Mineralienatlas (Deutsch)
11 - Online Mineral Museum
12 - QUT Mineral Atlas
13 - Ruff.Info

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

Illite

(K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)]
Dana No: 71.02.02d.02 Strunz No: 09.EC.60
Locality:

 

Notes:

 

 
   
 


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