Illite Mineral Data

Illite Mineral Data +

General Illite Information

Chemical Formula:

(K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)]

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

Empirical Formula:

K_0.6(H₃O)_0.4Al_1.3Mg_0.3Fe²⁺_0.1Si_3.5O₁₀(OH)₂·(H₂O)

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.

IMA Status:

Not Approved IMA 1998

Locality:

Maquoketa shale, Gilead, Calhoun County, Illinois, USA. Link to MinDat.org Location Data.

Name Origin:

Named in 1937 for the state of Illinois where the mineral was first described.

Synonym:

Gumbelite

Hydromica

Hydromuscovite

Illite Image

Images:

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

Axial Ratios:

a:b:c =0.5768:1:1.1492

Cell Dimensions:

a = 5.18, b = 8.98, c = 10.32, Z = 2; beta = 101.83° V = 469.85 Den(Calc)= 2.75

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 4.43(1), 2.56(0.85), 3.66(0.4),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Gualtieri A F , Journal of Applied Crystallography , 33 (2000) p.267-278, Accuracy of XRPD QPA using the combined Rietveld-RIR method, Locality: Napoli, Italy

Physical Properties of Illite

Cleavage:

[001] Perfect

Color:

White.

Density:

2.6 - 2.9, Average = 2.75

Diaphaniety:

Translucent

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Hardness:

1-2 - Between Talc and Gypsum

Luster:

Earthy (Dull)

Streak:

white

Optical Properties of Illite

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

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.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Illite

Electron Density:

r_electron=2.77 gm/cc
note: r_Illite=2.75 gm/cc.

Fermion Index

Fermion Index = 0.01424
Boson Index = 0.98576

Photoelectric:

PE_Illite= 2.33 barns/electron
U=PE_Illite x r_electron= 6.45 barns/cc.

Radioactivity:

GRapi = 87.50 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Illite - barely detectable

Illite Classification

Dana Class:

71.2.2d.2 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.2)with 2:1 Layers

(71.2.2d)Mica Group (Hydromica subgroup)

71.2.2d.1 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

71.2.2d.2 Illite * (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/m 2/m

71.2.2d.3 Vermiculite (Mg,Fe,Al)3(Al,Si)4O10(OH)2·4(H2O) C 2/m 2/m

71.2.2d.4 Brammallite* (Na,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/c 2/m

Strunz Class:

VIII/H.19-15 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica like with [Si4O10]4- and related groups

VIII/H.19 - Brammallite ? - Yakhontovite series

VIII/H.19-10 Brammallite* (Na,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/c 2/m

VIII/H.19-10a 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

VIII/H.19-15 Illite (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/m 2/m

VIII/H.19-20 Montmorillonite (Na,Ca)0,3(Al,Mg)2Si4O10(OH)2·n(H2O) C 2/m 2/m

VIII/H.19-30 Beidellite Na0.5Al2(Si3.5Al0.5)O10(OH)2·n(H2O) C 2/m or ORTH 2/m

VIII/H.19-40 Nontronite Na0.3Fe2(Si,Al)4O10(OH)2·n(H2O) C 2/m 2/m

VIII/H.19-50 Volkonskoite Ca0.3(Cr,Mg,Fe)2(Si,Al)4O10(OH)2·4(H2O) C 2/m 2/m

VIII/H.19-60 Swinefordite (Li,Ca0.5,Na)0.72(Li,Al,Mg)2.66(Si,Al)4O10(OH,F)2·2(H2O) C 2/m (MON or ORTH) 2/m

VIII/H.19-70 Yakhontovite (Ca,K)0.5(Cu,Fe,Mg)2Si4O10(OH)2·3(H2O) C 2/m 2/m

Other Illite Information

References:

NAME( Dana8) PHYS. PROP.(Eur. J. Min.,Vol.9,p821-827,1997) OPTIC PROP.(Heinrich65)

Search for Illite using:

[ALTAVISTA] [AOL] [About.com] [All-The-Web] [HotBot] [Ixquick] [LookSmart] [MAMMA] [MSN.COM] [Netscape] [Teoma] [Wikipedia] [YAHOO]

Visit our Advertisers for Illite :
AA Mineral Specimens
A-Rocks Auction
Adams Minerals
B and L Minerals
Dakota Matrix
Dan Weinrich Fine Minerals
Dan Weinrich Auctions
e-Rocks Auctions
Excalibur Minerals
Exceptional Minerals
Fabre Minerals
Greenside Minerals
John Betts Fine Minerals
Masons Minerals
Mineral News
Mineral of the Month Club
MineralsWeb Fine Minerals
Minernet.it
Rockshop.cz Kalat Fine Minerals
T G Fine Minerals
Wrights Rock Shop

Translate Illite Mineral Data :

Ask about Illite 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 Español

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: 71.2.2d.2 Strunz No: VIII/H.19-15
Locality:

Notes: