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Montmorillonite

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Tamminen Quarry, Greenwood, Oxford Co., Maine, USA
© 2004 Peter Cristofono

Show Montmorillonite Photos (18)
Formula:
(Na,Ca)
 
0.33
(Al,Mg)
 
2
Si
 
4
O
 
10
(OH)
 
2
·nH
 
2
O
System:MonoclinicColour:White, pale pink, buff, ...
Hardness:1 - 2
Name:For the type locality at Montmorillon, Vienne, Poitou-Charentes, France.


Montmorillonite-Vermiculite Group.

A clay mineral.

Classification of Montmorillonite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/H.19-20
Nickel-Strunz 10th (pending) edition ID:9.EC.40

9 : SILICATES (Germanates)
E : Phyllosilicates
C : Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets
Dana 8th edition ID:71.3.1a.2

71 : PHYLLOSILICATES Sheets of Six-Membered Rings
3 : Sheets of 6-membered rings with 2:1 clays
Hey's CIM Ref.:16.7.9

16 : Silicates Containing Aluminum and other Metals
7 : Aluminosilicates of Mg
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Type Occurrence of Montmorillonite

Type Locality:Montmorillon, Vienne, Poitou-Charentes, France
Year of Discovery:1847

Occurrences of Montmorillonite

Geological Setting:Alteration product of volcanic tuffs and ash.

Physical Properties of Montmorillonite

Lustre:Dull, Earthy
Diaphaneity (Transparency):Translucent
Colour:White, pale pink, buff, yellow, red, green
Hardness (Mohs):1 - 2
Cleavage:Perfect
on {001}
Fracture:Irregular/Uneven
Density (measured):2 - 3 g/cm3

Crystallography of Montmorillonite

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Space Group:B2/m (B1 1 2/m) [C2/m] {C1 2/m 1}
Cell Parameters:a = 5.17Å, b = 8.94Å, c = 9.95Å
β = 99.54°
Ratio:a:b:c = 0.578 : 1 : 1.113
Unit Cell Volume:V 453.53 ų (Calculated from Unit Cell)
Z:1
Morphology:Scaly crystals, clayey, compact, massive

Optical Data of Montmorillonite

Type:Biaxial (-)
RI values: nα = 1.485 - 1.535 nβ = 1.504 - 1.550 nγ = 1.505 - 1.550
2V:Measured: 5° to 30°
Maximum Birefringence:δ = 0.020

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:none
Pleochroism:Visible
Comments:X= colorless to pale brown, yellow green
Y= dark brown to yellow-green, olive-green, pale yellow
Z= brown to olive-green, pale yellow

Chemical Properties of Montmorillonite

Formula:
(Na,Ca)
 
0.33
(Al,Mg)
 
2
Si
 
4
O
 
10
(OH)
 
2
·nH
 
2
O
Essential elements:Al, H, Na, O, Si
All elements listed in formula:Al, Ca, H, Mg, Na, O, Si
Common Impurities:Fe,K

Relationship of Montmorillonite to other Species

Member of:Smectite Group
Related Minerals - Nickel-Strunz Grouping):
9.EC.05Minnesotaite
(Fe,Mg)
 
3
Si
 
4
O
 
10
(OH)
 
2
9.EC.05Talc
Mg
 
3
Si
 
4
O
 
10
(OH)
 
2
9.EC.05Willemseite
(Ni,Mg)
 
3
Si
 
4
O
 
10
(OH)
 
2
9.EC.10Ferripyrophyllite
Fe
 
2
Si
 
4
O
 
10
(OH)
 
2
9.EC.10Pyrophyllite
Al
 
2
Si
 
4
O
 
10
(OH)
 
2
9.EC.15Boromuscovite
KAl
 
2
[(OH)
 
2
|BSi
 
3
O
 
10
]
9.EC.15Celadonite
K(Mg,Fe
2+
 
)(Fe
3+
 
,Al)[(OH)
 
2
|Si
 
4
O
 
10
]
9.EC.15Chernykhite
(Ba,Na)(V
3+
 
,Al,Mg)
 
2
[(OH)
 
2
|(Si,Al)
 
4
O
 
10
]
9.EC.15Montdorite
(K,Na)
 
2
(Fe
2+
 
,Mn
2+
 
,Mg)
 
5
[(OH,F)
 
2
|Si
 
4
O
 
10
]
 
2
9.EC.15Muscovite
KAl
 
2
[(OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.15Nanpingite
CsAl
 
2
[(OH,F)
 
2
|AlSi
 
3
O
 
10
]
9.EC.15Paragonite
NaAl
 
2
[(OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.15Roscoelite
K(V,Al)
 
2
[(OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.15Tobelite
(NH
 
4
,K)Al
 
2
[(OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.15Aluminoceladonite
K(Mg,Fe
2+
 
)(Al,Fe
3+
 
)[(OH)
 
2
|Si
 
4
O
 
10
]
9.EC.15Chromphyllite
K(Cr,Al)
 
2
[(OH,F)
 
2
|AlSi
 
3
O
 
10
]
9.EC.15Ferro-aluminoceladonite
K(Fe
2+
 
,Mg)(Al,Fe
3+
 
)[(OH)
 
2
|Si
 
4
O
 
10
]
9.EC.15Ferroceladonite
K(Fe
2+
 
,Mg)(Fe
3+
 
,Al)[(OH)
 
2
|Si
 
4
O
 
10
]
9.EC.15Chromceladonite
K(Mg,Fe
2+
 
)(Cr,Al)[(OH)
 
2
|Si
 
4
O
 
10
]
9.EC.15Tainiolite
KLiMg
 
2
[F
 
2
|Si
 
4
O
 
10
]
9.EC.15Ganterite
(Ba,Na,K)(Al,Mg)
 
2
[(OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Annite
KFe
2+
3
[(OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Biotite
9.EC.20Ephesite
NaLiAl
 
2
[(OH)
 
2
|Al
 
2
Si
 
2
O
 
10
]
9.EC.20Hendricksite
K(Zn,Mg,Mn
2+
 
)
 
3
[(OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Masutomilite
(K,Rb)(Li,Mn
3+
 
,Al)
 
3
[(F,OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Norrishite
KLiMn
2+
2
[(OH)
 
2
|Si
 
4
O
 
10
]
9.EC.20Phlogopite
KMg
 
3
[(OH,F)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Polylithionite
KLi
 
2
Al[(F,OH)
 
2
|Si
 
4
O
 
10
]
9.EC.20Preiswerkite
NaMg
 
2
Al[(OH)
 
2
|Al
 
2
Si
 
2
O
 
10
]
9.EC.20Siderophyllite
KFe
2+
2
Al[(F,OH)
 
2
|Al
 
2
Si
 
2
O
 
10
]
9.EC.20Tetra-ferriphlogopite
KMg
 
3
[(OH,F)
 
2
|(Fe
3+
 
,Al)Si
 
3
O
 
10
]
9.EC.20Wonesite
(Na,K)(Mg,fe,Al)
 
6
(Al,Si)
 
8
O
 
20
(OH,F)
 
4
9.EC.20Zinnwaldite
KLiFe
2+
 
Al[(F,OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Eastonite
KMg
 
2
Al[(OH)
 
2
|Al
 
2
Si
 
2
O
 
10
]
9.EC.20Tetraferriannite
KFe
2+
3
[(OH)
 
2
|(Fe
3+
 
,Al)Si
 
3
O
 
10
]
9.EC.20Trilithionite
K(Li,Al)
 
3
[(F,OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Fluorannite
KFe
2+
3
[(F,OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Shirokshinite
KNaMg
 
2
[F
 
2
|Si
 
4
O
 
10
]
9.EC.20Shirozulite
K(Mn
2+
 
,Mg)
 
3
[(OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Sokolovaite
CsLi
 
2
AlSi
 
4
O
 
10
F
 
2
9.EC.20Aspidolite
NaMg
 
3
[(OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.20Fluorophlogopite
KMg
 
3
[(F,OH)
 
2
|AlSi
 
3
O
 
10
]
9.EC.25Brammallite
Na
 
0.65
Al
 
2.0
ٱAl
 
0.65
Si
 
3.35
O
 
10
(OH)
 
2
9.EC.30Margarite
CaAl
 
2
[(OH)
 
2
|Al
 
2
Si
 
2
O
 
10
]
9.EC.35Anandite
(Ba,K)(Fe
2+
 
,Mg)
 
3
[(O,OH)
 
2
|(Si,Al,Fe)
 
4
O
 
10
]
9.EC.35Bityite
CaLiAl
 
2
[(OH)
 
2
|BeAlSi
 
2
O
 
10
]
9.EC.35Clintonite
Ca(Mg,Al)
 
3
[(OH)
 
2
|Al
 
3
SiO
 
10
]
9.EC.35Kinoshitalite
(Ba,K)(Mg,Mn
2+
 
,Al)
 
3
[(OH)
 
2
|Al
 
2
Si
 
2
O
 
10
]
9.EC.35Ferrokinoshitalite
(Ba,K)(Fe
2+
 
,Mg)
 
3
[(OH,F)
 
2
|Al
 
2
Si
 
2
O
 
10
]
9.EC.35Oxykinoshitalite
(Ba,K)(Mg,Ti,Fe
3+
 
,Fe
2+
 
)
 
3
[(O,OH,F)
 
2
|(Si,Al)
 
4
O
 
10
]
9.EC.40Beidellite
(Na,Ca
 
0.5
)
 
0.3
Al
 
2
(Si,Al)
 
4
O
 
10
(OH)
 
2
·nH
 
2
O
9.EC.40Kurumsakite
(Zn,Ni,Cu)
 
8
Al
 
8
V
 
2
Si
 
5
O
 
35
·27H
 
2
O (or near)
9.EC.40Nontronite
Na
 
0.3
Fe
 
2
(Si,Al)
 
4
O
 
10
(OH)
 
2
·nH
 
2
O
9.EC.40Volkonskoite
Ca
 
0.3
(Cr,Mg,Fe)
 
2
(Si,Al)
 
4
O
 
10
(OH)
 
2
·4H
 
2
O
9.EC.40Yakhontovite
(Ca,Na)
 
0.5
(Cu,Fe,Mg)
 
2
Si
 
4
O
 
10
(OH)
 
2
·3H
 
2
O
9.EC.40Smectite
9.EC.45Hectorite
Na
 
0.3
(Mg,Li)
 
3
Si
 
4
O
 
10
(F,OH)
 
2
9.EC.45Saponite
Ca
 
0.25
(Mg,Fe)
 
3
(Si,Al)
 
4
O
 
10
(OH)
 
2
·nH
 
2
O
9.EC.45Sauconite
Na
 
0.3
Zn
 
3
(Si,Al)
 
4
O
 
10
(OH)
 
2
·4H
 
2
O
9.EC.45Spadaite
MgSiO
 
2
(OH)
 
2
·H
 
2
O
9.EC.45Stevensite
(Ca,Na)
 
x
Mg
 
3
Si
 
4
O
 
10
(OH)
 
2
9.EC.45Swinefordite
Li(Al,Li,Mg)
 
4
(Si,Al)
 
8
O
 
20
,(OH,F)
 
4
·xH
 
2
O
9.EC.45Zincsilite
Zn
 
3
Si
 
4
O
 
10
(OH)
 
2
·4H
 
2
O
9.EC.45Ferrosaponite
Ca
 
0.3
(Fe
2+
 
,Mg,Fe
3+
 
)
 
3
(Si,Al)
 
4
O
 
10
(OH)
 
2
·4H
 
2
O
9.EC.50Vermiculite
(Mg,Fe,Al)
 
3
(Al,Si)
 
4
O
 
10
(OH)
 
2
·4H
 
2
O
9.EC.55Baileychlore
(Zn,Fe,Al,Mg)
 
6
(Si,Al)
 
4
O
 
10
(OH)
 
8
9.EC.55Chamosite
(Fe
2+
 
,Mg)
 
5
Al[(OH)
 
8
|AlSi
 
3
O
 
10
]
9.EC.55Clinochlore
(Mg,Fe
2+
 
)
 
5
Al[(OH)
 
8
|AlSi
 
3
O
 
10
]
9.EC.55Cookeite
LiAl
 
4
(Si
 
3
Al)O
 
10
(OH)
 
8
9.EC.55Franklinfurnaceite
Ca
 
2
FeMn
 
3
MnZn
 
2
Si
 
2
O
 
10
(OH)
 
8
9.EC.55Gonyerite
(Mn,Mg)
 
5
Fe(Si
 
3
Fe)O
 
10
(OH)
 
8
9.EC.55Nimite
(Ni,Mg,Al)
 
6
(Si,Al)
 
4
O
 
10
(OH)
 
8
9.EC.55Orthochamosite
(Fe,Mg,Fe)
 
5
Al(Si
 
3
Al)O
 
10
(OH,O)
 
8
9.EC.55Pennantite
(Mn
 
5
Al)(Si
 
3
Al)O
 
10
(OH)
 
8
9.EC.55Sudoite
(Mg,Fe
2+
 
)
 
2
Al
 
3
[(OH)
 
8
|AlSi
 
3
O
 
10
]
9.EC.55Donbassite
Al
 
2
[Al
 
2.33
][Si
 
3
AlO
 
10
](OH)
 
8
9.EC.55Glagolevite
Na(Mg,Al)
 
6
[(OH,O)
 
8
|AlSi
 
3
O
 
10
]
9.EC.55Borocookeite
Li
 
1+3x
Al
 
4-x
[(BSi
 
3
)O
 
10
](OH)
 
8
 [0.00 <= x <=0.33]
9.EC.60Aliettite
Ca
 
0.2
Mg
 
6
(Si,Al)
 
8
O
 
20
(OH)
 
4
·4H
 
2
O
9.EC.60Corrensite
(Mg,Fe)
 
9
(Si,Al)
 
8
O
 
20
(OH)
 
10
·nH
 
2
O
9.EC.60Dozyite
Mg
 
7
Al
 
2
[(OH)
 
12
|Al
 
2
Si
 
4
O
 
15
]
9.EC.60Hydrobiotite
9.EC.60Karpinskite
(Ni,Mg)
 
2
Si
 
2
O
 
5
(OH)
 
2
9.EC.60Kulkeite
Mg
 
8
Al(AlSi
 
7
)O
 
20
(OH)
 
10
9.EC.60Lunijianlaite
Li
 
0.7
Al
 
6.2
(Si
 
7
AlO
 
20
)(OH,O)
 
10
9.EC.60Rectorite
(Na,Ca)Al
 
4
(Si,Al)
 
8
O
 
20
(OH)
 
4
·2H
 
2
O
9.EC.60Saliotite
Li
 
0.5
Na
 
0.5
Al
 
3
Si
 
3
AlO
 
10
(OH)
 
5
9.EC.60Tosudite
9.EC.60Brinrobertsite
Na
 
0.3
Al
 
4
[(OH)
 
2
|Si
 
4
O
 
10
]
 
2
 · 3.5 H
 
2
O
9.EC.65Macaulayite
(Fe,Al)
 
24
Si
 
4
O
 
43
(OH)
 
2
9.EC.70Burckhardtite
Pb
 
2
(Fe,Mn)AlTeO
 
2
Si
 
3
O
 
10
(OH)
 
2
·H
 
2
O
9.EC.75Ferrisurite
(Pb,Ca)
 
2-3
(CO
 
3
)
 
1.5-2
(OH,F)
 
0.5-1
[(Fe,Al)
 
2
Si
 
4
O
 
10
(OH)
 
2
]·nH
 
2
O
9.EC.75Surite
Pb(Pb,Ca)(CO
 
3
)
 
2
(Al,Fe,Mg)
 
2
(Si,Al)
 
4
O
 
10
(OH)
 
2
9.EC.75Niksergievite
(Ba,Ca)
 
2
(Al,Si)
 
7
O
 
10
(CO
 
3
)(OH)
 
6
·nH
 
2
O
9.EC.80Kegelite
Pb
 
12
(Zn,Fe)
 
2
Al
 
4
(SO
 
4
)
 
4
Si
 
11
O
 
38
 or near
Related Minerals - Hey's Index Grouping:
16.7.1Pyrope
Mg
 
3
Al
 
2
[SiO
 
4
]
 
3
16.7.2Sapphirine
(Mg,Fe)
 
4-x
Al
 
4+x
[Al
 
4+x
Si
 
2-x
O
 
18
]O
 
2
16.7.3Sapphirine-1A
(Mg,Al,Fe
2+
 
)
 
8
[(Al,Si,Fe
3+
 
)
 
6
O
 
18
]O
 
2
16.7.4Magnesiochloritoid
MgAl
 
2
[O|(OH)
 
2
|SiO
 
4
]
16.7.5Kulkeite
Mg
 
8
Al(AlSi
 
7
)O
 
20
(OH)
 
10
16.7.6Palygorskite
(Mg,Al)
 
5
(Si,Al)
 
8
O
 
20
(OH)
 
2
·8H
 
2
O
16.7.7Saponite
Ca
 
0.25
(Mg,Fe)
 
3
(Si,Al)
 
4
O
 
10
(OH)
 
2
·nH
 
2
O
16.7.8Aliettite
Ca
 
0.2
Mg
 
6
(Si,Al)
 
8
O
 
20
(OH)
 
4
·4H
 
2
O
16.7.10Baumite
(Mg,Al,Mn,Zn,Fe)
 
3
(Si,Al)
 
2
O
 
5
(OH)
 
4

Other Names for Montmorillonite

Synonyms:
AmagorsiteDaunialiteFuller's EarthGoumbrineGumbrine
StolpeniteWalkerite (of Dana)Walkthon
Esperanto names:
Montmorijonito
German names:
FullererdeGiliabitMontmorillonitStolpenit
Spanish names:
MontmorillonitaStolpenita
Varieties:
AlumodeweyliteAskaniteCalcium-MontmorilloniteDelanovite

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Montmorillonite

Reference List:Grim, Ralph Early & G. Kulbicki (1961), Montmorillonite: high-temperature reactions and classification: American Mineralogist: 46: 1329-1369.

Tettenhorst, R. and W.D. Johns (1966), Interstratification in montmorillonite: Clays and Clay Minerals: 25: 85-93.

McAtee, J.L. & W. Henslee (1969), Electron microscopy of montmorillonite dispersed at various pH: American Mineralogist: 54: 869-874.

Shutov, V.D., V.A. Drits, and B.A. Sakharov (1969a), On the mechanism of a postsedimentary transformation of montmorillonite into hydromica. In L. Heller, Ed., Proceedings International Clay Conference, Tokyo, 1969, 1: 523-532, Jerusalem University.

Shutov, V.D., V.A. Drits, and B.A. Sakharov (1969b), On the mechanism of a postsedimentary transformation of montmorillonite into hydromica: Discussion. In L. Heller, Ed., Proceedings International Clay Conference, Tokyo, 1969, 2: 126-129, Jerusalem University.

Tettenhorst, R. and Roberson, H.E. (1973) X-ray diffraction aspects of montmorillonite. American Mineralogist: 58: 73-80.

Gillespie, J. B., J.D. Lindberg & M.S. Smith (1974), Visible and near-infrared absorption coefficients of montmorillonite and related clays: American Mineralogist: 59: 1113-1116.

Lagaly, G., M. Fernandez-Gonzalez, and A. Weiss (1976), Problems in layer-charge determination of montmorillonites: Clay Minerals: 11: 173-187.

Sherman, D.M. and N. Vergo (1988), Optical spectrum, site occupancy, and oxidation state of Mn in montmorillonite: American Mineralogist: 73: 140-144.

American Mineralogist (1989): 74: 627.

Muller, F., G. Besson, A. Manceau, and V.A. Drits (1997), Distribution of isomorphous cations within octahedral sheets in montmorillonite from Camp-Bertaux: Physica and Chemistry of Minerals: 24: 159-166.

Christidis, George E. (2006), Genesis and compositional heterogeneity of smectites. Part III: Alteration of basic pyroclastic rocks - A case study from the Troodos Ophiolite Complex, Cyprus: American Mineralogist: 91: 685-701.

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    Localities for Montmorillonite

    Show Locality List (821 Items)
    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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    Copyright © Jolyon & Ida Ralph 1993-2008. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register.