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Kaolinite

A valid IMA mineral species - grandfathered
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About KaoliniteHide

Formula:
Al2(Si2O5)(OH)4
Colour:
White to cream and pale-yellow, also often stained various hues, tans and browns being common.
Lustre:
Waxy, Pearly, Dull, Earthy
Hardness:
2 - 2½
Specific Gravity:
2.68
Crystal System:
Triclinic
Name:
Named in 1637 by Song Yingxing for the ancient Chinese type locality "Kaoling (Gaoling)", meaning high ridge.
Polymorph of:
Mineral used in prehistoric times. Presumably the most important mineral in clay used in prehistoric pottery. The photo http://www.mindat.org/photo-620484.html shows the Sumerian symbol for clay: חלבנהπη in Hebrew and λός in Greek. Lutum in Latin. Kaolinite, by name, was known since the Yuan (Mongol) dynasty in the thirteenth century as "Kaolin earth" and was first properly described by Song Yingxing in 1637 in his book Tian Gong Kai Wu (translated: "Introduction to Heaven's Handicrafts" or "The Exploitation of the Works of Nature"). Its usefulness was introduced to the West by a French priest in 1712 (de Fourestier, 2005).

Found largely in masses—clay beds—usually with a bright white color, also pale yellow to light brown in color due to staining or mixture, rarely blue to blue-gray.

Kaolinite can have a lot of layer stacking variation, from highly ordered to highly disordered, while dickite and nacrite are effectively differently ordered polytypes. Poorly crystalline kaolinite is typical of low-grade sediments, especially non-marine, while dickite and nacrite form at higher temperatures, including many hydrothermal deposits.

de Ligny and Navrotsky (1999) showed that kaolinite is the thermodynamically stable phase and the polymorphs dickite, halloysite and nacrite are metastable phases mainly crystallising due to kinetic reasons.


Unique IdentifiersHide

Mindat ID:
2156
Long-form identifier:
mindat:1:1:2156:8

Similar NamesHide

Callainite
GaleniteA synonym of Galena
GliniteA synonym of Clay minerals
K-AluniteA synonym of Alunite
KaliniteA valid IMA mineral species - grandfatheredKAl(SO4)2 · 11H2O
KilliniteA synonym of 'Illite'
KleiniteA valid IMA mineral species - grandfathered(Hg2N)(Cl,SO4) · nH2O
KulaniteA valid IMA mineral speciesBa(Fe2+,Mn2+,Mg)2(Al,Fe3+)2(PO4)3(OH)3

IMA Classification of KaoliniteHide

Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Al2Si2O5(OH)4
Approval history:
Proposal 24-D is accepted, and neotype samples are defined for kaolinite. The type locality is the village of Gaoling, Jiangxi Province, China. Neotype material is deposited in the mineralogical collection of the Canadian Museum of Nature, Ottawa, Canada, under catalogue numbers CMNMC 91699 [JDZ-K8] and CMNMC 91700 [JDZ-W1].

Classification of KaoliniteHide

9.ED.05

9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
Dana 7th ed.:
71.1.1.2
15.8

15 : Silicates of Aluminum

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

SymbolSourceReference for Standard
KlnIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
KlnKretz (1983)Kretz, R. (1983) Symbols of rock-forming minerals. American Mineralogist, 68, 277–279.
KlnSiivolam & Schmid (2007)Siivolam, J. and Schmid, R. (2007) Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks: List of mineral abbreviations. Web-version 01.02.07. IUGS Commission on the Systematics in Petrology. download
KlnWhitney & Evans (2010)Whitney, D.L. and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187 doi:10.2138/am.2010.3371
KlnThe Canadian Mineralogist (2019)The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download
KlnWarr (2020)Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30

Pronunciation of KaoliniteHide

Pronunciation:
PlayRecorded byCountry
Jolyon RalphUnited Kingdom

Physical Properties of KaoliniteHide

Waxy, Pearly, Dull, Earthy
Transparency:
Translucent, Opaque
Colour:
White to cream and pale-yellow, also often stained various hues, tans and browns being common.
Streak:
White, or paler than the sample.
Hardness:
2 - 2½ on Mohs scale
Hardness Data:
Measured
Tenacity:
Sectile
Cleavage:
Perfect
on {001}.
Fracture:
Irregular/Uneven, Conchoidal, Sub-Conchoidal, Micaceous
Density:
2.68 g/cm3 (Measured)    2.63 g/cm3 (Calculated)

Optical Data of KaoliniteHide

Type:
Biaxial (-)
RI values:
nα = 1.553 - 1.563 nβ = 1.559 - 1.569 nγ = 1.560 - 1.570
2V:
Measured: 24° to 50°, Calculated: 44°
Birefringence:
0.017
Max. Birefringence:
δ = 0.007
Based on recorded range of RI values above.

Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.

Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.

Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.

Surface Relief:
Low (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).

This shows the grain boundary and Becke line effect under plane-polarised light, based on the contrast between this mineral's average refractive index and the mounting medium. It does not take into account mineral colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure - the conoscopic view for a grain cut perpendicular to the acute bisectrix, using this mineral's 2V. The two small white dots mark the melatopes - the points where the two optic axes emerge - and are shown only when they fall within the field of view. The coloured bands are isochromatics, and the dark bands are isogyres.

Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
none
Pleochroism:
Non-pleochroic

Chemistry of KaoliniteHide

Mindat Formula:
Al2(Si2O5)(OH)4
Element Weights:
Element% weight
O55.777 %
Si21.758 %
Al20.903 %
H1.562 %

Calculated from ideal end-member formula.
O
Si
Al
H
Common Impurities:
Fe,Mg,Na,K,Ti,Ca,H2O

Crystallography of KaoliniteHide

Crystal System:
Triclinic
Class (H-M):
1 - Pedial
Space Group:
P1
Cell Parameters:
a = 5.13 Å, b = 8.89 Å, c = 7.25 Å
α = 90°, β = 104.5°, γ = 89.8°
Ratio:
a:b:c = 0.577 : 1 : 0.816
Unit Cell V:
320.11 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Visible crystals extremely rare, typically 2-5 nanometer range, but may be up to 1.5 mm across. Platy, pseudohexagonal. Fibers and spheres have been observed using SEM imaging.

Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0012232KaoliniteBish D L, Von Dreele R B (1989) Rietveld refinement of non-hydrogen atomic positions in kaolinite Clays and Clay Minerals 37 289-2961989Keokuk, Iowa, USA0293
0012237KaoliniteBish D L (1993) Rietveld refinement of the kaolinite structure at 1.5 K Clays and Clay Minerals 41 738-7441993Keokuk, Iowa, USA01.5
0017947KaoliniteGruner W (1932) The Crystal Structure of Kaolinite _cod_database_code 1011045 Zeitschrift fur Kristallographie 83 75-8819320293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
7.17 Å(100)
4.37 Å(60)
4.19 Å(45)
3.58 Å(80)
1.62 Å(70)
1.59 Å(60)
1.59 Å(90)
Comments:
Data for kaolinite-1A. Several polytypes are known: -1Md, -2M1 ("dickite"), -2M2 ("nacrite"). Each has a slightly different powder pattern.

Geological EnvironmentHide

Paragenetic Mode(s):
Geological Setting:
A primary constiuent of clay beds formed by the decomposition of feldspar-bearing rocks.

Type Occurrence of KaoliniteHide

Place of Conservation of Type Material:
Neotype material is deposited in the mineralogical collection of the Canadian Museum of Nature, Ottawa, Canada, under catalogue numbers CMNMC 91699 [JDZ-K8] and CMNMC 91700 [JDZ-W1].

Synonyms of KaoliniteHide

Other Language Names for KaoliniteHide

Basque:Kaolinita
Catalan:Caolinita
Cornish:Pri gwynn
Czech:Kaolinit
Dutch:Kaoliniet
Estonian:Kaoliniit
Finnish:Kaoliini
French:Kaolinite
Hungarian:Kaolinit
Italian:Caolinite
Norwegian:Kaolinitt
Polish:Kaolinit
Simplified Chinese:高岭石
Slovak:Kaolinit
Swedish:Kaolinit
Traditional Chinese:高嶺石
Vietnamese:Cao lanh

Varieties of KaoliniteHide

Chrome-KaoliniteA Cr-bearing kaolinite.
Fe-KaoliniteA green, iron rich variety of Kaolinite
Keramite (of Hunt)Probably an impure Kaolinite, possibly dehydrated Halloysite
LivesiteA clay mineral intermediate to kaolinite and halloysite; a disordered kaolinite.
ParakaoliniteThe hypothetical end-member of the Kaolinite-Serpentine series

Common AssociatesHide

Associations Based on Photo Data:
264 photos of Kaolinite associated with QuartzSiO2
76 photos of Kaolinite associated with AzuriteCu3(CO3)2(OH)2
70 photos of Kaolinite associated with ChalcopyriteCuFeS2
50 photos of Kaolinite associated with CalciteCaCO3
49 photos of Kaolinite associated with PyriteFeS2
47 photos of Kaolinite associated with FluoriteCaF2
46 photos of Kaolinite associated with HematiteFe2O3
38 photos of Kaolinite associated with SideriteFeCO3
30 photos of Kaolinite associated with MimetitePb5(AsO4)3Cl
28 photos of Kaolinite associated with OrthoclaseK(AlSi3O8)

Related Minerals - Strunz-mindat GroupingHide

9.ED.'Clinochrysotile'Mg3(Si2O5)(OH)4Mon. 2/m
9.ED.05DickiteAl2(Si2O5)(OH)4Mon. m : Bb
9.ED.05NacriteAl2(Si2O5)(OH)4Mon. m : Bb
9.ED.05Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4Mon. m : Bm
9.ED.10HalloysiteAl2Si2O5(OH)4 · n(H2O)Mon. m : Bb
9.ED.10HisingeriteFe3+2(Si2O5)(OH)4 · 2H2OMon.
9.ED.10'Hydrohalloysite'Al2Si2O5(OH)4 · 2H2OMon. m
9.ED.15AntigoriteMg3(Si2O5)(OH)4Mon. m : Bm
9.ED.15Brindleyite(Ni,Al)3(Si,Al)2O5(OH)4Mon.
9.ED.15Fraipontite(Zn,Al)3((Si,Al)2O5)(OH)4Mon.
9.ED.15NépouiteNi3Si2O5(OH)4Orth.
9.ED.15PecoraiteNi3(Si2O5)(OH)4Mon.
9.ED.15GuidottiiteMn2Fe3+(Fe3+SiO5)(OH)4Hex. 6 : P63
9.ED.15LizarditeMg3(Si2O5)(OH)4Trig. 3m : P31m
9.ED.15Berthierine(Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4Mon. m : Bm
9.ED.15KellyiteMn2+2Al(AlSiO5)(OH)4Hex. 6 : P63
9.ED.15CronstedtiteFe2+2Fe3+((Si,Fe3+)2O5)(OH)4Trig. 3m : P31m
9.ED.15CaryopiliteMn2+3Si2O5(OH)4Mon.
9.ED.15AmesiteMg2Al(AlSiO5)(OH)4Tric. 1 : P1
9.ED.15Greenalite(Fe2+,Fe3+)2-3Si2O5(OH)4Mon.
9.ED.15ManandoniteLi2Al4(Si2AlB)O10(OH)8Orth. 222 : C2221
9.ED.20ChrysocollaCu2-xAlx(H2-xSi2O5)(OH)4 · nH2O, x < 1Orth.
9.ED.20Neotocite(Mn,Fe)SiO3 · H2O (?)Amor.
9.ED.20Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2OAmor.
9.ED.20ImogoliteAl2SiO3(OH)4
9.ED.25BismutoferriteFe3+2Bi(SiO4)2(OH)Mon. m : Bm
9.ED.25ChapmaniteFe3+2Sb3+(Si2O5)O3(OH)Mon. m : Bm
9.ED.30'Pianlinite'Al2Si2O6(OH)2Orth.

Fluorescence of KaoliniteHide

Not fluorescent in UV.

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Numerous: fillers and coatings in/on papers, for making china and various other earthenware items, an absorbant in dye tracers, a pore-forming enhancer for dye uptake in inks, as an absobant for spills, as a stain preventing coating on lithographic plate

Kaolinite in petrologyHide

Internet Links for KaoliniteHide

References for KaoliniteHide

Reference List:

Localities for KaoliniteHide

Showing 7,309 localities.

This 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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