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Halloysite

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Sounion Mine No. 06 ("Exi" Mine), Agia Varvara Mines (St Barbara Mines), Sounion Area, Lavrion District Mines, Lavrion (Laurion; Laurium) District, Attikí (Attica; Attika) Prefecture, Greece
© Steve Rust

Show Halloysite Photos (10)
Formula:
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
System:MonoclinicColour:White to tan, sometimes ...
Hardness:1 - 2
Name:Named in 1826 after the Belgian geologist Omalius d'Halloy.


Typically found as earthy to somewhat waxy looking extremely fine-grained clayey masses, white to tan and also occassionally bluish or greenish. Known as "endellite" in European literature and considered to be a hydrated mineral - the "hydrated halloysite" of North American literature.
Metahalloysite is dehydrated halloysite, and characterised by a reduced interlayer spacing.

Classification of Halloysite

IMA status:Approved
Explanation of status:Confusion exists between "halloysite" and "endellite." Most European literature has "hallyosite" as Al^2Si^2O^5(OH)^4 . 2H^2O and calls it "endellite." Most North American literature (not Dana 8th...) has it as Al^2Si^2O^5(OH)^4 - with the hydrated variety
Strunz 8th edition ID:8/H.25-40
Nickel-Strunz 10th (pending) edition ID:9.ED.10

9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
Dana 7th edition ID:71.1.1.4
Dana 8th edition ID:71.1.1.4

71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
Hey's CIM Ref.:15.10

15 : Silicates of Aluminum
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Type Occurrence of Halloysite

Type Locality:Angleur, Liège, Liège Province, Belgium
Year of Discovery:1826

Occurrences of Halloysite

Geological Setting:Halloysite is found in widely varied environments, including as an alteration of basaltic rocks, in hydrothermally altered fissure deposits in monzonites; it is also derived from feldspars, chlorites, micas, rhyolites, granites, volcanic ash, tuffs and pumices. More rarely found in granitic pegmatites, bauxites or laterites, and in some marine and glacial clays.

Physical Properties of Halloysite

Lustre:Waxy, Earthy
Diaphaneity (Transparency):Translucent, Opaque
Colour:White to tan, sometimes greenish or bluish, also chocolate brown to reddish.
Streak:Paler than the color, or white.
Hardness (Mohs):1 - 2
Fracture:Sub-Conchoidal
Density (measured):2 - 2.65 g/cm3
Density (calculated):2.14 g/cm3

Crystallography of Halloysite

Crystal System:Monoclinic
Class (H-M):m - Domatic
Space Group:Bb (B1 1b) [Cc] {C1c1}
Cell Parameters:a = 5.14Å, b = 8.9Å, c = 7.214Å
β = 99.7°
Ratio:a:b:c = 0.578 : 1 : 0.811
Unit Cell Volume:V 325.29 ų (Calculated from Unit Cell)
Z:2
Morphology:Typically found as extremely fine-grained clayey masses. Polytypes 7A and 10A are the most common. It has a tubular morphology at the nanometer scale.
X-Ray Powder Diffraction:
d-spacingIntensity
Halloysite-7A (1)
(
7.5(90)
4.42(100)
3.63(90)
2.56(80)
1.68(80)
1.48(90)
1.28(70)
1.23(70)
________(
(
Halloysite-7A (2)
(
7.3(65)
4.42(100)
3.62(60)
2.56(25)
2.37(<10)
1.68(20)
1.48(30)
_________(
(
Halloysite-10A (1)
(
10.1(90)
4.42(100)
3.34(90)
2.56(80)
1.68(80)
1.48(90)
1.28(70)
1.23(70)
________(
(
Halloysite-10A (2)
(
10.0(100)
4.36(700
3.35(40)
2.54(35)
1.67(10)
1.48(30)
1.28(10)
(

Optical Data of Halloysite

Type:Biaxial
RI values: nα = 1.553 - 1.565 nβ = 1.559 - 1.569 nγ = 1.560 - 1.570
Maximum Birefringence:δ = 0.007

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:r < v moderate

Chemical Properties of Halloysite

Formula:
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
Essential elements:Al, H, O, Si
All elements listed in formula:Al, H, O, Si
Common Impurities:Ti,Ca,Na,K,Fe,Cr,Mg,Ni,Cu

Relationship of Halloysite to other Species

Member of:Serpentine Group
Related Minerals - Nickel-Strunz Grouping):
9.ED.05Dickite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
9.ED.05Kaolinite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
9.ED.05Nacrite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
9.ED.05Odinite
(Fe,Mg,Al,Fe,Ti,Mn)
 
2.4
(Si,Al)
 
2
O
 
5
(OH)
 
4
9.ED.10Hisingerite
Fe
3+
2
Si
 
2
O
 
5
(OH)
 
4
·2H
 
2
O
9.ED.10Halloysite-7Å
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
9.ED.10Halloysite-10Å
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
·2H
 
2
O
9.ED.15Amesite
Mg
 
2
Al[(OH)
 
4
|AlSiO
 
5
]
9.ED.15Antigorite
(Mg,Fe
2+
 
)
 
3
[(OH)
 
4
|Si
 
2
O
 
5
]
9.ED.15Berthierine
(Fe,Fe,Mg)
 
2-3
(Si,Al)
 
2
O
 
5
(OH)
 
4
9.ED.15Brindleyite
(Ni,Mg,Fe)
 
2
Al(Si,Al)O
 
5
(OH)
 
4
9.ED.15Caryopilite
(Mn,Mg)
 
3
Si
 
2
O
 
5
(OH)
 
4
9.ED.15Chrysotile
Mg
 
3
Si
 
2
O
 
5
(OH)
 
4
9.ED.15Cronstedtite
Fe
2+
2
Fe
3+
 
[(Si,Fe
3+
 
)
 
2
O
 
5
](OH)
 
4
9.ED.15Fraipontite
(Zn,Al)
 
3
[(OH)
 
4
|(Si,Al)
 
2
O
 
5
]
9.ED.15Greenalite
Fe
 
2-3
Si
 
2
O
 
5
(OH)
 
4
9.ED.15Kellyite
Mn
2+
2
Al[(OH)
 
4
|AlSiO
 
5
]
9.ED.15Lizardite
Mg
 
3
[(OH)
 
4
|Si
 
2
O
 
5
]
9.ED.15Manandonite
LiAl
 
4
Si
 
3
BO
 
10
(OH)
 
6
9.ED.15Népouite
(Ni,Mg)
 
3
Si
 
2
O
 
5
(OH)
 
4
9.ED.15Pecoraite
Ni
 
3
[(OH)
 
4
|Si
 
2
O
 
5
]
9.ED.20Allophane
(Al
 
2
O
 
3
)(SiO
 
2
)
 
1.3-2
·2.5-3H
 
2
O
9.ED.20Chrysocolla
(Cu,Al)
 
2
H
 
2
Si
 
2
O
 
5
(OH)
 
4
·nH
 
2
O
9.ED.20Imogolite
Al
 
2
SiO
 
3
(OH)
 
4
9.ED.20Neotocite
(Mn,Fe,Mg)SiO
 
3
·H
 
2
O
9.ED.25Bismutoferrite
Fe
3+
2
Bi[OH|(SiO
 
4
)
 
2
]
9.ED.25Chapmanite
Fe
3+
2
Sb
3+
 
[OH|(SiO
 
4
)
 
2
]
Related Minerals - Hey's Index Grouping:
15.1Andalusite
Al
 
2
[O|SiO
 
4
]
15.2Kyanite
Al
 
2
[O|SiO
 
4
]
15.3Sillimanite
Al
 
2
[O|SiO
 
4
]
15.4Mullite
Al
 
8
[(O,OH,F)|(Si,Al)O
 
4
]
 
4
15.5Pyrophyllite
Al
 
2
Si
 
4
O
 
10
(OH)
 
2
15.6Dickite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
15.7Nacrite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
15.8Kaolinite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
15.9Metahalloysite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
15.11Allophane
(Al
 
2
O
 
3
)(SiO
 
2
)
 
1.3-2
·2.5-3H
 
2
O
Related Minerals - Dana Grouping):
71.1.1.1Dickite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
71.1.1.2Kaolinite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
71.1.1.3Nacrite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4

Other Names for Halloysite

Synonyms:
ConfolensiteEndelliteGalapectiteGlageriteGlossecollite
Gummite (of Breithaupt)Halloysite-10ÅHalloysite (of Berthier)Hydrated HalloysiteHydrohalloysite
IndianaiteLenziniteMountain SoapSmectite (of Salvetat)
Esperanto names:
Halojzito
German names:
GalapectitGalapektitGlageritGlossecollitHalloysit
HydrohalloysitHydrokaolinIndianaitLenzinit
Spanish names:
GalapectitaGlageritaGlossecollitaHalloysitaHydrohalloysita
IndianaitaLenzinita
Varieties:
Chrome-HalloysiteCuprian HalloysiteFerrian HalloysiteHalloysite-7Å

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.
Industrial Uses:Used in applications similar to those of kaolinite, such as high-strength cements and high-quality ceramics.

References for Halloysite

Reference List:Clays and Clay Minerals (1978): 26: 25.

Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig (1997), Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana: 1411.

Internet Links for Halloysite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Halloysite in the Natural History Museum (London) online catalogue
  • Halloysite details from Handbook of Mineralogy (PDF)
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    Localities for Halloysite

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