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Halloysite

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Laach lake volcanic complex, Eifel Mts, Rhineland-Palatinate, Germany
© Stephan Wolfsried

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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.

The name halloysite stands for the two grandfathered and distinct species Halloysite-7Å and Halloysite-10Å.
Halloysite-10Å is also known as "endellite" in European literature and considered to be a hydrated mineral - the "hydrated halloysite" of North American literature.

"Metahalloysite" (= Halloysite-7Å) is dehydrated halloysite, and characterised by a reduced interlayer spacing.

Originally reported from Angleur, Liège, Liège Province, Belgium.




Classification of Halloysite

IMA status:Not Approved
Explanation of status:Confusion exists between "halloysite" and "endellite." Most European literature has "halloysite" as Al2Si2O5(OH)4·2H2O (= Halloysite-10Å) and calls it "endellite." Most North American literature (not Dana 8th...) has it as Al2Si2O5(OH)4 (= Halloysite-7Å) - 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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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. The two "forms" Halloysite-7Å and Halloysite-10Å 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(70)
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.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
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:
ConfolensiteGalapectiteGlageriteGlossecolliteGummite (of Breithaupt)
Halloysite (of Berthier)IndianaiteLenziniteMountain SoapSmectite (of Salvetat)
Other Languages:
Esperanto:Halojzito
German:Galapectit
Galapektit
Glagerit
Glossecollit
Halloysit
Hydrohalloysit
Hydrokaolin
Indianait
Lenzinit
Spanish:Galapectita
Glagerita
Glossecollita
Halloysita
Hydrohalloysita
Indianaita
Lenzinita
Varieties:
Chrome-HalloysiteCuprian HalloysiteFerrian HalloysiteZirconian Halloysite

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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    Localities for Halloysite

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