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Halloysite

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Jean-Baptiste-Julien d'Omalius d'Halloy(1783-1875)
Formula:
Al2(Si2O5)(OH)4
System:
Monoclinic
Colour:
White to tan, sometimes ...
Hardness:
1 - 2
Name:
Named after the Belgian geologist Jean-Baptiste d'Omalius d'Halloy, (February 16th 1783 - January 15th 1875), who discovered the mineral. He was a nobleman, a statesman, and pioneer of modern geology in Belgium.
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

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.
9.ED.10

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

71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
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

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:
2 - 2.65 g/cm3 (Measured)    2.14 g/cm3 (Calculated)

Crystallography of Halloysite

Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Bb
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 Data:
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
Max Birefringence:
δ = 0.007
Image 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:
Al2(Si2O5)(OH)4
Essential elements:
All elements listed in formula:
Common Impurities:
Ti,Ca,Na,K,Fe,Cr,Mg,Ni,Cu

Relationship of Halloysite to other Species

Other Members of Group:
AmesiteMg2Al(AlSiO5)(OH)4
AntigoriteMg3(Si2O5)(OH)4
Baumite(Mg,Al,Mn,Zn,Fe)3(Si,Al)2O5(OH)4
Berthierine(Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4
Brindleyite(Ni,Al)3(Si,Al)2O5(OH)4
Caryopilite(Mn,Mg)3(Si2O5)(OH)4
ChrysotileMg3(Si2O5)(OH)4
Clinochrysotile
CronstedtiteFe22+Fe3+((Si,Fe3+)2O5)(OH)4
DickiteAl2(Si2O5)(OH)4
Fraipontite(Zn,Al)3((Si,Al)2O5)(OH)4
GreenaliteFe2-3(Si2O5)(OH)4
KaoliniteAl2(Si2O5)(OH)4
KellyiteMn22+Al(AlSiO5)(OH)4
LizarditeMg3(Si2O5)(OH)4
ManandoniteLi2Al4(Si2AlB)O10(OH)8
NacriteAl2(Si2O5)(OH)4
Népouite(Ni,Mg)3(Si2O5)(OH)4
Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4
Orthochrysotile
Parachrysotile
PecoraiteNi3(Si2O5)(OH)4
Webskyite
9.ED.05DickiteAl2(Si2O5)(OH)4
9.ED.05KaoliniteAl2(Si2O5)(OH)4
9.ED.05NacriteAl2(Si2O5)(OH)4
9.ED.05Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4
9.ED.10HisingeriteFe23+(Si2O5)(OH)4 · 2H2O
9.ED.10Halloysite-7ÅAl2(Si2O5)(OH)4
9.ED.15AmesiteMg2Al(AlSiO5)(OH)4
9.ED.15AntigoriteMg3(Si2O5)(OH)4
9.ED.15Berthierine(Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4
9.ED.15Brindleyite(Ni,Al)3(Si,Al)2O5(OH)4
9.ED.15Caryopilite(Mn,Mg)3(Si2O5)(OH)4
9.ED.15ChrysotileMg3(Si2O5)(OH)4
9.ED.15CronstedtiteFe22+Fe3+((Si,Fe3+)2O5)(OH)4
9.ED.15Fraipontite(Zn,Al)3((Si,Al)2O5)(OH)4
9.ED.15GreenaliteFe2-3(Si2O5)(OH)4
9.ED.15KellyiteMn22+Al(AlSiO5)(OH)4
9.ED.15LizarditeMg3(Si2O5)(OH)4
9.ED.15ManandoniteLi2Al4(Si2AlB)O10(OH)8
9.ED.15Népouite(Ni,Mg)3(Si2O5)(OH)4
9.ED.15PecoraiteNi3(Si2O5)(OH)4
9.ED.15GuidottiiteMn2Fe3+(Fe3+SiO5)(OH)4
9.ED.20Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
9.ED.20ChrysocollaCu2-xAlx(H2-xSi2O5)(OH)4 · nH2O (x < 1)
9.ED.20ImogoliteAl2SiO3(OH)4
9.ED.20Neotocite(Mn,Fe,Mg)SiO3 · H2O
9.ED.25BismutoferriteFe23+Bi(SiO4)2(OH)
9.ED.25ChapmaniteFe23+Sb3+(Si2O5)O3(OH)
15.1AndalusiteAl2(SiO4)O
15.2KyaniteAl2(SiO4)O
15.3SillimaniteAl2(SiO4)O
15.4MulliteAl4+2xSi2-2xO10-x
15.5PyrophylliteAl2(Si4O10)(OH)2
15.6DickiteAl2(Si2O5)(OH)4
15.7NacriteAl2(Si2O5)(OH)4
15.8KaoliniteAl2(Si2O5)(OH)4
15.9Metahalloysite
15.11Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
71.1.1.1DickiteAl2(Si2O5)(OH)4
71.1.1.2KaoliniteAl2(Si2O5)(OH)4
71.1.1.3NacriteAl2(Si2O5)(OH)4

Other Names for Halloysite

Other Information

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:
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

Localities for Halloysite

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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