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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 ...
Lustre:
Waxy, Earthy
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 occasionally bluish or greenish.

The name halloysite currently 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.

Also reported as a biomineral formed by the action of lichen (e.g., Lasallia spp., Mucor spp., etc.) on cave deposits and waters (vide Burford et al., 2003).


Classification of Halloysite

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

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)

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
Elements listed in formula:
Common Impurities:
Ti,Ca,Na,K,Fe,Cr,Mg,Ni,Cu

Crystallography of Halloysite

Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Bb
Cell Parameters:
a = 5.14 Å, b = 8.9 Å, c = 7.214 Å
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)
(
(

Occurrences of Halloysite

Relationship of Halloysite to other Species

Other Members of Group:
DickiteAl2(Si2O5)(OH)4
Greenalite(Fe2+,Fe3+)2-3Si2O5(OH)4
KaoliniteAl2(Si2O5)(OH)4
ManandoniteLi2Al4(Si2AlB)O10(OH)8
NacriteAl2(Si2O5)(OH)4
Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4
Serpentine SubgroupD3[Si2O5](OH)4 D= Mg, Fe, Ni, Mn, Al, Zn
9.ED.Clinochrysotile
9.ED.05DickiteAl2Si2O5(OH)4
9.ED.05KaoliniteAl2Si2O5(OH)4
9.ED.05NacriteAl2Si2O5(OH)4
9.ED.05Odinite(Fe3+,Mg,Al,Fe2+)2.5(Si,Al)2O5(OH)4
9.ED.10HisingeriteFe2Si2O5(OH)4 · 2H2O
9.ED.10Halloysite-7ÅAl2Si2O5(OH)4
9.ED.15AmesiteMg2Al(AlSiO5)(OH)4
9.ED.15AntigoriteMg3Si2O5(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.15CaryopiliteMn32+Si2O5(OH)4
9.ED.15ChrysotileMg3Si2O5(OH)4
9.ED.15Cronstedtite(Fe2+,Fe3+)3(Si,Fe3+)2O5(OH)4
9.ED.15Fraipontite(Zn,Al)3(Si,Al)2O5(OH)4
9.ED.15Greenalite(Fe2+,Fe3+)2-3Si2O5(OH)4
9.ED.15Kellyite(Mn2+,Mg,Al)3(Si,Al)2O5(OH)4
9.ED.15LizarditeMg3Si2O5(OH)4
9.ED.15ManandoniteLi2Al4(Si2AlB)O10(OH)8
9.ED.15NépouiteNi3Si2O5(OH)4
9.ED.15PecoraiteNi3Si2O5(OH)4
9.ED.15GuidottiiteMn2Fe3+(SiFe3+)O5(OH)4
9.ED.20AllophaneAl2O3(SiO2)1.3-2.0 · 2.5-3.0H2O
9.ED.20Chrysocolla(Cu2-xAlx)H2-xSi2O5(OH)4 · nH2O
9.ED.20ImogoliteAl2SiO3(OH)4
9.ED.20Neotocite(Mn2+,Fe2+)SiO3 · H2O
9.ED.25BismutoferriteFe23+Bi(SiO4)2(OH)
9.ED.25ChapmaniteFe23+Sb3+(SiO4)2(OH)
15.1AndalusiteAl2SiO5
15.2KyaniteAl2OSiO4
15.3SillimaniteAl2OSiO4
15.4MulliteAl4+2xSi2-2xO10-x (x~0.4)
15.5PyrophylliteAl2Si4O10(OH)2
15.6DickiteAl2Si2O5(OH)4
15.7NacriteAl2Si2O5(OH)4
15.8KaoliniteAl2Si2O5(OH)4
15.9MetahalloysiteAl2(Si2O5)(OH)4
15.11AllophaneAl2O3(SiO2)1.3-2.0 · 2.5-3.0H2O
71.1.1.1DickiteAl2Si2O5(OH)4
71.1.1.2KaoliniteAl2Si2O5(OH)4
71.1.1.3NacriteAl2Si2O5(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.

Halloysite in petrology

Common component of (items highlighted in red)

References for Halloysite

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

Gaines, R.V., Skinner, H.C.W., Foord, E.E., Mason, B., Rosenzweig, A. (1997) Dana's New Mineralogy: The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana: 1411.

Burford, E.P., Kierans, M., Gadd, G.M. (2003): Geomycology: fungi in mineral substrata. Mycologist: 17(3): 98-107; DOI: 10.1017/S0269915X03003112

Joussein, E., Petit, S., Churchman, J., Theng, B., Righi, D., Delvaux, B. (2005) Halloysite clay minerals — A review. Clay Minerals: 40: 383–426.

Internet Links for Halloysite

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https://www.mindat.org/min-1808.html
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Localities for Halloysite

Mineral and/or Locality  
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