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Halloysite

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Jean-Baptiste-Julien d'Omalius d'Halloy(1783-1875)
Formula:
Al2(Si2O5)(OH)4
Colour:
White to tan, sometimes greenish or bluish, also chocolate brown to reddish.
Lustre:
Waxy, Earthy
Hardness:
1 - 2
Specific Gravity:
2 - 2.65
Crystal System:
Monoclinic
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
Transparency:
Translucent, Opaque
Colour:
White to tan, sometimes greenish or bluish, also chocolate brown to reddish.
Streak:
Paler than the color, or white.
Hardness:
1 - 2 on Mohs scale
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
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 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

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)
(
(

Synonyms of Halloysite

Other Language Names for Halloysite

Varieties of Halloysite

Chrome-Halloysite

A pale blue chromian Halloysite

Cuprian Halloysite

A cupriferous variety of halloysite

Ferrian Halloysite

Fe rich Halloysite variety

Zirconian Halloysite

Halloysite with content 3-4 wt.% ZrO2.

Relationship of Halloysite to other Species

Other Members of this 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

Common Associates

Associated Minerals Based on Photo Data:
Atacamite68 photos of Halloysite associated with Atacamite on mindat.org.
Libethenite45 photos of Halloysite associated with Libethenite on mindat.org.
Pseudomalachite25 photos of Halloysite associated with Pseudomalachite on mindat.org.
Chrysocolla18 photos of Halloysite associated with Chrysocolla on mindat.org.
Adamite3 photos of Halloysite associated with Adamite on mindat.org.
Kornerupine2 photos of Halloysite associated with Kornerupine on mindat.org.
Mimetite2 photos of Halloysite associated with Mimetite on mindat.org.
Olivenite2 photos of Halloysite associated with Olivenite on mindat.org.
Chamosite2 photos of Halloysite associated with Chamosite on mindat.org.
Cerussite1 photo of Halloysite associated with Cerussite on mindat.org.

Related Minerals - Nickel-Strunz Grouping

9.ED.Clinochrysotile
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.10HisingeriteFe3+2(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.15CaryopiliteMn2+3Si2O5(OH)4
9.ED.15ChrysotileMg3(Si2O5)(OH)4
9.ED.15CronstedtiteFe2+2Fe3+((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.15KellyiteMn2+2Al(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
9.ED.20ImogoliteAl2SiO3(OH)4
9.ED.20Neotocite(Mn,Fe,Mg)SiO3 · H2O
9.ED.25BismutoferriteFe3+2Bi(SiO4)2(OH)
9.ED.25ChapmaniteFe3+2Sb3+(Si2O5)O3(OH)

Related Minerals - Hey's Chemical Index of Minerals Grouping

15.1AndalusiteAl2(SiO4)O
15.2KyaniteAl2(SiO4)O
15.3SillimaniteAl2(SiO4)O
15.4MulliteAl4+2xSi2-2xO10-x
15.5PyrophylliteAl2Si4O10(OH)2
15.6DickiteAl2(Si2O5)(OH)4
15.7NacriteAl2(Si2O5)(OH)4
15.8KaoliniteAl2(Si2O5)(OH)4
15.9MetahalloysiteAl2(Si2O5)(OH)4
15.11Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O

Related Minerals - Dana Grouping (8th Ed.)

71.1.1.1DickiteAl2(Si2O5)(OH)4
71.1.1.5Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4

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:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
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

mindat.org URL:
https://www.mindat.org/min-1808.html
Please feel free to link to this page.

Localities for Halloysite

Mineral and/or Locality  
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