Mineralogy Database

Halloysite Mineral Data

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General Halloysite Information

Help on Chemical  Formula: Chemical Formula: Al2Si2O5(OH)4
Help on Composition: Composition: Molecular Weight = 258.16 gm
   Aluminum  20.90 %  Al   39.50 % Al2O3
   Silicon   21.76 %  Si   46.55 % SiO2
   Hydrogen   1.56 %  H    13.96 % H2O
   Oxygen    55.78 %  O
            ______        ______ 
            100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Al2Si2O5(OH)4
Help on Environment: Environment: A product of hydrothermal alteration or surface weathering of aluminosilicate minerals, as feldspars. Formed by dehydration of endellite above 110 deg. C.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1826
Help on Locality: Locality: Angleur, Li´┐Żege, Belgium. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named after Baron Omalius d'Halloy (1707-1789).
Help on Name Pronunciation: Name Pronunciation: Halloysite + Pronunciation Say HALLOYSITE
Help on Synonym: Synonym: Endellite
  ICSD 26716
  PDF 29-1489
  halloysite-10 Ang.

Halloysite Image

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  Pseudomalachite   Halloysite

Comments: Deep green pseudomalachite crystals on cuprous halloysite.
Location: Black Pine Mine, Philipsburg, Granite Co., Montana, USA. Scale: Crystal size 1-2 mm.
© John Veevaert

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Comments: Pale tan sectile porcelaneous massive halloysite.
Location: Monroe County, Indiana, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Halloysite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.5775:1:1.6741
Help on Cell Dimensions: Cell Dimensions: a = 5.14, b = 8.9, c = 14.9, Z = 4; beta = 101.9° V = 666.97 Den(Calc)= 2.57
Help on Crystal System: Crystal System: Monoclinic - Domatic H-M Symbol (m) Space Group: Cc
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 10(1), 4.36(0.7), 3.35(0.4),2.54(0.35), 1.48(0.3), 1.672(0.14), 1.281(0.08),

Physical Properties of Halloysite

Help on Cleavage: Cleavage: None
Help on Color: Color: White, Yellowish white, Reddish white, Brownish white, Greenish white.
Help on Density: Density: 2.55 - 2.65, Average = 2.59
Help on Diaphaneity: Diaphaneity: Translucent to opaque
Help on Fracture: Fracture: Earthy - Dull, clay-like fractures with no visible crystalline affinities, (e.g. howlite).
Help on Habit: Habit: Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).
Help on Hardness: Hardness: 2 - Gypsum
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Earthy (Dull)
Help on Streak: Streak: white

Optical Properties of Halloysite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.043 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.031 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2189,KPDmeas= 0.2164,KC= 0.226
Ncalc = 1.58 - 1.6
Help on Optical Data: Optical Data: Biaxial (?), a=1.553-1.565, b=1.559-1.569, g=1.56-1.57, bire=0.0050-0.0070

Calculated Properties of Halloysite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.59 gm/cc
note: Specific Gravity of Halloysite =2.57 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PEHalloysite = 1.48 barns/electron
U=PEHalloysite x rElectron Density= 3.83 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Halloysite is Not Radioactive

Halloysite Classification

Help on  Dana Class: Dana Class: (71)Phyllosilicate Sheets of Six-Membered Rings
  (71.01)with 1:1 layers
  (71.01.01)Kaolinite group Dickite Al2Si2O5(OH)4 Cc m Kaolinite Al2Si2O5(OH)4 P1 1 Nacrite Al2Si2O5(OH)4 Cc m Halloysite Al2Si2O5(OH)4 Cc m Endellite? Al2Si2O5(OH)4•2(H2O) Cc m Odinite (Fe,Mg,Al,Fe,Ti,Mn)2.5(Si,Al)2O5(OH)4 Cm m
Help on  Strunz Class: Strunz Class: 09.ED.10 09 - SILICATES (Germanates)
  09.E - Phyllosilicates
  09.ED -Phyllosilicates with kaolinite layers
09.ED.10 Endellite! Al2Si2O5(OH)4•2(H2O) Cc m
09.ED.10 Hisingerite Fe2Si2O5(OH)4•2(H2O) Unk Mono
09.ED.10 Halloysite Al2Si2O5(OH)4 Cc m
09.ED.10 Sturtite? (Fe3)(Mn2,Ca,Mg)Si4O10(OH)3•10(H2O) None

Other Halloysite Information

Help on References: References: NAME( AntBidBlaNic2) PHYS. PROP.(AntBidBlaNic2) OPTIC PROP.(Mason68)
Help on See Also: See Also: Links to other databases for Halloysite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Franklin Minerals(Palache)
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - MinDAT
12 - Mineralienatlas (Deutsch)
13 - NSDL Reciprocal Net (JAVA)
14 - Online Mineral Museum
15 - QUT Mineral Atlas
16 - Ruff.Info
17 - Scandinavian mineral gallery

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Dana No: Strunz No: 09.ED.10





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