Allophane Mineral Data

Allophane Mineral Data +

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General Allophane Information

Chemical Formula:

Al2O3·(SiO2)1.3-2·((H2O))2.5-3

Composition:

Molecular Weight = 225.11 gm

Aluminum 23.97 % Al 45.29 % Al₂O₃

Silicon 16.22 % Si 34.70 % SiO₂

Hydrogen 2.24 % H 20.01 % H₂O

Oxygen 57.57 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

(Al₂O₃)(SiO₂)_1.3·2.5(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1816

Locality:

Link to MinDat.org Location Data.

Name Origin:

From the Greek allos - "other" and phanos - "to appear."

Synonym:

Protoallophane

Schrotterite

Allophane Image

Images:

Allophane

Comments: Blue, cuprian, botryoidal allophane on matrix.
Location: Reiche Zeche Mine, Himmelfahrt Mine, Freiberg, Freiberg District, Erzgebirge, Saxony, Germany. Scale: Picture size 5 mm.
© Thomas Witzke / Abraxas-Verlag

Allophane Crystallography

Crystal System:

Amorphous- No Crystals

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 11(1), 3.3(0.8), 2.2(0.6),

Physical Properties of Allophane

Cleavage:

None

Color:

White, Green, Blue, Yellow, Brown.

Density:

1.9

Diaphaniety:

Translucent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Botryoidal - "Grape-like" rounded forms (e.g.. malachite).

Habit:

Encrustations - Forms crust-like aggregates on matrix.

Habit:

Stalactitic - Shaped like pendant columns as stalactites or stalagmites (e.g. calcite).

Hardness:

3 - Calcite

Luminescence:

None.

Luster:

Waxy

Streak:

white

Optical Properties of Allophane

Gladstone-Dale:

CI meas= -0.087 (Poor) - where the CI = (1-KPDmeas/KC)
KPDmeas= 0.2542,KC= 0.234

Optical Data:

Isotropic, n=1.47-1.496.

Calculated Properties of Allophane

Electron Density:

r_electron=1.92 gm/cc
note: r_Allophane=1.90 gm/cc.

Fermion Index

Fermion Index = 0.00785
Boson Index = 0.99215

Photoelectric:

PE_Allophane= 1.37 barns/electron
U=PE_Allophane x r_electron= 2.64 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Allophane is Not Radioactive

Allophane Classification

Dana Class:

71.1.4.1 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.1)with 1:1 layers

(71.1.4)Allophane group

71.1.4.1 Allophane Al2O3·(SiO2)1.3-2·((H2O))2.5-3 None

71.1.4.2 Hisingerite Fe2Si2O5(OH)4·2(H2O) Unk Mono

71.1.4.3 Imogolite Al2SiO3(OH)4 ? Mono

71.1.4.4 Neotocite (Mn,Fe)SiO3·(H2O)(?) None

71.1.4.5 Zinalsite! Zn2AlSi2O5(OH)4·2(H2O)(?) Mono

Strunz Class:

VIII/H.26-10 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica like with [Si4O10]4- and related groups

VIII/H.26 - Allophane - Sturtite series

VIII/H.26-10 Allophane Al2O3·(SiO2)1.3-2·((H2O))2.5-3 None

VIII/H.26-30 Imogolite Al2SiO3(OH)4 ? Mono

VIII/H.26-40 Odinite (Fe,Mg,Al,Fe,Ti,Mn)2.5(Si,Al)2O5(OH)4 Cm m

VIII/H.26-50 Hisingerite Fe2Si2O5(OH)4·2(H2O) Unk Mono

VIII/H.26-60 Neotocite (Mn,Fe)SiO3·(H2O)(?) None

VIII/H.26-70 Sturtite* (Fe3)(Mn2,Ca,Mg)Si4O10(OH)3·10(H2O) None

Other Allophane Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Duda&Rejl90) OPTIC PROP.(Heinrich65)

See Also:

Links to other databases for Allophane :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - MinMax(Deutsch)
11 - MinMax(English)
12 - Mineralienatlas (Deutsch)
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - YupRocks

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Print or Cut-and-Paste your Allophane Specimen Label here :

Allophane

Al2O3·(SiO2)1.3-2·((H2O))2.5-3
Dana No: 71.1.4.1 Strunz No: VIII/H.26-10
Locality:

Notes: