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![Mineralogy Database Mineralogy Database](/images/Hedyphane_Crystal.gif) |
Allophane Mineral Data
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General Allophane Information
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Chemical Formula: |
Al2O3•(SiO2)1.3-2•((H2O))2.5-3 |
Composition: |
Molecular Weight = 225.11 gm |
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Aluminum 23.97 % Al 45.29 % Al2O3 |
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Silicon 16.22 % Si 34.70 % SiO2 |
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Hydrogen 2.24 % H 20.01 % H2O |
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Oxygen 57.57 % O |
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______ ______ |
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100.00 % 100.00 % = TOTAL OXIDE |
Empirical Formula: |
(Al2O3)(SiO2)1.3•2.5(H2O) |
Environment: |
In marlstone rocks (TL) and weathering product of volcanic ash. |
IMA Status: |
Valid Species (Pre-IMA) 1816 |
Locality: |
Grafenthal, Thuringia, Germany Link to MinDat.org Location Data. |
Name Origin: |
From the Greek allos - "other" and phanos - "to appear" in allusion to its change when blowpiped. |
Name Pronunciation: |
Allophane + Pronunciation |
Synonym: |
Ilbaite |
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Protoallophane |
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Schrotterite |
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Allophane Image |
Images:
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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 |
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Allophane Crystallography
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Crystal System: |
Amorphous- No Crystals |
X Ray Diffraction: |
By Intensity(I/Io): 3.3(1), 2.25(0.2), 1.4(0.1),1.23(0.05), 1.86(0.05), |
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Physical Properties of Allophane
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Cleavage: |
None |
Color: |
White, Green, Blue, Yellow, Brown. |
Density: |
1.9 |
Diaphaneity: |
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: |
Fluorescent, Short UV=blue. |
Luster: |
Waxy |
Streak: |
white |
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Optical Properties of Allophane
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Gladstone-Dale: |
CI meas= -0.087 (Poor) - where the CI = (1-KPDmeas/KC) KPDmeas= 0.2542,KC= 0.234 Ncalc = 1.44 |
Optical Data: |
Isotropic, n=1.47-1.496. |
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Calculated Properties of Allophane
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Electron Density: |
Bulk Density (Electron Density)=1.92 gm/cc note: Specific Gravity of Allophane =1.90 gm/cc. |
Fermion Index: |
Fermion Index = 0.0078541141 Boson Index = 0.9921458859 |
Photoelectric: |
PEAllophane = 1.37 barns/electron U=PEAllophane x rElectron Density= 2.64 barns/cc. |
Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Allophane is Not Radioactive |
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Allophane Classification
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Dana Class: |
71.01.04.01 (71)Phyllosilicate Sheets of Six-Membered Rings |
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(71.01)with 1:1 layers |
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(71.01.04)Allophane group |
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71.01.04.01 Allophane Al2O3•(SiO2)1.3-2•((H2O))2.5-3 None |
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71.01.04.02 Hisingerite Fe2Si2O5(OH)4•2(H2O) Unk Mono |
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71.01.04.03 Imogolite Al2SiO3(OH)4 ? Mono |
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71.01.04.04 Neotocite (Mn,Fe)SiO3•(H2O)(?) None |
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71.01.04.05 Zinalsite! Zn2AlSi2O5(OH)4•2(H2O)(?) Mono |
Strunz Class: |
09.ED.20 09 - SILICATES (Germanates) |
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09.E - Phyllosilicates |
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09.ED -Phyllosilicates with kaolinite layers |
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09.ED.20 Allophane Al2O3•(SiO2)1.3-2•((H2O))2.5-3 None |
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09.ED.20 Chrysocolla (Cu,Al)2H2Si2O5(OH)4•n(H2O) Unk Ortho |
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09.ED.20 Neotocite (Mn,Fe)SiO3•(H2O)(?) None |
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09.ED.20 Imogolite Al2SiO3(OH)4 ? Mono |
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Other Allophane Information
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References: |
NAME( Dana8) PHYS. PROP.(Collectors Book of Fluorescent Minerals) 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 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
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: 71.01.04.01 Strunz No: 09.ED.20
Locality:
Notes:
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