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|System:||Amorphous||Colour:||White, pale blue to ...|
|Name:||From the Greek άλλος ("allos") for "other" or "different" and φαίνεσθαι ("phaenesthai"), "to appear", in allusion to the change it undergoes in a blowpipe flame.|
Amorphous hydrous silicate of aluminium, composition not fixed. Principal member of the nominal "Allophane Group."
Copper-bearing varieties can be confused with chrysocolla.
Colourless varieties may be confused with hyalite.
The nano-sized particles have a ball-shaped morphology.
Related to imogolite.
Classification of Allophane
|IMA status:||Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"|
|Strunz 8th edition ID:||8/H.26-10|
|Nickel-Strunz 10th (pending) edition ID:||9.ED.20|
9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
|Dana 7th edition ID:||188.8.131.52|
|Dana 8th edition ID:||184.108.40.206|
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
|Hey's CIM Ref.:||15.11|
15 : Silicates of Aluminum
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Type Occurrence of Allophane
|Type Locality:||Gräfenthal, Thuringian Forest, Thuringia, Germany|
|Place of Conservation of Type Material:||Mining Academy, Freiberg, Germany, 26104.|
|Year of Discovery:||1816|
Occurrences of Allophane
|Geological Setting:||A weathering product of volcanic ash. In hydrothermally altered igneous rocks, from the breakdown of feldspars, and in hydrothermal veins, typically related to copper deposits. In sedimentary rocks, including chalk and coal beds.|
Physical Properties of Allophane
|Diaphaneity (Transparency):||Transparent, Translucent|
|Colour:||White, pale blue to sky-blue, green, brown|
Crystallography of Allophane
|Morphology:||Rarely observed as ring-shaped particles, with diameters of 50 ºA, which in three dimensions may represent sections through hollow spherules or polyhedra. As hyaline crusts and masses; stalactites and flowstones.|
Chemical Properties of Allophane
|Simplified for copy/paste:||(Al2O3)(SiO2)1.3-2·2.5-3H2O|
|Essential elements:||Al, H, O, Si|
|All elements listed in formula:||Al, H, O, Si|
Relationship of Allophane to other Species
|Related Minerals - Nickel-Strunz Grouping):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Allophane
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Allophane
Hausmann, J.F.L. & Stromeyer, F. (1816): Über Silberkupferglanz und Allophan.- Göttingische Gelehrte Anzeigen 2, 1251-1253.
Snetsinger, K.G. (1967): High-alumina allophane as a weathering product of plagioclase. American Mineralogist 52, 254-262.
Kitagawa, Y. (1974): Dehydration of allophane and its structural formula. Amer. Mineral., 59, 1094-1098.
Henmi, T. and K. Wada (1976): Morphology and composition of allophane. Amer. Mineral., 61, 379-390.
Wada, S.I. and K. Wada (1977): Density and structure of allophane. Clay Minerals Bull., 12, 289-298.
Bailey, S.W. (1980): Summary of recommendations of AIPEA nomenclature committee on clay minerals. Amer. Mineral., 65, 1-7.
Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig (1997): Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana: eighth edition. John Wiley and Sons, Inc., 1819 pp.: 1432.(1997).
Internet Links for Allophane
|Specimens:||The following Allophane specimens are currently listed for sale on minfind.com.|
Localities for Allophane
The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.