Allophane
This page is currently not sponsored. Click here to sponsor this page.
Formula:
(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
System:
Amorphous
Colour:
White, pale blue to ...
Lustre:
Waxy
Hardness:
3
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.
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
Approved, 'Grandfathered' (first described prior to 1959)
8/H.26-10
9.ED.20
9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
Dana 7th ed.:
71.1.5.1
71.1.5.1
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
15.11
15 : Silicates of Aluminum
15 : Silicates of Aluminum
Physical Properties of Allophane
Waxy
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
White, pale blue to sky-blue, green, brown
Streak:
White
Hardness (Mohs):
3
Tenacity:
Brittle
Cleavage:
None Observed
None
None
Fracture:
Conchoidal
Chemical Properties of Allophane
Formula:
(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
IMA Formula:
Al2O3(SiO2)1.3-2.0 · 2.5-3.0H2O
Elements listed in formula:
Common Impurities:
Ti,Fe,Mg,Ca,Na,K
Crystallography of Allophane
Crystal System:
Amorphous
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.
Occurrences of Allophane
Type Occurrence of Allophane
Place of Conservation of Type Material:
Mining Academy, Freiberg, Germany, 26104.
Relationship of Allophane to other Species
Common Associates:
| 9.ED. | Clinochrysotile | |
| 9.ED.05 | Dickite | Al2(Si2O5)(OH)4 |
| 9.ED.05 | Kaolinite | Al2(Si2O5)(OH)4 |
| 9.ED.05 | Nacrite | Al2(Si2O5)(OH)4 |
| 9.ED.05 | Odinite | (Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4 |
| 9.ED.10 | Halloysite | Al2(Si2O5)(OH)4 |
| 9.ED.10 | Hisingerite | Fe23+(Si2O5)(OH)4 · 2H2O |
| 9.ED.10 | Halloysite-7Å | Al2(Si2O5)(OH)4 |
| 9.ED.15 | Amesite | Mg2Al(AlSiO5)(OH)4 |
| 9.ED.15 | Antigorite | Mg3(Si2O5)(OH)4 |
| 9.ED.15 | Berthierine | (Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4 |
| 9.ED.15 | Brindleyite | (Ni,Al)3(Si,Al)2O5(OH)4 |
| 9.ED.15 | Caryopilite | Mn32+Si2O5(OH)4 |
| 9.ED.15 | Chrysotile | Mg3(Si2O5)(OH)4 |
| 9.ED.15 | Cronstedtite | Fe22+Fe3+((Si,Fe3+)2O5)(OH)4 |
| 9.ED.15 | Fraipontite | (Zn,Al)3((Si,Al)2O5)(OH)4 |
| 9.ED.15 | Greenalite | (Fe2+,Fe3+)2-3Si2O5(OH)4 |
| 9.ED.15 | Kellyite | Mn22+Al(AlSiO5)(OH)4 |
| 9.ED.15 | Lizardite | Mg3(Si2O5)(OH)4 |
| 9.ED.15 | Manandonite | Li2Al4(Si2AlB)O10(OH)8 |
| 9.ED.15 | Népouite | (Ni,Mg)3(Si2O5)(OH)4 |
| 9.ED.15 | Pecoraite | Ni3(Si2O5)(OH)4 |
| 9.ED.15 | Guidottiite | Mn2Fe3+(Fe3+SiO5)(OH)4 |
| 9.ED.20 | Chrysocolla | Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O |
| 9.ED.20 | Imogolite | Al2SiO3(OH)4 |
| 9.ED.20 | Neotocite | (Mn,Fe,Mg)SiO3 · H2O |
| 9.ED.25 | Bismutoferrite | Fe23+Bi(SiO4)2(OH) |
| 9.ED.25 | Chapmanite | Fe23+Sb3+(Si2O5)O3(OH) |
| 15.1 | Andalusite | Al2(SiO4)O |
| 15.2 | Kyanite | Al2(SiO4)O |
| 15.3 | Sillimanite | Al2(SiO4)O |
| 15.4 | Mullite | Al4+2xSi2-2xO10-x |
| 15.5 | Pyrophyllite | Al2Si4O10(OH)2 |
| 15.6 | Dickite | Al2(Si2O5)(OH)4 |
| 15.7 | Nacrite | Al2(Si2O5)(OH)4 |
| 15.8 | Kaolinite | Al2(Si2O5)(OH)4 |
| 15.9 | Metahalloysite | Al2(Si2O5)(OH)4 |
| 15.10 | Halloysite | Al2(Si2O5)(OH)4 |
Other Names for Allophane
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.
References for Allophane
Reference List:
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. American Mineralogist: 59: 1094-1098.
Henmi, T., Wada, K. (1976) Morphology and composition of allophane. American Mineralogist: 61: 379-390.
Wada, S.I., Wada, K. (1977) Density and structure of allophane. Clay Minerals Bulletin: 12: 289-298.
Bailey, S.W. (1980) Summary of recommendations of AIPEA nomenclature committee on clay minerals. American Mineralogist: 65: 1-7.
Parfitt, R.L., Furkert, R.J., Henmi, T. (1980) Identification and structure of two types of allophane from volcanic ash soils and tephra. Clays and Clay Minerals: 28: 328-334.
van der Gaast, S.J., Wada, K., Wada, S.I., Kakuto, Y. (1985) Small-angle X-ray powder diffraction, morphology, and structure of allophane and imogolite. Clays and Clay Minerals: 33: 237-243.
Gaines, R.V., H. Skinner, 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: eighth edition. John Wiley and Sons, Inc., 1819 pp.: 1432.
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. American Mineralogist: 59: 1094-1098.
Henmi, T., Wada, K. (1976) Morphology and composition of allophane. American Mineralogist: 61: 379-390.
Wada, S.I., Wada, K. (1977) Density and structure of allophane. Clay Minerals Bulletin: 12: 289-298.
Bailey, S.W. (1980) Summary of recommendations of AIPEA nomenclature committee on clay minerals. American Mineralogist: 65: 1-7.
Parfitt, R.L., Furkert, R.J., Henmi, T. (1980) Identification and structure of two types of allophane from volcanic ash soils and tephra. Clays and Clay Minerals: 28: 328-334.
van der Gaast, S.J., Wada, K., Wada, S.I., Kakuto, Y. (1985) Small-angle X-ray powder diffraction, morphology, and structure of allophane and imogolite. Clays and Clay Minerals: 33: 237-243.
Gaines, R.V., H. Skinner, 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: eighth edition. John Wiley and Sons, Inc., 1819 pp.: 1432.
Internet Links for Allophane
mindat.org URL:
https://www.mindat.org/min-139.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
Specimens:
The following Allophane specimens are currently listed for sale on minfind.com.
Mosset rare earths deposit, Mosset, Pyrénées-Orientales, Occitanie, France