Allophane
A valid IMA mineral species - grandfathered
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About Allophane
Formula:
(Al2O3)(SiO2)1.3-2 · 2.5-3H2O
Colour:
White, pale blue to sky-blue, green, brown
Lustre:
Waxy
Hardness:
3
Specific Gravity:
2.75
Crystal System:
Amorphous
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 (a few nm across) have a ball-shaped morphology. Essentially, the mineral consists of a single modified gibbsite sheet rolled into a porous nanoball.
Related to imogolite, another nanomineral.
Copper-bearing varieties can be confused with chrysocolla.
Colourless varieties may be confused with hyalite.
The nano-sized particles (a few nm across) have a ball-shaped morphology. Essentially, the mineral consists of a single modified gibbsite sheet rolled into a porous nanoball.
Related to imogolite, another nanomineral.
Unique Identifiers
Mindat ID:
139
Long-form identifier:
mindat:1:1:139:7
GUID
(UUID V4):
(UUID V4):
70d7764a-c1d9-4f66-a9c2-3f7613a54989
Classification of Allophane
Approved, 'Grandfathered' (first described prior to 1959)
Type description reference:
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
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Symbol | Source | Reference |
---|---|---|
Alp | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Alp | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Physical Properties of Allophane
Waxy
Transparency:
Transparent, Translucent
Colour:
White, pale blue to sky-blue, green, brown
Streak:
White
Hardness:
3 on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
None
None
Fracture:
Conchoidal
Density:
2.75 g/cm3 (Measured)
Optical Data of Allophane
Type:
Isotropic
RI values:
n = 1.468 - 1.512
Birefringence:
Isotropic minerals have no birefringence
Surface Relief:
Moderate
Comments:
RI from air dried sample
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:
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.
Comment:
Amorphous
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
- Å | () |
Comments:
No PXRD pattern has been determined according to the Handbook of Mineralogy.
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Stage 3b: Earth’s earliest hydrosphere | >4.45 |
16 : Low-? aqueous alteration of Hadean subaerial lithologies (see also #23) | |
Near-surface Processes | |
23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
50 : Coal and/or oil shale minerals | <0.36 |
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.
Type Occurrence of Allophane
General Appearance of Type Material:
hyaline crusts and masses; stalactites and flowstones.
Place of Conservation of Type Material:
Mining Academy, Freiberg, Germany, 26104.
Reference:
Hausmann, J.F.L. and Stromeyer, F. (1816) Über Silberkupferglanz und Allophan. Göttingische Gelehrte Anzeigen: 2: 1251-1253.
Synonyms of Allophane
Other Language Names for Allophane
Varieties of Allophane
Allophane-evansite | Phosphate-enriched Allophane. |
Cupro-Allophane | A variety of Allophane containing Cu. |
Ferriallophane | A ferrian allophane. Originally described from Moscow Oblast' (Moscovskaya Oblast'), Central Region, Russia. |
Phosphate-Allophane | A variety containg 7.97% P2O5. |
Plumballophane | A silica-alumina gel containing PbO. |
Common Associates
Associated Minerals Based on Photo Data:
108 photos of Allophane associated with Malachite | Cu2(CO3)(OH)2 |
83 photos of Allophane associated with Azurite | Cu3(CO3)2(OH)2 |
63 photos of Allophane associated with Chrysocolla | Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O, x < 1 |
20 photos of Allophane associated with Quartz | SiO2 |
18 photos of Allophane associated with Baryte | BaSO4 |
16 photos of Allophane associated with Brochantite | Cu4(SO4)(OH)6 |
15 photos of Allophane associated with Goethite | α-Fe3+O(OH) |
14 photos of Allophane associated with Copper | Cu |
14 photos of Allophane associated with Dundasite | PbAl2(CO3)2(OH)4 · H2O |
12 photos of Allophane associated with Hematite | Fe2O3 |
Related Minerals - Strunz-mindat Grouping
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 | Fe3+2(Si2O5)(OH)4 · 2H2O |
9.ED.10 | Hydrohalloysite | Al2Si2O5(OH)4 · 2H2O |
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 | Mn2+3Si2O5(OH)4 |
9.ED.15 | Cronstedtite | Fe2+2Fe3+((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 | Mn2+2Al(AlSiO5)(OH)4 |
9.ED.15 | Lizardite | Mg3(Si2O5)(OH)4 |
9.ED.15 | Manandonite | Li2Al4(Si2AlB)O10(OH)8 |
9.ED.15 | Népouite | Ni3Si2O5(OH)4 |
9.ED.15 | Pecoraite | Ni3(Si2O5)(OH)4 |
9.ED.15 | Guidottiite | Mn2Fe3+(Fe3+SiO5)(OH)4 |
9.ED.15 va | Chromoamesite | Mg2(Al,Cr)(AlSiO5)(OH)4 |
9.ED.20 | Chrysocolla | Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O, x < 1 |
9.ED.20 | Imogolite | Al2SiO3(OH)4 |
9.ED.20 | Neotocite | (Mn,Fe,Mg)SiO3 · H2O |
9.ED.25 | Bismutoferrite | Fe3+2Bi(SiO4)2(OH) |
9.ED.25 | Chapmanite | Fe3+2Sb3+(Si2O5)O3(OH) |
9.ED.30 | Pianlinite | Al2Si2O6(OH)2 |
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.
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:
References for Allophane
Reference List:
Localities for Allophane
Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
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Belgium | |
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Bolivia | |
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Canada | |
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Colombia | |
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DR Congo | |
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Ecuador | |
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Greece | |
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Hungary | |
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Indonesia | |
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Ireland | |
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Japan | |
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Kazakhstan | |
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Kenya | |
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Kyrgyzstan | |
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Laos | |
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Mexico | |
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Middle East | |
Morocco | |
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Netherlands | |
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New Zealand | |
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Norway | |
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Pacific Ocean | |
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Peru | |
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Poland | |
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Portugal | |
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| Michele DondiIdentified by Michele Dondi: Visual Identification, XRD |
| CEDOMIdentified by Michele Dondi: XRD |
| Michele DondiIdentified by Michele Dondi: Visual Identification, XRD |
Romania | |
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Russia | |
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Sweden | |
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Taiwan | |
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| Rolf LuetckeIdentified by Rolf Luetcke: Visual Identification |
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| [var: Allophane-evansite] |
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Zambia | |
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Mars | |
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Quick NavTopAbout AllophaneUnique IdentifiersClassification Mineral SymbolsPhysical Properties Optical Data Chemical Properties Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesVarietiesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Mosset rare earths deposit, Mosset, Prades, Pyrénées-Orientales, Occitanie, France