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Allophane

Big Photo

Kamariza Mines (Kamareza Mines), Agios Konstantinos [St Constantine] (Kamariza), Lavrion District Mines, Lavrion (Laurion; Laurium) District, Attikí (Attica; Attika) Prefecture, Greece
© Steve Rust

Show Allophane Photos (36)
Formula:
(Al
 
2
O
 
3
)(SiO
 
2
)
 
1.3-2
·2.5-3H
 
2
O
System:AmorphousColour:Blue, green, brown, ...
Lustre:Vitreous, PearlyHardness:3
Name:From the Greek allos - "other" and phanos - "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.

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:71.1.5.1
Dana 8th edition ID:71.1.5.1

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, Reichmannsdorf, Thuringian Forest, Thuringia, Germany
Year of Discovery:1816

Occurrences of Allophane

Geological Setting:A weathering product of volcanic ash; also a hydrothermal alteration product of feldspars.

Physical Properties of Allophane

Lustre:Vitreous, Pearly
Diaphaneity (Transparency):Transparent, Translucent
Colour:Blue, green, brown, colourless, yellow, white
Streak:White
Hardness (Mohs):3
Tenacity:Brittle
Cleavage:None Observed
None
Fracture:Conchoidal

Crystallography of Allophane

Crystal System:Amorphous

Chemical Properties of Allophane

Formula:
(Al
 
2
O
 
3
)(SiO
 
2
)
 
1.3-2
·2.5-3H
 
2
O
Essential elements:Al, H, O, Si
All elements listed in formula:Al, H, O, Si
Common Impurities:Ti,Fe,Mg,Ca,Na,K

Relationship of Allophane to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
9.ED.05Dickite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
9.ED.05Kaolinite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
9.ED.05Nacrite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
9.ED.05Odinite
(Fe,Mg,Al,Fe,Ti,Mn)
 
2.4
(Si,Al)
 
2
O
 
5
(OH)
 
4
9.ED.10Halloysite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
9.ED.10Hisingerite
Fe
3+
2
Si
 
2
O
 
5
(OH)
 
4
·2H
 
2
O
9.ED.10Halloysite-7Å
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
9.ED.15Amesite
Mg
 
2
Al[(OH)
 
4
|AlSiO
 
5
]
9.ED.15Antigorite
(Mg,Fe
2+
 
)
 
3
[(OH)
 
4
|Si
 
2
O
 
5
]
9.ED.15Berthierine
(Fe,Fe,Mg)
 
2-3
(Si,Al)
 
2
O
 
5
(OH)
 
4
9.ED.15Brindleyite
(Ni,Mg,Fe)
 
2
Al(Si,Al)O
 
5
(OH)
 
4
9.ED.15Caryopilite
(Mn,Mg)
 
3
Si
 
2
O
 
5
(OH)
 
4
9.ED.15Chrysotile
Mg
 
3
Si
 
2
O
 
5
(OH)
 
4
9.ED.15Cronstedtite
Fe
2+
2
Fe
3+
 
[(Si,Fe
3+
 
)
 
2
O
 
5
](OH)
 
4
9.ED.15Fraipontite
(Zn,Al)
 
3
[(OH)
 
4
|(Si,Al)
 
2
O
 
5
]
9.ED.15Greenalite
Fe
 
2-3
Si
 
2
O
 
5
(OH)
 
4
9.ED.15Kellyite
Mn
2+
2
Al[(OH)
 
4
|AlSiO
 
5
]
9.ED.15Lizardite
Mg
 
3
[(OH)
 
4
|Si
 
2
O
 
5
]
9.ED.15Manandonite
LiAl
 
4
Si
 
3
BO
 
10
(OH)
 
6
9.ED.15Népouite
(Ni,Mg)
 
3
Si
 
2
O
 
5
(OH)
 
4
9.ED.15Pecoraite
Ni
 
3
[(OH)
 
4
|Si
 
2
O
 
5
]
9.ED.20Chrysocolla
(Cu,Al)
 
2
H
 
2
Si
 
2
O
 
5
(OH)
 
4
·nH
 
2
O
9.ED.20Imogolite
Al
 
2
SiO
 
3
(OH)
 
4
9.ED.20Neotocite
(Mn,Fe,Mg)SiO
 
3
·H
 
2
O
9.ED.25Bismutoferrite
Fe
3+
2
Bi[OH|(SiO
 
4
)
 
2
]
9.ED.25Chapmanite
Fe
3+
2
Sb
3+
 
[OH|(SiO
 
4
)
 
2
]
Related Minerals - Hey's Index Grouping:

- +
15.1Andalusite
Al
 
2
[O|SiO
 
4
]
15.2Kyanite
Al
 
2
[O|SiO
 
4
]
15.3Sillimanite
Al
 
2
[O|SiO
 
4
]
15.4Mullite
Al
 
8
[(O,OH,F)|(Si,Al)O
 
4
]
 
4
15.5Pyrophyllite
Al
 
2
Si
 
4
O
 
10
(OH)
 
2
15.6Dickite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
15.7Nacrite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
15.8Kaolinite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4
15.9Metahalloysite
15.10Halloysite
Al
 
2
Si
 
2
O
 
5
(OH)
 
4

Other Names for Allophane

Synonyms:
AllophaniteElhuyariteIlbaiteRazoumofskynRazumofskin
RiemaniteRiemannite
Other Languages:
German:Allophan
Allophanit
Elhuyarit
Ilbait
Riemanit
Riemannit
Italian:Allofane
Spanish:Allophanita
Elhuyarita
Ilbaita
Riemanita
Riemannita
Varieties:
Cupro-AllophaneFerriallophanePhosphate-AllophanePlumballophane

Other Information

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

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.

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

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    Localities for Allophane

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