Chloraluminite
A valid IMA mineral species - grandfathered
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About Chloraluminite
Formula:
AlCl3 · 6H2O
Colour:
Colourless to white; yellowish; colourless in transmitted light.
Specific Gravity:
1.644
Crystal System:
Trigonal
Name:
In allusion to the composition, containing CHLORine and ALUMINium.
A deliquescent, hydrated chloride mineral.
Unique Identifiers
Mindat ID:
1012
Long-form identifier:
mindat:1:1:1012:8
IMA Classification of Chloraluminite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
AlCl3·6H2O
First published:
1874
Classification of Chloraluminite
3.BC.05
3 : HALIDES
B : Simple halides, with H2O
C : M:X = 1:3
3 : HALIDES
B : Simple halides, with H2O
C : M:X = 1:3
9.3.3.1
9 : NORMAL HALIDES
3 : AX3
9 : NORMAL HALIDES
3 : AX3
8.6.2
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
6 : Halides of Al
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
6 : Halides of Al
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Cla | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Chloraluminite
Transparency:
Transparent
Colour:
Colourless to white; yellowish; colourless in transmitted light.
Streak:
White
Comment:
Soft
Density:
1.644 g/cm3 (Measured) 1.666 g/cm3 (Calculated)
Comment:
Measured on synthetic
Optical Data of Chloraluminite
Type:
Uniaxial (-)
RI values:
nω = 1.560 nε = 1.507
Max. Birefringence:
δ = 0.053
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
None to Very Low
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Chemistry of Chloraluminite
Mindat Formula:
AlCl3 · 6H2O
Element Weights:
Elements listed:
Crystallography of Chloraluminite
Crystal System:
Trigonal
Class (H-M):
3m(32/m) - Hexagonal Scalenohedral
Space Group:
R3c
Setting:
R3c
Cell Parameters:
a = 11.83 Å, c = 11.91 Å
Ratio:
a:c = 1 : 1.007
Unit Cell V:
1,443.48 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Occurs in crystalline crusts and stalactites. Rhombohedral (natural crystals); prismatic [0001] (artificial crystals).
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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CIF File Best | x | y | z | a | b | c
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Labels
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0009342 | Chloraluminite | Buchanan D R, Harris P M (1968) A neutron and X-ray diffraction investigation of aluminium chloride hexahydrate Acta Crystallographica B24 954-960 |  | 1968 | synthetic | 0 | 293 |
| 0009341 | Chloraluminite | Buchanan D R, Harris P M (1968) A neutron and X-ray diffraction investigation of aluminium chloride hexahydrate Acta Crystallographica B24 954-960 | | 1968 | synthetic | 0 | 293 |
| 0017919 | Chloraluminite | Andress K, Carpenter C (1934) Kristallhydrate. II.Die Struktur von Chromchlorid- und Aluminiumchloridhexahydrat _cod_database_code 1011008 Zeitschrift fur Kristallographie 87 446-463 | 1934 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.297 Å | (100) |
| 3.246 Å | (55) |
| 2.308 Å | (50) |
| 3.89 Å | (40) |
| 2.764 Å | (40) |
| 3.68 Å | (35) |
| 5.95 Å | (25) |
Comments:
Synthetic
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45b : [Other oxidized fumarolic minerals] |
Type Occurrence of Chloraluminite
General Appearance of Type Material:
crusts
Place of Conservation of Type Material:
Natural History Museum, Paris, France, 107480.
Geological Setting of Type Material:
As crusts around acidic fumaroles.
Associated Minerals at Type Locality:
Synonyms of Chloraluminite
Other Language Names for Chloraluminite
Dutch:Chloraluminiet
German:Chloraluminit
Chloralluminit
Chloralluminit
Italian:Chloralluminio
Russian:Хлоралюминит
Spanish:Cloraluminita
Related Minerals - Strunz-mindat Grouping
| 3.BC.10 | 'Hydromolysite' | FeCl3 · 6H2O |
Other Information
Thermal Behaviour:
Decomposes at a low tempeature.
Notes:
Deliquescent. Very soluble in water.
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 Chloraluminite
mindat.org URL:
https://www.mindat.org/min-1012.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Chloraluminite
Reference List:
Localities for Chloraluminite
Showing 10 localities.
symbol to view information about a locality.
The 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).
All localities listed without proper references should be considered as questionable.
Antarctica | |
| Viramonte et al. (1974) |
El Salvador | |
| Stoiber et al. (1974) |
France | |
| Wittern et al. (1997) |
Guatemala | |
| Stoiber et al. (1974) |
Italy (TL) | |
| Palache et al. (1951) |
| Pelloux (1927) +2 other references | |
| Steffen Möckel analysis |
Nicaragua | |
| Stoiber et al. (1974) |
Poland | |
| Kruszewski (2012) |
Russia | |
| Vergasova et al. (1977) +1 other reference |
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La Fossa crater, Vulcano Island, Lipari, Eolie Islands, Metropolitan City of Messina, Sicily, Italy