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Aluminite
Sulfate mineral
Sulfate mineral
| Field | Value |
|---|---|
| name | Aluminite |
| category | Sulfate mineral |
| image | Aluminite - Newhaven, Sussex, England.jpg |
| imagesize | 260px |
| caption | Aluminite from Newhaven, Sussex, England |
| formula | Al2SO4(OH)4·7H2O |
| IMAsymbol | A |
| strunz | 7.DC.05 |
| system | Monoclinic |
| class | Prismatic (2/m) |
| (same H-M symbol) | |
| symmetry | *P*21/c |
| unit cell | a = 7.44, b = 15.583 |
| c = 11.7 [Å]; β = 110.18°; Z = 4 | |
| color | White to grayish white |
| habit | Needles and fibrous masses |
| cleavage | None |
| fracture | Irregular/uneven |
| tenacity | Friable |
| mohs | 1 - 2 |
| luster | Dull to earthy |
| streak | White |
| diaphaneity | Translucent, opaque if massive |
| gravity | 1.66–1.82 |
| opticalprop | Biaxial (+) |
| refractive | nα = 1.459 nβ = 1.464 nγ = 1.470 |
| birefringence | δ = 0.011 |
| 2V | Measured: 90°, calculated: 86° |
| references |
(same H-M symbol) c = 11.7 [Å]; β = 110.18°; Z = 4 | length fast/slow =
Aluminite is a hydrous aluminium sulfate mineral with formula: Al2SO4(OH)4·7H2O. It is an earthy white to gray-white monoclinic mineral which almost never exhibits crystal form. It forms botryoidal to mammillary clay-like masses. It has a very soft Mohs hardness of 1–2 and a specific gravity of 1.66–1.82.
It forms in clay and lignite deposits as an oxidation product of pyrite and marcasite along with aluminium silicates. It also occurs in volcanic sublimates, in native sulfur deposits and rarely in caves. It occurs in association with basaluminite, gibbsite, epsomite, gypsum, celestine, dolomite and goethite.
It was first described in 1807 from Halle, Saxony-Anhalt, Germany and named for its aluminium content. It is also known as alley stone, halite and websterite (named after Orcadian geologist Thomas Webster).
Aluminite is used by tile and masonry workers to reduce the setting time of mortars.
References
References
- Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
- "Handbook of Mineralogy".
- "Mindat w/ locations".
- "Webmineral".
This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.
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