|General and classification|
|chemical formula||Al 2 [(OH) 4 | SO 4 ] • 7H 2 O|
(and possibly department)
|Sulfates (and relatives)|
System no. to Strunz
and to Dana
|7.DC.05 ( 8th edition : VI / D.06)
|Similar minerals||massive magnesite and howlite|
|Crystal class ; symbol||monoclinic prismatic; 2 / m|
|Space group||P 2 1 / c (No. 14)|
a = 7.44 Å ; b = 15.58 Å; c = 11.70 Å
β = 110.2 °
|Formula units||Z = 4|
|Mohs hardness||1 to 2|
|Density (g / cm 3 )||measured: 1.66 to 1.82; calculated: 1.794|
|Break ; Tenacity||earthy in aggregates; crumbly, friable|
|colour||white, gray, yellowish|
|transparency||translucent to opaque|
n α = 1.459
n β = 1.464
n γ = 1.470
|Birefringence||δ = 0.011|
|Optical character||biaxial positive|
|Axis angle||2V = measured: 90 °; calculated: 86 °|
|Chemical behavior||Easily soluble in hydrochloric acid|
Aluminite ( Websterite , Halle earth ) is a rarely occurring mineral from the mineral class of " sulfates ( and relatives )". It crystallizes in the monoclinic crystal system with the chemical composition Al 2 [(OH) 4 | SO 4 ] · 7 H 2 O and develops exclusively earthy, grape-like or kidney-like, bulbous aggregates from microscopic (up to 0.1 mm long), needle-like aggregates Crystals in white, gray or yellowish color with white streak color .
Etymology and history
The name aluminite is derived from the main element aluminum contained in the mineral , the content of which can be up to 15.68%.
Aluminite was first described in 1730 by Johann Jakob Lerche , who called the white tubers Lac lunae , terra lenis and friabilis candidissima , which were pulled out of the ground during the construction of a botanical garden in Halle an der Saale . In his description, Lerche mainly goes into the medical importance of the mineral, which when mixed with rock crystal stimulates milk production in mothers and alleviates fever attacks and urinary stones.
The mineral was examined in more detail by various scientists, including Johann Christian von Schreber in 1759, Abraham Gottlob Werner in 1780, again by Schreber together with Frischmann in 1781, Simon in 1802 and finally Buchholz in 1806, the result of which coincided with that of Simon.
The name aluminite was in use at least since 1801 by Christian Friedrich Schumacher (1757-1830), but as a rock name for various alum slate (e.g. "earthy aluminite", "schisty common aluminite", "slatey shiny aluminite") . In this sense, Carl Constantin Haberle also used this name, but at the same time expanded its meaning and transferred it to the mineral for the first time in 1805.
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the aluminite belonged to the mineral class of "sulfates, selenates, tellurates, chromates, molybdates, tungstates" and there to the department of "water-containing sulfates with foreign anions ", where it was classified as Namesake of the "Aluminit Group" with the system no. VI / D.06 and the other members Felsőbányait , Hydrobasaluminit , Jurbanit , Khademit , Mangazeit , Meta-Aluminit , Rostit and Zaherit .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, also assigns the aluminite to the class of “sulfates (and relatives)” and there to the “sulfates (selenates etc.) with additional anions H 2 O “a. However, this is more precisely subdivided according to the relative size of the cations involved and the crystal structure, so that the mineral is classified in the sub-section “with medium-sized cations; Chains of edge-sharing octahedra "can be found, where together with butlerite , meta-aluminite, parabutlerite the" butlerite group "with the system no. 7.DC.05 forms.
The systematics of minerals according to Dana assigns the aluminite to the class of "sulfates, chromates and molybdates" and there into the category of "hydrated sulfates with hydroxyl or halogen". There he is together with Mangazeit of the unnamed group July 31, 2004 within the subdivision “ Hydrogen sulfates with hydroxyl or halogen with (A + B 2+ ) 2 (XO 4 ) Z q • x (H 2 O) ”.
Aluminite crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 7.44 Å ; b = 15.58 Å; c = 11.70 Å and β = 110.2 ° and 4 formula units per unit cell .
Aluminite looks very similar to the minerals howlite and magnesite when they occur in moderate to massive form and can therefore be confused with them. However, untreated aluminite is much softer ( Mohs hardness 1 to 2) and, in contrast to howlite and magnesite, can be scratched with the fingernail.
Education and Locations
At moderate temperatures, aluminite is formed as a reaction product of sulfuric acid with aluminum-rich silicic acid compounds with splitting of marcasite or pyrite and is mostly found in clay soils or lignite veins. There it occurs in paragenesis with basaluminite , celestine , dolomite , epsomite , gibbsite , gypsum and goethite, among others .
In Germany, aluminite has so far only been found at its type locality in Halle an der Saale.
So far (as of 2010), aluminite has been found at around 60 sites around the world, including the Mount Morgan Mine near Rockhampton in Australia; in Azerbaijan ; at Calama in Chile; in the Chinese provinces of Fujian and Yunnan ; in the French regions of Brittany , Grand Est and Île-de-France ; on Vesuvius and in the "Grotta del Vetriolo" near Levico Terme in Italy; in the "Ikuno Mine" on Honshū in Japan; in the Canadian mining area around Dawson ; in Kazakhstan ; Pakistan ; Romania ; near Podolsk , on Iturup and on Mount Sokolow near Saratow in Russia; Banská Bystrica and Prešov in Slovakia; at Matatiele and Mbombela in South Africa; Bohemia and Moravia in the Czech Republic; in several regions of Hungary ; in Venezuela ; in several regions of England and in several states of the United States of America .
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 615 (first edition: 1891).
- Petr Korbel, Milan Novák: Mineral Encyclopedia (= Villager Nature ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 .
- Mineral Atlas: Aluminite (Wiki)
- Mineral cabinet - class 6: sulfates, tungstates and molybdates
- RRUFF Database-of-Raman-spectroscopy - Aluminite (English)
- American-Mineralogist-Crystal-Structure-Database - Aluminite (English)
- Webmineral - Aluminite (English)
- Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 400 .
- Aluminites . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 66 kB ; accessed on August 18, 2017]).
- Mindat - Aluminite (English)
- Meyers Konversationslexikon - Aluminit
- Thomas Witzke : Discovery of aluminite
- Carl Constantin Haberle: Contributions to a general introduction to the study of mineralogy as corrective comments and additions. Weimar 1805, pp. 262, 335 ( available online in the Google book search)