Aluminite

• Websterite
• Hallische earth

Aluminite ( websterite, Hallische Earth ) is a rarely occurring mineral from the mineral class of " sulfates ( and Related ) ". It crystallizes in the monoclinic crystal system with the chemical composition Al 2 [( OH) 4 | SO4 ] · 7 H2O and developed exclusively earthy, grape-like or low one, nodular aggregates of microscopic (up to about 0.1 mm in length), needle-like crystals in white, gray or yellowish in color with white stroke color.

Special Features

Aluminite sees the minerals howlite and magnesite, when they occur in nieriger to bulk form, very similar and can therefore be confused with them. However, untreated Aluminite much softer ( Mohs hardness 1-2 ) and can be unlike howlite and magnesite scratched with a fingernail.

Etymology and history

The name Aluminite is derived from the included mineral major element aluminum whose content can be up to 15.68%.

Was first described in 1730 by Johann Jakob Aluminite Lark, who described the white tubers as Lac lunae, terra lenis and friabilis candidissima who were brought in the construction of a botanical garden in Halle an der Saale from the ground. In his description lark deals particularly on the medical importance of the mineral, the rock crystal mixed in mothers stimulate the production of milk and soothing was with fevers and urinary stones.

The mineral was further investigated by various scientists, including Schreber 1759, Abraham Gottlob Werner in 1780, again from the allotment together with Frischmann 1781, Simon 1802, and finally Buchholz in 1806, the result of which coincided with that of Simon.

The name Aluminite was indeed at least since 1801 by Christian Friedrich Schumacher ( 1757-1830 ) in use, but as a rock name for various alum shale (eg " walk- Aluminite ", " crooked Riger common Aluminite ", " crooked Riger shiny Aluminite "). In this sense, Carl Constantin Haberle used this name, but delivered Advanced slight its importance and transferred it in 1805 for the first time on the mineral.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Aluminite the mineral class of " sulfates, selenates, tellurates, chromates, molybdates, tungstates " and then to the Department of " water -containing sulfates with foreign anions " belonged, where he served as named the " Aluminite group " with the system no. Formed VI/D.06 and the other members Felsőbányait, Hydrobasaluminit, Jurbanit, Khademit, manganese time, meta- Aluminite, Rostit and Zaherite.

The valid since 2001 and used by the IMA 9th edition of the Strunz'schen Mineral classification assigns the Aluminite also in the class of " sulfates ( and Related ) " and then in the Department of " sulfates ( selenates, etc.) with additional anions, with H2O " one. However, this is precisely divided according to the relative size of the involved cations and the crystal structure, so that the mineral according to its composition in the subdivision " with medium-sized cations; Chains of edge- sharing octahedra " is to find where it together with Butlerit, meta Aluminite, Parabutlerit the " Butleritgruppe "with the system no. 7.DC.05 forms.

The classification of minerals according to Dana assigns the Aluminite in the class of " sulfates, chromates and molybdates " and there in the department of " hydrated sulfates with hydroxyl or halogen". There he is, together with Time Manga of the unnamed group 31.07.04 within the subdivision " water -containing sulfates with hydroxyl or halogen with (A B2 ) 2 ( XO4 ) Zq • x (H2O) ".

Education and Locations

Aluminite formed at moderate temperatures as the reaction product of sulfuric acid with aluminum-rich silica compounds with cleavage of marcasite or pyrite and is usually found in clay soils or brown coal veins. There in paragenesis occurs among other Basaluminit, celestite, dolomite, epsomite, gibbsite, gypsum and goethite.

In Germany Aluminite has been found only at its type locality Halle an der Saale.

Worldwide, Aluminite so far (as of 2010) are detected in about 60 localities, so among other things in the " Mount Morgan Mine" at Rockhampton in Australia; in Azerbaijan; at Calama in Chile; in the Chinese provinces of Fujian and Yunnan; in the French provinces of Brittany, Champagne- Ardenne and Ile- de -France; Vesuvius and the " Grotta del Vetriolo " in Levico Terme, Italy; in the " Ikuno Mine " on Honshu in Japan; in the Canadian mining area around Dawson; in Kazakhstan; Pakistan; Romania; in Podolsk, on Iturup and at Mount Sokolow from Saratov in Russia; Banská Bystrica and Prešov in Slovakia; in 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.

Crystal structure

Aluminite crystallizes in the monoclinic space group P21 / c ( Raumgruppen-Nr. 14) with the lattice parameters a = 7.44 Å; b = 15.58 Å; c = 11.70 Å and β = 110.2 °, and four formula units per unit cell.