Chamosite

Chamosite ( Chamoisit ) is a commonly occurring mineral from the mineral class of silicates and Germanates. It crystallizes in the monoclinic crystal system with the chemical composition ( Fe2 , Mg, Fe 3 ) 5Al [ (OH, O) 8 | AlSi3O10 ] and developed predominantly scaly, oolitic or massive mineral aggregates of gray, gray-green, brown or black color.

Etymology and history

Chamosite 1820 was first described by Pierre Berthier, of the mineral after its type locality Chamoson ( municipality in the district Conthey in the French speaking part of the canton of Valais, Switzerland ) named.

Classification

In the old ( 8th edition ) and new classification of minerals according to Strunz ( 9th edition ) of the chamosite is part of the Department of " layer silicates ( phyllosilicates ) ". The 9th edition of Strunz'schen Mineral classification divided here but now more precisely following the structure of the silicate layers, wherein the mineral according to the division of the " layer silicates ( phyllosilicates ) with mica sheets, composed of tetrahedral and octahedral nets " can be found.

The classification of minerals according to Dana sorted the chamosite also in the Department of phyllosilicates. In the scheme of Dana is further clarified by the crystal structure. However, here the lower section will be described as a " six-membered rings of layers, alternating 1:1, 2:1, and octahedral ."

Education and Locations

Chamosite forms by metamorphism or hydrothermal processes in iron-rich sediments and is then often found in the company of other iron-bearing sedimentary minerals such as goethite, hematite, magnetite and siderite, but also calcite, kaolinite, olivine, plagioclase, pyrite, pyroxene and / or quartz.

So far Chamosite was at 265 archaeological sites discovered (as of 2009), so among other things in Bahariyya (Egypt ); Constantine ( Algeria); Biggenden Shire / Queensland, Yancowinna County / New South Wales and Queenstown / Tasmania (Australia ); the provinces of Liège and Luxembourg in Belgium; Departamento La Paz and Potosí Department in Bolivia; Minas Gerais and Pará in Brazil; Bulgaria; Hebei, Hunan and Jiangxi provinces in China; Baden- Württemberg ( Black Forest), Bavaria, Saxony, Thuringia and other regions in Germany; Pays de la Loire in France; in Crete (Greece); England and Wales in the United Kingdom; some regions in Italy; Honshu and Shikoku in Japan; New Brunswick, Ontario and Quebec ( Mont St -Hilaire ) in Canada; Cordoba in Colombia; Telemark and Vestfold in Norway; Hohe Tauern (Carinthia and Salzburg) in Austria; several regions in Russia and Slovakia; Bern, Obwalden, Uri and Valais in Switzerland; some regions of Spain; Mpumalanga and Northern Cape in South Africa; Bohemia and Moravia in the Czech Republic; and many regions in the United States.

Also on the seabed of the Mid-Atlantic Ridge, more precisely, the " Markov - Depth " from the Sierra Leone Fracture Zone samples have already been taken up by chamosite.

Chamosite heard among some others to the discovered on Mars minerals.

Crystal structure

Chamosite crystallizes in the monoclinic crystal system, space group C2 / m with lattice parameters a = 5.373 Å; b = 9.306 Å, c = 14.222 Å and β = 97 ° 53 'and two formula units per unit cell.