Wüstite

Wustite, also under the chemical name of iron ( II) oxide is known, a rare occurring mineral in the mineral class of " oxides and hydroxides ." It crystallizes in the cubic crystal system with the chemical composition FeO and mostly developed crusts, intergranular fillings and massive aggregates, which have a metallic luster.

Wustite is opaque in any form. Its color varies between brown and black in daylight, in reflected light, however, it appears gray.

Etymology and history

Named wustite 1927 according to the German iron and steel watchers and founding director of the Kaiser Wilhelm Institute for Iron Research Fritz Wüst ( 1860-1938 ).

Was first described scientifically in 1927 by the mineral Rudolf Schenck and Th thing man. As a type locality applies Scharnhausen in Baden- Württemberg.

Classification

Already in the now outdated but still in use 8th edition of the mineral classification by Strunz was one of wustite to mineral class of " oxides and hydroxides " and then to the Department of " oxides with the molar ratio of metal: oxygen = 2: 1 and 1: 1" where he collaborated with bunsenite, calcium oxide, Manganosit, Monteponit, Murdochit and periclase the " periclase - group " with the system no. IV/A.04 formed.

The 9th edition used since 2001, valid and of the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the wustite also in the class of " oxides and hydroxides " and there in the department of " oxides with the molar ratio of metal: oxygen = 2: 1 and 1: 1 ". This division, however, is further subdivided by the exact relationship between cations and anions as well as the relative size of the cations, so that the mineral according to its composition in the subsection " cation: anion ( M, O ) = 1: 1 (and to 1: 1, 25); " is to find where it together with bunsenite, calcium oxide, Manganosit, Monteponit and the periclase " with only small to medium-sized cations periclase - group "with the system no. 4.AB.25 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the wustite in the class of " oxides and hydroxides " and there in the department of " oxides ". He is also, together with periclase, bunsenite, Manganosit, Monteponit, calcium oxide and Hongquiit in the " Periklasgruppe ( isometric, Fm3m ) " 04:02:01 to find within the subdivision " Simple oxides with a cation charge of 2 ( AO) ".

Education and Locations

Wustite is one of two main components of the lower mantle (see also 1700 - km discontinuity ), but forms at the earth's surface primarily as a conversion product of other iron-bearing minerals at high temperatures in a highly reducing environment, such as in highly reduced, ferrous basalts. He finds himself in the form of inclusions in diamonds, as the deposition product of deep-water sources ( black smokers ) as well as Fe -Mn- Mikrosphärolite in different geological environments and in some meteorites. Accompanying minerals occur among others akaganeite, dignified iron, goethite, hematite, ilmenite, lepidocrocite, magnetite, maghemite, pyrite, pyrrhotite and troilite.

As anthropogenic, that is, caused by human influence, connection is wustite but as an important intermediate link in the reduction of iron ores known and is mainly produced during the smelting in the blast furnace from the previously formed magnetite. The equilibrium reaction between wustite and magnetite is as follows:

In addition, he is also known as weathering product of iron smelting slag or hot processing or heat treatment of ferrous metals ( mill scale ).

As a rare natural mineral formation wustite has so far (as of 2012) detected only at a few localities, of which approximately 30 localities as have been established. Apart from its type locality Scharnhausen the mineral found in Germany still in the alluvial soil of the Glad Bach at Oberwolfach in Baden -Württemberg, in the slags of ferrous metallurgy combine East ( EKO ) at ironworks town in Brandenburg, near Bühl near Kassel in Hesse, in Hölltal near Lautenthal in Lower Saxony, in the zinc smelter Genna / Iserlohn ( Letmathe ) in North Rhine -Westphalia and at the crest of the mountain at Joldelund in Schleswig -Holstein.

Other localities lie including Australia, Azerbaijan, China, France, Namibia, Oman, Poland, Romania, Russia, South Africa, the Czech Republic, the United States of America (USA ) and outside the earth in moon rocks.

Crystal structure

Wustite crystallizes in cubic space group Fm3m ( Raumgruppen-Nr. 225 ) with the lattice parameters a = 4.31 Å and four formula units per unit cell.