Itacolumite

The rock itakolumite is a special, rare variety of quartzite , a sandstone that is metamorphically transformed under the influence of pressure and temperature . The binding agent that holds the individual quartz grains together consists of various sheet silicates , mainly talc or chlorite , occasionally also sericite . In some varieties, the physical properties of the talc flakes (low hardness , easy displacement) make the rock in thin plates flexible (flexible or elastic sandstone, also called articulated quartz ). With increasing content of sheet silicates and decreasing quartz content, itacolumite shows transitions to chlorite, talc and mica slate .

Itakolumite is found as a member of the Huronian (slate) formation, especially in Brazil , where it is composed of high mountains in Minas Gerais and Goiás and the eponymous mountain Itacolomi (in the Serra do Espinhaço ). In addition to its essential mixture, the rock here contains gold , coarse and broken, accompanied by pyrite and arsenopyrite , hematite , magnetite , tourmaline , mica ; it is occasionally interspersed with quartz veins , and the talc and chlorite shales occur in it in the form of deposits. In Brazil, itakolumite is also the parent rock for diamonds . Otherwise it is found in North and South Carolina ( Sauratown Mountains ), in the Urals and in Portugal .

See also: List of rocks

literature

• RV Dietrich, BJ Skinner: The rocks and their minerals. Ott, Thun 1984, ISBN 3-7225-6287-2