Mudstone
Mudstone is a pelitic sedimentary rock ( grain size smaller than 0.002 mm) and consists mainly of clay minerals (e.g. montmorillonite , illite and smectite ). Further mixtures are quartz , feldspar and carbonates . Heavily bituminous mudstones are called oil shale . Slate clay stones, which are easily split but not metamorphic on the layer surfaces , are called slate .
Clay stones come in many different colors, such as light to dark gray, black, red and green. Additions of limonite , hematite , chlorite and organic carbon compounds such as bitumen or coal are decisive for the color .
Mudstone, which is transformed under pressure and temperature and usually splits into thin leaves, is called slate . The cleavage surfaces of this metamorphic rock sometimes do not run parallel to the strata.
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Occurrence in Germany (selection):
- Messel in the Darmstadt-Dieburg district ( Hesse )
- Holzmaden ( Baden-Württemberg )
- Ohmden ( Swabia )
- Niederschöna ( Saxony )
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Use:
- Clay stones made from swellable clay minerals ( montmorillonite ) are used in the brick and ceramic industries.
literature
- Johannes Hartlieb: Regional recording of the claystones of the Rhenish-Westphalian Coal Mountains and attempt to evaluate them as guide horizons. Springer Fachmedien Wiesbaden GmbH, Wiesbaden 1961.