Greywacke

Greywacke is a term from the miners' language of the resin. He called gray to green-gray sandstones with interests in rock debris, for example, quartzite, phyllite or slate. The term is usually used only for rocks that come from the Paleozoic or even older.

Demarcation

The use is attested since at least 1780. Wacke here is an obsolete name for boulders.

In Germany greywacke is also an obsolete stratigraphic name for rocks of the Lower Carboniferous of Kulmfazies. Greywacke can be found in Central Europe, for example in the old hull mountains such as resin or Rhenish and Thuringian Slate Mountains. About the same old greywacke occur in the Alps as a narrow strip north of the Central Alps to days ( greywacke zone ).

According Vinx (2005) greywacke is now used only as a rock designation in the field. The correct name of the ore would Litharenit.

Formation

Greywacke are marine, clastic sediments, which are preferably deposited in the environment of formation and erosion of mountains. You have often extended delivery area from which the raw material of the greywacke is transported to the sea and is deposited as coastal sediment mass. By instabilities have not yet solidified deposits in their storage can begin to flow and produce turbidity currents, with which the material can be transported over long distances. The current comes to a standstill, larger rock fragments are stored at the bottom, while smaller fragments sink slowly. This produces a stratification graded in vertical section. The resulting rock is called a turbidite; it is the typical rock a Flyschablagerung.

Composition

The relatively soft, usually dark rocks represent a class of sandstones (mostly plagioclase ) consist of quartz, feldspar, silica or clay shale and rock fragments in a clayey matrix (matrix). The proportion of the rock matrix is in this case more than 15%, usually consists of clay minerals, chlorites and micas and causing the usually dark (green) gray color. Greywacke are medium-to fine-grained, partly grainy, highly strengthened, poorly sorted and rounded, often graded and finely laminated.

After HG Hucke Wood ( 1963) consist of greywacke

  • 28-53 % quartz
  • 25-47 % feldspar
  • 4-21 % mica
  • 4-25 % chlorite
  • 0-6 % carbonates
  • 1-3% accessory minerals

Greywacke can be divided into quartz Wacken ( dominant quartz content ) differ Feldspatwacken (quartz, feldspar and small amounts of rock fragments ) and lithic Wacken with a high content of rock fragments.

Use

Greywacke is as Grauwackeschotter widespread use as a generic building material for railway lines as well as paving stone.

Types of natural stone

  • Lindlarer greywacke
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