Fruit slate

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Theumaer fruchtschiefer with relatively large cordierite - porphyroblasts
Theuma fruit slate, polished surface
Artistic design with Theuma fruit slate on a column in Dresden (made around 1960)

Fruit slates are contact metamorphites that emerged from clay stones .

Origin and mineral inventory

They arise at very low pressures (low-metamorphic rocks) and at temperatures of around 500 ° C. At this temperature, cordierite develops to the size of the grain of the grain, which has an impact on the name. The mineral inventory includes cordierite , muscovite , potassium feldspar , quartz , biotite and hornblende .

Occurrence

In Germany, fruit slate occurs as contact metamorphic rock in the Harz , Ore Mountains , Odenwald and Vogtland . The best-known deposits are the deposits at Theuma and Tirpersdorf (both in Vogtland), in which clayey sedimentary rocks of the Ordovician in the immediate vicinity of the Variscan Bergen granite pluton were contact metamorphic overprinted. The Theumaer and Tirpendorfer fruit slate has found widespread use beyond the region.

use

The traditional main application is in the form of rough products for masonry of various types. The Theuma fruit slate is also split or ground as a facade panel, floor panel and plinth facing. The architectural components also include window and door frames, columns and steps. There are also occasional artistic and sculptural applications.
In the past, sluice and well covers as well as containers for galvanic baths and acids were made from the Theuma fruit slate .

The use of Theuma fruit slate can be traced back to the Middle Ages. One example are plates in the 14th century crypt of the Johanniskirche (1122) in Plauen .

Web links

literature

  • Georg Dehio: Handbook of the German art monuments. Saxony: The districts of Dresden, Karl-Marx-Stadt, Leipzig . Deutscher Kunstverlag, Berlin 1990. ISBN 3-422-03016-6 (unchanged reprint of the edition published in Leipzig in 1965)
  • Carl Gäbert, Alexander Steuer, Karl Weiss: The usable rock deposits in Germany . Union Deutsche Verlagsgesellschaft, Berlin 1915 ( Handbook of the Stone Industry , Volume 1), including Chapter 7 (pp. 147–174): Kingdom of Saxony (by Carl Gäbert), pp. 153–154
  • Fruit slate quarry near Theuma. In: Plauen and the middle Vogtland (= values ​​of our homeland . Volume 44). 1st edition. Akademie Verlag, Berlin 1986, pp. 155–156.
  • Walter Maresch, Olaf Medenbach: Rocks . Mosaik Verlag, Munich 1987, ISBN 3-576-10699-5 . P. 252.

Individual evidence

  1. ↑ Ulrich Sebastian: The geology of the Erzgebirge . Springer Spectrum, Berlin, Heidelberg 2013, ISBN 978-3-8274-2976-6 , pp. 246-247 .