Redwitzit
As Redwitzit several rock types in are Fichtelgebirge to Marktredwitz referred. Two Redwitzites, the Seußen Redwitzite and the Wölsauer Redwitzite, were important for the extraction of natural stone . It's tonalite . These deposits are located near Seußen and Röthenbach (Arzberg) in the Fichtel Mountains in Upper Franconia . They originated in the Upper Carboniferous . Both natural stones are no longer being mined.
Occurrence
Several Redwitzit types occur in the Marktredwitz area; at Grafenstein near Leutenberg fine-grained light gray with a high proportion of quartz ; at Röthenbach medium gray with little quartz; near Lorenzreuth, dark gray rocks with quartz encased in amphibole and titanium ; at Wölsau dark gray, low-quartz rocks with biotite and pyrite and at Haag black, medium-grain rocks without quartz. Depending on their mineral composition, the occurrence varies between tonalite and gabbro rock . The rock colors vary from light to medium and dark gray to almost black.
geology
Originally, Redwitzite were gabbroide melts that penetrated tunnels and crevices of sediments. These sediments and rocks were melted. In these melting processes, the mineral inventory changed and dioritic and quartz-dioritic rocks were created. Penetrating granitic melts changed the mineral inventory again and converted the rocks into tonalites. Marbles were also partially melted. The deposits therefore vary considerably in their mineral inventory.
Naming
The rock was called "Redwitzit" in 1916 by the leading Bavarian petrographer at the time, Ernst Weinschenk from Würzburg, after a dispute over whether it should be better known as "Wunsiedelite". Weinschenk offered this name to the amateur geologist Oskar Gebhardt, who came from the Fichtel Mountains , in exchange for some olivine basalt exhibits that were in his private collection.
Seußener Redwitzit
Rock description and mineral inventory
It is a small-grained gray-black tonalite interspersed with white feldspar. Tonalites are differentiated from other rocks by the absence of alkali feldspars. Its dark appearance is due to the dark mineral biotite and the weak greenish color is produced by the chloritization. The grain size is between 0.5 and 1.0 millimeters. The plagioclase feldspars can be up to 1 cm in size. Its weathering behavior is very good and can be compared with that of granites. It can be polished.
The Seußen Redwitzite contains 43 percent plagioclase , 27 percent quartz and 26 percent biotite. As accessory minerals are chlorite , rutile , apatite , zircon and opaque minerals ago. A mineralogically similar natural stone is the Wölsauer Redwitzite , which hardly differs from the Seußen Redwitzite .
use
Seußener Redwitzit was used for paving stones, floor slabs, masonry, tombs and, because of its fine grain, for sculpture earlier.
The so-called "Marktredwitz-Tor", the "Redwitzit-Brunnen" in Marktredwitz and the former pavement of the Königsplatz in Munich are made of this stone.
literature
- Wolf-Dieter Grimm: picture atlas of important monument rocks of the Federal Republic of Germany. Edited by the Bavarian State Office for Monument Preservation, Lipp-Verlag, Munich 1990, ISBN 3-87490-535-7 , Seussener Redwitzit.
Web links
Individual evidence
- ↑ a b Alfons Baier, Die Redwitzitvorkommen von Marktredwitz / Ofr., Ed. v. Geozentrum Nordbayern , accessed on August 1, 2008.
- ^ Grimm: memorial stones. Rock No. 017 (see literature).