Rochlitz porphyry

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Rochlitz porphyry
Main features
group Volcanite
Subgroup Volcanic (rhyolite tuff)
Occurrence Germany, Saxony, Rochlitz
colour light red, light brown-reddish
use Stone, facade cladding, floor coverings

Trade names z. T. Rochlitzer Porphyrtuff
Dismantling situation current dismantling
Division into hard and soft stone Soft rock
Age Rotliegend
Reference example Kunigunden Church in Rochlitz, Basilica in Wechselburg
Special marks partially yellow-red to brick-red bands
Template: Infobox natural stone / maintenance / picture is missing

The Rochlitzer Porphyry , also Rochlitzer Porphyrtuff , is a volcanic rock , which is called rhyolithic tuff according to modern petrographic nomenclature . According to its genesis, it is an ignimbrite , i.e. H. around the deposits of a pyroclastic density flow . The Rochlitzer porphyry has been quarried as natural stone on the Rochlitzer Berg and in a smaller quarry on the Poplarhöhe near Rochlitz in Saxony for many centuries and has become known far beyond its region with its petrographically misleading name. Numerous art-historically significant buildings have been built from Rochlitz porphyry.

Rock description

It is a red, red-violet, brown, gray-yellow rock. It is often crisscrossed with irregular crevices. There are also fragments of slate and grains of sand from layers of the Lower Permian . The Rochlitz porphyry is a very porous rock and is characterized by numerous inclusions such as round quartz and feldspars . Numerous yellowish bands run through the deposit.

The correct petrographic name is (volcanic) tuff, because the deposit was formed as a deposit of pyroclastic density currents . The rock is thickly banked; the banks correspond to individual density streams.

The historically handed down name of this building and sculptural rock is misleading according to modern rock nomenclature , because rocks with typical porphyry structures had different conditions of formation. It is important to pay attention to the different uses in the technical languages ​​of geologists and rock processors.

In the 19th century it was not yet separated in this case. In 1836, the geologist Carl Friedrich Naumann describes the rock deposits on and around the Rochlitzer Berg in his explanations of the geognostic chart of the Kingdom of Saxony . With regard to the conditions of the deposits, he explained: According to their petrographic peculiarities, the following porphyries are to be distinguished: 1.) the lower Rochlitz porphyry, 2.) the upper Rochlitz porphyry, ... and further ... lavender blue, pearl gray, flesh to brick red very much porous matrix with a lot of quartz grains and little stone pulp; the bladder spaces covered with bright red clay; this variety is especially valued as a stone . This is essentially the basis of the continued use of the term by technical and craft users as well as in architectural and art-historical contexts.

Emergence

Individual flow units of the "Rochlitzer Porphyry"

The Rochlitzer Porphyrtuff was created by the activity of a volcano in the area of ​​the Rochlitzer Berg at the time of the Rotliegend in Unterperm . The starting material was a silica-rich magma, which was erupted in gigantic Plinian volcanic eruptions in the form of pyroclastics and lava flows . Due to the silica-rich magma, the pyroclastics were primarily sedimented in the form of pyroclastic flow deposits . The resulting rocks are called tuffs . In particularly hot pyroclastic density flows, there was also partial melting and / or amalgamation of the components; a melted tuff or ignimbrite was created. The latter name comes from Latin and is made up of “ignis” for “fire” and “imbris” for “rain”.

The pyroclastics ejected during these eruptions (flowing and falling deposits) accumulated in the further course to a thickness of several hundred meters in the resulting deposit. In other literature the thickness is described as 80 meters. The rock unit in which the Rochlitz porphyry dominates is also called the Rochlitz Formation in modern terminology .

processing

The blasted material is transported with the help of wheel loaders and trucks to the plant, which is only a few meters away. There the blocks are brought into the size suitable for further processing using a wire saw , bridge saw and gate . After that, the Rochlitz porphyry can be further processed with manual and mechanical methods.

use

Façade panels in anchor installation, Rochlitz porphyry with fresh paint and veins

Stone finds, the age of which is estimated to be around 3000 years, prove that the Rochlitz porphyry long before our era, e.g. B. was used as a grinding stone.

The stone has been sold for centuries under the trade name Rochlitzer Porphyr , Rochlitzer Porphyrtuff or, more rarely, Rochlitzer marble .

Rochlitz porphyry is mainly used for brickwork, facades and stone carvings. It has also been used for modern and historical sculptures, garden and landscape design, tombs, etc. When used as panels, the minimum thickness is 4 cm. The porosity of the rock is relatively high at 30% by volume. When used as floor panels, the relative abrasion resistance must be observed. Rochlitzer Porphyry is resistant to frost and aggressions. However, it cannot be polished, only fine-tuning is possible. Its popularity with sculptors results from the fact that it can be worked like soft rock .

The most qualitative rock is quarried from the Gleisbergsbruch and the hardest from the mill quarry. In the Schilling Quarry, rock with a lively structure and yellow grain is mined, which is used for facade and floor panels. According to a geological report, there will be enough useful rock for the next 80 years.

The rock, which is not suitable for stone production, is ground as Rochlitz porphyry gravel and used for the construction of sports fields and tennis courts. It was the “Rochlitz Blanket” that colored the running tracks of the sports facilities at the 1936 Summer Olympics red.

Company history

Already in 1585 a stone quarry was opened by the stonemason family Haberkorn, which remained in the possession of this family for 300 years. In 1907 a plant was opened in Breitenborn in Saxony with a siding. In 1910 the master stonemason Emil Haberkorn acquired the plant and the seven combined quarries.

Before the Second World War, up to 300 people were employed in quarries and in the factory of this company. After the end of the war, a family member of the Haberkorns reopened the quarries and the factory in 1948. These were nationalized in 1972. The extraction technology in the seven quarries and the sawing technology had remained at the pre-war level. With the turnaround came the end for the state-owned company. After a successful reprivatisation, the company was re-established by the Haberkorns in 1991. He has eight employees.

Buildings and sculptures

Romanesque portal in the Wechselburg monastery

With the erection of ecclesiastical mansions, the stone finally experienced its breakthrough. In central and west Saxony it has become a monumental stone that has shaped the architecture. The Rochlitz porphyry quarries can prove historical and modern uses.

Further use

At the end of the 1990s, the product range of the United Porphyry Quarries was expanded.

Gallery for dismantling

literature

  • Jens Czoßek: Saxon marble - the "Porphyrtuff" from Rochlitz. In: The earth is popping! Volcanoes in Saxony. Exhibition catalog Museum der Westlausitz Kamenz . Kamenz 2008, ISBN 3-910018-47-5 , pp. 11-21.
  • William Clemens Pfau: History of the stone factory on the Rochlitzer mountains. Messages from the Association for Rochlitz History. Vol. 2, 1898 ( digitized version ).
  • Heiner Siedel: Saxon "Porphyrtuffe" from the Rotliegend as building stones: occurrence and mining, application, properties and weathering. Institute for Stone Conservation e. V. Report No. 22, 2006 ( PDF ).
  • Karlfried Fuchs: Natural stones from all over the world. Callwey stone card index in 2 volumes. Volume 2. Callwey-Verlag, Munich 1997, ISBN 3-7667-1267-5 , pp. 251 f.

Web links

Commons : Rochlitzer Porphyry  - Collection of images, videos and audio files

Individual evidence

  1. Carl Friedrich Naumann : Explanations on Section XIV of the geognostic chart of the Kingdom of Saxony and the adjoining federal states, or geognostic sketch of the area between Taucha, Strehla, Bräunsdorf and Altenburg . Dresden, Leipzig 1836, pp. 112, 115.
  2. G. Schwerdtner, H. Anger, M. Störr: The kaolin deposits of the Kemmlitzer Revier. Mining monograph. Mining in Saxony, 13: 116 pp., Dresden 2007.
  3. ^ Friedrich Müller: INSK compact. The international natural stone index for the current market . Volume 1. Index sheet 38.4. Ebner Verlag Ulm 1997.
  4. Rochlitz Porphyry . In: natursteinonline.de. Retrieved November 12, 2016.
  5. a b To website "Werksteine"
  6. a b c Axel Kalenborn: A new beginning for the Rochlitz porphyry. In: Stein Heft 12/1991, p. 28 ff.

Coordinates: 51 ° 1 '22.5 "  N , 12 ° 45' 48.1"  E