Harz granite

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Harz granite of the birch head granite type, matt cut (sample approx. 10 cm long)

The Harz granite can be divided into five types, all of which were used as natural stone : Knaupsholz granite , Birkenkopf granite , Wurmberg granite , Königskopf granite and Ilsestein granite . The first three granites mentioned are widely used in northern Germany, Belgium and the Netherlands , and later also in the GDR . The Knaupsholz granite was " one of the most important stones of the former GDR for a long time ".

At the moment only the Knaupsholz granite is mined.

geology

The granite plutons of the Harz - Brocken , Ramberg and Oker plutons - formed towards the end of the Variscan Orogeny in the Upper Carboniferous around 300 million years ago. The result are these natural stones of "Ur-resin" which at that time part than in the folded sedimentary and volcanic rocks of a vast folding mountain , deep underground large was system magma formed blow and through any cooling and crystallization rates due to several different colored granites froze. The Harz granites are part of the Brocken granite complex, which is the largest granite complex in the Harz with an area of ​​165 km². The Harz gabbro deposit is part of this complex, it arose in the early phase of the Brocken magmatism from a magma that had a lower SiO 2 content than the younger magmas from which the granites emerged.

Quarries

The large companies before the Second World War in 1938 included the Zureck company in Wernigerode (100 to 110 employees) and the Hannoversche Basaltwerke mbH with its granite quarries department in Wernigerode (60 to 70 employees), as well as the Braunlager Granit- und Schotterwerke GmbH (45 Employees). In addition, there were 5 to 7 medium-sized and 15 to 17 small businesses with a total of around 600 employees. At that time, the sales areas were the entire Reich, Belgium and the Netherlands.

After the war in 1948, 30 to 40 people were employed in the Braunlager granite and gravel works and in another company in Lower Saxony, an unknown number of quarry workers. No exact figures are available about the companies located in the GDR. The Knaupsholz and Birkenkopf quarries located in the GDR, as well as the operational parts of the Zureck company in Wernigerode, were expropriated on November 5, 1945.

At the beginning of the 1950s, the following quarries in the Brocken granite area were named by Sickenberg: Eckerloch , Schneeloch, Gebbertsberg, Wurmberg, Haserode, Wolfklippen, Großer and Kleiner Birkenkopf, Knaupsholz, Ottofels, Neustätter Hau, Forsthaus Plessenburg and "Perforated Stone". In 1958 there were still eight quarries in operation in the GDR, but only two in 1969 (Knaupsholz and Birkenkopf).

Knaupsholz granite

Occurrence
The Knaupsholz granite is mined in the forest village of Knaupsholz in the Harz National Park between the Wernigerode districts of Drei Annen Hohne and Schierke , one kilometer east of the Schierke train station in Saxony-Anhalt . The Knaupsholz granite was one of the most important stones of the GDR.
Mineral inventory
The Knaupsholz granite is gray-red in color and coarse-grained. It contains 33.5 percent quartz , 45.9 percent alkali feldspar , 15.1 percent plagioclase , 4.8 percent biotite and chlorite and 0.7 percent ore minerals such as magnetite , pyrite , hematite and 0.7 accessories . The alkali feldspar crystals can be up to 18 mm in size.

Birch head granite

Occurrence
The Birkenkopf granite was quarried at the Großer Birkenkopf south of Wernigerode- Hasserode . It is a medium-grain granite with a bluish-gray color. In the quarry, 30 to 40 percent raw blocks for sawing work and 50 percent usable rock rubble could be obtained. The quarry is no longer being mined.
Mineral inventory
Birkenkopf granite contains 31.3 percent quartz, 42.6 percent alkali feldspar, 20.4 percent plagioclase, 5.4 percent biotite and chlorite, and 0.3 percent ore minerals such as magnetite , pyrite and hematite .

Wurmberg granite

Wurmberg granite, pattern approx. 10 × 8 cm
Occurrence
The Wurmberg granite quarry was about 2.5 kilometers north of Braunlage and 250 meters high on the Wurmberg . It is a pale red, fine to coarse-grained granite. The quarry has not been in operation since spring 1974.
Mineral inventory
This granite contains 31 percent quartz, 42 percent alkali feldspar, 20 percent plagioclase, 7 percent biotite, and less than 1 percent accessories such as zircon , apatite , rutile , muscovite and opaque minerals.

King's head granite

Occurrence
The Königskopf granite was extracted in a quarry near Königskrug , which was then abandoned in the 1960s. Due to the current location in the Harz National Park, it is unlikely that it will reopen. It is a light red to deep red (flesh-red) granite.
Mineral inventory
The Königskopf granite contains 33 percent quartz, 42 percent orthoclase in a mineral grain size of 2 to 5 mm to max. 15 mm, 22 percent plagioclase, 5 percent biotite and 0.7 percent accessories.

Ilsestein granite

The Ilsestein granite lies on the northern edge of the Harz Mountains and is part of the Brocken massif. It emerges between the Eckertal and around Hasserode as an 11 km long strip with a width of around 2 km. The rock consists of a clearly intruded , strongly red colored rock. At the contact with the Harzburg gabbronorite, the granite has angular gabbro xenolites . The magma of the Ilsestein granite is said to have risen as the last magma pulse of the Brocken complex and is the intrusion richest in quartz within the Brocken massif. Characteristic features of granite are adhesions between quartz and orthoclase . The rock contains black tourmaline and numerous 2–5 cm large drusen with fillings of quartz, orthoclase, albite and other minerals. Its use and strength as a stone is limited by these druses and it is therefore only of local importance.

use

Schierker mountain church
Soviet memorial in Berlin-Tiergarten made of resin granite with a bronze figure of a soldier

Harz granite is weatherproof , polishable and resistant to aggressive chemical compounds. Due to their technical properties, they are used outdoors and because of their decor for interior construction.

These granites were used as solid stone for bridge construction, masonry, door and window ledges, stairs and floor slabs, facade cladding, tombstones, as paving and packing layers; the Knaupsholz granite is used as granite gravel for road construction in the Harz National Park . At the moment (as of 2009) only the Knaupsholz and Birkenkopf quarries are still in operation, with the following uses:

Technical buildings

Road surfaces, paving, masonry and bridge structures in Lower Saxony and Northern Germany, Magdeburg, Hamburg and Berlin; Lock structures and bank reinforcements on the Mittelland and Kiel Canal .

Memorials and buildings

Buchenwald , Ravensbrück and Sachsenhausen memorials and memorials ; Soviet memorials in Berlin-Tiergarten and Berlin-Treptow ; Interior construction of the Schillermuseum in Weimar ; Church in Schierke; Cultural palaces of the GDR; Deutsche Bank and town hall stairs in Wernigerode.

See also

List of types of granite

literature

Kurt Mohr: Geology and mineral sites of the Harz. 2nd Edition. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart 1933, ISBN 3-510-65154-5 , pp. 223ff.

Individual evidence

  1. ↑ Friedrich Müller: The Knaupsholz granite from the resin. in: natural stone. 1991 Available online ( Memento of the original from August 1, 2012 in the web archive archive.today ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed July 26, 2009. @1@ 2Template: Webachiv / IABot / www.baufachinformation.de
  2. ↑ further information ( memento from July 19, 2011 in the Internet Archive ) on regionalgeologie-ost.de
  3. ^ TU Clausthal-Zellerfeld: The geological / structural units of the Harz ( Memento from March 5, 2005 in the Internet Archive ), accessed on July 26, 2009.
  4. ^ Sickenberg: Deposits of Lower Saxony. P. 22.
  5. ↑ Knaupsholz Quarry , ed. from the Harzer Schmalspurbahnen interest group ( Memento of the original from July 13, 2011 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed July 26, 2009.  @1@ 2Template: Webachiv / IABot / www.ig-hsb.de
  6. ↑ Otto Sickenberg: stones and earth. The deposits and their management. Geology and deposits of Lower Saxony. 5th volume. Dorn-Verlag, Bremen, Horn 1951.
  7. ^ Mohr: Geology of the Harz Mountains. P. 413.
  8. ↑ a b c d e f Werner Schwate: Harzer Granit - Mining and Use: in Stein 1993. W. Online ( Memento of the original from January 5, 2013 in the web archive archive.today ) Info: The archive link was inserted automatically and has not yet been checked . Please check the original and archive link according to the instructions and then remove this notice. at baufachinformation.de, accessed on July 26, 2009. @1@ 2Template: Webachiv / IABot / www.baufachinformation.de
  9. ^ Mohr: Geology of the Harz Mountains. P. 414.
  10. ^ Wolf-Dieter Grimm: Pictorial atlas of important memorial stones of the Federal Republic of Germany. ed. from the Bavarian State Office for Monument Preservation, Rock No. 014, Lipp-Verlag, Munich 1990, ISBN 3-87490-535-7 .
  11. ↑ Königskopf granite quarry on mineralienatlas.de
  12. ↑ Maximilian Zundel, Carl ‑ Heinz Friedel, Jens C. Grimmer: "Magnetic fabric constraints for syn-magmatic doming of the laccolithic Brocken granite pluton (Harz Mountains, northern Germany)" In: International Journal of Earth Sciences, 2019, DOI = 10.1007 / s00531-019-01679-w
  13. ^ Mohr: Geology of the Harz Mountains. P. 226f and 236.
  14. ↑ Information from regionalgeologie-ost.de ( memento from July 19, 2011 in the Internet Archive ), accessed on July 27, 2009.