Basalt tuff Habichtswald

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Hercules building on the Wilhelmshöhe made of basalt tufa Habichtswald

Basalt tuff Habichtswald is also called Habichtswälder Tuff or Kasseler Tuff and petrologically Habichtswald-Lapillituff . The mining of this rock took place in the Habichtswald in the Drusel valley near Kassel in the state of Hesse until 1941. The light yellowish-brown rock was used, among other things, on the Herkules building and the Löwenburg at Wilhelmshöhe near Kassel.

geology

The Vogelsberg , the Kuppenrhön , parts of the Hohe Rhön and the Lower Hessian Depression (with Knüll and Habichtswald) in Hesse were shaped by volcanism in the Tertiary in the Miocene 14 to 7 million years ago. The subsequent erosion and weathering decisively re-shaped these landscapes around 6 to 7 million years ago.

The Habichtswald was the center of the Lower Hessian volcanic activity. This took place in two periods, whereby the rocks of the older period in the southern Habichtswald are preserved and the younger effusions occur mainly in the northern Habichtswald at the Great Steinhaufen, Essigberg , Wuhlhagen, Hunrodsberg, Möllersruh, Kuhberg etc. The magmas were brought up from a depth of 75 to 90 kilometers. According to an investigation from the 1950s, six basalts and basalt tuffs were distinguished.

Geological description and mineral inventory

A staffagebau in the Bergpark Wilhelmshöhe made of Habichtswälder tuff. The weathering damage can be clearly seen at the foot of the half-columns and in the transition from the base to the structure (there with white salt formation).

The basalt tuff Habichtswald is a light, yellowish-brown tuff with up to centimeter-sized dark gray and olive gray lapilli . Lapilli are pea-sized to nut-sized (2–64 mm) pyroclasts (rock fragments) that are formed during an explosive volcanic eruption. The pore volume of this rock is around 21 percent, and because of its high porosity the rock is very light and weighs 2.12 t per m³. The pore space was originally larger and was subsequently filled up to a third with chalcedony . The mineral inventory is 66 percent glassy; the proportion of pyroxene is 17 percent, of chalcedony 14 percent, olivine , quartz grains , opaque minerals and accessories each 1 percent.

In addition to the coarse-grained types, there are also finer-grained variants of the Habichtswälder basalt tuff. This rock also contains components of other sedimentary rocks , so-called xenolites . Quartz and feldspar occur as fragments of other rocks. The texture of this tuff is directionless and spongy porous.

Dismantling

The mining took place in the quarry on the Drusel am Essigberg, Kuhberg and Hirzstein . This tuff, which reaches a thickness of up to 26 meters, was easily win and was break damp easy to work state. It is one of the soft rocks . The occurrence is criss-crossed by numerous fissures . There are other similar rocks in the area around the Habichtswald.

use

Historical illustration of the Löwenburg

This tuff was mainly used for solid structures, tombs and monumental structures such as the Hercules building and Löwenburg in the Wilhelmshöhe mountain park in Kassel. In the past it was also used as an oven stone . Habichtswald Tuff is very poorly weather-resistant. After a short time, the rock will sand or gravel and it can crumble off like a shell.

literature

  • Wolf-Dieter Grimm: picture atlas of important memorial stones of the Federal Republic of Germany , ed. from the Bavarian State Office for Monument Preservation, Rock No. 049, Lipp-Verlag. Munich 1990. ISBN 3-87490-535-7

Web links

Individual evidence

  1. ↑ The volcanism of the Hessian volcanic country ( Memento from May 27, 2005 in the Internet Archive ).
  2. ^ Dienemann: Usable rocks, p. 98.
  3. ^ Schäfer: Geological observation. P. 169 (see web link).
  4. ↑ a b Grimm: Bildatlas, Gesteins No. 049 (see literature).
  5. ↑ a b W. Dienemann and O. Burre: The usable rocks of Germany and their deposits with the exception of coal, ores and salts , Enke-Verlag, Stuttgart 1929, p. 102.
  6. ↑ Hesse raw material security concept. Technical report natural stones and natural stone, p. 90, ed. v. Hessian State Office for Environment and Geology, Hessian Ministry for the Environment, Rural Areas and Consumer Protection, Environmental Alliance Hesse - Alliance for Sustainable Location Policy. Processing status: November 20, 2006 .

Coordinates: 51 ° 18 '14.3 "  N , 9 ° 24' 3.6"  E