Rorschacher sandstone
Rorschacher sandstone , also called Staader sandstone or Bodensee sandstone , describes a sandstone that was extracted over centuries in numerous quarries in the region around Rorschach (Switzerland) , Staad SG , Wienacht and Unterbilchen and is still mined there today. It is a sedimentary rock and because of its natural appearance belongs to the zone of flat sandstone .
Emergence
In the Miocene , the period between 26 million and 7 million years before our time, the Lake Constance area was covered by a shallow sea , similar to today's Adriatic . The Appenzellerland was a coastal plain, comparable to today's Po plain . The “Ur-Bregenz Ach” and “Ur-Rhein” poured into the shallow Molasse Sea, building two deltas rich in rubble on the coast. In between, in today's Staad - St. Gallen area , there was a sandy beach in a bay, created from the abrasion of rocks from the still developing young Alps. The sands were solidified into a rock that can now be mined near the surface through superimposed pressure and the inflow of binding agents.
Towards the end of the Miocene, the last mountain building phase of the Alps began . Due to the strong thrust of the African plate from the south, the sandstone deposits in the Lake Constance area were tilted and lifted. These rocks do not belong to the sandstone zone , but to the erect molasse zone of the northern edge of the Alps.
The sandstone deposits in the Rorschach - Staad - Thal area have been mined as "Rorschach sandstone" for over 600 years.
use
Over the centuries, some important historical buildings were built from this natural stone in the Lake Constance area. a. the Minster of Constance , parts of the Munot in Schaffhausen , the port of Rorschach and Lindau and a large number of houses in Meersburg . Today there are also modern buildings, such as B. the fountain in front of the Norddeutsche Genossenschaftsbank in Hanover or the stairs in front of the University of Zurich-Irchel.
In this day and age of Rorschach sandstone for Garden Design (will dry stone walls , stairs and exterior coverings), cladding ( curtain wall panels , façade masonry ) renovation ( window jambs , floor belts , pillars ) and interior (flooring, stair coverings, fireplace used coverings). Due to its fine-grained, even structure, it is also suitable for sculpting work.
Spire and octagon of the Konstanz Minster made of Rorschach sandstone
Floor covering and stairs made of Rorschacher sandstone, polished
Petrography
The sandstone of the Rorschacher type is a sandstone of a very regular gray color with a clear tinge of "greenish or bluish" and of uniform structure, since the grain sizes of the quartz hardly fluctuate within the same banks. The dark points of this sandstone are characteristic.
The deposited layers of the Rorschacher sandstone are different. The upper layer is suitable for rough masonry stones , the middle layer for rough floor slabs and the lower layer for stone and stone carving work.
The fine to medium-grained rock consists of quartz, mica , carbonate minerals and feldspars .
It has a clear bank, which results in very smooth solution surfaces, which is why it is also called slab sandstone. Light-colored mica flakes can usually be seen on the storage surfaces. The direction of the stratification is weakly recognizable in the machined state.
| Compressive strength | Flexural strength | Open porosity | Bulk density | Water absorption |
|---|---|---|---|---|
| approx. 100 N / mm² | approx. 10 N / mm² | approx. 7% by volume | about 2.5 g / cm³ | approx. 6% by volume |
| DIN EN 1926: 2006 | DIN EN 12372: 2006 | DIN EN 1936: 2006 | DIN EN 1936: 2006 | DIN EN 13755: 2008 |
The Rorschacher sandstone is frost-resistant in its ashlar quality. It is not acid-resistant.
swell
- F. de Quervain: The usable rocks of Switzerland. Kümmerly & Frei, Bern 1969
- F. de Quervain, M. Gschwind: The usable rocks of Switzerland . (Geotechnical Commission of the Swiss Natural Research Society) Bern 1934
- Bärlocher Steinbruch & Steinhauerei AG, CH-9422 Staad
Web links
- Volker von Seckendorf: Petrographic description of a natural stone (Rorschacher sandstone) (PDF; 10.0 MB)
- Surface of the Rorschacher sandstone
Individual evidence
- ↑ natursteinonline.de : Rorschacher sandstone
- ↑ Quervain, 1969, pp. 210-212
- ↑ a b c Karlfried Fuchs: Natural stones from all over the world, discover, determine, use . Vol. 2, Callwey, Munich 1997, ISBN 3-7667-1267-5 , sheet 227.
- ↑ Quervain, 1969, p. 210
- ↑ Quervain, Gschwind, 1934, p. 242
- ↑ rorschacher-stein-fachrechner.ch (PDF; 2.4 MB): Roman Koch: Der Rorschacher Sandstein - History and Properties , p. 22, accessed on December 3, 2012