Gemstone mines Steinkaulenberg
The Steinkaulenberg gemstone mines are located in Idar-Oberstein and are the only "mineral mines " * in Europe that are accessible to visitors.
geology
The Steinkaulenberg near Idar-Oberstein is located on the north-western edge of the Saar-Nahe basin . The filling of this fossil sedimentary basin consists of siliciclastic sedimentary rocks of the Upper Carboniferous (including some powerful coal layers) and from just such sedimentary rocks as well as volcanic rocks of the Permian ( Permian series ). The Steinkaulenberg is made up of layers of volcanic rock from the Lower Oberrotliegend, which are grouped together under the name Grenzlager-Gruppe , because they are located between the mighty sediment sequences of the Unter- and Oberrotliegend (corresponds roughly to the Donnersberg formation in the current nomenclature). The rock is called latitandesite because of its exact composition . This is an intermediate volcanic rock, which means that it has a moderately high SiO 2 content. It is very dark in the unweathered condition and has a porphyritic structure with phenocrysts of feldspar . The very fine-grained matrix of the rock also consists mainly of feldspar. Plagioclase (soda lime feldspar) represents more than 50% of the feldspar content. In addition, the rock contains potassium feldspar , quartz , pyroxene and, to a lesser extent, other minerals. The gemstones of the Steinkaulenberg are varieties of the mineral quartz (see below ). They fill larger cavities in the rock.
history
The gemstone deposits in the Saar-Nahe region were first mentioned in 1375 by the Metz canon Otto von Diemeringen . The lords of Oberstein , as the competent sovereigns, allowed their subjects to dig for gemstones in exchange for every third hundredweight of the yield in the area around today's mines.
Originally, the gemstone graves looked for the gemstones for days. The overburden fields were called " Kaulen ", hence the name Steinkaulenberg. Only later was also underground search for gems and studs were in the mountains sunk . During the French occupation from 1792, the French mining law, which was still in full force until 1874 and regulated the mining of gemstones, was therefore in force.
The mining was stopped from 1875 , after two generations of Idar-Obersteiners had already worked in mine construction in Brazil. These procured large quantities of new raw material for the continuation of the gemstone industry. In 1978 the buried tunnels were exposed again and opened up for tourism .
Since then, the Steinkaulenberg has been operated by Edelsteinminen GmbH Idar-Oberstein. She is a wholly owned subsidiary of the Steinkaulenberg-Weiherschleife e. V. and runs the business of the gemstone mines. The Friends of Steinkaulenberg-Weiherschleife e. V. was also founded in 1978, any natural or legal person can become a member of the association.
Visitor galleries and mineralization
The show tunnel in Steinkaulenberg is about 400 meters long. In groups, visitors are guided through the tunnel and can see the formation of the mineralization, the history of mining and the processing of the gemstones. It is open from March 15th to November 15th. Visits are not possible in winter. Around 50,000 visitors come each season.
The gemstones found in the mines are both microcrystalline (extremely fine-grained) and macrocrystalline varieties of the mineral quartz (chemical: silicon dioxide , SiO 2 ). Since quartz in general and its varieties in particular are not too rare and also have a comparatively low hardness for gemstones (quartz has Mohs' hardness 7, corundum - with the varieties ruby and sapphire - has hardness 9, diamond has hardness 10), One speaks here of " semi-precious stones ". The microcrystalline quartz varieties in the Steinkaulenberg are agate and jasper , the macrocrystalline ones are amethyst (colored violet), smoky quartz (gray-brownish) and rock crystal (highly transparent-colorless).
The mineralization in Steinkaulenberg did not develop together with the volcanic rock in which it is located, but only later. The quartz has been precipitated in natural cavities in the rock from hot, aqueous solutions containing SiO 2 . These filled cavities are called geodes , almonds or drusen . Macrocrystalline quartz often occurs inside a geode made of microcrystalline quartz at the edge. The quartz geodes can still be viewed in the "parent rock" in the visitor gallery.
"Gemstone Camp"
Mining fields have been created on former spoil heaps, in which children and young people in particular can search for gemstones themselves. The objects to be found there are, however, brought to the fields to promote tourist attractiveness. In the gemstone camp, the “hobby prospectors” are provided with picks, picks and spades. On site, the groups are also given the opportunity to prepare spit roast and other grilled goods on the fire.
Remarks
- * Minerals or minerals are all solid, naturally occurring inorganic chemical compounds . Here "minerals" but used in an exclusive sense in which it exclusively to non- ore refers minerale or rather on minerals that are not in the corresponding pits for the recovery of metals were mined, but for the production of jewelry and decorative stones and for sale to mineral collectors.
Individual evidence
- ↑ Gemstone Mine Steinkaulenberg ( Memento from April 22, 2016 in the Internet Archive ) on the official website of Idar-Oberstein (tourism section)
- ↑ Complete paragraph according to the Idar-Oberstein gemstone region - geology & mineralogy of the region on the website of Edelsteinminen GmbH Idar-Oberstein
- ↑ Section up to this point according to the history of the Steinkaulenberg gem mines on the website of Edelsteinminen GmbH Idar-Oberstein
- ↑ The Edelsteinminen GmbH - General information on the website of the Edelsteinminen GmbH Idar-Oberstein
- ↑ Jörg Staiber: Sights effectively set in light. Rhein-Zeitung, March 20, 2016
- ↑ Edelsteinminen Steinkaulenberg - tour in Steinkaulenberg on the website of Edelsteinminen GmbH Idar-Oberstein
- ↑ Procure yourself - gemstone camp and prospecting fields on a website of Ph. Karl Hahn & Co eK Idar-Oberstein