Shell panel

from Wikipedia, the free encyclopedia
Shell cover from the Schmalgraf pit ( Kelmis )
Shell cover with pyrite layers and a little galena (lead luster) on limestone (also Schmalgraf pit)
Shell cover from the Hammerberg mine near Stolberg in North Rhine-Westphalia

Shell diaphragm is a term from mineralogy and denotes a paragenesis of various sulfide minerals . This special mixture of minerals is dominated by sphalerite ( zinc blende ) and wurtzite , but there are often other additions of galena , pyrite or marcasite as well as chalcopyrite and other minerals.

In the case of the shell cover, the associated minerals are deposited on the subsurface as a strip-like, shell-like alternating layer . Depending on the color of the deposited mineral, the individual layers can vary in intensity from yellow to reddish, brown or gray to black . The thickness of the layers ranges from a few tenths of a millimeter to a few centimeters.

Etymology and history

The term shell screen was coined in 1800 by Dietrich Ludwig Gustav Karsten in his publication Mineralogical Tables with regard to the latest discoveries [...] and refers to the zinc screen as the main component and the shell structure of the mineral mixture. Other well-known synonyms are radiation diaphragm and liver diaphragm .

Education and Locations

Shell diaphragm forms mainly in hydrothermal displacement deposits towards the end of the hydrothermal precipitation process in the epi- to telethermal area. In the process, a colloidal sulphide gel is first created from limestone , which contains the finest particles of zinc sulphide (ZnS), lead sulphide (PbS) and iron sulphide (FeS 2 ), which over time grow together ( coagulate ) to form larger aggregates and ultimately due to changes in chemical composition and concentration as well as the pressure and temperature in rhythmical sequence precipitate .

Around 100 locations for shell panels have been documented worldwide (as of 2019), but most of them are located in Europe.

The best-known sites include the area around Wiesloch in Baden-Württemberg, in particular the Grube Segen Gottes mine, which operated until 1954 , where stalactites made of shell panels with concentric drawings were discovered, some of which were between 30 and 40 centimeters long and up to a diameter of 15 centimeters should have been. Dezimetergroßen also for its extraordinary finds of partially traubigen aggregates is the lime - Quarry Rohdenhaus in Wülfrather limestone region in North Rhine-Westphalia. In Austria, shell panels are mainly known from the Antoni and Max pits in the Bad Bleiberger district of Kreuth in Carinthia, with pieces of shell panels also up to a decimeter in size.

Other well-known sites in Europe include the Carrière du Cimetière quarry near Andenne- Seilles and several pits near Moresnet in the Belgian municipality of Plombières , the Trèves (Occitania) and Orpierre (Provence-Alpes-Côte d'Azur) pits in France and the Orzeł Biały mine near the Silesian village of Bytom in Poland. Occasionally, shell panels are also known from Argentina, Australia, Bolivia, Brazil, Bulgaria, China, Greece, Ireland, Italy, Japan, Canada, Morocco, Mexico, Nigeria, Peru, Slovenia, Spain, the Czech Republic, Tunisia, the United Kingdom and the United States United States of America.

use

The main components sphalerite and wurtzite are important zinc ores due to their high zinc content . However, the deposits of shell ore are too rare to be of economic importance and are therefore only occasionally mined as ore when they are locally accumulated .

Similar to the agate , the bowl cover with its multi-colored banding also has a very aesthetic effect . Despite their low Mohs hardness , which fluctuates between 3.5 and 4, the bowl cover is therefore often used as a gemstone and offered in the form of polished disks and craft items as well as tumbled stones and cabochons .

See also

literature

  • Dietrich Ludwig Gustav Karsten : Mineralogical tables worked out with consideration of the latest discoveries and provided with explanatory notes . 1800.
  • Karl Ludwig Weiner, Rupert Hochleitner: Profile: Shell panel . In: Lapis mineral magazine . Volume 10, volume 12 . Weise, December 1985, ISSN  0176-1285 , p. 9-11 .
  • Werner Lieber: The bowl cover from Wiesloch . In: Lapis mineral magazine . Volume 10, volume 12 . Weise, December 1985, ISSN  0176-1285 , p. 35-44 .

Web links

Commons : Cupboard  - collection of pictures, videos and audio files

Individual evidence

  1. Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 312, 362 .
  2. ^ Karl Ludwig Weiner, Rupert Hochleitner: Profile: Shell panel . In: Lapis mineral magazine . Volume 10, volume 12 . Weise, December 1985, ISSN  0176-1285 , p. 10 .
  3. a b List of localities for shell diaphragms in the Mineralienatlas and Mindat
  4. Werner Lieber: The bowl cover from Wiesloch . In: Lapis mineral magazine . Volume 10, volume 12 . Weise, December 1985, ISSN  0176-1285 , p. 38 .
  5. Pictures of shell panel from the Rohdenhaus quarry, Wülfrath, North Rhine-Westphalia, Germany. In: mindat.org. Hudson Institute of Mineralogy, accessed June 17, 2019 .
  6. Pictures of the shell panel from the Antoni pit. Retrieved June 17, 2019 . and the Max mine near Kreuth in Austria. In: mindat.org. Hudson Institute of Mineralogy, accessed June 17, 2019 .