Deposits of industrial minerals and other useful rocks
Categories: Nature and Environment › Geology and raw materials › Mineral raw materials
The term industrial minerals is used to refer to special minerals or rocks which are of importance for specific technical processes and applications. Thus, they are situated between industrial raw materials (rocks and earth) and mineralisations.
Minerals
- Quartz: Natural quartz crystals are sometimes used in measurement technology (apparatus for frequency controls, piezocrystals) or for the production of optical components. In the chemical and ceramic industries, pure quartz (from quartzite) is sometimes used. In addition, in many locations quartzite sand is extracted for glass production (glass works), as moulding sand for glass for foundries or for filling material in the brick and tile industry.
- Feldspar: (mostly alkaline feldspar) is used in the ceramic industry. In Switzerland, no significant natural deposits exist.
- The alumosilicates andalusite, cyanite and sillimanite: They are sometimes important raw materials for the production of heat resistant high quality ceramics. The deposits in Switzerland are interesting from the scientific point of view but commercially insignificant.
- Garnet: It can be used from a technical point of view for abrasive and cutting materials. The few locations where garnet is found (for example, Val Tremola, TI) do not respect the necessary conditions for extraction.
- Olivine: With the use appropriate techniques, olivine sand can be extracted from ultrabasic olivine-rich rocks (foundries). Because of the difficult access conditions, domestic deposits have never been used.
- Barite and fluorite: They are used for various technical applications (e.g. the production of heavy concrete). Fluorite is also used in the metallurgy industry as a solvent (aluminium electrolysis) and in the chemical industry for the production of hydrofluoric acid and other fluorite compounds.
- Corundum: It's suitable for abrasives, cutting or polishing materials. In Switzerland, no significant deposits exist.
- Graphite: It's used in the electronics industry and for electrolysis. Except for the lightly graphitised anthracites from the canton Wallis, graphite exists only sparsely in Switzerland and has never been used technically.
Salts and Phosphates
- Salt: In the strict sense of the term, «salt deposits» only refer to deposits of potassium salt and rock salt. Rock salt (chemically sodium chloride = NaCl) is widely used, while no deposit of potassium salt has been found in Switzerland up to the present. Salt is currently extracted by lixiviation. Salt extraction centres in Switzerland are found at Hochrhein (Swiss United Swiss Saltworks on Rhine; Schweizerhalle, Riburg) and near Bex (VD). The annual production is between 250,000 and 350,000 tons (Schweizerhalle, Riburg) and 30,000 to 40,000 tons (Bex).
- Phosphate: Of all the numerous phosphate minerals, only the mineral apatite, in its earthy form also termed phosphorite (calcium phosphate), has a practical application as the initial components for the production of phosphate fertilisers. Up until the present, no extraction has taken place due to unfavourable geographical positions.
Rocks
- Talc, steatite (soapstone) and Serpentine: The easily worked, heat resistant and heat accumulating soapstone has been a sought after material for over two thousand years. Primarily, it was used for the production of wood burning ovens. The slabs were generally extracted from small, local deposits and worked on site. The most important regions were: Sopraceneri, especially Val Maggia und Val Verzasca, Wallis (southern lower Wallis valleys, Lötschental, Vispertäler, Goms), Uri (Urserental) and Graubünden (Tavetsch, Bergell).
- Talc: It's used, on the one hand, in ground form (paper industry, ceramic, lubrication agents or fill material) and, on the other hand, talc-rich rocks are widely used for the production of ovens because of their high heat accumulating capacity and workability.
- Asbestos: It was once extracted from ultrabasic rocks, e.g. in Alpe Quadrada (GR), near Zeneggen (VS), Sils Maria (GR) and in Geisspfad (VS). Raw asbestos was sometimes spun to obtain filaments and sometimes worked to form asbestos board and Eternit panels. Today, asbestos is no longer extracted.
- Dolomite: It's used for the extraction of magnesium and the production of fireproof stones and in the steel industry (oven linings).
- Magnesite: It serves as an important raw material for the extraction of magnesium metal (metallurgy, light construction materials) as well as for the production of fireproof oven linings. No significant deposits have yet been found.
Text Sources
- Kündig & de Quervain (1953): Fundstellen mineralischer Rohstoffe in der Schweiz. Bern: Kümmerly & Frey. (= Organ der Schweizerischen Naturforschenden Gesellschaft)
- SGTK, Schweizerische Geotechnische Kommission (ed.) (1997): Die mineralischen Rohstoffe der Schweiz. Zürich: Schweizerische Geotechnische Kommission
Data Sources
- SGTK, Schweizerische Geotechnische Kommission (2015): Rohstoffinventar der Schweiz
Data Owners: Swiss Geotechnical Commission, ETH Zurich (SGC)
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