feldspar is valued for a low iron and refractory mineral content, a low cost per unit of Al2O3, no volatiles and no waste. Ceramics: Feldspars are used in the ceramic industry as a flux to form a glassy phase in bodies during firing, and thus promote vitrif ication. They also are used as a source of alkalies and alumina in glazes. The compostiion use of feldspar in different ceramic formulations varies depending on various factors, including the properties of the individual garde, the other raw materials and the requirements of the finished products. However, typical additions include: tableware, 15% to 30% feldspar; high-tension electrical porcelains, 25% to 35%; sanitaryware, 25%; wall tile, 0% to 10%; and dental porcelain up to 80% feldspar. Earth sciences: In earth sciences and archaeology, feldspars are used for potassium-argon dating, argon-argon dating and luminescence dating. Minor use: some household cleaners use feldspar to give a mild abrasive action. Production The USGS estimated global production of feldspar in 2020 to be 26 million tonnes, with the top four producing countries being: China 2 million tonnes; India 5 million tonnes; Italy 4 million; Turkey 7.6 million tonnes. Commercial grades Typical mineralogical and chemical analyses of three commercial grades used in ceramics are: Extraterrestrial In October 2012, the Curiosity rover has found a high feldspar content in a Mars rock. Images See also Rainbow lattice sunstone References Further reading Bonewitz, Ronald Louis (2005). Rock and Gem. New York: DK Publishing. . External links Tectosilicates Triclinic minerals Monoclinic minerals Industrial minerals