Strontianite from the Korkodinskoye deposit of jewelery andradite (Middle Urals)

Abstract

Te relevance of the work is due to the need to study the mineralogy of the Ural gems, in this case deposits of jewelry andradite (demantoid and topazolite). Te purpose of the work – description and detailed instrumental study of strontianite from paragenesis with gem topazolite, which was established at the Korkodinskoye deposit. Research methodology. Strontianite was studied at the Institute of Geology and Geochemistry named afer academician A. N. Zavaritsky, Ural Branch of the Russian Academy of Sciences (Ekaterinburg), the Institute of Mineralogy of the Ural Branch of the Russian Academy of Sciences (Miass) and the Ural State Mining University (Ekaterinburg). For its study, the whole complex of modern research methods was used. Chemical, geochemical, X-ray and X-ray spectral studies were carried out, and the method of IR spectrometry was also used. Results and conclusions. Carbonate was found in a fssure-vein zone in association with garnet (topazolite) among tectonized serpentinites at the Korkodinskoe deposit of gem andradite. According to the chemical composition, strontianite is extremely calcium. Crystal chemical formula of the carbonate: (Sr0,48Ca0,45Ba0,04Mg0,03)1,00CO3 . In terms of chemical composition, the carbonate of the Karkodinskoe deposit is very similar to the strontianite of the Buldymsky massif; apparently, this is a typochemical feature of all strontium carbonates from ultramafc bodies. For strontianite, the results of powder difractometry and IR spectroscopy are given, which are very close to the reference data. Strontianite belongs to the post-garnet stage of mineral formation, and the source of strontium for carbonate was small bodies of quartz-plagioclase metasomatites occurring at the site. Te results obtained do not agree with the latest model of the formation of the Korkodinsky ultramafc massif proposed by A. Yu. Kisin with co-authors. Te discovery of strontianite in a fssure-vein zone with andradite (topazolite) is another evidence of the formation of demantoid-bearing bodies afer the formation of gabbro and granitoid intrusions.