Mg-rich thomsonite-Ca from chromitites of the Lekkhoyla occurrence, Voykar-Syn’ya massif, Polar Urals
S.V. Berzin, D.A. Zamyatin, V.V. Khiller
The paper describes a previously unknown isomorphic series between thomsonite-Ca and a hypothetical Mg-rich zeolite. The Mg-rich thomsonite-Ca was found for the frst time in hydrothermal veins of the Lekkhoyla chromite occurrence (Polar Urals, Russia). The mineral contains up to 6.5 wt. % MgO (up to 1.35 f.u. Mg, O = 20) and exhibits a continuous isomorphism between Mg2+ and Na+ and Ca2+. The formula of the Mg-richest thomsonite-Ca is Na0.37Mg1.35Ca1.59Si5.18 Al4.35O20 ? 6(?)H2O (O = 20). The Raman spectra of thomsonite-Ca and Mg-rich thomsonite-Ca are similar both showing no bands typical of other minerals.
Figures 7. Tables 2. References 12.
Key words: thomsonite-Ca, zeolites, isomorphic series, hydrothermal vein, chromite, Voykar-Syn’ya massif, Polar Urals.
S.V. Berzin, Institute of Geology and Geochemistry UB RAS, ul. Akademika Vonsovskogo 15, Yekaterinburg, 620016 Russia; sbersin@ya.ru
D.A. Zamyatin, Institute of Geology and Geochemistry UB RAS, ul. Akademika Vonsovskogo 15, Yekaterinburg, 620016 Russia;
V.V. Khiller, Institute of Geology and Geochemistry UB RAS, ul. Akademika Vonsovskogo 15, Yekaterinburg, 620016 Russia
- Gatta G.D., Kahlenberg V., Kaind R., Rotiroti N., Cappelletti P., de’ Gennaro M. (2010) Crystal structure and low-temperature behavior of «disordered» thomsonite. American Mineralogist, 95, 495–502.
- Gurbanova O.A., Rastsvetaeva R.K., Pekov I.V., Turchkova A.G. (2001) Crystal structure of the Sr-rich thomsonite. Doklady Earth Sciences, 376, 101–104.
- Keusen H.R., Peters T. (1980) Preiswerkite, an Al-rich trioctahedral sodium mica from the Geisspfad ultramafc complex (Penninic Alps). American Mineralogist, 65, 1134–1137.
- Oberti R., Ungaretti L., Tlili A., Smith D.C., Robert J.-L. (1993) The crystal structure of Preiswerkite. American Mineralogist, 78, 1290–1298.
- Pekov I.V., Lovskaya Е.V., Turchkova A.G., Chukanov N.V., Zadov A.E., Rastsvetaeva R.К., Kononkova N.N.(2001) [Thomsonite-Sr (Sr,Ca)2Na[Al2Si5O20]?6–7Н2O, a new zeolite mineral from Khibiny massif (Kola Peninsula) and thomsonite-Ca – thomsonite-Sr an isomorphous series]. Zapiski RMO [Proceedings of the Russian Mineralogical Society], 130(4), 46–55. (in Russian)
- Ross M., Flohr M.J.K., Ross D.R. (1992) Crystalline solution series and order-disorder within the natrolite mineral group. American Mineralogist, 77, 685–703.
- Savelieva G.N., Batanova V.G., Berezhnaya N.A., Presnyakov S.L., Sobolev A.V., Skublov S.G., Belousov I.A. (2013) Polychronous formation of mantle complexes in ophiolites. Geotectonics, 47, 167–179.
- Savelieva G.N., Suslov P.V., Larionov A.N., Berezhnaya N.G. (2006) Age of zircons from chromites in the residual ophiolitic rocks as a refection of upper mantle magmatic events. Doklady Earth Sciences, 411A, 1401–1406.
- Strunz H., Nickel E. (2001) Strunz Mineralogical Tables. Ninth Edition. Chemical-Structural Mineral Classifcation System. Schweizerbart and borntraeger sci. publ., 870 p.
- Tlili A. (1990) Spectroscopies Raman et infrarouge, et cristallochimied es micas naturels et synthetiques dans le systeme: Li-Na-K-Ca-Mg-Fe-Mn-Al-Ga-Si-Ge-O-H-D. Ph.D. thesis. Paris, Museum National d’Histoire Naturelle, 299 p.
- Vakhrusheva N.V. (1996) [Metamorphism of chromite-bearing ultramafc rocks of the Polar Urals]. Ph.D. thesis. Yekaterinburg, UGGGA, 24 p. (in Russian).
- Wise W.S., Tschernich R.W. (1978) Habits, crystal forms and composition of thomsonite-Ca. Canadian Mineralogist, 16, 487–493.
МINERALOGY № 3 2020