Inclusions of koragit in topaz from pegmatites of the Mokrusha deposit (Urals, Russia)

N. I. Ponomareva, V. V. Gordienko, A. V. Antonov, S. V. Krivovichev, A. R. Nesterov, M. I. Kazantseva.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2018. V. 147. N 5. P. 61-68

https://doi.org/10.30695/zrmo/2018.1475.04

Full text is available on eLIBRARY.RU

Language: Russian

Abstract

The present communication is devoted to the study of inclusions in topaz from the Mokrusha pegmatite deposit field (Urals). Inclusions in topaz are represented by intergrowths of small crystals of manganocolumbite, cassiterite and a mineral corresponding to niobium tungstate with impurities of manganese, tantalum and iron. On the basis of microprobe and X-ray analyses it is confirmed the identity between the mineral and koragoite previously described by A. V. Voloshin and co-authors in granite pegmatites of south-western Pamirs, Tajikistan. The formula of the mineral is: (Mn_2.02Fe_0.98)_∑3.00(Nb_2.296Ta_0.640Ti_0.062)_∑3.00(Nb_1.04Mn_0.960) _∑2.00(W_1.343Nb_0.664)_∑2.00O₂₀.

Key words: mineral inclusions, topaz, koragoite, pegmatite, Mokrusha deposits, Urals.