A sequence of formation of «uranpyrochlore» and fluorocalciopyrochlore in alkali pegmatites from the Vishnevye Mountains, South Urals
V.I. Popova, V.A. Popov, I.A. Blinov, V.A. Kotlyarov, S.M. Lebedeva
The sequence of formation of pyrochlore crystals of various morphology and composition is considered in an aggregate with ilmenite and feldspar of nepheline-feldspar pegmatite at Mt. Dolgaya (Vish-nevye Mountains, South Urals): altered yellowish green «uranium pyrochlore» with a UO3 content of 7.62– 42.44 wt. % in different parts of the crystal, and also fuorocalciopyrochlore, fersmite, and associated minerals. The alteration of «uranpyrochlore» includes fersmitization and silicifcation in contrast to relatively late fuo-rocalciopyrochlore and fersmite. The compositions and Raman spectra of altered «uranpyrochlore» and later fuorocalciopyrochlore are given.
Keywords: titanoniobates, «uranpyrochlore», fuorocalciopyrochlore, fersmite, formation sequence, Vishnevye Mountains, Southern Urals.
Received 06.08.2021, accepted 19.04.2022
MINERALOGY 2 2022