Mineralogical-geochemical features of corundum Miaskite-pegmatite from mine no. 210 (Ilmeny mountains, South Urals): preliminary results

Miaskite-pegmatite of mine no. 210 exhibits an unusual mineral composition for the Ilmeny Mountains. It contains a signifcant amount of sapphire-like corundum (uncommon of nepheline-bearing pegmatites) and various Th-bearing minerals («thoro-aeschinite», pyrochlore, phosphates). Pegmatite has a zonal structure, in which the central nepheline and lateral feldspar zones difer in composition of rock-forming and accessory minerals. Corundum is found in all zones of pegmatite. Accessory minerals of the central, eastern, and western zones include (i) Ti-niobates (columbite, pyrochlore, srilankite), zircon, spinel and thorianite, (ii) columbite, pyrochlore and zircon, and (iii) columbite, «ilmenor…