BELKOVITE FROM CALCITE-DOLOMITIC CARBONATITES OF THE SEBLJAVR MASSIF (KOLA PENINSULA)

摘要

Belkovite has been found in calcite-dolomitic carbonatites forming bitrigonal prismatic crystals and kidney-shaped aggregates. It associates with calcite, alstonite, baritocalcite, strontianite, ancylite-(Ce), pyrochlore, chlorite and sulphides. Colour from light-yellow to brown, sometimes zonal-painted. Comparative study of chemical composition has been made (microprobe analysis) for belkovites from Sebljavre and Vuorijarvi massifs. It is shown that, despite the difference in composition and formation stage of host carbonatites, belkovite has crystallized in the same conditions: while the late hydrothermal alteration of the host rocks. Presence of high barium minerals is the common feature of belkovite-bearing mineral associations.