Mineralogical and Petrographic Characteristics of Aillikites of the Yuzhnaya Pipe, Zima Alkaline-Carbonatite Complex, Eastern Sayan

Abstract During the mineralogical and petrographic study of the aillikites of the Yuzhnaya pipe, Zima alkaline complex, special attention was devoted to the chemical composition of the main minerals—micas, clinopyroxenes, amphiboles, spinel and garnet supergroup minerals. For zoned macro-phenocrysts of ore minerals — Ti-magnetite and a potentially new Ca–Fe–Ti-oxide protophase, the solid decay structures into two phases are described: magnetite + ulvospinel/ilmenite and perovskite + magnetite. An unusual Ti–Zr garnet with a “Mg-morimotoiteˮ hypothetical Ca3(TiMg)(SiO4)3 end-member (content—up to 40 mol %) was also identified in the studied aillikites.