Solid Solutions of Karelianite and Eskolaite (Slyudyanka Complex, Southern Baikal Area): Genesis and a Possible Petrogenetic Indicator

A continuous solid-solution series between the end-members eskolaite (98 wt.% Cr2O3) and karelianite (93 wt.% V2O3) has been revealed in Cr-V-bearing rocks of the Slyudyanka metamorphic complex. Chromium and vanadium oxides crystallized as karelianite-eskolaite minerals during regional high-temperature prograde (granulite facies) metamorphism and participated in the formation of other Cr-V and Cr-V-bearing phases. Ferrian karelianite (up to 12 wt.% Fe2O3) and three-component solid solutions Esk(12-50)Kar(45-60)Hem(6-30) occur in metamorphic rocks that have particular protolith compositions (Fe-Kar) and in later metasomatic rocks ((Cr, V, Fe)(2)O-3). Natural eskolaite and karelianite are discussed in terms of paragenesis, and their crystallization conditions are compared with the conditions of their laboratory synthesis.