ABSTRACT
As an accessory phase, chrome-spinels are almost always present in the dunites, harzburgites, lherzolites, wehrlites, pyroxenites, olivine and some non-olivine gabbroids constituting the mafic-ultramafic massifs within the folded regions and platforms, as well as presented in abyssal xenoliths of alkali-basalts and kimberlites. As a part of many massifs they form deposits of various scale and schlieren of massive and densely disseminated ores, as well as cross veins, most often localized among the dunites and harzburgites. By their structure and chemical composition their chrome-spinels belong to the multiple oxide groups. A considerable variation of the main components – MgO, FeO, Al2O3 and Cr2O3 is observed in its content. Chemical formula of the chrome-spinels is usually written as follows:
(Mg, Fe2+)(Cr, Al, Fe3+)2O4.
