Abstract The Ambodiriana series (migmatites, mica schists, and so-called amphibole pyroxenites) of the Tamatave region, Madagascar, is cut by ultrabasic intrusions, some of which carry chromite. These ultrabasic rocks have been moderately metamorphosed since emplacement. The chromite ore occurs in veinlets that dip in the same direction as the surrounding schists. Their chromite content ranges from 60 to 86 percent, but the Cr/Fe ratio is too low for metallurgical purposes.