This is a circular, 7.5 km diameter complex consisting of both intrusive and extrusive rocks. The earliest suite is one of olivine gabbros which were followed by monzodiorites and amphibole-biotite monzosyenites and these in turn by a central plug of riebeckite-arfvedsonite-biotite granite, which was itself intruded by a finer grained granite of similar mineralogy. The volcanic rocks, which form an outer circle, include hawaiite, potassic mugearite and benmoreite and alkaline rhyolite. There are radiating dykes of trachyte and spheroidal rhyolite in which pyrochlore has been identified (Lasserre, 1966). Analyses of 10 rocks are given by Deruelle et al. (1991).