A series of five sills and plugs of the Ipora Group are emplaced in sandstones of the Devonian Furnas Formation and comprise nine main outcrop areas. The northernmost group of Lambari covers about 70 km2 and is principally of basanite, which is a highly vesicular rock with phenocrysts of augite, hornblende and labradorite in a matrix of the same minerals, together with biotite (5-10%), opaques and accessory apatite, barkevikite, carbonate and analcime which may form euhedral crystals, possibly after leucite. Trachytes, with phenocrysts of alkali feldspar in a matrix of alkali feldspar, sodic plagioclase and a little quartz, form one mass in the Lambari sills and the 2 km diameter circular mass of Papira. The two sill outcrops of Fazenda do Toninho, both some 4 km2, are of an alkali pyroxenite composed of augite/Ti-augite (70%), biotite, a little olivine and accessory zeolite, plagioclase and opaques. Diorama is a 4x2 km sill principally of trachybasalt and 'andesite basalt'.