Buriti is an Ipora Group intrusion of about 16 km2 displaced by a north-south-trending sinistral fault and emplaced in Precambrian granites and syenites and sandstones of the Devonian Furnas Formation. It consists of alaskites of K-feldspar, quartz, hornblende and opaques, together with 'nordmarkites' of perthite, plagioclase and quartz. It is not clear from the available descriptions whether it is peralkaline. The nearby Mata Azul tinguaite dyke is 2.5 km in length and 7-20 m thick; it has a fluidal texture at the margins. It contains phenocrysts of sanidine of 0.5-2 cm, nepheline, aegirine-augite/aegirine, biotite, sphene and dodecahedra of (?)analcime, set in a matrix of the same mineralogy together with opaques and secondary cancrinite.