This is a zoned intrusion of about 5 km diameter forming a hill and emplaced in Devonian Furnas sandstones. There is a central core of dunite surrounded by peridotites and pyroxenites and these in turn by a border group of alkaline gabbros and nepheline syenite. The dunites are partially serpentinized. The pyroxenites, as well as 'augite', contain olivine and a little plagioclase. These rocks pass gradually into biotite-bearing gabbros. The nepheline syenites are coarse rocks with nepheline phenocrysts up to 1. 5 cm, perthite, 'sanidine' phenocrysts and Ti-augite zoned to aegirine. A small area of rock composed essentially of pyroxene and magnetite and described as jacupirangite occurs, while small veins of carbonatite with phlogopite cut the dunite.
PENA, G.S. and FIGUEIREDO, A.J.A. 1975. Projeto Goiama II, relatorio final. Departamento Nacional da Producao Mineral. Companhia de Pesquisa de Recursos Minerais, 1: 121-61.
RODRIGUES, C. de S. and LIMA, P.R.A. dos S. 1984. Carbonatitic complexes in Brazil. Companhia Brasileira de Metalurgia e Mineracao: 1-17