Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

Morro Do Engenho


Occurrence number: 
Longitude: -51.67, Latitude: -15.53

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.

Garnierite occurs in laterite, with an estimated reserve of 70 million tons averaging 1.27% Ni (Rodrigues and Lima, 1984).

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

Fig. 1_196 The Ipora Group of occurrences of alkaline intrusions of central Goias.
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith