This is a neck of 'ultrabasic-alkaline' rocks occurring southeast of Coromandel; little known.
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A small volcanic chimney cuts slates of the Bambui Group. Described as 'alkali olivine basalt', but contains perovskite, biotite (10%) and serpentine (35%), with some zeolite (Barbosa et al. 1970).
This occurrence comprises a dyke of ijolite and a chimney of olivine basalt.
Picritic and feldspathoidal alkali basalts occur, probably as necks; poorly known.
A large oval complex of about 65 km2 is emplaced into quartzites and phyllites of the Precambrian Bambui Group, which it domes. A thick lateritic cover averages about 150 m in thickness. Drilling has shown the core to consist of carbonatite, pyroxenite, dunite and peridotite.
A suite of pebbles and cobbles of carbonatite and alkaline rocks, including pulaskite, urtite, melteigite and alkali gabbro, occur within conglomerates of the Cretaceous Uberaba Formation. They are thought to derive from an unknown intrusion, not those lying to the west, i.e.
Serra do Bueno consists of a series of small necks and dykes intruding low grade schists. The rocks are 'alkali olivine basalts', containing perovskite and zeolite.
At least 12 of a much larger number of radioactive anomalies in the Bambui area prove to be pipes up to about 100 km in diameter, which are usually filled with breccia.
Tapira is an almost circular intrusion about 6 km in diameter emplaced in Precambrian quartzites of the Canastra Group, which strike parallel to and dip away from the contact. The complex is deeply weathered for between 30 and 200 m.
The Sacramento complex consists of a sequence of alkali basaltic flows, tuffs, breccias, dykes and plugs of Cretaceous age.