Polygenetic lateritic iron ores on BIF's in Minas Gerais/Brazil

The aim of this paper was a mineralogical-geochemical investigation of the weathering processes in the BIF's (banded iron formation) of the Ferteco area, M.G. Brazil. A several hundred meter deep Proterozoic supergene alteration is overprinted by younger, mainly Cenozoic weathering processes. The later is characterized by surface related increase of gibbsite and goethite and by groundwater governed newformation of magnetite, traces of Mn-minerals and local elevated gold contents. The canga on top is interpreted as residual breccia.