EVOLUÇÃO MINERALÓGICA DOS JACUPIRANGUITOS DE JACUPIRANGA (SP) DURANTE A ALTERAÇÃO INTEMPÉRICA

Resumo

Samples were collected from a weathering profile developed above pyroxenites belonging to the alkaline massif of Jacupiranga. The primary minerals titanoaugite, magnetite, perovskite, phlogopite, and olivine - were first partially transformed by a hydrothermal alteration process and the completely altered by weathering. The earlier products of the supergene alteration of the pyroxenites -are smectites; these minerals change into kaolinite and goethite which are the principal components of the lateritic cover. This paper deals with micromorphological aspects of these transformations.