Aspectos geológicos, gemológicos e econômicos do depósito de ametista de Alto Bonito, Marabá, SE do Estado do Pará

Abstract

The mining amethyst Alto Bonito is located in the municipality of Maraba, southeast of Pará. The region is inserted in the Carajás Mineral Province, mais precisamente no Domínio Carajás, middle part of the System Transcurrent Cinzent, as a structural feature rhombohedral called Cururu. It was discovered in 1979, but only began to be explored in the early 80s, of miming of naked hills. Today, the mine represent one of the largest deposits of amethyst of the Brazil, where são extracted amethyst and citrine, the latter being produced by the miners of COOPERGEMAS by treatment heat. The crystals occur in veins hydrothermal embedded metamorphic sequence in the grau down belonging Supergroup Itacaiúnas, with quartzite and metarenites the Rio Novo Group (2658±43 Ma). The mineralization occurs in amethyst associated with hydraulic implosion breccias and stockwork specularite vein, besides the important mineral paragenesis marked by quartz, muscovite, sericite, hematite, tourmaline, rutile, kaolinite and florencite. A hot spring source unknown of attractive on-site visit, and may be associated with significant mineralization of the veins.