Petrografia e mineralogia do depósito mineral de ferro localizado na terminação leste da falha Carajás, município de Curionópolis/PA

Abstract

The iron deposit of the LBR Mineração Ltd. company, object of this work, is located in the central portion of the Curionópolis region, southeastern of the Pará state, about 136 km from Marabá, Pará. Geologically, this area is inserted in the southeastern boundary of the Amazonian Craton, a region known worldwide for possessing one of the most expressive mineral provinces of the world, the Carajás Mineral Province. This deposit is hosted by altered Banded Iron Formations of the Rio Novo group. These rocks were classified according to their alterations degree as ―Iron Ore‖, which are composed almost exclusively of hematite with subordinate magnetite, as well as maghemite and quartz in irrelevant quantities. Petrographic analysis in just two samples of this ―Ore‖ – one from the edge and another from the body’s center – showed that the hematite amount increases from the edge to mineral deposit center, whereas the other way around happens to the magnetite. It was also noted that the martitization process is intense in the two samples, but there are more preserved magnetitic cores in the boundary deposit hematite crystals, showing a lower oxidation in relation to the center. Hematite crystals preserving the magnetite cubic habits are very common. Comparing the chemical analysis provided by the company with those performed during the preparation of this work, was verified that LBR Mineração has a very pure mineral deposit with a high grade, on average greater than 67% of iron.