Guilherme Ferreira da Silva

Ocorrência de horizonte cromífero no Complexo Trincheira, município de Corumbiara, sudeste de Rondônia

The Trincheira Mafic-ultramafic Complex comprises a Mesoproterozoic layered intrusion hosted in metasedimentary rocks of the southwestern portion of the Amazonian Craton. This intrusion has an outcropping area of approximately 35 km2, however, it has been associated to a larger ellipsoidal magnetic anomaly with N-S elongated shape. The Trincheira Complex is composed of partially metamorphosed pyroxenites, websterites, gabbros and anorthosites. The complex hosts Cr-rich layers associated to relevant concentrations of Ni. High concentrations of Cu, Co and V have also been detected. Preliminary analysis performed with portable X-ray diffraction indicates up to 13% Cr and occurrence of cochromite, a special variety of chromite enriched in cobalt, nickel and iron, whereas ICP-MS analyses returned concentrations of up to ~3600 ppm Cr.

Indício de mineralização de manganês no município de Comodoro, Mato Grosso, novas oportunidades para a indústria mineral

Evidence of massive manganese was found in the northwest of the State of Mato Grosso, in the municipality of Comodoro. The area is located in the southwest portion of the Amazonian Craton, in the Calimian Jauru Tectonic Domain, which comprises metasedimentary rocks of the Rio Galera Complex and calc-alkaline granites of the Pindaituba Intrusive Suite (Praia Alta and Rio Piolho granites). Chemical analysis of the manganese-bearing sample yielded the following oxide and element concentrations: MnO = 61.4%, BaO = 13.2%, Cu = 751 ppm, Mo = 417 ppm, Pb = 4642 ppm, U = 107.8 ppm and Ce = 1608 ppm. Petrographic analysis allowed the identification of pyrolusite as the manganese mineral totaling 95% of the analyzed sample and 5% of gangue minerals.