The copper-gold Visconde deposit is located about 15 km east of the Sossego deposit, at the transition zone between the Carajás Domain and the Rio Maria Granite-Greenstone Terrane, Carajás Mineral Province (CMP). The Visconde deposit is hosted by felsic metavolcanic rocks, granites and gabbros/diorites, but dacites, mafic and serpentine-rich ultramafic rocks are also mineralized, though locally. These rocks are hydrothermally altered at varying grades, being sodic alteration (albite + scapolite), calcic-sodic I (actinolite + tourmaline + epidote + magnetite), potassic (biotite ± allanite, K-feldspar), calcic-sodic II (albite + calcite + actinolite+ epidote + quartz + hematite) and chloritisation the most important types, which evolved in that order and are in part superimposed. The mode of occurrence of the hydrothermal minerals has been controlled by the tectonic regime that grades from ductile to brittle-ductile. The sulfide precipitation (pyrite + chalcopyrite + bornite ± pentlandite ± molibdenita) occurred in all alteration stages, but was most voluminous following biotitization. Chalcopyrite and bornite dominate, especially in the breccias. The sulfide and oxide assemblages characterizes a metal suite of Cu-Au-Fe-Mo-Ni, while gangue minerals (allanite, tourmaline and apatite) indicates significant entrance of LREE, B and P into the hydrothermal system by the circulating fluids. The mineral parageneses allow to infer that the early fluids were highly saline (marialitic scapolite), hot and relatively reduced (magnetite), but became progressively less saline, cooler and more oxidized (hematite) as they reacted with the mineral environment or mixed with superficial fluids. Similar geological setting, host rocks, alteration types, metal suite and mineralization styles support both the Visconde and Sossego deposits to be classed in the same metallogenetic category.
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