Characteristic of Alteration and Mineralization of Sulfide Deposits at Sasak area, Tana Toraja, Indonesia

This study aims to determine the characteristics of hydrothermal alteration and the mineralization of sulfide deposits in the Sasak area. The method used is field research which includes observations of lithology, geomorphology, and geological structures and subsurface data collection with geomagnetic and polarization induction (IP), laboratory analysis methods in the form of petrographic, mineragraphy, AAS, and Fire Assay. The alteration characteristics start from strong intense potassic, argillic, and intense silicification to strong intense prophylitic. The mineralization is sulfide consisting of galena (PbS), sphalerite (ZnS), chalcopyrite (CuFeS2), and covellite (CuS) as well as a small amount of chalcocite (CuS2). Limonite, magnetite, and quartz are the dominant accompanying minerals, while gold-silver (Au-Ag) tends to be associated with limonite or quartz. Covellite tends to exist on the surface of chalcopyrite. Galena, sphalerite, chalcopyrite, and covellite are complexly bound to pyrite minerals or between the three minerals in fine sizes, there is even superfine galena as inclusions in pyrite. Based on the characteristics of alteration and mineralization indicates a porphyry-type deposit.