Towards a better understanding of a Co-rich hydrothermal system: Punta Corna (Western Alps, Italy)

Abstract. This study presents new geochemical, mineralogical, and petrographic data on the Co-Fe-Ni vein system of Punta Corna (PC) in the Western Alps, Italy. The mineralogical phases identified include arsenides belonging to the skutterudite and safflorite (Fe-Co-Ni tri- and diarsenides) solid solutions, tetrahedrite, and sulfides (chalcopyrite, minor pyrite and rare sphalerite and galena). Gangue minerals comprise carbonates (mainly siderite, ankerite and calcite) and quartz. Field and mineralogical observations show a distinct geochemical zonation within the deposit system. No Co or Ni occur to the west, with only Fe-bearing minerals observed. Co-Ni arsenides are present in the central region, with a higher proportion of Ni diarsenides than Co-bearing phases. To the east, Co arsenides prevail. Additional sampling, micro-textural characterization and geochemical investigations are ongoing, yet these preliminary observations agree with the genetic model recently proposed for similar types of deposits and suggest that the hydrothermal system may have formed through a complex geological history, with multiple mineralizing events and variations in fluid composition and possibly temperature.