Acid drainage from sulfides hosting gold mineralization (Furtei, Sardinia)

Abstract

 The past mining activity for kaolin minerals left several abandoned quarries in the area of Furtei (southern Sardinia). Recently, gold mineralization has been found in association with intensely altered andesitic rocks, and an open-pit gold mine is expected to open in the near future. Twenty-one water samples were analyzed for a wide range of major and trace elements, in order to define the present hydrochemical situation before exploitation starts. Waters interacting with the altered andesitic rocks had higher salinity and metal concentrations than waters in contact with nonaltered rocks. Acid drainage and high concentrations of metals (Al, Fe, Mn, Zn, Cu, As) in solution were observed in waters leaching the mineral deposit. An environmental impact study is urgently called for since the waste material derived from the exploitation is expected to enhance acidification and metal-releasing processes, due to the increase in the specific yield, which favors the oxidation of sufide minerals.