THE ABANDONED PB-ZN MINE OF INGURTOSU, SARDINIA (ITALY)

The Ingurtosu Pb-Zn mine, situated in the southwestern part of Sardini a, has been in production from the beginning of the last century up to 1968. The orebody consists of galena/sphalerite/barite/siderite veins in Ordovician arenaceous and phyllitic sediments, near the contact wi th a Hercynian batholith. Abundant tailings were collected in a pond f rom which they were discharged during the winter months into the sea v ia the Rio Naracauli stream. Today this area of outstanding scenic bea uty, is degraded by tailings and waste rock scattered all along the st ream. Material derived from mining activities was studied for grain si ze, mineralogical and geochemical composition. The Rio Naracauli was s ampled over a length of ten kilometers at regular intervals, The resul ts can be summarized as follows: (a) tailings contain a varying, but o ften quite high, percentage of Pb; lower percentages were found for Zn and Cd; (b) a sharp increase in dissolved Zn, Cd and Pb was observed in the Rio Naracauli where it leached the tailings; and (c) tailings a nd waste rocks should be recycled or revegetated.