Environmental Effects of the Acid Rains and Mine Drainage Around the Murgul VMS Copper Deposit, Eastern Pontides, Turkey

Abstract

The Murgul copper deposit is located 7 km to the south of Murgul (Artvin) in the north-eastern part of Turkey and has been in modem operation since the 1940's. The deposit is hosted in dacitic pyroclastics of Upper Cretaceous and covered by acidic tufts, mudstone, micritic limestone and sandstone of Upper Cretaceous. The massive lens composed mainly of chalcopyrite and sphalerite is already mined out and the current production is from the stockwork zone within the dacitic pyroclastics. The ore is composed mainly of pyrite and chalcopyrite, and sphalerite, galena and sulphosalts to a lesser extent. There is a vertical variation in the chemistry and mineralogy of the deposit; sphalerite and galena increase towards upper levels of the deposit (Akqay and Tfiysiiz, 1998). Quartz is the main gangue mineral; baryte, sericite, gypsum, siderite and ankerite also occur in minor amounts. The stockwork zone is characterised by an intense silicic alteration grading outward into sericite and chlorite-rich zones (Schneider et al., 1988). The Murgul deposit has a reserve of 30,000,000 tons of ore grading at 0.97% Cu. Annual production is about 3 million tons of ore yielding 25000-30000 tons of Cu concentrate, 25000-30000 tons of sulphur and 10000-15000 tons of sulphuric acid (Akgay and Tfiysfiz, 1998). Karadeniz teknik Oniversitesi, Jeoloji Milk B61., 61080 Trabzon, Turkey