Ore and Gangue Minerals of the Hera Au-Pb-Zn-Ag Deposit, Cobar Basin, NSW

Abstract

The Hera Au-Pb-Zn-Ag deposit is located within the Cobar Basin of the Lachlan Orogen. The deposit was classified as a Cobar-type deposit, however the presence of skarn gangue mineral assemblages associated with the main mineralisation and host-rocks suggest a much higher temperature of ore formation. These gangue assemblages also are the first occurrence of these for deposits within the Cobar Basin. The gold at Hera shows poor correlation with the other metals and minerals suggesting multiple generations of crystallisation. The primary silver minerals in the deposits are Ag-sulfosalts (tetrahedrite), acanthite and dyscrasite?. The presence of Ag-sulfosalts often closely associated with gudmundite within the main mineral assemblages. Scheelite is quite common and associated with the main sulphides and also within the host siltstone.