Mineralogy of gold in polymetallic deposits of Serbia

Abstract

Gold-bearing polymetallic sulfide deposits are common in Serbia, and mostly occur in the Karpato-Balkan and, to a lesser extent, the Serbo-Macedonian metallogenic province. These deposits - Coka Marin (Majdanpek), Grabova Reka (Blagojev Kamen), Lece (Medvedja) and Veliki Cip (Boranja) - are dominated by Cu and/or Pb-Zn mineralisation that contains a variety of Pb, Zn, Cu and Fe (± Sb, As, Bi) sulfides and sulfosalts, as well as native elements. Gangue minerals are composed of quartz, carbonates and rare silicates and barite. Based on their gold content these deposits can be divided in three groups: 1. polymetallic deposits with a high gold content (>1 g/t). 2. polymetallic deposits with an intermediate gold content (0.1 to 1 g/t), and 3. polymetallic deposits with a low gold content ( LT 0.1 g/t). Gold occurs as native gold or as an alloy with silver. Native gold ranges in size from 5 to 20 μm, with a few rare grains over 100 μm, as isolated grains or as microveins (in the first group of deposits). Its distribution within the deposit in uneven. Native gold in the second group is smaller in size (1-5 μm, rarely 20 μm), where it is uniformly distributed in a quartz-silicate matrix. The third group is of no economical importance. The subject of research has been the first group of polymetallic deposits.