Noble metal admixtures in the galena from gold deposits and placers of Trans-Amur province
The authors characterize certain features of chemical composition of the galena sampled from the gold deposits (Pioneer), gold-polymetallic deposits (Berezitivoye), polymetallic deposits (Chagoyanskoye) and a gold placer (the Vesely stream in Nizhneselemdzhinsky ore-placer zone), located in Trans-Amur gold province. The contents of gold and other admixtures in the galena of the above deposits are defined. The deposits are found to have the tendency towards the increase in the gold content of galena in the raw from proper polymetallic deposits to gold-polymetallic and gold. The occurences of gold-bearing and silver-bearing galena in alluvial and deluvial deposits enables one to determine the type of the original source at the early stages of region exploration. Using the placer deposit of the Vesely stream as an example, the authors show that the gold-silver ration in galena increases in the zone of hypergenesis. They also prove that exogenous processes cause structural and compositional changes in minerals.