Mode of occurrence of gold in micro- disseminated strata-bound Sb-Au deposits, Qinling region, china

摘要

Optical studies, backscattered electron images, secondary ion spectrometry and high- precision transmission electron imaging demonstrate that gold is strongly correlated with arsenic on a microscopic scale in the sediment-hosted micro-disseminated gold deposits. The positive correlation between Au and As, despite varying Au/As ratio, is persistent in arsenian pyrite overgrowths and arsenopyrite. It is found that gold occurs in native state as submicro beads in association with arsenic-bearing sulfides. The extremely small grain size of gold may indicate a very rapid process of deposition.