TYPOMORPHIC CHARACTERISTICS OF PYRITE-ARSENOPYRITE-ANTIMONITE AND OCCURRENCE OF GOLD IN GOLD DEPOSIT: A case study of the gold deposits in Hunan Province

In the gold deposits in Hunan Province and other similar regions, gold is highly enriched in pyrite, arsenopyrite and antimonite. These gold-bearing sulfides (arsenides) have typical typomorphic characteristics. Most of the gold in pyrite and, especially, in arsenopyrite is invisible, as particles less than 0.1 μm. As a result, the gold cannot be seen in optical microscope. Even if by the electron microprobe and high-power X-ray scanning, the gold mineral concentration is not found. This raises divergence of views about the occurrences of gold in such minerals, i.e. ultramicro particles or isomorphs in mineral lattices. Therefore the study on the typomorphic characteristics of pyrite and arsenopyrite and the occurrence of gold is importance for the utilization of gold. Based on experiments and ore-dressing results in related gold deposits, the invisible gold in pyrite and arsenopyrite is considered to exit as nanometer gold (mineral gold), but not lattice gold (structure gold).