THE ARSENOPYRITE TYPOMORPHIC CHARACTERISTICS AND AU OCCURRENCE STATE IN THE GOLD DEPOSIT

The arsenopyrite in almost all Au deposit bears gold. And it is the main bearing mineral of gold, same as the pyrite. The invisible gold is usually concentrated in arsenopyrite in preference to any other. The Au in arsenopyrite is 2-5 times even one order of magnitude highter than that in pyrite and the Au distribution ratio is also very high. The Au-bearing arsenopyrite is generally euhedral, subhedral, long-prismatic, plate-prismatic and prismatic, etc. The chemical composition of it belongs to the type rich in S and poor in As and is characterized by richness in trace elements Sb, Ni, Se, low microhardness and the increased cell parameter a0. There is not microscopic Au in most polished sections with arsenopyrite, which is difficult to be discovered even by microprobe analysis. It is tentatively believed that the goldin arsenopyrite is mainly in the micrograined state of nanometer order.