Typomorphic characteristics of arsenopyrite in Precambrian gold deposit, Hunan

In Precambrian gold deposits, especially in the As Au deposits of Hunan,ar senopyrite is widely distributed, gold contents is generally 120×10 -6 ～250×10 -6 and the rate of gold distribution is 64 3% ～ 93 1%. The arsenopyrite is the main carrier mineral of gold. The formation of arsenopyrite have early and late stages and the chemical composition is rich in S and poor in As. The arsenopyrite is typomorphically charactered by the rich trace elements, such as Sb, (Se), Ni and Co, poor Mn and the raise of unit cell parameter a 0. There isn't microgold in the most of polished sections with Au bearing arsenopyrite, even by the electron microprobe, there isn't gold yet. Therefore, it has divergence that gold occurres in arsenopyrite by ultramicro grain or lattice gold. Based on many experimental research in the relative gold deposits, it is considered that invisible gold mostly occurred in arsenopyrite by nanometer fine grain.