Hydrocarbon gas survey performed around various rock bodies, ores, wallrocks and surface soils has revealed that organic matter took part in the ore forming process of the Gejiu ore deposit, that there exist hydrocarbon gas halos around orebodies, and that dintinct hydrocarbon gas anomalies are present over known orebodies. It is held that organic matter might have played a much greater role in precipitation, diagenesis, mobilization and migration as well as mineralization of metallic elements than we have already known. Hence, much more imporance should be attached to the study of applying organic hydrocarbon gas to the prospecting for metallic ore deposits.