Abstract:The NiuxingbaLiumukeng AuAgPbZn polymetallic deposit in the Yinkeng ore field is located in the YuduGanxian ore cluster area, south Jiangxi Province. Field investigation, systematic mineralographical observation, and electronic probe composition analysis indicate that bismuth is one important associated element in the NiuxingbaLiumukeng AuAgPbZn polymetallic deposit, and occurs as an independent mineral or microparticles in internal or marginal parts of early formed sulfide. Bibearing minerals are versatile, including pavonite, matildite, gustavite, berryite, aikinite, emplectite, krupkaite and tetradymite. Compared with Pangushan quartz veintype WBi deposit in the same ore cluster area, two ore deposits contain two Bibearing mineral associations (PbAgBiS and TeBiS), but vary in mineral occurrence and contents. CuPbBi element association is found only in the NiuxingbaLiumukeng deposit. The presence of bismuth minerals suggest the deposit belongs to AuBi(low Te)S system, and formed in the geological environment with medium and low temperature, medium high density and low salinity. Bismuth migrated in the form of sulfide complexes after massive gases escaping and sulfur fugacity increasing which was compelled by boiling oreforming fluid derived from magma. With precipitation of sulfide (e.g. pyrite), a large amount of sulphur were transferred into goldbearing minerals and telluride. Further decreasing of temperature and sulfur fugacity during the evolution of oreforming fluid resulted in deposition of bismuth sulfosalt minerals at the late stage of mineralization. Bi promoted gold migration and enrichment during the process of mineralization. Bibearing minerals at the two deposits present some differences in occurrence state, chemical components, forming environment, and precipitation mechanism, suggesting Bi’s preference in oreforming process and thus playing a significant role in tracing oreforming material source.