Abstract:As the largest skarn type copper polymetallic deposit in China, the Jiama deposit has preserved the important information of skarn formation, evolution and mineralization. The geological and geochemical characteristics of the Jiama deposit have been studied by some researchers, but there is still a lack of summary of skarn mineralogy and its zoning pattern, which restricts the perfection of the deposit model. In this paper, the mineral assemblage, mineral composition and zonation characteristics of skarn are studied through detailed field geological logging, systematic optical microscopy and electron probe analysis. A set of typical calcareous skarn minerals have been identified in the deposit, including garnet, pyroxene, wollastonite, vesuvianitae of prograde stage and epidote, chlorite, amphibole of retrograde stage. The mineralogy and mineral chemical compositions display an outward zonation with respect to the source porphyry. The wollastonite skarn mainly present to the contact zone between skarn and marble, and displays no zonation and hosts mainly bornite mineralization. From the proximal skarn to the intermediate skarn to the distal skarn in the garnet-pyroxene skarn, the garnet/pyroxene ratio varies from >20:1 to ~10:1 to ~5:1, the garnet color varies from red-brown to brown-green to green-yellow, the average compositon of garnet varies from Ad71.82Gr26.52Pyr1.61 to Ad62.09Gr36.26Pyr1.55 to Ad54.37Gr44.10Pyr1.46, and the mineralization changes from Mo-Cu±Au±Ag to Cu±Mo±Au±Ag to Pb-Zn±Cu±Au±Ag ores, respectively. The mineral assemblage and chemical composition characteristics of skarn are important indicators of ore forming environment and mineralization type. The skarn zonation pattern can effectively guide ore prospecting and exploration.