Application of X-ray Powder Diffraction and Inductively Coupled Plasma-Mass Spectrometry in Study on Mineralogical Characteristics and Significance of Wolframite from Xihuashan Tungsten Deposit, Jiangxi Province

The Xihuashan tungsten deposit is a typical large quartz-vein type tungsten deposit with systematical study, but researches on chemical composition and spatial distribution regulation of wolframite are relatively less. Based on microscopic mineralogy, the crystal structure, chemical composition, REEs and trace elements, geochemical characteristics of wolframite selected from different levels of Xihuashan tungsten deposit were studied using X-ray Powder Diffraction and Inductively Coupled Plasma-Mass Spectrometry. The obtained lattice parameters of a₀(0.477nm), b₀(0.573 nm), c₀(0.498 nm), β (90°21') showed that the wolframite belongs to manganese tungsten ore. It is lightly different from lattice parameters of previous studies, which is caused primarily by isomorphous substituting on Fe and Mn. The chemical components of wolframite contain mainly WO₃, FeO and MnO, showing some regularity in space, indicating migration features of ore-forming material. The wolframite also contains multiple kinds of trace elements. Sc, Y, Nb and Ta show dynamic changes of content in the vertical direction, which reflect complexity of ore fluid migration. The chondrite-standardized REEs distribution patterns are characterized by left-leaning shapes with high ΣREEs (397.16×10^-6-1071.11×10^-6), relatively heavy REEs enrichment and strong Eu negative anomaly. By comparing the REEs characteristics of wolframite from four typical tungsten deposits including Xihuashan, Pangushan, Taoxikeng and Dajishan, the results show that the wolframite in the inner contact zone of the granite body is characterized by relatively high ΣREEs with obvious REEs fractionation. Wolframite in the inner granite body and outer contact zone is characterized by relatively low ΣREEs with unobvious REEs fractionation. Wolframite in the outer contact zone of the granite body is characterized by large changes of ΣREEs and REEs contents and fractionation. Wolframite composition characteristics can not only be used to indicate migration features of ore-forming material in space, but also to discriminate ore-forming material sources and ore genesis.