Abstract:The Zhazixi W—Sb deposit, located in the Xuefeng Range, western Hunan, is a typical one of the veinfilled hydrothermal deposits. Scheelite is a widespread mineral in this hydrothermal deposit. In the present contribution, the REE insitu analyses have been performed by laser ablationinductively coupled plasmamass spectrometry (LA-ICP-MS) on scheelite samples collected from the Zhazixi mining district. It is revealed there is obvious REE inhomogeneity among the scheelite samples analyzed in this study. REE concentrations and chondritenormalized patterns can change abruptly among different scheelite grains in the same thin section, even in different part of the same grain. The chondritenormalized REE distribution patterns of scheelite from the Zhazixi deposit can be classified into the MREEenriched type, MREEdepleted type and REEflat type; these three REE patterns can exist independently or coexist in certain scheelite sample. Even in the same scheelite mineral grain in some thin sections, the above three REE patterns can simultaneously appear, probably revealing a complete dynamic evolution process that reflects this scheelite formed as follows: MREE in the early oreforming fluid are incorporated into scheelite, the precipitation of this MREErich scheelite will significantly alter the composition of hydrothermal fluid and produce a MREEdepleted fluid, which results in the subsequent formation of MREEflat and MREEdepleted scheelite. Therefore, LA-ICP-MS method may be a potential tool to identify the dynamic process of oreforming hydrothermal fluids. In addition, cautions have been taken for traditional REE analyses of bulk samples, lest some mistaken information or conclusions should be obtained.