2:15 PM - 2:30 PM
[HRE16-07] Microscopic study on rare earth elements in ion-adsorption type ore of China
Keywords:Ion-adsorption type rare earth ore, LA-ICP-MS, FIB-TEM, XAFS, NanoSIMS
XRD measurements indicated that the weathered granite is mainly composed of quartz, K-feldspar and kaolinite. The results of SEM-EDS and LA-ICP-MS measurements showed that “kaolinitic particle” is abundant with REE compared to the other minerals. These results suggest that the kaolinitic particles are major reservoir of REE in the ore. The elemental mapping for a kaolinitic particle by LA-ICP-MS showed that each element is distributed heterogeneously in the particle. The SEM-EDS analyses also suggested that the kaolinitic particle is composed of several minerals. For further micro-analyses, cross sections were processed from the kaolinitic particles by FIB. XAFS study on the cross sections suggested that REE are basically hydrated in the particle. STEM-EDS analyses revealed that the kaolinitic particle contains illite and hematite in addition to kaolinite. Considering general weathering process, it can be assumed that K-feldspar was altered into illite and further into kaolinite during chemical weathering. Elemental mapping with high spatial resolution by NanoSIMS clarified that REE are distributed in kaolinite and illite.