EMPA-SEM Study on the Rare Earth Minerals from the Huayangchuan Uranium Rare Polymetallic Deposit, Shaanxi Province

BACKGROUND The Huayangchua polymetallic deposit is a super-large mineral deposit that has economic endowments of uranium and rare earth resources. The deposit is characterized by the unique ore types and complex mineral assemblage. Systematic mineralogical studies can reveal the main rare-earth minerals and the occurrence of REE, providing an important reference for the comprehensive utilization and metallurgical technology of rare earth elements. OBJECTIVES To provide new insight for mineralogy using the in-situ observation and analysis technology. METHODS The field emission scanning electron microscope (SEM), electron microprobe analysis (EMPA) and energy dispersive X-ray spectrometer (EDS) were used to systematically study ore minerals of the Huayangchuan deposit. RESULTS The rare earth elements in the Huayangchuan deposit mainly occurred in two states. Independent rare-earth minerals included allanite (La2O3 6.49%-7.61%, Ce2O3 11.50%-14.00%), monazite (La2O3 16.30%-21.21%, Ce2O3 32.06%-39.18%), bastnasite (La2O3 12.86%-14.20%, Ce2O3 36.67%-39.90%), fergusonite (La2O3 1.19%-2.11%, Ce2O3 1.29%-2.30%, Y2O3 22.67%-25.88%), and xenotime (La2O3 2.29%-3.58%, Ce2O3 1.89%-2.37%, Y2O3 39.77%-42.80%). REE also occurred as isomorphism in apatite, pyrochlore and sphene. CONCLUSIONS REE occurs as rare-earth minerals in the Huayangchuan deposit, including allanite, monazite, bastnasite, fergusonite and xenotime, as well as isomorphism in apatite, pyrochlore and sphene. The REEs in the Huayangchuan deposit are dominated by light rare earth elements, such as La and Ce, with minor heavy rare earth element Y.