Bastnäsite nanoparticles in carbonatite-syenite-hosted REE deposit: implication for La and Ce migration and bastnäsite growth.

Affiliation

Liu R(1), Bo B(2), Tao D(3), Chen G(4).
Author information:
(1)School of Resources and Environmental Engineering, Shandong University of Technology, Zibo, 255000, China.
(2)801 Institute of Hydrogeology and Engineering Geology, Shandong Provincial Bureau of Geology & Mineral Resources
(Shandong Provincial Geo-mineral Engineering Exploration Institute), Jinan, 250014, China.
(3)School of Resources and Environmental Engineering, Shandong University of Technology, Zibo, 255000, China. Electronic address: [Email]
(4)Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China. Electronic address: [Email]

Abstract

High-resolution transmission electron microscopy observations of bastnäsite from the Maoniuping rare earth element (REE) deposit at Panxi, SW China, revealed the presence of nanoparticles in the surface of bastnäsite crystal. The nanoparticles are identified as the bastnäsite nanocrystals, with 5-30 nm in length, by energy-dispersive spectrometry and fast fourier transform patterns. This represents the first observation of bastnäsite nanoparticle in nature, confirming a new form of migration and precipitation of La and Ce in the hydrothermal fluids. Meanwhile, we herein reveal that random attachment of small bastnäsite nanoparticles during aggregation-based growth initially produces large bastnäsite nanoparticles, driven by the tectonic stress. Subsequent evolution of the random aggregation and orientation of large bastnäsite nanoparticles result in bastnäsite crystal formation, driven by the tectonic stress and inherent surface stress. This underlines the bastnäsite crystallization by random aggregation and the significant role of tectonic stress in forming the bastnäsite crystal in REE deposit.