Nanostructure reveals REE mineral crystallization mechanisms in granites from a heavy REE deposit, South China

Aiguo Shi, Cheng Xu, Anton R. Chakhmouradian, Martin P. Smith, Jindrich Kynicky, Chaoxi Fan, Chunwan Wei, Guangxi Kuang

Research output: Contribution to journalArticlepeer-review


Weathering crusts after granites are the most important source of heavy rare-earth elements (HREE) worldwide. Although HREE in these deposits is known to be inherited from parental rocks, the origin of HREE enrichment and the reasons why it is rare outside of China remains unclear. Here, we report the occurrence of variably organized nanoparticles of Ce-poor (<0.2 wt%), Nd-Y-rich bastnäsite-(La), and associated cerianite in parental granites from a HREE deposit, South China. The mineral contains high-HREE abundances (up to 13 wt% Y2O3). Synchrotron radiation-induced X-ray diffraction and high-resolution transmission electron microscopy analyses suggest that the mineral grew as disordered nanocrystals and (nearly) coaligned nanoparticle aggregations, thus supporting “nonclassical” crystallization mechanisms by particle attachment under hydrothermal conditions. The nanocrystal-line Ce-poor, Nd-Y-rich bastnäsite-(La) precipitated at rapidly decreasing temperature related to the influx of externally derived fluids, which caused CO2-H2O immiscibility and REE supersaturation. This interpretation is supported by petrographic data and microthermometric analysis of fluid inclusions in quartz. Unusually high fO2 resulted in Ce oxidation and decoupling from trivalent lanthanides, producing polycrystalline mineralization.
Original languageEnglish
Pages (from-to)2261-2271
Number of pages11
JournalAmerican Mineralogist
Issue number12
Publication statusPublished - 8 Dec 2022

Bibliographical note

Funding Information:
This research was supported financially by the National Natural Science Foundation of China (41825008, 92162219) and Guangxi Natural Science Foundation (Guike AB22035045, 2020GXNSFGA297003). M.S. acknowledges support from the UK-RI Natural Environment Research Council grant NE/V008935/1. J.K. was supported by the Czech Science Foundation GACR EXPRO (grant number 19-29124X).

Publisher Copyright:
© 2022 De Gruyter. All rights reserved.


  • Ce-poor and Nd-Y-rich bastnäsite-(La)
  • nanoparticles
  • crystallization by particle attachment
  • oxygen fugacity
  • REE deposits
  • South China Granite


Dive into the research topics of 'Nanostructure reveals REE mineral crystallization mechanisms in granites from a heavy REE deposit, South China'. Together they form a unique fingerprint.

Cite this