Science Daily October 9, 2020
Carbonatites and associated rocks are the main source of rare earth elements (REEs). REE mineralization occurs in hydrothermal assemblages within or near carbonatites, suggesting aqueous transport of REE. An international team of researchers (UK, Australia) conducted experiments from 1200°C and 1.5 GPa to 200°C and 0.2 GPa using light and heavy REE, crystallizing fluorapatite intergrown with calcite through dolomite to ankerite. All experiments contained solutions with anions previously thought to mobilize REE (chloride, fluoride, and carbonate), but REEs were extensively soluble only when alkalis were present. Dysprosium was more soluble than lanthanum when alkali complexed. Addition of silica either traps REE in early crystallizing apatite or negates solubility increases by immobilizing alkalis in silicates. Additional complexing with alkalis is required for substantial REE transport in and around carbonatites as a precursor for economic grade-mineralization…read more. Open Access TECHNICAL ARTICLEÂ
QEMSCAN mineral identification maps of the experimental runs. Credit: Science Advances 09 Oct 2020: Vol. 6, no. 41, eabb6570