Economic and Environmental Geology

Fig. 4.

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Fig. 4. UCC-normalized REE patterns of the REE-bearing coal deposits. (a) Terrigenous coals have LREE enriched L-type patterns because of LREE favorable phosphate minerals. (b) Tuffaceous coals have flat type or HREE enriched patterns. HREE enriched patterns occur when organic ligand is primary REE taker. (c) Hydrothermal (exfiltrational) coals have HREE enriched H-type pattern. MREE enriched M-type patterns occur when humic matter is possessing majority of REEs.
Econ. Environ. Geol. 2022;55:241-59
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