Aspects of rare earth element enrichment in Central Appalachian coals

Abstract

The concentration of lanthanides, Y, and Sc, collectively rare earth elements (REE), and their modes of emplacement in Appalachian coals, with emphasis on Manchester and Fire Clay coals in eastern Kentucky are the focus of this investigation. Those coals have distinct REE concentrations and relationships related to the position of the lithotype within the coal seam, such as the ratio of light to heavy lanthanides (LREE/HREE). In the Manchester coal, the high-S upper lithotypes have lower REE concentrations and different LREE/HREE than the low-S lithotypes. In the Fire Clay coal, the position of the lithotype relative to the REE-enriched tonstein is important, with the coal immediately below the tonstein having significantly higher REE than other lithotypes. Lithotypes in the middle of the coal bench above the tonstein have high LREE/HREE, possibly indicating a hydrothermal influence on the REE emplacement.