Mineralogy of a rare earth element-rich Manchester coal lithotype, Clay County, Kentucky

Abstract Many Eastern Kentucky coals have high-REE contents, with lithotypes of the Pennsylvanian-age Manchester coal rivaling some of the richest concentrations in the Fire Clay coal, arguably the premier resource in terms of concentration and aerial extent. A > 2000-ppm-REE + Y (REY; ash basis; 2.13% ash) Manchester coal lithotype, analyzed first by scanning electron microscopy, was selected for detailed transmission electron microscopy/ energy dispersive x-ray spectroscopy/ fast Fourier transform/ selected area electron diffraction investigation (TEM/EDS/FFT/SAED). The mineral grains extracted from the coal, seemingly fragments of one or more 2- to 3-μm spherical nodules, proved to have a phosphate (rhabdophane?) rim with a light REE (La through Sm) and Gd association. The core of the nodule and the region surrounding the nodule is Al Si rich but the mineralogy could not be determined. The nodule may be a mineralized coprolite, the product of the microfauna inhabiting the peat.