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

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[sbnd]Si rich but the mineralogy could not be determined. The nodule may be a mineralized coprolite, the product of the microfauna inhabiting the peat.