Petrology of the Fire Clay coal, Bear Branch, Perry County, Kentucky

The Middle Pennsylvanian Duckmantian-age Fire Clay coal has traditionally been a valuable, high-quality coal resource and, owing the synchronous deposition of a lanthanide-rich volcanic ash fall, is one of the premier coal-based, rare earth resources in the World. While much of the coal is composed of high-vitrinite bright lithotypes, the Bear Branch sections of the coal stand out as having liptinite- and inertinite-rich lithologies, particularly in the split below the ash-fall tonstein. The liptinite and inertinite macerals were concentrated, in part, due to the poor and non-preservation of small lycopod-, tree fern-, calamites-, and cordaites-derived humic material. Regionally, the sub-tonstein part of the Fire Clay coal has an irregular thickness, ranging from no coal to about 60-cm thick at Bear Branch, one of the thicker sections in the region.