Four compositional groups, based on the independent parameters of ash yield, sulfur forms, palynology, petrography, and low-temperature ash mineralogy are recognized in the Stockton and Fire Clay coal beds (Kanawha Formation, Middle Pennsylvanian) from the central Appalachian Basin. The four compositional groups are (1) an arboreous lycopod-dominant group, defined by high percentages of Lycospora and vitrinite (telocollinite), generally low but variable ash yield and sulfur content, and a mixed illite-kaolinite-quartz low-temperature ash mineralogy; (2) a transitional group defined by a mixture of lycopods (arboreous and “herbaceous” forms) and ferns, increased percentages of inertinite and desmocollinite (degraded vitrinite), low ash yield...