Cannel coals: implications for classification and terminology

Cannel coals are tough, massive coals with a dull luster that break with an even, compact grain and conchoidal cross fractures. Historically, cannel c oals were of significant economic and social importance during the early in dustrialization of the USA. They were the source for a sophisticated petroc hemical industry and a fuel source for heating, gas making, coke making and oil generation. Petrographic data, proximate analysis and ultimate analysi s data were obtained for 68 cannel coals from Kentucky to decide how well t he cannel coals fit the generally-accepted definitions of a cannel coal. Fo ur maceral assemblages were found-sporinite with abundant medium-grained vi trinite and inertinite, sporinite with abundant fine-grained vitrinite and inertinite of which micrinite is abundant (bituminite may be present), algi nite with abundant fine-grained vitrinite and inertinite, and alginite and bituminite with minor vitrinite and inertinite. Volatile matter and H/C rat ios are highest for those samples with abundant liptinite with a sample fro m Breckenridge having the highest value of each. Five samples were analyzed by the Rock-Eval method. The S-2 and HI indices show that the coals would make excellent source rocks. Discrepancies between the values for the five samples are related to maceral composition and there may be a good correlat ion between source rock potential and importance as a feedstock for synthet ic crude oil production in the 1800s. The maceral composition of the microl ithotypes is related to the environment of deposition. Coal composed of ass emblage (i) formed in humic peat swamps in which unusually large numbers of spores were introduced, possibly because of unusual, climatically controll ed reproductive cycles. Coals composed of assemblages (ii) to (iv) formed a s sapropelic coals in lakes at some stage of peat swamp development. (C) 19 99 Elsevier Science B.V. All rights reserved.