AN INVESTIGATION OF THE VITRINITE MACERAL GROUP IN MICROLITHOTYPES USING DENSITY GRADIENT SEPARATION METHODS

Several sets of microlithotypes derived from channel samples have been separated by density gradient centrifugation. Detailed density distribution data and elemental data for the separated vitrinites reveal that there are easily discernible differences in various types of vitrinites found in different microlithotypes. Moreover, the vitrinite in closely allied vitrite microlithotypes also can have different densities and chemical compositions. Although it appears that liptinite content may be an important marker for the aliphatic character of the coals, the results suggest that other factors, probably related to the paleoenvironment, may also play a strong role. Physical and chemical variations that can be seen, even within a single microlithotype such as vitrite, reenforce the view that there is a need for more concern about the physical state of a coal sample in coal research.