The Bureau of Mines has developed an automated reflectance scanning microscope system, primarily for determination of volume proportions, size distribution, and mode of association of the physical (petrographic) components of coals. The process, which is potentially more rapid and objective and less tedious than a visual microscopic procedure, involves magnetic tape recording of several million reflectance readings on micrometer sized areas of polished coal surface, and computer analysis and interpretation of some characteristics of the coal components. Results of petrographic analysis by automated reflectance scanning microscopy and conventional visual microscopy have been compared for four coals on the basis of a partially arbitrary interpretation of reflectance distributions. Such comparisons indicate fairly good agreement of results by the two methods for at least three of the coals, particulary in showing the considerably higher proportions of exinite and lower amounts of vitrinite in dull coal samples contrasted with bright coals. Despite the interpretation being arbitrary, the interest of other laboratories in such research, and possible advantages of greater objectivity and rapidity of analysis and correlation with coal utilization, encourage further study along these lines.
Fuel, V. 50, August 1971, PP. 226-235