Macerals, coal, spectra

The most recent petrographic method used to characterize coal macerals is quantitative fluorescence analysis. In this method the macerals are excited by incident ultraviolet light and the spectrum of the resulting fluorescent light is used to characterize the macerals. This technique has led to the discovery of new macerals (18), the quantitative discrimination between certain macerals in a given coal (19), and the correlation of the fluorescence properties of macerals to the rank, and technological properties of coal (20-22). 

Alternatively, if better quality data is required only for some small regions of the spectrum, then those regions alone can be scanned to shorten the time needed to obtain an acceptable signal to noise level. The ability to analyze small regions of a coal sample is important even for a single maceral type such as vitrinite. For example, substantial variations occur in the structure (10,11) and swell ability (12) of different microscopic areas of vitrinite from the same coal. 

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