Maceral reflectance distribution

Figure 3. Reflectance distribution of macerals in tymcal coals with the same maceral contents but of different ranks ( liptinite (Uj vitrinite inertinite)...

Fig. 4.4 Example of reflectance distributions for various maceral groups in a kerogen sample.

Pieces of coal are mixtures of materials somewhat randomly distributed in differing amounts. The mineral matter can be readily distinguished from the organic, which is itself a mixture. Coal properties reflect the individual constituents and the relative proportions. By analogy to geologic formations, the macerals are the constituents that correspond to minerals that make up individual rocks. For coals, macerals, which tend to be consistent in their properties, represent particular classes of plant parts that have been transformed into coal (40). Most detailed chemical and physical studies of coal have been made on macerals or samples rich in a particular maceral, because maceral separation is time consuming. 

This classification of the seams is justified and is well reflected in the proximate analyses and distribution of the vitrinoid types distinguished on the basis of reflectance values. The variation of the different macerals in each zone is shown in Figures 4 and 4a. 

In addition to maceral distribution, organic petro-graphers determine vitrinite reflectance as a measure of geothermal evolution of sedimentary organic matter. For more details of microscopic analysis see Taylor et al.(1998). 

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