Relationship between the maximum and the random reflectance of vitrinite for coal from the Upper Silesian Coal Basin (Poland)

The relationship between the maximum and random reflectance of vitrinite, Rmax and Rr, for Upper Silesian coal is represented by the equation: Rmax=1.090Rr−0.052. When the random reflectance is higher than 0.90%, the difference between Rmax and Rr values becomes significant. Rmax is a more precise rank indicator, the standard deviation is much smaller than the standard deviation of the random reflectance value, which is larger due to the optical anisotropy of vitrinite.