- nconsistently fine-granular coal essentially devoid of megascopic layers.DISCUSSION — Nonbanded coal may be interbedded with common banded coal, or form a discrete layer at the top or at the bottom of the seam, or may compose the entire seam. It is formed from natural accumulations of finely comminuted plant detritus and commonly includes a significant amount and variety of remains of pollen grains, spores, planktonic algae, wax and resin granules, as well as other fragments of plants. These materials, containing markedly higher amounts of volatile matter than vitrain and some other attrital components, are more abundant in this variety of coal than they are in common types of banded coal.Also, nonbanded coal may contain more disseminated detrital mineral matter, chiefly clay, than associated banded coals, and in the field it may be difficult to distinguish from bone coal. Nonbanded coal is much less common than banded coal in North America.
ASTM D121-09a Standard Terminology of Coal and Coke. 2014.
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