Petrography of coal from the Usmun Region of the South Yakutsk Basin

Gas and long-flame coal in Jurassic continental deposits are described. The principal components of the humic coal are the preserved, cellular-textured remains of grassy and shrubby plants which lived in low, inundated swamps. These produced to a minor extent spores and pollen which had poorly developed protective tissue. During coalification, the components were altered with uneven intensity; in particular, the rate of alteration of alginite exceeded that of vitrinite.