Sapropelic coals are non-banded coals. They are relatively uncommon, and tend to occur as single bands in parts of humic coals, rather than as whole seams, although seams comprised entirely of sapropelic coals occur. Sapropelic coals are very homogenous in appearance, and often break with a conchoidal (glass-like) fracture. Sapropelic coals are subdivided into cannel and boghead coals, which are distinguished by their microscopic components. Further subdivision of sapropelic coals is discussed in Hutton and Hower (1999).
Sapropelic Coal Lithotypes:
Cannel coals are sapropelic coals or coal bands composed almost entirely of spores and pollen. They are black to dark gray in color and very hard.
Boghead coals are sapropelic coals or coal bands composed almost entirely of algae. They are similar in appearance to cannel coals, but may be brownish.