Coal | Types of Coal: Peat, Lignite, Bituminous Coal ...
Jan 25, 2016· In time, material that had been plants became coal. Coals are classified into three main ranks, or types: lignite, bituminous coal, and anthracite. These classifications are based on the amount of carbon, oxygen, and hydrogen present in the coal. Coals other constituents include hydrogen, oxygen, nitrogen, ash, and sulfur.