Anthracite coal
A type of coal, relatively hard, jet black, with a metallic lustre, sub-conchoidal fracture, unbanded, with less than 10% volatiles and more than 90% carbon. It burns with intense heat and a non-luminous flame. Coal: carbon-rich mineral deposit formed from the remains of fossil plants. These are deposited initially as peat, but burial and increase in temperatures at depth bring about physical and chemical changes. The process of ‘coalification’ results in the production of coals of different ranks (‘coal series’), from peat, through the bituminous coals and lignite, to anthracite. Each rank marks a reduction in the percentage of volatiles and moisture, and an increase in the percentage of carbon. They are termed ‘woody’ or ‘humic’ coals if formed from fragments of trees or bushes. If the major constituents of coal are pollen grains and/or finely divided plant debris, the term ‘sapropelic coal’ is used.— A Dictionary of Geology and Earth Sciences (4 ed.), Oxford University Press
