Anthracite Cornwall, which was used as a pigment. The term is also used to refer to some Carboniferous rock strata found in both Britain and in the Rhenish hill countries (the Culm Measures). Lastly, it may refer to coal exported from Britain during the 19th century. In American English, "culm" refers to the waste or slack from anthracite mining, mostly dust and small pieces not suitable for use in home furnaces. Anthracite is similar in appearance to the mineraloid jet and is sometimes used as a jet imitation. Anthracite differs from ordinary bituminous coal by its greater hardness (2.75–3 on the
Anthracite times been futile, and several such combustion areas exist today. The existence of an underground combustion site can sometimes be identified in the winter where fallen snow is seen to be melted by the warmth conducted from below. Proposals for harnessing this heat as geothermal energy have not been successful. A vein of anthracite that caught fire in Centralia, Pennsylvania in 1962 has been burning ever since, turning the once-thriving borough into a ghost town. Among current producers, Russia, China and Ukraine have the largest estimated recoverable reserves of anthracite. Other countries with substantial reserves include Vietnam and North Korea.