Anthracite (Greek Ανθρακίτης, literally "a type of coal", from Anthrax 1, coal) is a hard, compact variety of mineral coal that has a high lustre. It has the highest carbon count and contains the fewest impurities of all coals, despite its lower calorific content.

Anthracite is the highest of the metamorphic rank, in which the carbon content is between 92% and 98%. The term is applied to those varieties of coal which do not give off tarry or other hydrocarbon vapours when heated below their point of ignition. Anthracite ignites with difficulty and burns with a short, blue, and smokeless flame.

Other terms which refer to anthracite are blue coal, hard coal, stone coal (not to be confused with the German Steinkohle or Dutch steenkool which are broader terms meaning all varieties of coal of a stonelike hardness and appearance, like bituminous and often anthracite as well, as opposed to Lignite, which is softer), blind coal (in Scotland), Kilkenny coal (in Ireland), crow coal (or craw coal from its shiny black appearance), and black diamond ("Blue Coal" is the term for a once-popular, specific, trademarked brand of anthracite, mined by the Glen Alden Coal Company in Pennsylvania, and sprayed with a blue dye at the mine before shipping to its Northeastern U.S.A. markets to distinguish it from its competitors). The imperfect anthracite of north Devon and north Cornwall (around Bude) in England, which is used as a pigment, is known as culm. Culm is also the term used in geological classification to distinguish the strata in which it is found and similar strata in the Rhenish hill countries are known as the Culm Measures. In America, culm is used as an equivalent for waste or slack in anthracite mining.

Properties

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, its higher relative density of 1.3-1.4, and luster, which is often semi-metallic with a mildly brown reflection. It contains a high percentage of fixed carbon and a low percentage of volatile matter. It is also free from included soft or fibrous notches and does not soil the fingers when rubbed. Anthracitization is the transformation of bituminous into anthracite.

The moisture content of fresh-mined anthracite generally is less than 15 percent. The heat content of anthracite ranges from 22 to 28 million Btu per short ton (26 to 33 MJ/kg) on a moist, mineral-matter-free basis. The heat content of anthracite coal consumed in the United States averages 25 million Btu/ton (29 MJ/kg), on the as-received basis (i.e., containing both inherent moisture and mineral matter). Note: Since the 1980s, anthracite refuse or mine waste has been used for steam electric power generation.