—anthracitic /an'threuh sit"ik/, anthracitous /an"threuh suy'teuhs/, adj./an"threuh suyt'/, n.a mineral coal containing little of the volatile hydrocarbons and burning almost without flame; hard coal. Also called anthracite coal.[1810-15; prob. < F < L (Pliny) anthracitis kind of coal. See ANTHRAC-, -ITE1]
* * *or hard coalCoal containing more fixed carbon than any other form of coal and the lowest amount of volatile (quickly evaporating) material, giving it the greatest heat value.The most valuable of the coals, it is also the least plentiful, making up less than 2% of all coal reserves in the U.S., with most of the known deposits occurring in the East. Anthracites are black and have a brilliant, almost metallic lustre. Hard and brittle, they can be polished and used for decorative purposes. They are difficult to ignite but burn with a pale-blue flame and require little attention to sustain combustion. In the past they were used for domestic heating, but today they have given way to other sources of energy (e.g., natural gas and electricity).
* * *▪ mineralalso called hard coalthe most highly metamorphosed form of coal. It contains more fixed carbon (86 percent or greater on a dry, ash-free basis) than any other form of coal and the least amount of volatile matter (14 percent or less on a dry, ash-free basis), and it has calorific values near 35 megajoules per kilogram (approximately 15,000 British thermal units per pound), not much different from the calorific values for most bituminous coal. Anthracite is the least plentiful form of coal. It is found mostly in the eastern part of the United States and makes up less than 2 percent of all coal reserves in the country. Smaller amounts of anthracite occur in South Africa, Australia, western Canada, China, and other countries.Anthracites are black to steel gray in colour and have a brilliant, almost metallic lustre. They can be polished and used for decorative purposes. Hard and brittle, anthracites break with conchoidal fracture into sharp fragments. Unlike many bituminous coals, they are clean to the touch. Although anthracites are difficult to ignite, they burn with a pale blue flame and require little attention to sustain combustion. In the past they were used for domestic heating because they produce little dust upon handling, burn slowly, and emit relatively little smoke. Anthracite is rarely used for this purpose today because of its limited abundance and relatively high cost and the ready availability of other sources of energy (e.g., natural gas and electricity) for heating purposes. Although anthracites usually occur in geologically deformed areas, such as in the intensely folded sedimentary rocks of the anthracite region of Pennsylvania, U.S., their origin is due to higher than normal heating caused by the presence of nearby igneous (igneous rock) intrusions or high geothermal gradients. Both of these phenomena produce temperatures much higher than those reached at depth in most sedimentary basins. For instance, in Antarctica, large igneous sills intruded the coal measures and converted some of the existing bituminous coal to anthracite. Temperatures ranging from 170 to 250 °C (about 340 to 480 °F) are thought to be necessary for the formation of anthracite.Otto C. Kopp
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