ANTHRACITE

also called Hard Coal, most highly metamorphosed variety of coal. It contains more fixed carbon (about 90 to 98 percent) than any other form of coal and the lowest amount of volatile matter (less than 8 percent), giving it the greatest calorific, or heat, value. Because of this, anthracite is the most valuable of the coals. It is, however, also the least plentiful. Anthracite makes up less than 2 percent of all coal reserves in the United States. Most of the known deposits occur in the eastern part of the United States. Anthracites are black and have a brilliant, almost metallic lustre. They can be polished and used for decorative purposes. Hard and brittle, anthracites break with conchoidal fractures into sharp fragments that 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. They are particularly adaptable for domestic use because they produce little dust upon handling and burn slowly while emitting relatively little smoke. They are sometimes mixed with bituminous coal for heating factories and other commercial buildings to reduce the amount of smoke produced but are seldom used alone for this purpose because of their high cost.