Anthracite Mohs scale), 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 coal 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
Energy value of coal "Q" is a complex function of the elemental composition of the coal. "Q" can be determined experimentally using calorimeters. Dulong suggests the following approximate formula for "Q" when the oxygen content is less than 10%: where "C" is the mass percent of carbon, "H" is the mass percent of hydrogen, "O" is the mass percent of oxygen, and "S" is the mass percent of sulfur in the coal. With these constants, "Q" is given in kilojoules per kilogram. Energy value of coal The energy value of coal, or the fuel content, is the amount of potential energy in coal that