Coal grade A is black charcoal, often with a grayish shade. It is sometimes found in its color and colorful run. It gives a black and velvety line on a porcelain plate. Also Coal grade A (anthracite) is characterized by a strong metallic luster. It has great viscosity, is not sintered, has good electrical conductivity. Its highest solidity on the mineralogical scale is 2.0-2.5, its organic mass density is 1500-1700 kg/m3. The heat of its combustion is 33.9-34.8 MJ/kg (8100-8350 kcal/kg).
