Anthracite

Anthracite is a hard, compact variety of coal that has a submetallic luster. It has the highest carbon content, the fewest impurities, and the highest calorific content of all types of coal except for graphite.

Anthracite is the most metamorphosed type of coal (but still represents low-grade metamorphism), in which the carbon content is between 92.1% 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.