anthracite
Anthracite is the hardest type of coal.
Anthracite is the hardest type of coal.
Anthracite
Anthracite
ANTHRACITE!
Anthracite is the hardest type of coal.
Anthracite is the hardest type of coal.
Anthracite is the hardest type of coal.
Anthracite
Anthracite, the hardest coal, forms from the greatest pressure.
Anthracite
ANTHRACITE!
Lignite is the youngest and softest coal; bituminous is mid-grade coal, and anthracite is the hardest and hottest burning coal. Even brown coal.
oldest
Earth's oldest living inhabitant "Methuselah" has reached the age of 4,768 years.
Bituminous coal is the most common type of coal.
Anthracite is metamorphosed bituminous coal, a coal with the highest percentage of carbon of the coal varieties.