Which coal have highest calorific value?

Anthracite type of coal have the highest calorific value, which is approximately 25 million BTU (British Thermal Units) per ton. It is also known as the hardest kind of coal and this type of coal difficult to burn. Other kinds of coal like bituminous coal and lignite coal have lower calorific values and also used for fuel. The calorific value of bituminous and lignite carries between 10-15 million BTU per ton. BTU means ‘British Thermal Units.