Coal is formed from decomposed plants. Water and dirt pile on top of the dead plant remains. Over thousands of years heat and pressure would continuously heap up on the plant remains leading to chemical and physical reactions and pushing out the oxygen, turning these remains into coal.
Coals are classified into four types: lignite, bituminous coal, anthracite and peat.
1.Lignite is a new form of coal. It is brown, soft and fibrous, containing moisture and discernible plant material. The lignite reserves are found in Neyveli in Tamil Nadu and is used for the generating power.
2.Anthracite is a hard, black, shiny form of coal without any moisture and very low volatile content. Because of this, it generates low smoke and is known as a smokeless fuel. It is existent in parts of Jammu and Kashmir.
3. Bituminous coal is a highly buried one can be open to increased temprature.It is popular for commercial use. Metallurgical coal is high grade bituminous coal used in smelting iron in blast furnaces.
4.Decaying plants in swamps gives rise to peat. It is a coal with low carbon and high moisture and cannot b heated at high temperature.