Coal

Peat

Peat forms from decomposed plant material. Lignite is compacted peat. As lignite is further compacted and exposed to higher temperatures in the earth, it becomes bituminous coal. As temperature and pressure further increase, bituminous coal becomes anthracite. The carbon content in lignite is about 25%. Due to high temperature and pressure, the carbon content increases to about 90% in anthracite. [LM] {CC}