Explanation
It is formed by carbonization of ancient plant remains buried under the stratum, mainly composed of more than 95% carbon, hydrogen, oxygen and a small amount of nitrogen, sulfur or other elements. According to the degree of carbonization, it can be divided into peat, lignite (brown brown coal, black lignite), bituminous coal (raw coal), and anthracite. The carbonization degree of bituminous coal is the highest. Coal is a very important energy source and an important raw material for metallurgical and chemical industries.
Classification
Inorganic non-metallic materials -> Carbon materials