Why is coal not a mineral?

Coal is not considered a mineral because it is made from organic material and does not have a fixed chemical composition or crystalline structure. Minerals are naturally occurring inorganic substances that have a definite chemical formula and a crystalline structure. 

Coal, on the other hand, is formed from the remains of ancient plants that were buried and compressed over millions of years. Because coal comes from plants, it is made of organic compounds like carbon, hydrogen, and oxygen.

Another reason coal is not a mineral is that it doesn’t have a fixed composition. Different types of coal, like lignite, bituminous, and anthracite, have different amounts of carbon and other materials. Also, coal does not form crystals, which is a key property of minerals. Therefore, even though coal is found in nature and is useful as a fuel, it is not classified as a mineral.