Coal is a sedimentary rock found in stratus layers. It is black or black with brown hues. Coal has been used for hundreds of years for a variety of uses but primarily in industry and production. Coal is unlike other kinds of rocks because it is carbon based and made of organic carbon. The carbon dioxide in coal is not oxidized and remains within the rock waiting to be released. Coal is pretty much made up of fossilized peat matter. Coal beds can be found throughout the continents and can be found in rocks that date as far back as the Proterozoic period.