Coal is known as fossil fuel because Coal and petroleum are both composed of dead material that has been buried beneath the earth for a very long time. By decomposition, the dead matter turns into fossils at extremely high pressure and temperatures which are then used as fossil fuels. Who discovered fossil fuels?

chemist Caspar Neumann

The first use of the term "fossil fuel" occurs in the work of the German chemist Caspar Neumann, in English translation in 1759. Petroleum is called 'Liquid Gold' since it is liquid and just like gold, it has a high commercial value. It is generally called so in order to imply its significance. It also serves directly or indirectly as a source for various organic products that are useful and essential for humans.