Graphite is a mineral consisting of nearly pure carbon C. Similar to coal but with much less impurities in form of ashes, water and sulfur. Coal is normally formed by moores growing continually by a continuous downlift of the surface. So the trees and other plants do not decompose, but form huge layers of peat. Later this peat is pressed by sediments on top, also it becomes warmer and warmer because of heat of the earth. The longer this process takes and the higher the pressure and temperature are, the purer the carbon becomes. Brown coal or lignite is a coal of lowest quality, pit coal or hard coal is a high quality coal, but graphite is nearly pure carbon. With even higher pressures and temperatures, diamonds would be formed.
The temperatures and pressures necessary to form graphite are high enough to also alterate the surrounding rocks. So graphite is typically found in coal beds, between layers of metamorphic limestones, marbles and carbon rich shales.
The mineral graphite has a layered structure that consists of rings of six carbon atoms arranged in widely spaced horizontal sheets. This means, graphite crystallizes in the hexagonal system.
Graphite burns, so it could be used as a fuel. Sometimes it is used to produce very hot fires in industrial processes. But normally the use of graphite is much broader and it is rather rare and expensive (compared to coal). The most common use is also the explanation for the name: it is derived from the Greek word graphein, to write. Graphite is used to produce pencils by putting a thin bar of graphite into a wooden tube. It was named by the German chemist and mineralogist A. G. Werner in 1789.