Boron Carbide

Boron Carbide is an extremely hard material.  It is artificially produced and is used as an abrasive and in cutting tools.  It is also used in composite materials. 

Boron Carbide is made by heating carbon with boron oxide in an electric furnace.  The boron oxide is reduced, forming boron carbide.  The resulting powder is pressed at high temperature to form the material. 

Boron Carbide is has a tendency to absorb neutrons.  Hence, it is also used as control rods in nuclear reactors to control the chain reaction.