Carbon in its elemental form is one of the softest (graphite) and hardest (diamond) materials found in nature. Applications for graphitic carbon include in lubricant formulations and as the replacement for lead in pencils. Diamond has numerous industrial applications due to its extreme hardness and resistance to heat and pressure. Graphene is a nanoscale ultra thin film or foil with thicknesses as small as 1 nanometer which can be produced from either silicon carbide or graphite flake processing. These include in drill bits and grinding media and grinding equipment. Carbon also finds application in steel alloys, in various filtering and purification technologies and as a neutron moderator in nuclear power plants. Carbon  is available as a nanoparticle and in single-walled, double-walled and multi-walled nanotubes with purities from 99% to 99.999% ( ultra-high purity ).