Graphite

Pure graphite is a mineral form of the element carbon.  It is an extremely soft mineral and it breaks into minute, flexible flakes that easily slide over one another.

This feature accounts for graphite’s distinctive greasy feel that makes graphite a good lubricant.

Graphite is the only non-metal element that is a good conductor of electricity.  Natural graphite is used mostly in what are called refractory applications, for example in the crucibles used in the steel industry.