Why is graphite a good lubricant?

Graphite is a mineral made of loosely bonded sheets of carbon atoms, giving it a slippery texture that makes it a very effective lubricant. This slippery quality also makes graphite a good material for pencil lead because it easily sloughs off onto paper.

Thanks to its chemical structure, graphite is a naturally slippery material that tends to crumble easily. Graphite is often contrasted with diamond, one of the hardest materials known to man, because both are made of carbon atoms arranged in a crystalline structure but with dramatically different results.