It is a non-metallic element, known since ancient times. Pure carbon forms are amorphous carbon (found in sources as charcoal, coal, coke, Lignite, and Peat) and the crystals Graphite, a very soft, dark-grey or black, lustrous material, and Diamond, the hardest substance known. All living organisms contain carbon.

Carbon has seven isotopes: carbon -12 is the basis for Atomic weights, carbon -14 with a half-life of 5,730 years is used to trace chemical reactions and to date geologic and archaeological specimens.