Jet, also known as coal jade, is a type of lignite. It is an organic gemstone composed of organic matter (C, H, O, N, and S) and sometimes contains impurities of quartz and clay. Jet has a dense but light body and is black. It has a metal-like lustre upon polishing. It is a fossilised organic material that is transformed after prolonged burial. In Europe, jet has been used as a gemstone for almost a thousand years. In China, jet artefacts have been found in the Neolithic cultural relics in Liaoning Province. The major production areas of high-quality jet are Britain, France, Czech Republic, Italy, Russia and China.