Carbon has no melting point at ordinary pressure

Nearly every solid you can name has a melting point: heat it past a certain temperature and it turns to liquid. Carbon does not — at least not under the air pressure we live in.

Push graphite to roughly 3,825C (around 6,917F) and it does something strange. Instead of melting, it sublimes: the solid converts directly into vapor, skipping the liquid phase entirely. As work for the U.S. Department of Energy confirms, graphite at high temperature passes straight from solid to gas. That is why “the melting point of carbon” is a question with no simple answer at atmospheric pressure.

To liquefy carbon you have to crush it as you cook it.

The reason is carbon’s phase diagram. Liquid carbon only exists above its triple point, which sits at roughly 100 times atmospheric pressure. According to Guinness World Records, graphite can be obtained as a liquid only by heating it to about 4,526C under high pressure. Below that pressure there is no liquid region at all — making carbon’s blistering 3,825C the highest sublimation point of any element, and a melting point that, in everyday air, simply does not exist.