Lithium be cut with a knife. When cut, it possesses a silvery-white color that quickly changes to gray as it oxidizes to lithium oxide. While it has one of the lowest melting points among all metals (180 °C), it has the highest melting and boiling points of the alkali metals. Lithium has a very low density (0.534 g/cm), comparable with pine wood. It is the least dense of all elements that are solids at room temperature; the next lightest solid element (potassium, at 0.862 g/cm) is more than 60% denser. Furthermore, apart from helium and hydrogen, it is less dense than
Metallic hydrogen increases significantly, the band-gap gradually fell to . Because the thermal energy of the fluid (the temperature became about due to compression of the sample) was above , the hydrogen might be considered metallic. Many experiments are continuing in the production of metallic hydrogen in laboratory conditions at static compression and low temperature. Arthur Ruoff and Chandrabhas Narayana from Cornell University in 1998, and later Paul Loubeyre and René LeToullec from Commissariat à l'Énergie Atomique, France in 2002, have shown that at pressures close to those at the center of the Earth () and temperatures of , hydrogen is still