Niobium is a lustrous, grey, ductile, paramagnetic metal in group 5 of the periodic table, with an electron configuration in the outermost shells atypical for group 5. The metal takes on a bluish tinge when exposed to air at room temperature for extended periods. Despite a high melting point in elemental form (2,468 °C), it has a lower density than other refractory metals. Furthermore, it is corrosion-resistant, exhibits superconductivity properties, and forms dielectric oxide layers.