Properties of niobium

Niobium is a lustrous gray metal that is paramagnetic and belongs to group 5 on the periodic table. High-purity niobium metal is ductile, but hardens with increasing impurity content.

Burning niobium metal in air turns the surface black. Although it has a high melting point in the monatomic state (2,468 °C), its density is lower than that of other refractory metals. Niobium is resistant to many acids except hydrofluoric acid, but it interacts with molten caustics and gives off hydrogen.