Hafnium is a
chemical element; it has
symbol Hf and
atomic number 72. A
lustrous, silvery gray,
tetravalent transition metal, hafnium chemically resembles
zirconium and is found in many zirconium minerals. Its existence was
predicted by Dmitri Mendeleev in 1869, though it was not identified until 1922, by
Dirk Coster and
George de Hevesy. Hafnium is named after the Latin name for
Copenhagen, where it was discovered. The element is obtained only by separation from zirconium, with most of the world's hafnium production coming from processes that also produce zirconium. These processes make use of
heavy mineral sands ore deposits, which include the minerals
zircon,
rutile, and
ilmenite, among others. This photograph shows the front and back sides of four pellets of 99.9%-pure
argon-arc remelted hafnium ingots, with visible crystalline structures. Each pellet is about 3 centimetres (1.2
in) in diameter. The visible colours are caused by a
thin-film effect in the surface oxide layer.
Photograph credit: Heinrich Pniok
