The chemical element hafnium
Hafnium is a shiny silver-grey, corrosion-resistant transition and heavy metal of high density (13.31 g/cm3). The element is named after the Latin name of the city of Copenhagen (Hafnia) in which it was discovered.
The first evidence of hafnium was found as early as 1912, but it was not discovered until 1974 as one of the last stable elements of the periodic table. Hafnium, with a content of 4.9 ppm in the continental earth crust, is not very common on earth, comparable with the elements bromine and cesium.
If hafnium is present in a high purity, it is relatively soft and flexible. It is easy to work with by rolling, forging and hammering. However, if traces of oxygen, nitrogen or carbon are present in the material, it becomes brittle and difficult to process. The melting point (2227 °C) and boiling point (4450 °C) of hafnium are the highest in the titanium group. Biological functions are not known, it does not normally occur in the human organism and is non-toxic.