Hafnium is an element that is chemically very similar to zirconium. It generally only occurs in zirconium minerals such as zircon and follows zirconium very closely in the metallurgical processes used to make zirconium metal. For some applications the 2% (generally) hafnium content in the zirconium metal is not of consequence, but for some applications the content of zirconium has to be reduced. Some hafnium is separated (costly and difficult operation) for those applications where hafnium is required.
