Name       : Hafnium
Symbol     : Hf
Atomic #   : 72
Atom weight: 178.49
Melting P. : 2227
Boiling P. : 4602
Oxidation  : +4
Pronounced : HAF-ni-em
From       : The Latin for city of Copenhagen, Hafnia
Identified : Dirk Coster and George Charles de Hevesy in 1923
Appearance : Silvery, ductile metal
Note       : Making control rods for nuclear reactors
             
[Properties]

  Hafnium looks and feels much like stainless steel, but it is much heavier.
It is a transition Group-IVB metal; like most metals in this part of the
periodic table, it is protected from corrosion by a tough oxide film that
begins the moment the bare metal is exposed to the atmosphere.
  The chemical and physical properties of hafnium and zirconium are so much
alike that the two are nearly impossible to separate entirely. Likewise,
hafnium containing less then 2% zirconium is considered a high-grade sample.
  Hafnium is an excellent absorber of thermal neutrons. This, combined with
its high resistance to corrosion, makes it an ideal material for control
rods in nuclear reactors.