Hafnium

Hafnium is a lustrous, silvery-gray transition metal that resists corrosion and behaves much like zirconium. It occurs mixed with zirconium in minerals such as zircon, so it is obtained mainly as a by-product when zirconium is separated; the two metals are difficult to distinguish chemically. Hafnium’s strong ability to absorb neutrons makes it useful in control rods that regulate nuclear reactors. Its oxide, a compound rather than the metal itself, is used as an insulating material in some microprocessor circuits, while hafnium metal is also added to specialized high-temperature alloys.