Praseodymium is soft, silvery, malleable, and ductile. It is somewhat more resistant to corrosion in air than europium, lanthanum, cerium, or neodymium, but it does develop a green oxide coating that falls off when exposed to air. As with other rare-earth metals, it should be kept under a light mineral oil or sealed in plastic.
Melting point: 931 °C Boiling point: 3520 °C
A foil is a thin sheet of pure metal. Given its fragile nature, some foils have protective coatings.