Lutetium occurs in very small amounts in nearly all minerals containing yttrium, and is present in monazite to the extent of about 0.003%, which is a commercial source. The pure metal has been isolated only in recent years and is one of the most difficult to prepare. The metal is silvery white and relatively stable in air.
Melting point: 1663 °C Boiling point: 3402 °C
A foil is a thin sheet of pure metal. Given its fragile nature, some foils have protective coatings.