Cobalt is a brittle, hard metal, resembling iron and nickel in appearance. It has a metallic permeability of about two thirds that of iron. Cobalt tends to exist as a mixture of two allotropes over a wide temperature range. The transformation is sluggish and accounts in part for the wide variation in reported data on physical properties of cobalt.
Melting point: 1495 °C Boiling point: 2927 °C
A foil is a thin sheet of pure metal. Given its fragile nature, some foils have protective coatings.