Cobalt: physical properties
Cobalt is a brittle, hard, silver-grey transition metal with magnetic properties similar to those of iron (it is ferromagnetic). It has a high melting point and is hard-wearing even at high temperatures. Its alloys also possess useful properties and so it finds use in high speed steels and cutting tools for instance. The physical properties of cobalt resulted in its use in a cobalt-chromium-molybdenum alloy (Vitallium, 1937) that is strong, has a good corrosion resistance and is tolerated by the body. These days cobalt alloys are used less as they are heavy.
Expansion and conduction properties
The image above is a virtual representation of cobalt metal calculated by Patrick Callet using the complex diectric function of the element only.