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The word cobalt comes from the German Kobald which means goblin or evil spirit (cobalt is toxic).

Cobalt element

Name: Cobalt
Symbol: Co
Atomic Number: 27
Atomic Mass: 58.9332 u
Number of Protons/Electrons: 27
Number of Neutrons: 32
Melting Point: 1495.0 °C (1768.15 K, 2723.0 °F)
Boiling Point: 2870.0 °C (3143.15 K, 5198.0 °F)
Classification: Transition Metal
Crystal Structure: Hexagonal

Cobalt Blue

Cobalt compounds have been used since ancient times to give a distinctive blue color to porcelain, glass, ceramics, inks, paints and varnishes.
It was found:

  • in Ancient Egyptian sculptures
  • in Persian jewelry from the third millennium BC
  • in the Roman Empire, ruins of Pompeii (destroyed in 79 AD)
  • in China dating from the Tang dynasty (618-907 AD)

The most common is the cobalt blue, but there are also ceruleum, new blue, smalt, cobalt yellow and cobalt green.

Cobalt around us

  • in Universe 0.0003%
  • in Sun 0.0004%
  • in Meteorites 0.059%
  • in Humans 2×10-6%


In addition to being used as a dye, cobalt is also important to nutrition being an essential part of vitamin B12.


Twenty-six isotopes of cobalt have been identified, from which the only stable one is cobalt-59. Cobalt-60 is an important radioisotope, used as a radioactive tracer and in the production of gamma rays.


Cobalt is a hard, lustrous, silver-gray metal and is used in the preparation of magnetic, high-strength alloys.