Atomic number: 27

Symbol: Co

Category: transition metal

Density at 25°C: solid 8.90 g·cm−3

Cobalt like other transition metals has a similar look, being silvery and shiny. But it is never found in nature in it's natural pure form. It is most known for the compound it makes called cobalt blue. The name cobalt comes from the German Kobold meaning goblin.

A slice of cobalt purified  metal. image: adapted from wikipedia

Use, natural applications or common combinations: 

  • blue pigments.
  • magnets, alloys
  • gives a blue colour to glass
  • in vitamin B12 as part of an co-enzyme centre

Basic characteristics:

  • Standard atomic weight: 58.933 195(5)
  • Melting point: 1495 °C
  • Boiling point: 2927 °C
  • Radioactivity:  almost all stable naturally
    • some isotopes are used in medicine for radiotherapy 60Co with a half-life of 5.2714 years produces gamma rays that are quite hazardous.