Cobalt (Co) Element Properties
Atomic Mass 58.9332
Atomic Number 27
Name Origins German, koblad = "goblin."
Year Discovered 1735
Discovery Credits Discovered by G. Brandt at Stockhlm, Sweden.
Remarks Lustrous, silvery-blue, hard mental; ferromagnetic. Stable in air, slowly attacked by dilute acids. Cobalt 60 is a useful radio isotope. Used in alloys for magnets, ceramics, catalysts, and paints.

Diagnostic tests: 
A beautiful blue bead is obtained with using the borax bead test in the oxidizing and reducing flame. If sulfur or arsenic is present, the mineral should be roasted first to oxidize those elements.
A magnetic mass is obtained if the mineral is powdered, mixed with soda (Na2CO3), and fused in a reducing flame (Note, Iron and Nickel are also yield magnetic masses).
In solution, cobalt forms pink to red to blue solutions, yielding a bluish pink precipitate (Co2+(OH)2) on adding NaOH. H2O2 will turn the precipitate black (Co3+(OH)3).

References Emsley, J., 1991; THE ELEMENTS : Sec. Ed., Clarendon Press, Oxford, 251 p.
See Also WebElements, ChemiCool
Naturally Occurring Isotopes
Symbol Isotope Mass Isotope Nuclide Number Isotope Number Natural Abundance Half-life Half-life Units Decay Mode Decay Mode MeV Decay Mode %
Co 58.993798 59 27 100.0000%   Stable