ETYM German kobalt, prob. from kobold, kobel, goblin, Mid. High Germ. kobolt.
Hard, lustrous, gray, metallic element, symbol Co, atomic number 27, atomic weight 58.933. It is found in various ores and occasionally as a free metal, sometimes in metallic meteorite fragments. It is used in the preparation of magnetic, wear-resistant, and high-strength alloys; its compounds are used in inks, paints, and varnishes.
The isotope Co-60 is radioactive (half-life 5.3 years) and is produced in large amounts for use as a source of gamma rays in industrial radiography, research, and cancer therapy. Cobalt was named in 1730 by Swedish chemist Georg Brandt (1694–1768); the name derives from the fact that miners considered its ore worthless because of its arsenic content.
A hard ferromagnetic silver-white bivalent or trivalent metallic element; a trace element in plant and animal nutrition; SYN. Co, atomic number 27.
Co · atomic number 27