Template:POTD/2012-06-29
Chips of cobalt, electrolytically refined, as well as a 1 cm3 cube for comparison. Cobalt is a hard, lustrous, silver-gray metal that is found naturally only in chemically combined form. Cobalt-based blue pigments have been used since ancient times for jewelry and paints, as well as blue-colored glass.Photo: Alchemist-hp