The element with atomic number 27, named after the German word for “goblin,” is cobalt. Its symbol is Co, and its name is linked to kobold, a mischievous spirit or goblin associated with German mining folklore.
Sixteenth-century German miners encountered cobalt-containing ores that looked promising but yielded little silver and released poisonous arsenic fumes when smelted. They blamed these troublesome ores on kobolds, supernatural creatures thought to interfere with mining. The ore name eventually became associated with the element.
Swedish chemist Georg Brandt identified cobalt as a distinct metal in 1735, making it one of the first elements discovered since antiquity. Cobalt compounds had already been used for centuries to create deep blue pigments in glass, ceramics, and jewelry.
Cobalt is also important biologically: it forms the central atom in vitamin B12 compounds. A frequent trap is nickel, another hard metallic element nearby in the periodic table, but nickel’s name has a different folklore-based origin and its atomic number is 28.