Cobalt (Co) was discovered by Swedish chemist Georg Brandt in 1735. Readers learn that cobalt is a transition metal, and that it is ferromagnetic. Only cobalt, nickel, and iron (and some of their alloys) can permanently align their atoms and become a permanent magnet. Cobalt can be found in rocky ores in Africa and Canada. It is very active chemically and forms many compounds, including cobaltous and cobaltic salts. Cobalt is used as a coloring agent, in paints, glass, ceramics, and enamels. A radioactive isotope of cobalt, called cobalt-60, can be used as a tracer in industry to show where pipes are leaking, and in medicine by doctors as a radioactive dye to trace out a person's blood vessels in part or all of a person's body in helping them to diagnose many kinds of illness.