Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt in the Earth's crust is found only in chemically combined form, save for small deposits found in alloys of natural meteoric iron.
C 0542 (OTTO) Cobalt wire, 1.5 mm (0.06in) dia, 99.95% (metals basis) - used as a radioactive tracer and for the production of high energy gamma rays.