Cobalt

Cobalt is a chemical element; it has symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, somewhat brittle, gray metal.

Swedish chemist and mineralogist

hypothetical salted bomb

Experiment designed to test Albert Einstein's theory of general relativity

medical use of gamma rays from the radioisotope cobalt-60 to treat conditions

thumb|right|300px|Blaafarveværket in Åmot Blaafarveværket, or the Blue Colour Works, was a mining and industrial company located at Åmot in Modum in Buskerud, Norway, which existed from 1776 to 1898, and which was Norway's largest mining company in the first half of the 19th century. The works mined cobalt ore and manufactured by smelting blue cobalt glass (smalt) and cobalt blue (cobalt aluminate) pigment. It is currently a large open-air industrial museum and an art gallery; it is the largest and best preserved mine museum in Europe, and one of Norway's most visited attractions.

deep blue colored glass with cobalt

Radioactive contamination accident in Mexico

Intoxication caused by excessive levels of cobalt in the body

2000 radiation accident in Thailand