Lithium is a soft, silver-white metal that is the lightest metal of the alkali group. It is highly reactive and was discovered in 1817 by Johan August Arfvedson. Lithium has many uses such as in batteries, calculators, aircraft and spaceships when mixed with aluminum, and some medical treatments, but it also plays a role in hydrogen bombs and experimental nuclear reactors. Lithium deposits are found in Chile, the US, Australia, Russia, China, Zimbabwe and Canada within minerals and clays.