Lithium is the first of the alkali group of metals, discovered (1817, Sweden) by Johan August Arfvedson and named for the Greek lithos, “stone.” A soft, silvery metal, has many uses, including the production of glass, lithium batteries, and a strong, light alloy with aluminum for airplanes. Lithium carbonate is used in the treatment of mental illness, and an unknown amount is used as lithium hydride in the production of nuclear weapons.