Indium

Indium is a silvery metal so soft it can be scratched with a fingernail. Ferdinand Reich and Theodor Richter discovered it in 1863 from a bright indigo line in its spectrum, which gave it its name. It is recovered as a byproduct of zinc refining, mostly in China and South Korea.

Most indium becomes indium oxide, which is mixed with tin oxide to make indium tin oxide, a film that conducts electricity yet is clear as glass. It forms the transparent electrodes in each LCD panel. Mixed into indium gallium nitride, indium sets the color of light each LED chip gives off: more indium shifts it from violet toward blue and green.