Indium (pronounced /indiem/, IN-dee-um) is a chemical element with chemical symbol In and atomic number 49. This rare, soft, malleable and easily fusible post-transition metal is chemically similar to aluminium or gallium but more closely resembles zinc (zinc ores are also the primary source of this metal).
USGS Indium Information
Indium is produced mainly from residues generated during zinc ore processing. It was named after the indigo line in its atomic spectrum. The first large-scale application for indium was as a coating for bearings in high-performance aircraft engines during World War II. Afterwards, production gradually increased as new uses were found in fusible alloys, solders, and electronics. In the middle and late 1980's, the development of indium phosphide semiconductors and indium-tin-oxide thin films for Liquid Crystal Displays (LCD) aroused much interest. By 1992, the thin-film application had become the largest end use. The amount of indium consumed is largely a function of worldwide LCD production.