The metal contains an indigo blue line in its spark spectrum. It was discovered by Ferdinand Reich and Hieronymous Theodor Richter in 1863 while they were carrying out tests with a spectrograph. The name "indium" is derived from indigo.
Indium is produced mainly from the residues when processing zinc and other metal ores. Resources are scare, a fact reflected in the world price. In January 2003 the metal sold for around $60 per kilogram; by August 2006 the price had shot up to over $1000 per kilogram.
Indium is used to make LCDs for flat-screen tvs. It is also used as a semiconducting material in the latest solar cell technology, one that promises to be twice as efficient as conventional designs.