Indium is a chemical element represented by the symbol In and the atomic number 49. It is a soft metal with bright silvery-white coloration. It is the 61st most common element in the crust of the Earth and less than 10 minerals are known to contain the metal. It is commonly obtained commercially from the residues left over during zinc ore processing, although a similar method can be used in lead, tin, copper and iron mining as well. Some of the largest deposits of the metal are found in Canada and Bolivia. Indium shares chemical similarities with gallium and thallium and this led to its discovery.
Who discovered indium?
Indium was discovered in 1863 when German Chemists Ferdinand Reich and Hieronymous Theodor Richter tested ores from Saxony at the Freiberg University of Mining and Technology where they worked. They made the discovery after dissolving the minerals from these ores and testing for thallium, which was already known at the time, with spectroscopy. Instead of seeing the green lines associated with thallium they noticed a bright blue line. No other element was known to cause a bright blue line so they concluded they had discovered a new element, which they named indium from the color indigo that they witnessed. This was confirmed not long after and a year later Richter was able to isolate the pure metal. In 1867 a 0.5 kg (1.1 lb) cast of pure indium was shown at the World Fair.
Did you know?
Ferdinand Reich was totally color blind and could not see the colors during their experiments. He partnered with Richter so that he could examine the colors who would then describe them to Reich!