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For transistors.
Atomic Number:49Atomic Symbol:In
Atomic Weight:114.82Electron Configuration:2-8-18-18-3
Shells:2,8,18,18,3Filling Orbital:5p1
Melting Point:156.61oCBoiling Point:2000oC
Description:Rare silver-white metal
Uses:Used to coat high speed bearings


(from the brilliant indigo line in its spectrum) Discovered by Reich and Richter, who later isolated the metal. Indium is most frequently associated with zinc materials, and it is from these that most commercial indium is now obtained; however, it is also found in iron, lead, and copper ores. Until 1924, a gram or so constituted the world's supply of this element in isolated form. It is probably about as abundant as silver. About 4 million troy ounces of indium are now produced annually in the Free World. Canada is presently producing more than 1,000,000 troy ounces annually. The present cost of indium is about $1 to $5/g, depending on quantity and purity. It is available in ultrapure form.


  • Indium is a very soft, silvery-white metal with a brilliant luster.
  • The pure metal gives a high-pitched "cry" when bent.
  • It wets glass, as does gallium.


  • It has found application in making low-melting allows; an alloy of 24% indium - 76% gallium is liquid at room temperature.
  • It is used in making bearing alloys, germanium transistors, rectifiers, thermistors, and photoconductors.
  • It can be plated onto metal and evaporated onto glass, forming a mirror as good as that made with silver but with more resistance to atmospheric corrosion.


There is evidence that indium has a low order of toxicity; however, care should be taken until further information is available.

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