It is very malleable and ductile and can undergo almost limitless deformation. Indium was discovered in 1863 in sphaleritic, a sulfide ore of zinc, by Ferdinand Reich and Theodor Richter of Germany.
Indium is about as rare as silver.
The metal dissolves in mineral acids but is unaffected by potassium hydroxide or boiling water. When heated in the presence of the halogens or sulfur, direct combination takes place. The Earth's crust contains on the average about 0.05 part per million indium by weight. The element does not occur uncombined nor in independent minerals but as a trace in many minerals, particularly those of zinc and lead, from which it is obtained as a by-product. Though found mainly in sphalerite, significant quantities of indium also are contained in ores of copper, lead and tin.