Indium (In)
Discovered spectroscopically in 1863 and isolated in 1864, indium is named for the indigo (blue) line in its spectrum. It is most frequently associated with zinc materials, is a by-product of zinc refinement, and can be found in iron, lead, and copper ores.
This post-transition metal is very soft and silvery-white with a bright luster. It wets glass and makes a high-pitched noise when bent (due to crystal twinning).
Indium is critical to modern technology, especially in the semiconductor industry. It is used to make alloys with low melting temperatures; in soft-metal high-vacuum seals; to create transparent conductive coatings on glass, and in transistors, rectifiers, thermistors, and photoconductors.