The discovery of germanium is one of the first great successes of the periodic table of elements. Chemist Clemens Winkler in 1886 had received a mineral, argyrodite, known to contain sulfur and silver. Those elements left 6% of the mass unaccounted for. After extensive purification steps, Winkler isolated a new element.
This new element had properties in common with several known elements, including antimony and arsenic, but Winkler tested a larger sample and determined that it was most similar to silicon. The creator of the periodic table, Dmitri Mendeleev, had predicted an unknown element existed in a gap under silicon, and this new element filled the gap. Winkler called it germanium after his young nation of Germany.
Germanium was a chemical footnote until World War II. Its semiconductor properties now started to be useful, and germanium saw use in electronic diodes. Germanium dominated the semiconductor industry for two decades until silicon started replacing it.
Mining and Production
Germanium minerals exist, but not in economically meaningful quantities. Instead, germanium is extracted as a byproduct from zinc-lead ores. World production is quite small, around 165 tonnes in 2014, with 3/4 refined in China.
Properties and Uses
Germanium is a brittle lustrous metalloid with a silvery color. As stated, it is a semiconductor and the material for earlier solid-state diodes and transistors.
Germanium is seldom used now where ubiquitous silicon can replace it. It is still incorporated, however, into high-speed semiconductors that use both elements. (Silicon-germanium alloys have a fast response time.)
Germanium dioxide is a crystal with a very high index of refraction (it bends light) over many frequencies. It is therefore used in optical fibers and lenses, particularly lenses for infrared systems.