Germanium is metalloid, which means it has properties of both metals and nonmetals. Germanium is one of the few elements that expand when it freezes, like water does. Others include gallium, silicon, bismuth and antimony. Germanium is mined in Alaska, Tennessee, China, the United Kingdom, Ukraine, Russia and Belgium.
Shiny and dark silvery gray, germanium is an important component in semiconductors and fibre optics. Highly reflective, pure germanium is a ‘p-type’ semiconductor, where conductivity depends largely on added impurities. Germanium reacts negatively to nitric acid and aqua regia, but it is stable in water, acids, and alkalies in absence of dissolved oxygen. Germanium is too brittle and hard to be rolled or drawn. Another useful property of germanium is that it has a high index of refraction. This means that if light goes through a lens coated with germanium, the light will pass almost straight through without being bent. This makes germanium very useful for coating camera lenses and microscopes. . Due to its optical properties, germanium is used in fibre-optics, infrared optics and in solar cell applications.
The first generation of semiconductors were based solely on germanium, then lower-cost silicon was used. Later, silicon-germanium alloys were developed
Germanium’s value was recognized during World War II, according to Emily Darby, a chemistry student at Harvey Mudd College, when it was used in high-resolution radar receivers. The first germanium transistor was invented shortly afterwards.
There have been claims that germanium may be beneficial for health, including improving the immune system, oxygen supply in the body, and destroying free radicals. There is, however, little to no scientific support of these claims, and using germanium supplements or medications can lead to many side effects, including kidney damage, anaemia, muscle weakness and lack of coordination, and elevated liver enzymes.