Germanium is a chemical element with the symbol Ge and atomic number 32. This lustrous, hard, silver-white metalloid is chemically similar to tin. Germanium forms a large number of organometallic compounds and is an important semiconductor material used in transistors. It is named after the country of Germany.

Germanium is a hard, grayish-white element that has a metallic luster and the same crystal structure as diamond. Germanium is a semiconductor. In its pure state, this metalloid is crystalline, brittle and retains its lustre in air at room temperature. Zone refining techniques have led to the production of crystalline germanium for semiconductors that have an impurity of only one part in 1010. Along with gallium, bismuth, antimony and water, it is one of the few substances that expands as it solidifies (i.e. freezes) from its molten state. Germanium releases high energy electrons if bombarded with alpha particles and is used in combination with radon for the nuclear batteries patented by Bruce Perreault.