Germanium

Germanium was one of several chemical elements whose existence was predicted in 1869 by Russian chemist Dmitri Mendeleev.

The element germanium was discovered a little over 25 years later, at a mine near Freiberg, Germany. There, a miner found an unusual stone that wound up in the hands of German chemist Clemens Winkler. Winkler analyzed the mineral and found that something like 7% of its mass didn’t belong to any known element. In 1886, Winkler separated out a new element from the mineral. The element's properties matched up almost exactly with what Mendeleev had predicted for element 32, making the discovery an important proof of Mendeleev's idea that elements follow a repeating pattern in the periodic table.

Germanium is a whitish-grey metalloid (meaning that it has some properties of a metal and some non-metallic properties). In its pure state, germanium is crystalline and brittle.

Initially, there were few uses for germanium. That changed in the aftermath of World War II, when researchers figured out that germanium was a semiconductor (a material that has conductivity somewhere between that of a conductor and an insulator). Semiconductors are important components in modern electronics. Components like diodes and transistors quickly came to depend on germanium to function.

Later, silicon—which is cheaper to produce than germanium—replaced germanium in many electronics. Although germanium isn’t as popular as it used to be, it’s still used in things like camera lenses, microscopes, and thermal imaging cameras. In countries other than the United States, it’s used to help make polyethylene terephthalate (PET), a common polyester. Germanium can also be used in detectors that identify radiation sources, like at airport security—something to think about the next time you watch your shoes disappear into a scanning machine!

Germanium forms relatively few compounds. Germanium oxide is transparent to infrared light, which makes it useful in infrared spectroscopes and in other optical equipment like camera lenses. Some germanium compounds aren’t toxic to mammals, but kill bacteria, which makes them useful in medications.

There are five naturally occurring germanium isotopes: germanium-70, germanium-72, germanium-73, germanium-74, and germanium-76. All these isotopes are stable (non-radioactive), except for germanium-76, which is slightly radioactive.

At least 27 radioactive germanium isotopes have been made in laboratories. The most stable of these isotopes, germanium-68, has a half-life of 271 days. The least stable, germanium-60, has a half-life of 30 milliseconds.

Germanium is a rare element. Most commercially produced germanium is a byproduct of zinc ore processing. China is the largest producer of the world’s germanium. Canada, Finland, Russia, and the United States are also major germanium producers.