Tellurium is a metalloid chemical element which is used in a variety of industries, primarily in the form of an additive to an assortment of compounds and alloys. It is relatively rare on the Earth's surface, and it is usually found in combination with other materials, such as gold. Tellurium can be isolated through chemical or electrolytic processes. Because of its rarity, the element can be expensive, especially in a pure form.
Franz Muller von Reichenstein was the first to identify tellurium, in 1782, and it was isolated and named in 1798 after the Latin word for earth. In a pure form, the element is brittle and silvery white, with a crystalline structure. The atomic number of tellurium is 52, and the element is identified with the symbol Te on the periodic table of elements. It is considered mildly toxic, so people should avoid extended exposure to tellurium, especially inhalation exposure. While severe poisoning appears to be rare, the element can cause a distinctive garlicky breath in surprisingly low concentrations.
In glassmaking, tellurium may be added to glass for color. The element is also added to metal alloys to make them stronger and more ductile, and it is used in the production of solar panels and some semiconductors as well. Most famously, it was used in the casing of the first atom bomb, and it has also had historical use in steel production. Some ceramics may also integrate tellurium, and it may be mixed with optical glass and lenses.
Because tellurium usually occurs in the form of compounds, it is considered a byproduct of the mining industry, with most companies mining for other materials and separating tellurium during their refining process. This practice distinguishes tellurium from metals like gold, which companies actively seek out and specifically mine for. Because the process to separate naturally mingled elements can be environmentally harmful, mining companies must use rigorous programs to control their facilities and prevent contamination.
Consumers generally do not interact directly with tellurium. Some employees in various industries may handle the element, especially if they work with frequently alloyed metals like iron which may be blended with tellurium for strength. In the production of semiconductors, tellurium is often blended with mercury and cadmium to make a semiconductor which is capable of reading infrared radiation. This semiconductor tends to be expensive, making it suitable only for scientific research and high end military applications.