Tellurium was discovered in 1783 by Franz Joseph Muller von Reichstein in Romania. The name is derived from the Latin word "tellus," meaning "earth." Its melting point is 722.66 K and its boiling point is 1261 K, and its density is 6.24 g/cm3.
The principle source of tellurium is as a byproduct of copper extraction. It is mostly used in alloys with other metals. It is added to lead to improve its strength and durability, and in steel and copper it makes the metals more workable. Tellurium is also used in blasting caps, and has potential applications in solar panels. Humans exposed to as little as 0.01 mg/m3 or less in air develop "tellurium breath", which has a garlic-like odour.