The name tellurium traces back to the Latin word tellus, meaning “Earth,” placing it among the rare handful of elements named after our own planet.

For all that nominal connection to Earth, the element is surprisingly scarce here. Tellurium is actually less abundant in Earth’s crust than gold, appearing only in trace quantities across most rock formations. Paradoxically, it is thought to be considerably more common throughout the broader universe. The leading explanation for the discrepancy is that early in Earth’s formation, tellurium combined with volatile compounds and was effectively lost before it could concentrate in the crust.

Its discovery came in the late 1700s, when miners extracting gold ore kept encountering a puzzling substance that refused to behave like anything previously catalogued.

Tellurium carries atomic number 52 and the chemical symbol Te. It belongs to the chalcogen group, sharing a family with oxygen, sulfur, and selenium. Despite that kinship with elements essential to life, tellurium itself is mildly toxic to humans.

Its physical appearance shifts depending on its form. Pure crystalline tellurium has a silvery-white, metallic look, while the powdered or amorphous version runs dark gray to black. Like antimony, it is classified as a metalloid, straddling the boundary between metals and nonmetals. Also like antimony, it is brittle rather than malleable, crumbling under pressure rather than bending.

When ignited, it produces a notably distinctive blue-green flame. Even limited exposure to the element carries an unusual side effect: tellurium breath, a persistent garlic-like odor that emanates from the body even after minimal contact.

Industrially, tellurium’s most prominent modern application is in cadmium telluride solar panels, a technology that has become an important part of the renewable energy landscape. It also played a significant role in earlier data storage technology, with tellurium compounds forming a key component of rewritable CDs and DVDs. In metallurgy, small additions of tellurium to copper or steel improve how easily those metals can be machined and enhance their resistance to corrosion.

Historically, Japan, Canada, and the United States have been among the leading producers of the element.

Beyond Earth, tellurium has been detected in distant stars, lending observational support to theories about how heavy elements are forged and distributed during supernova events.