Tellurium (Te): Guide to Properties, Uses, and Market Price

The element that confused scientists for centuries now drives clean energy innovation

Metalloids occupy a unique position on the periodic table, exhibiting properties that bridge metals and nonmetals. These elements display intermediate electrical conductivity, making them valuable semiconductors. Metalloids typically have a metallic luster but are brittle rather than malleable. Their semiconductor properties allow them to conduct electricity under certain conditions while acting as insulators under others. This dual nature makes metalloids essential for modern electronics, solar cells, and thermoelectric devices that convert heat to electricity.

In this article, we explore tellurium's properties, its fascinating discovery history, critical applications in renewable energy and electronics, and the global supply challenges facing this rare but essential element.

Properties of tellurium

What does tellurium look like?

Tellurium is a silvery-white metalloid with a bright metallic luster that resembles tin in appearance. In its crystalline form, it displays a lustrous, reflective surface with a slight bluish tinge. Tellurium atoms form spiral chains in the crystal structure, creating a distinctive hexagonal lattice. The element is brittle and can be easily pulverized into powder, unlike ductile metals. When precipitated from solution, tellurium can form an amorphous black-brown powder, though debate exists whether this form is truly amorphous or composed of microscopic crystals.

Will we ever run out of tellurium?

Tellurium is one of the rarest stable solid elements in Earth's crust, with an abundance of approximately one part per billion, comparable to platinum and rarer than gold. This extreme scarcity makes tellurium approximately 10,000 times rarer on Earth than rubidium, despite being more cosmically abundant. The rarity is attributed to conditions during the solar system's formation when volatile tellurium compounds were lost from Earth's material.

Despite its rarity, adequate supplies currently exist because tellurium is obtained primarily as a byproduct of copper refining. Approximately one pound of tellurium is recovered from refining 550 tons of copper. The growing demand for solar cells and thermoelectric applications creates supply concerns, making efficient recycling and sustainable extraction increasingly important for future availability.

Can tellurium be recycled

Yes, tellurium can be recycled, though recycling infrastructure remains underdeveloped compared to demand. Recycling helps address the extreme scarcity of tellurium and reduces environmental impacts from primary extraction.

Recycled tellurium is commonly sourced from:

• End-of-life cadmium telluride solar panels
• Discarded thermoelectric cooling devices containing bismuth telluride
• Semiconductor manufacturing waste and electronic scrap
• Steel and copper alloy manufacturing residues

Where can tellurium be found?

Tellurium is occasionally found uncombined in nature, but more commonly occurs in minerals combined with gold, silver, copper, lead, and other metals. The element is obtained primarily as a byproduct during the electrolytic refining of copper and lead.

• Calaverite: A gold telluride mineral containing the chemical formula AuTe₂, historically significant as the ore from which tellurium was first isolated.
• Sylvanite: A silver-gold telluride mineral that serves as both a gold ore and tellurium source.
• Tetradymite: A bismuth telluride sulfide mineral found in hydrothermal deposits.
• Copper Refinery Anode Slimes: The primary commercial source of tellurium, recovered from the residues produced during electrolytic copper refining.

Tellurium is produced primarily in Japan, the United States, Canada, China, and Russia. These countries have significant copper and lead refining operations that generate tellurium as a valuable byproduct. Japan is the world's largest producer, followed by North America. Unlike most elements, tellurium production depends entirely on copper and lead mining activity rather than dedicated tellurium mining.

Is tellurium expensive?

Tellurium commands moderate prices reflecting its extreme rarity and growing demand for solar energy and electronics applications. While not as expensive as precious metals like gold or platinum despite comparable crustal abundance, tellurium prices can fluctuate significantly based on copper refining output and demand from solar cell manufacturers. The element's value is increasing as renewable energy technologies expand globally.

Does tellurium have a biological role?

Tellurium has no known essential biological function in humans or other organisms. The element is toxic and teratogenic, meaning it can disturb the development of embryos or fetuses. Exposure to even very small quantities of tellurium, as little as 0.01 milligrams per cubic meter of air or less, causes a characteristic condition called tellurium breath, which produces a garlic-like odor. This occurs because the body metabolizes tellurium into dimethyl telluride, a volatile compound with a distinctive smell that is exhaled through the lungs and excreted in sweat and urine. Prolonged exposure may cause abdominal pain, constipation, vomiting, liver damage, and respiratory system harm.

What is pure tellurium used for?

• Solar Cells: Cadmium telluride thin-film solar panels represent approximately 40 percent of tellurium consumption. These panels achieve efficiency ratings of 11 to 13 percent, superior to amorphous silicon alternatives at 7 to 9 percent efficiency, making them crucial for renewable energy expansion.
• Thermoelectric Devices: Bismuth telluride compounds account for approximately 30 percent of tellurium use. These materials convert temperature differences into electrical power or provide solid-state cooling without moving parts, used in portable generators and precision temperature control.
• Metallurgy: About 15 percent of tellurium enhances metal properties. Adding tellurium to steel and copper improves machinability without reducing electrical conductivity. In lead alloys, tellurium increases resistance to vibration, fatigue, and sulfuric acid corrosion, essential for battery applications.
• Rubber Production: Approximately 5 percent of tellurium vulcanizes rubber, producing materials with superior mechanical and thermal properties compared to sulfur-vulcanized rubber, less susceptible to aging and degradation.
• Infrared Detectors: Mercury cadmium telluride semiconductors are photosensitive materials used in infrared detectors, night vision equipment, thermal imaging cameras, and the Hubble Space Telescope's Wide Field Camera.
• Rewritable Optical Media: Tellurium is used in rewritable CDs and DVDs, where its phase-change properties allow data to be written, erased, and rewritten multiple times.
• Blasting Caps: Tellurium serves as an ingredient in electric blasting caps and explosive detonators.

What are the main compounds with tellurium?

• Tellurium Dioxide (TeO₂) : The main product of burning tellurium in air. Used in acousto-optic materials, optical fiber amplification, specialty glasses with high refractive indices, and as a ceramic colorant. It is amphoteric, acting as both an acid and base depending on solution conditions.
• Cadmium Telluride (CdTe) : A crystalline compound that forms the basis of highly efficient thin-film solar panels. CdTe solar cells have some of the greatest efficiencies among photovoltaic materials and are a cornerstone of renewable energy technology.
• Bismuth Telluride (Bi₂Te₃) : A semiconductor material with exceptional thermoelectric properties. Used in solid-state refrigeration, portable power generation, and thermoelectric cooling devices. Achieves conversion efficiency of approximately 8 percent with zT values around 1.05.
• Lead Telluride (PbTe) : A narrow bandgap semiconductor used in thermoelectric devices, infrared detectors, and deep-space power generation applications where extreme temperature differences exist.
• Hydrogen Telluride (H₂Te) : A highly unstable, colorless gas analogous to hydrogen sulfide and hydrogen selenide. It is the tellurium analog of water but far less stable, decomposing readily.
• Tellurium Hexafluoride (TeF₆) : A colorless, highly toxic gas with a foul odor. Prepared by passing fluorine gas over tellurium metal at 150 degrees Celsius. It hydrolyzes in water to form telluric acid and is more chemically reactive than its sulfur analog.

Who discovered tellurium?

Tellurium was isolated before being recognized as a distinct element, causing confusion among scientists throughout the 1700s. Researchers found a mysterious substance in various ores that exhibited both metallic and non-metallic properties. Unable to identify it, they called it aurum paradoxum, meaning paradoxical or illogical gold, or metallum problematicum, meaning problem metal.

In 1782, Austrian mineralogist Franz Joseph Müller von Reichenstein worked with an ore called German gold from Transylvania. After a thorough investigation lasting three years and including more than 50 tests, Müller isolated a new material that defied analysis. He determined its specific gravity, noted it produced white smoke with a radish-like odor when heated, imparted a red color to sulfuric acid, and formed a black precipitate when the solution was diluted with water. Unable to identify the substance, Müller called it aurum paradoxum and metallum problematicum because it did not exhibit predicted properties for antimony.

In 1789, Hungarian scientist Pál Kitaibel independently discovered the element in an ore from Deutsch-Pilsen previously thought to be argentiferous molybdenite, but he later gave credit to Müller. Müller sent a sample to Torbern Bergman in Uppsala, Sweden, but Bergman died before analyzing it. Years later in 1796, Müller sent another sample to German chemist Martin Heinrich Klaproth in Berlin, who confirmed Müller's findings and produced a pure sample. In 1798, Klaproth named the new element tellurium, from the Latin word tellus meaning Earth, mirroring the naming of selenium from selene meaning Moon discovered 30 years later.

Is tellurium dangerous?

Yes, tellurium and many of its compounds are toxic and must be handled with appropriate safety precautions. Exposure to very small concentrations, as little as 0.01 milligrams per cubic meter of air or less, causes tellurium breath, a distinctive garlic-like odor resulting from the body metabolizing tellurium into dimethyl telluride. This volatile compound is exhaled through the lungs and secreted in sweat and urine, serving as a clear indication of tellurium exposure.

Tellurium is teratogenic, meaning it can cause serious harm to developing embryos and fetuses, making it particularly dangerous for pregnant individuals. Prolonged or significant exposure can cause abdominal pain, constipation, vomiting, damage to the liver, and harm to the respiratory system. Workers in industries using tellurium should follow strict safety protocols including proper ventilation, protective equipment, air quality monitoring, and immediate medical attention if exposure occurs. Despite its toxicity, pure metallic tellurium is somewhat less dangerous than many of its chemical compounds.

Fun facts about tellurium

• Tellurium has an unusual property on the periodic table: its atomic mass of 127.60 atomic mass units exceeds that of iodine at 126.90, the element immediately following it. This atomic mass inversion puzzled scientists before atomic number was understood as the true organizing principle of the periodic table.
• Despite being one of the rarest elements in Earth's crust at one part per billion, tellurium is actually more abundant than rubidium in the cosmos. The extreme terrestrial rarity resulted from tellurium's volatile compounds being lost during Earth's formation in the solar nebula.
• In the early 1920s, American chemist Thomas Midgley Jr. discovered that adding tellurium to gasoline prevented engine knocking. However, this application was abandoned because it gave drivers' breath an unbearable garlic-like odor from exhaust fumes.
• Recent quantum physics research has discovered that layered compounds of tellurium with rare-earth elements demonstrate exotic quantum properties. In 2022, physicists identified a novel axial Higgs-like particle in these materials that may be relevant to dark matter research.
• Tellurium is slightly photosensitive, meaning its electrical conductivity increases when exposed to light. This semiconductor property makes it valuable for photosensitive applications including the Hubble Space Telescope's infrared detector.
• When tellurium burns in air or oxygen, it produces a distinctive blue-green flame while forming tellurium dioxide, making it visually identifiable during combustion.
• Tellurium is the lightest element known to exhibit alpha decay, though this occurs only in certain radioactive isotopes, not in the stable forms found naturally.

Scientific data verified from RSC, Britannica, and the Minerals Education Coalition.