REEx challenges Wall Street to value entire rare earth supply chains, not just mines, ranking MP Materials and Lynas as top picks while flagging USA Rare
Element Profile
Terbium
Symbol
Tb
Atomic number
65
Group
Heavy rare earth
Properties
Density
8.23 g/cm³
Melting point
1359 °C
Boiling point
3230 °C
Crustal abundance
1.2 ppm
Supply Risk
Supply risk
Extreme
Geological scarcity
High
Primary economic driver
High-temperature magnets & green phosphors
Overview
About Terbium
Terbium (Tb, atomic number 65) is a heavy rare earth metal with two main jobs. It helps neodymium magnets keep their strength when they run hot, and its compounds give off the green light in many phosphors. China does most of the separation and refining of the magnet rare earths, terbium among them, according to the IEA. That puts terbium and its magnet partner, dysprosium, at the center of efforts to build a rare earth supply chain outside China.
What terbium is
Terbium is a soft, silvery metal and one of the heavy rare earth elements. Like the other rare earths, it has to be separated from its chemical neighbors by ion exchange or solvent extraction.
The physical properties listed on this page are from the Royal Society of Chemistry periodic table. Crustal abundance is from U.S. Geological Survey Professional Paper 1802, which puts terbium at 1.2 parts per million, about a quarter of dysprosium's 5.2.
Discovery and name
Swedish chemist Carl Gustaf Mosander identified terbium in Stockholm in 1843. He was studying yttria, an oxide Johan Gadolin had found in an Ytterby ore later named gadolinite (RSC). Mosander split it into yttria, erbia and terbia, and the names of the last two were confused for decades afterward (LANL). Terbium is named after Ytterby, the Swedish village where several of the lanthanides were found (RSC).
Why high-temperature magnets use terbium
Neodymium-iron-boron (NdFeB) magnets lose coercivity, their resistance to demagnetization, as they heat up. Terbium does the same job as dysprosium in these magnets: a small amount in place of some neodymium raises coercivity, so motors in electric vehicles and generators in wind turbines can run hotter. Magnet consultant Stan Trout wrote in a 2013 column for Magnetics Business & Technology that terbium works slightly better than dysprosium at raising coercivity. Terbium is also far scarcer, as the abundance figures above show.
Grain-boundary diffusion is one of the main ways the industry uses less of either metal. Magnet makers coat a finished magnet with dysprosium or terbium and heat it, so the heavy rare earth collects along the boundaries between grains. A 2015 technical paper from Arnold Magnetics reported that diffusion with either metal cut heavy rare earth content in one common high-temperature grade from more than 4% to about 2%. The USGS says substitutes exist for some heavy rare earth uses but are generally less effective.
Green phosphors for screens and lighting
Some terbium compounds give off bright green light when energized (LANL). That makes terbium a green phosphor in fluorescent lamps, low-energy bulbs and television screens, according to the Royal Society of Chemistry. USGS also lists terbium phosphors in flat panel displays and some LED lighting (USGS PP 1802).
Terbium phosphors make medical X-rays safer by allowing shorter exposure times, and terbium appears in the security inks on euro banknotes (RSC).
Terfenol-D and magnetostriction
Terfenol-D is an alloy of terbium, dysprosium and iron that changes shape in a magnetic field (RSC). That property, called magnetostriction, turns electrical energy into motion. In the late 1970s the U.S. Navy asked scientists at the Ames Laboratory for a material to drive high-powered sonar for tracking submarines. The technology was licensed to Etrema Products in 1987, according to Iowa State University. One consumer device used a terbium alloy rod to turn a window or tabletop into a loudspeaker (LANL).
Other uses
- Solid-state devices. Terbium is a doping agent in calcium fluoride, calcium tungstate and strontium molybdate (RSC).
- Lasers. Terbium salts are used in lasers (RSC).
- Sensors and probes. It is used in oxygen sensors, fiber-optic stress sensors and biological and medical probes (RSC).
Where terbium comes from
Terbium is recovered from monazite and bastnaesite and is also found in euxenite (RSC). Heavy rare earths are less abundant than light ones but are concentrated in some ores, especially ion-adsorption clays (USGS).
Those clays sit mainly in southern China and, increasingly, Myanmar, according to a May 2026 Asialink analysis. Global Witness reported in May 2024 that Myanmar had become the single largest source of heavy rare earths, with the material shipped to China for processing. Global Witness linked that expansion to environmental damage and harm to local communities. Outside Asia, USGS reported a Brazilian mine producing mixed ionic-clay concentrate with elevated terbium and dysprosium in 2025.
Export controls and supply risk
On April 4, 2025, China's Ministry of Commerce and customs agency placed terbium under export licensing in Announcement No. 18. The rule also covers samarium, gadolinium, dysprosium, lutetium, scandium and yttrium, along with their metals, alloys, oxides, compounds and magnet materials.
In October 2025, China moved to add holmium, erbium, thulium, ytterbium and europium to the controls, then suspended that expansion in November 2025, before it took effect (IEA; CIRS). As of December 2025 China had begun issuing general export licenses to selected exporters, according to USGS. Under MOFCOM Announcement No. 70, the suspension of the October measures was set to end on November 10, 2026. As of early October 2026, China had not announced an extension of that suspension, and the April controls on terbium remained in force.
The IEA reported in October 2025 that China accounted for about 91% of separation and refining of the magnet rare earths, which include terbium, and 94% of sintered permanent magnet production. USGS shipping data showed China as the source of all U.S. terbium compound and metal imports from 2021 to 2024, and U.S. net import reliance for heavy rare earth compounds and metals was 100% in 2025.
Supply outside China (as of October 2026)
Several projects aim to separate terbium outside China. The test is steady output of oxide that magnet makers have qualified.
- Lynas Rare Earths, Malaysia. Lynas produced its first terbium oxide at its Malaysian plant in June 2025, a month after its first dysprosium oxide, according to the company's June 2025 ASX announcement. The feed was ore from Mount Weld in Western Australia. When it announced first dysprosium in May 2025, Lynas called itself the only commercial producer of separated heavy rare earths outside China.
- MP Materials, Mountain Pass, California. The U.S. Department of Defense (now the Department of War) lent the company $150 million in August 2025 to build heavy rare earth separation (USGS). The circuit is rated at 200 metric tons a year of dysprosium and terbium (MP Materials). The company said the circuit reached mechanical completion in May 2026. In August the company said it remained on track to begin producing both later in 2026, according to coverage of its earnings call. REEx found no public confirmation of terbium output as of October 2026.
- Serra Verde, Brazil. The ionic-clay mine noted above received approval for a U.S. International Development Finance Corporation loan in November 2025 (USGS; Bloomberg). It ships concentrate for separation elsewhere.
Recycling
The Royal Society of Chemistry puts terbium's recycling rate below 10%, and USGS reported that only small quantities of heavy rare earths were recovered from permanent magnets in 2025. In January 2025 the Pentagon awarded $5.1 million to a Houston recycler to recover rare earths from electronic waste (The Defense Post). In November 2025 the Pentagon offered a conditional $80 million loan to ReElement Technologies for a planned plant in Marion, Indiana. ReElement stopped pursuing the offer in July 2026 (NS Energy).
Old lighting is a second source. REEx reported in November 2024 that the Department of Defense gave $4.22 million to Rare Earth Salts of Beatrice, Nebraska, to expand terbium oxide production. REEx reported that the company recovers terbium from discarded fluorescent bulbs.
What drives terbium demand and supply
Terbium demand follows demand for magnets that must hold their strength at high temperature, led by electric vehicle motors and wind generators. Supply outside China depends on new separation plants reaching steady output and on how China administers its licenses. Diffusion methods and recycling can stretch each kilogram further.
Frequently asked questions
What is terbium used for?
Mostly as an additive in neodymium-iron-boron magnets, where it helps them keep their strength at high temperatures, and as a green phosphor in displays and lighting. It is also part of Terfenol-D, a shape-changing alloy first developed for sonar, and appears in lasers, sensors and solid-state devices.
How is terbium different from dysprosium in magnets?
Both raise a magnet's coercivity, its resistance to demagnetization, so it can run hotter. Terbium works slightly better per unit, according to a 2013 industry column, but it is about a quarter as abundant in Earth's crust. Grain-boundary diffusion lets magnet makers use less of either.
Where does terbium come from?
Heavy rare earths are concentrated in ion-adsorption clay deposits, found mainly in southern China and, increasingly, Myanmar. Most separation of the magnet rare earths, terbium among them, happens in China, according to the IEA, and Lynas began producing separated terbium oxide in Malaysia in June 2025.
Does China restrict terbium exports?
Yes. Since April 4, 2025, exporting terbium and its compounds, alloys and magnet materials from China has required a license under MOFCOM Announcement No. 18. Those April controls were not part of China's later suspension and remained in force as of early October 2026.
What is Terfenol-D?
Terfenol-D is an alloy of terbium, dysprosium and iron that changes shape in a magnetic field, turning electrical energy into motion. In the late 1970s the U.S. Navy asked the Ames Laboratory to develop it for high-powered sonar. The technology was licensed for commercial use in 1987.
Primary Uses
- High-temperature NdFeB magnet additive (including grain-boundary diffusion)
- Green phosphors for displays and lighting
- Terfenol-D magnetostrictive alloy (sonar transducers, speakers)
- Solid-state devices and lasers
- Sensors and medical X-ray phosphors
Producing Projects
Companies
Found in Products
REEx Intelligence
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