Terbium stands apart within the rare earth supply chain as the most commercially valuable of the HREE oxides tracked by USGS MCS 2025, priced at $810/kg in 2024e (≥99.99% Tb₄O₇) — more than three times the price of dysprosium oxide ($260/kg) and nearly 15 times the price of neodymium oxide ($56/kg). This premium reflects Tb's unique combination of high demand growth (driven by clean energy applications) and extreme supply concentration in Chinese ion adsorption clay deposits. Unlike the light rare earths (La, Ce, Nd), which are produced in large volumes from LREE-dominant bastnaesite at Mountain Pass and Bayan Obo, terbium is predominantly recovered from heavy-REE-enriched ion adsorption clays in southern China's Jiangxi, Fujian, and Guangdong provinces — a deposit type with essentially no significant non-Chinese counterpart at commercial scale. Burma (Myanmar) and Thailand contribute HREE clay production, but Chinese processing of their concentrates means China controls the full value chain.

Terbium's fastest-growing and now dominant application is as a coercivity enhancer in NdFeB permanent magnets for high-temperature environments — specifically EV traction motors and direct-drive wind turbine generators. Both applications require magnets that maintain strong fields at operating temperatures well above ambient (EV motors: >150°C); adding Tb or Dy at ~0.1–0.5 wt% dramatically increases the magnet's coercivity and operating temperature ceiling. Advanced grain-boundary diffusion techniques reduce the required HREE loading per magnet (by concentrating Tb/Dy at grain boundaries rather than dissolving it throughout the alloy), partially dampening demand growth per unit of EV or wind capacity, but the absolute growth in EV and wind deployment more than offsets this efficiency gain. This demand dynamic drove the 2021–2022 price surge to $2,051/kg and is the structural force maintaining Tb prices well above the long-run lows seen for bulk LREEs. Phosphors — once the dominant Tb end use (Tb³⁺ green emission in tri-color fluorescent lamps) — remain significant but are in structural decline with the ongoing shift to LED lighting.

China's direct targeting of terbium in its April 2025 export controls — explicitly naming Tb alongside Dy, Sm, Gd, Lu, Sc, and Y — marked the sharpest formalization of Tb supply risk since the 2010–2012 REE export restriction era. Unlike neodymium and praseodymium, which are targeted indirectly through NdFeB magnet technology and equipment controls, Tb was named as a directly controlled substance, with export licenses required for Tb metal, Tb₄O₇ oxide, and processed alloy products. Building resilient non-Chinese Tb supply chains requires developing non-Chinese ion adsorption clay operations at scale — a decade-long challenge involving ore body development, hydromet processing, and separation technology — or developing viable magnet designs with substantially reduced or eliminated Tb loading. Neither pathway is close to commercial realization at the scale required to replace Chinese HREE supply.