America's rare-earth stockpile holds far less than funding suggests. Explore the gap between authorized dollars and delivered, provenance-clean kilograms
Element Profile
Samarium
Symbol
Sm
Atomic number
62
Group
Light rare earth
Properties
Density
7.52 g/cm³
Melting point
1072 °C
Boiling point
1794 °C
Crustal abundance
7.05 ppm
Supply Risk
Supply risk
High
Geological scarcity
Medium
Primary economic driver
Defense and aerospace SmCo magnets
Overview
About Samarium
Samarium (Sm, atomic number 62) is a light rare earth metal whose most important job is in samarium-cobalt magnets. Those magnets keep their strength at temperatures that weaken neodymium magnets, so they go into missiles, military aircraft and other hardware that runs hot. China put samarium under export licensing in April 2025, which turned a small market into a defense supply problem.
What samarium is
Samarium is a silvery metal in the lanthanide series. Like the other rare earths, it occurs mixed with its chemical neighbors and has to be separated from them by solvent extraction or ion exchange before industry can use it. REEx files it with the light rare earth elements, as do the U.S. Geological Survey and a 2022 U.S. Department of Energy report. Other groupings differ. Lynas Rare Earths describes samarium as a heavy rare earth, and law firm Holland & Knight described China's April 2025 controls as covering medium and heavy rare earths.
The physical properties listed on this page are from the Royal Society of Chemistry periodic table.
Discovery and a name taken from a mineral
French chemist Paul-Émile Lecoq de Boisbaudran isolated samarium in 1879 from didymium extracted from the mineral samarskite. The element takes its name from that mineral. Samarskite in turn honors Vasili Samarsky-Bykhovets, a Russian mining official who supplied the ore sample. The Royal Society of Chemistry calls samarium the first naturally occurring element named after a living person, though only indirectly through the mineral. Work on samarium later led chemists to gadolinium and europium.
Why samarium-cobalt magnets matter for defense
Samarium-cobalt (SmCo) magnets are less powerful than neodymium-iron-boron magnets but tolerate heat better, so engineers use them where heat stress is an issue, according to USGS Professional Paper 1802-O. Magnet maker Arnold Magnetic Technologies says the maximum operating temperature of SmCo is more than twice that of neodymium magnets, and its output changes less as temperature moves. SmCo magnets also resist corrosion better and do not need a protective coating, according to a 2015 review by Binnemans and Jones.
Neodymium magnets can be made more heat-resistant by adding dysprosium, but SmCo is still used in the aircraft and military industries, the 2015 review noted. The New York Times reported in June 2025 that samarium magnets drive fast-moving motors in missile nose cones and that Lockheed Martin puts about 50 pounds of them in each F-35 fighter. USGS reported that the U.S. stockpile's potential purchases for fiscal 2025 included 60 tons of samarium-cobalt alloy.
SmCo is a niche product by volume. The 2015 review put its share of the permanent magnet market below 2%. Neodymium magnets displaced SmCo after 1985 because they have a higher energy density and cost less to make. They are mostly iron, while SmCo needs costly cobalt. Samarium cannot simply replace neodymium inside a neodymium magnet, the review added.
Other uses
- Cancer pain treatment. The radioactive isotope samarium-153 is the active part of Quadramet, an injected drug that relieves bone pain in adults whose cancer has spread to the bone, according to the European Medicines Agency.
- Nuclear reactors. Samarium absorbs neutrons well and is used in reactor control rods (RSC, LANL).
- Glass, optics and lighting. Samarium goes into infrared-absorbing glass and specialized ceramics, doped crystals for lasers, and carbon arc lamps used in film studios (RSC).
- Chemistry. Samarium is used in catalysts, and samarium iodide is a reagent chemists use to build complex molecules (LANL).
- Batteries. USGS lists samarium among the rare earths used in nickel-metal hydride battery alloys.
Where samarium comes from
Samarium is not geologically scarce. USGS puts its average crustal abundance at about 7 parts per million, and it occurs mainly in monazite and bastnaesite alongside the other light rare earths (RSC). Monazite also carries thorium, so its mining and processing waste is radioactive and has to be managed, according to USGS. In 2025, rare earth ores were mined in China, the United States, Australia, Brazil, India and several other countries, according to USGS Mineral Commodity Summaries 2026.
Mines run for neodymium and praseodymium produce more samarium than the market uses, the 2015 review found. The supply risk sits in separation. The New York Times reported in June 2025 that China produced the entire world's supply of samarium, and that a French plant at La Rochelle had refined samarium for Western militaries until 1994.
Export controls and supply risk
On April 4, 2025, China's Ministry of Commerce and customs agency placed samarium under export licensing in Announcement No. 18. The listing covers samarium metal and alloys, samarium-cobalt permanent magnet materials, samarium oxide and samarium compounds. The rule also covers gadolinium, terbium, dysprosium, lutetium, scandium and yttrium.
Licenses could be issued only on the basis of the final user, the New York Times reported in June 2025. By December 2025, foreign companies using samarium for military purposes could no longer buy it from China, the paper reported. In October 2025, China widened its controls to more rare earths, then suspended that expansion in November 2025, before it took effect (IEA). As of December 2025 the April controls remained in effect, although 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 samarium remained in force.
Supply outside China (as of October 2026)
The test for each source below is steady output that magnet makers have qualified.
- Lynas Rare Earths, Malaysia. Lynas produced its first samarium oxide in March 2026, ahead of its April forecast, according to the company's March 2026 ASX announcement. Lynas said in March 2026 that it was the only commercial producer of separated heavy rare earth oxides outside China. In its August 2026 annual results, Lynas said customer qualification was underway and it expected to fill its first samarium orders in the quarter ending September 2026. It expected to add samarium capacity in 2028. REEx found no public confirmation that those first orders had shipped as of early October 2026.
- A French stockpile refined in Britain. Less Common Metals, near Liverpool, found roughly 200 tons of decades-old samarium nitrate at a Solvay plant in France and began refining it into metal, the New York Times reported in December 2025.
- U.S. projects. The same report said MP Materials' $150 million loan from the U.S. Department of Defense (now the Department of War) would expand its California processing to handle samarium. That work could take years. It also said the U.S. military had given $22.4 million in grants to Ucore Rare Metals for a Louisiana plant to produce samarium and gadolinium. REEx found no public confirmation of commercial samarium output from these U.S. projects as of October 2026.
The volumes needed to build a rare earth supply chain for samarium outside China are small. An analyst quoted in the December 2025 report estimated U.S. defense needs at less than 200 tons a year.
Recycling
The Royal Society of Chemistry puts samarium's recycling rate below 10%. USGS reported that only limited quantities of rare earths were recovered from batteries, permanent magnets and fluorescent lamps 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). Samarium has two long-lived, naturally radioactive isotopes, so samarium oxide powder needs careful handling, the 2015 review noted. Solid SmCo magnets pose no such problem.
What drives samarium demand and supply
Demand tracks military and aerospace programs that need magnets able to work in high heat, plus smaller medical, nuclear and optical uses. On the supply side, the open questions are how China administers its licenses and whether plants outside China reach steady, qualified output. Cobalt supply and cost also shape how widely SmCo magnets are used.
Frequently asked questions
What is samarium used for?
Mainly in samarium-cobalt magnets, which keep their strength at high temperatures in missiles, military aircraft and other demanding hardware. Smaller uses include the bone-pain drug samarium-153, reactor control rods, infrared-absorbing glass, lasers and catalysts.
Why use samarium-cobalt magnets instead of neodymium magnets?
Samarium-cobalt magnets are less powerful than neodymium magnets, but they keep their strength at much higher temperatures and resist corrosion without a coating. Neodymium magnets cost less, so SmCo is used mainly where heat would weaken a neodymium magnet.
Is samarium a light or heavy rare earth?
REEx, the USGS and the U.S. Department of Energy group samarium with the light rare earths. Lynas Rare Earths describes it as a heavy rare earth, and some summaries of China's export controls call it a medium rare earth.
Does China restrict samarium exports?
Yes. Since April 4, 2025, exporting samarium and its compounds, alloys and samarium-cobalt 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.
Where is samarium produced outside China?
Lynas Rare Earths began producing separated samarium oxide in Malaysia in March 2026. Two U.S. projects have received federal funding to process samarium, and a decades-old French stockpile has been refined into metal in Britain.
Primary Uses
- Samarium-cobalt (SmCo) high-temperature permanent magnets
- Samarium-153 for bone cancer pain relief (Quadramet)
- Neutron absorber in nuclear reactor control rods
- Infrared-absorbing glass, specialty ceramics and laser crystals
- Catalysts and samarium iodide reagent in chemical synthesis
- Nickel-metal hydride battery alloys
Producing Projects
Companies
Found in Products
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