samarium

American  

[suh-mair-ee-uhm] / səˈmɛər i əm /

noun

Chemistry.

1. a rare-earth metallic element discovered in samarskite. Sm; 150.35; 62; 7.49.

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samarium British  

/ səˈmɛərɪəm /

noun

1. a silvery metallic element of the lanthanide series occurring chiefly in monazite and bastnaesite and used in carbon-arc lighting, as a doping agent in laser crystals, and as a neutron-absorber. Symbol: Sm; atomic no: 62; atomic wt: 150.36; valency: 2 or 3; relative density: 7.520; melting pt: 1074°C; boiling pt: 1794°C

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samarium Scientific  

/ sə-mâr′ē-əm /

1. A silvery-white metallic element of the lanthanide series that exists in several forms and has seven naturally occurring isotopes. It is used to make glass that absorbs infrared light and to absorb neutrons in the fuel rods of nuclear reactors. Atomic number 62; atomic weight 150.36; melting point 1,072°C; boiling point 1,791°C; specific gravity approximately 7.50; valence 2, 3.

2. See Periodic Table

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Etymology

Origin of samarium

From New Latin, dating back to 1875–80; see origin at samarskite, -ium

Example Sentences

Geological Survey last year found samarium was the highest-risk mineral for disruption, with shortages potentially costing U.S. industry billions of dollars.

From The Wall Street Journal • Apr. 26, 2026

According to the US specialist newsletter Rare Earth Exchanges, US aerospace firm Lockheed Martin is the biggest American user of samarium, employed to make magnets that can withstand extremely high temperatures.

From Barron's • Feb. 4, 2026

Rare earths, like samarium and terbium, are critical to the production of technologies set to shape the world in the coming decades – including electric vehicles and highly advanced weapons systems.

From BBC • Apr. 25, 2025

Lockheed Martin, which manufactures the jets, had said the issue was "related to a magnet on the F-35 Turbomachine manufactured by Honeywell that includes cobalt and samarium alloy."

From Reuters • Oct. 8, 2022

In 1879, however, Lecoq de Boisbaudran showed that Mosander’s “didymium” contained samarium; while the residual “didymium,” after removal of samarium, was split by Auer v.

From Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 4 "Diameter" to "Dinarchus" by Various