rare earth

plural rare earths

1. chemistryAny of the naturally occurring oxides of the lanthanide metals; they are widely distributed in relatively small concentrations and are used in glassmaking, ceramic glazes etc.

   Meronyms: rare earth element, rare earth metal

   1 more example

   The metallic base of yttria, a very rare earth, discovered in a mineral called godolinite.

   1841, Henry Minchin Noad, Lectures on Chemistry, Including Its Applications in the Arts, and the Analysis of Organic and Inorganic Compounds, page 375

   Synonyms: rare earth mineral

2. A rare earth element.

   Near-synonym: lanthanide

   2 more examples

   Despite their name, rare earths are not so rare. The most common, cerium, is as plentiful in the Earth's crust as copper or lead. The difference between them and more familiar materials is that, in nature, rare earths are almost never found on their own. Rather, they're mixed with other minerals, and often at low concentrations, making them difficult to mine economically.

   2025 July 18, Timothy McLaughlin, “A Rebel Army Is Building a Rare-Earth Empire on China's Border. The Kachin Independence Organization fought for decades in obscurity. Now it's supplying essential minerals to manufacturers around the world”, in Bloomberg Businessweek, archived from the original on 18 Jul 2025

   But the government also gave MP Materials a decade-long guaranteed price floor for its products, such as the rare earths neodymium-praseodymium, at twice recent market rates (leaving aside the fact prices have soared this week as MP Materials has cut ties with China).

   2025 August 30, Gillian Tett, “America’s new ‘patriotic’ capitalism”, in FT Weekend, London: The Financial Times Ltd., →ISSN, →OCLC, page 7

   Synonyms: rare earth metal, lanthanide