rare earth

Noun

rare earth (plural rare earths)

1. Any 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
   • 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
   • 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...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...

   Synonyms:

   rare earth metal, lanthanide