rare earth

From rare +‎ earth. First use appears c. 1841 in the publications of Henry Minchin Noad. See cite below.

rare earth (plural rare earths)

1. (chemistry) 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.

   Synonym: rare earth mineral

   Meronyms: rare earth element, rare earth metal

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

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

2. A rare earth element.

   Synonym: rare earth metal

   Hypernyms: metal < element < substance, material

   Near-synonym: lanthanide

   • 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^[1], archived from the original on 18 July 2025:

     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.

• rare-earth element on Wikipedia.Wikipedia
• “rare earth”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.