The rare earths comprise 17 chemical elements: Lanthanum; Cerium; Praseodymium; Neodymium; Promethium; Samarium; Europium; Gadolinium; Terbium; Dysprosium; Holmium; Erbium; Thulium; Ytterbium; Lutecium; Scandium; Yttrium[i].
[i] United Nations. (2014), United Nations Conference on Trade and Development. Commodities at a glance. Special edition on rare earths. N°5. https://unctad.org/fr/system/files/official-document/suc2014d1_fr.pdf.