Tot de zeldzame aardmetalen behoren 17 scheikundige elementen in het periodieke systeem, te weten 15 lanthaniden (lanthanium, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium) plus scandium en yttrium.
Rare earth elements are a set of 17 chemical elements in the periodic table, specifically 15 lanthanides (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium) as well as scandium and yttrium.