Rare earths are a group of 17 elements, including the lanthanides, plus yttrium and scandium. They have similar chemical structures that give them unique mechanical, chemical, metallurgical, optical, catalytic, nuclear, magnetic, and abrasive properties. While not necessarily rare in term of their occurrence within the earth’s crust the presence of rare earths in commercially viable deposits is relatively limited.   The rare part of the name refers to the difficulty in obtaining the pure elements and not their abundance.

Rare Earth Element
Lanthanum	La
Cerium	Ce
Praseodymium	Pr
Neodymium	Nd
Samarium	Sm
Europium	Eu
Gadolinium	Gd
Terbium	Tb
Dysprosium	Dy
Holmium	Ho
Erbium	Er
Thulium	Th
Ytterbium	Yb
Lutetium	Lu
Yttrium	Y