Praseodymium Reference Libraries
A rare earth is an oxide of a rare earth element. Often rare earth elements themselves are loosely called "rare earths". As to exactly what is a "rare earth" element is a matter of some ambiguity. The narrowest definition restricts it to the lanthanides, which are lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium,...
- Boughs or branches.
- Warbling of birds in trees.