Rare Earth

Name:
Rare Earth
Detailed information:
One of a group of 15 chemically related elements in group IIIB of the periodic table (lanthanide series). Their names and atomic numbers are as follows:

lanthanum	La	57
cerium	Ce	58
praseodymium	Pr	59
neodymium	Nd	60
promethium	Pm	61
samarium	Sm	62
europium	Eu	63
gadolinium	Gd	64
terbium	Tb	65
dysprosium	Dy	66
holmium	Ho	67
erbium	Er	68
thulium	Tm	69
ytterbium	Yb	70
lutetium	Lu	71

Source:Monazite, bastnasite, and related fluocarbonate minerals as well as minerals of the yttrium group. These ores contain varying percentages of rare-earth oxides, which are often loosely called rare earths. Rare earth elements also occur as fission products of uranium and plutonium. Occurrence:(Monazite) India, Brazil, Florida, Carolinas, Australia, South Africa; (bastnasite) California. 

The elements 57–62 are known as the cerium subgroup, and 63–71 as the yttrium subgroup. Yttrium, atomic number 39, although not a rare-earth element, is found associated with the rare earths and is separated only with difficulty.

See Didymium.