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Rare Earth Elements

The rare earths are not particulary rare, being a family of metals with atomic numbers 58 to 71. More than 100 minerals are known to contain one or more of the rare lanthanides. Only two of these minerals, monazite* and bastnasite**, are commercially important. The challenge with rare earths is their natural concentration to form a deposit and then the separation of rare earth elements. A mineral like monazite may contain half a dozen or more different rare earth elements. Today, a standard procedure is available for separating the rare earth elements from each other. In many lanthanides, pure metal is made by treating its fluorine compound with calcium.

 

 

ABBREVIATIONS


RE       = Rare Earth

REM    = Rare Earth Metals

REE     = Rare Earth Elements

REO    = Rare Earth Oxides

TREO  = Total Rare Earth Oxides

LREE   = Light Rare Earth Elements (La-Sm)

HREE  = Heavy Rare Earth Elements (Eu-Lu)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PERIODIC TABLE


 


The elements Scandium (21), yttrium (39), lanthanum(57) and Thorium(90) usually occur with the rare earths and are commonly classed with them. 

The rare-earth metals or lanthanides were divided into three categories by Jöns Jakob Berzelius (1779–1848) :

- The cerium subgroup,which comprised of 57-lanthanum, 58-cerium, 59-praseodymium, 60-neodymium, and 62-samarium (61-Promethium does not occur naturally).

- The terbium subgroup includes 63-europium, 64-gadolinium, and 65-terbium.

The remaining lanthanides are placed in the yttrium subgroup. Strictly speaking, yttrium is not a rare earth. Because the properties of yttrium resemble those of heavy rare earths, its name has been used as a designating adjective.

- The yttrium subgroup includes 66-dysprosium, 67-holmium, 68-erbium, 69-thulium, 70-ytterbium, and 71-lutetium.

The most common lanthanoids in these minerals are, in order, cerium, lanthanum, neodymium, and praseodymium. Monazite mineral also contains thorium and ytrrium.

 *Monazite:     reddish-brown phosphate mineral containing rare earth (Ce, La, Th, Nd, Y)PO4
**Bastnasite : carbonate fluoride minerals with chemical formula (Ce, La, Y)CO3F   


Compiled by LKConsult - January 2009


Name Symbol Atomic number Group Subgroup
Lanthanum La 57 LREE (Light Rare Earth Elements) cerium subgroup
Cerium Ce 58 LREE cerium subgroup
Praseodymium Pr 59 LREE cerium subgroup
Neodymium Nd 60 LREE cerium subgroup
Promethium Pm 61 LREE  
Samarium Sm 62 LREE cerium subgroup
Europium Eu 63 HREE (Heavy Rare Earth Elements) terbium subgroup 
Gadolinium Gd 64 HREE terbium subgroup 
Terbium Tb 65 HREE terbium subgroup 
Dysprosium Dy 66 HREE yttrium subgroup
Holmium Ho 67 HREE yttrium subgroup
Erbium Er 68 HREE yttrium subgroup
Thulium Tm 69 HREE yttrium subgroup
Ytterbium Yb 70 HREE yttrium subgroup
Lutetium Lu 71 HREE yttrium subgroup
         
Scandium Sc 21    
Yttrium Y  39    

Source: tables numériques et formulaires A.Olza, F.Taillard ; ed SPES 1978 / manual of mineralogy ; James D. Dana ed. John Wiley & sons; Wikipedia / http://www.periodni.com/http://www.chemistryexplained.com/elements/index.html;http://www.lenntech.com/periodic-chart.htm; HEFA Rare Earth Canada.

 

REE 'The basics'