Rare Earth Elements

Often abbreviated as “REE”, these 16 elements include (preceded by their atomic numbers): 21 scandium (Sc), 39 Yttrium (Y) and the 14 elements that comprise the lanthanidesInclude the following elements elements (preceded by their atomic numbers): 57 lanthanum (La), 58 cerium (Ce), 59 praseodymium (Pr), 60 neodymium (Nd), 61 promethium (Pm), 62 samarium (Sm), 63 europium (Eu), 64 gadolinium (Gd), 65 terbium (Tb), 66 dysprosium (Dy), 67 holmium (Ho), 68 erbium (Er), 69 thulium (Tm), 70 Click on Term to Read More excluding 61 Promethium, an extremely rare and radioactive elementSubstance composed of atoms, each of which has the same atomic number (Z) and chemical properties. The chemical properties of an element are determined by the arrangement of the electrons in the various shells (specified by their quantum number) that surround the nucleus. In a neutral atom, the number of Click on Term to Read More. These elements show closely related geochemical behaviors associated with their filled 4f atomic orbital. REEs are used to infer petrological mechanisms that have affected a rock due to preferential fractionationConcentration or separation of one mineral, element, or isotope from an initially homogeneous system. Fractionation can occur as a mass-dependent or mass-independent process. Click on Term to Read More of some REEs relative to others. REEs are also useful for dating rocks, as some their radioactive isotopes display long half-lives.

• LREE (light rare-earth elements) include these 8 elements (preceded by their atomic numbers): 57 lanthanum (La), 58 cerium (Ce), 59 praseodymium (Pr), 60 neodymium (Nd), 61 promethium (Pm), 62 samarium (Sm), 63 europium (Eu), 64 gadolinium (Gd). They are grouped together based on their increasing unpaired electrons.
• Although Scandium is the lightest of the rare earths, it is not classified as a LREE or HREE due to its different chemical and physical properties and is considered in a class by itself.¹
• HREE (heavy rare-earth elements) include these 8 elements (preceded by their atomic numbers): 65 terbium (Tb), 66 dysprosium (Dy), 67 holmium (Ho), 68 erbium (Er), 69 thulium (Tm), 70 ytterbium (Yb), 71 lutetium (Lu) and 39 Yttrium (Y). They are grouped together based on their paired electrons.

As related to meteorites, REE patterns refer to the abundances of rare-earth elements relative to those in chondritic meteorites.