1) Elements 58 to 71 
The series of f-block elements between lanthanum and hafnium.This is a group of fifteen closely related elements and are known as the rare earth or inner transition elements. They are so alike that they are difficult to seperate from each other and usually all occur together in nature.
(rare earth metals) The fourteen elements of the upper row on the inner-transition metals on the periodic table that follow the element lanthanum (#57). Some reference sources include lanthanum in this series others do not. For all of these elements the filling orbital is 4f. This series is a sub-series of the transition metals.Elements 58 to 71 (after lanthanum)
Elements 58 to 71 (after lanthanum)
Those elements with atomic numbers 57-71 which closely resemble one another chemically and were once difficult to separate from one another. ... Synonym: rare earth elements. ... Origin: Lanthanum, first element of the series ... (05 Mar 2000) ... 
Group of elements, very similar in chemical properties, once thought to be extremely rare. They take up numbers 57 through 71 on the periodical table. Also called rare earth elements.
This is a group of fifteen closely related elements and are known as the rare earth or 'inner transition' elements. They are so alike that they are difficult to seperate from each other and usually all occur together in nature.
Type: Term Pronunciation: lan′thă-nīdz Definitions: 1. Those elements with atomic numbers 57-71 that closely resemble one another chemically and were formerly difficult to separate from one another. they vary in the electrons in the 4f orbital. Synonyms: rare earth elements
Commonly referred to as 'Rare Earth' metals. Examples Neodymium, Lanthanum and Ytrrium.
the row of elements beneath the periodic table, from cerium to lutetium; also called rare earths.
Commonly referred to as 'Rare Earth' metals. Examples