Noun
earth metal (plural earth metals)
(chemistry, obsolete) Any of the four metals aluminum, gallium, indium and thallium of the boron group in the periodic table of elements.
As with magnesium salts and other alkaline earth metal salts, to some degree soluble in water. Source: Internet
In the periodic table, it appears to the right of the alkaline earth metal barium and to the left of the lanthanide cerium. Source: Internet
Lanthanum is taken into consideration as a rare earth metal because the process to mine it is difficult, time-consuming and expensive. Source: Internet
Characteristics Radium is the heaviest known alkaline earth metal and is the only radioactive member of its group. Source: Internet
In late 1938 they found evidence of isotopes of an alkaline earth metal in their sample. Source: Internet