Erbium is a soft, malleable, lustrous, silvery metal.
It is a member of the lanthanide series in group IIIb of the periodic table . With other rare earths its oxide occurs in the mineral gadolinite, found in Sweden. Erbium does not oxidize in air as rapidly as some of the other rare-earth metals . The discovery of erbium is generally credited to Carl G. Mosander, although he did not succeed in isolating the element. In 1843 he separated from gadolinite three oxide fractions that he called yttria, erbia, and terbia.