noun.
A soft, malleable, silvery rare-earth element, used in metallurgy and nuclear research and to color glass and porcelain. Atomic number 68; atomic weight 167.26; melting point 1,529°C; boiling point 2,868°C; specific gravity 9.066; valence 3. cross-reference: Periodic Table.
The Century Dictionary and Cyclopedia
noun.
Chemical symbol, Er; A rare metal found along with yttrium, terbium, and a number of other rare elements in some rare minerals, as euxenite, fergusonite, and gadolinite, in which it exists as a tantalate or silicate.
the GNU version of the Collaborative International Dictionary of English
noun.
A rare earth element of the lanthanide series associated with several other rare elements in the mineral gadolinite from Ytterby in Sweden. Symbol Er. It has atomic number 68 and an atomic weight of 167.26. The pure element is metallic with a bright, silvery luster. It is relatively stable in air, not oxidizing as quickly as some other rare earths. Its salts are rose-colored and give characteristic spectra, and the pink oxide has been added as a colorant in glass and porcelain enamel glazes. Its sesquioxide Er2O3 is called erbia.