A rare metallic element associated with several other rare elements in the mineral gadolinite from Ytterby in Sweden. Symbol Er. Atomic weight 165.9. Its salts are rose-colored and give characteristic spectra. Its sesquioxide is called erbia.
- 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 1,497°C; boiling point 2,900°C; specific gravity 9.051; valence 3. See Table at element.