Wordorigins.org

Erbium, element 68, is yet another element named after the mining village of Ytterby, Sweden. The metal was discovered and named in 1843 by Swedish chemist Carl Gustaf Mosander.¹ Erbium has the chemical symbol Er.

The other elements named after Ytterby are yttrium, ytterbium, and terbium.

¹Oxford English Dictionary, erbium, 2nd Edition, 1989, Oxford University Press, accessed 23 October 2009, http://dictionary.oed.com/cgi/entry/50077427.