dianium

from The Collaborative International Dictionary of English v.0.48

Dianium \Di*a"ni*um\, n. [NL., fr. L. Diana; either as the name
   of the Roman goddess, or from its use in OE. as a name of
   silver.] (Chem.)
   Same as {Columbium}. [Obs.]
   [1913 Webster]