The Collaborative International Dictionary of English v.0.48:

Vesbium \Ves"bi*um\, n. [NL., from L. Vesuvius, contr. Vesbius,
   Vesuvius.] (Chem.)
   A rare metallic element of which little is known. It is said
   by Scacchi to have been extracted from a yellowish
   incrustation from the cracks of a Vesuvian lava erupted in
   1631.

   Note: It is not a recognized element. Actual identity?
         [1913 Webster]