philippium

from The Century Dictionary.

• noun A supposed new chemical element announced by Delafontaine as present in the mineral samars-kite. Its existence has not been confirmed; what was supposed to be its oxid has been shown to be a mixture, probably, for the most part, of terbia and yttria.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Chem.) A rare and doubtful metallic element said to have been discovered in the mineral samarskite.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun chemistry, obsolete A supposed metallic element obtainable from samarskite, later discovered to be a mixture of yttrium and terbium.