Source : Webster's Revised Unabridged Dictionary (1913)

Nepheline \Neph"e*line\, Nephelite \Neph"e*lite\, n. [gr. ?
   cloud: cf. F. n['e]ph['e]line. Cf. {Nebula}.] (Min.)
   A mineral occuring at Vesuvius, in glassy agonal crystals;
   also elsewhere, in grayish or greenish masses having a greasy
   luster, as the variety el[ae]olite. It is a silicate of
   aluminia, soda, and potash.

Source : WordNet®

nepheline
     n : a whitish mineral consisting of sodium aluminum silicate or
         potassium aluminum silicate in crystalline form; used in
         the manufacture of ceramics and enamels [syn: {nephelite}]