Source : Webster's Revised Unabridged Dictionary (1913)

Wulfenite \Wul"fen*ite\, n. [So named after F. X. Wulfen, an
   Australian mineralogist.] (Min.)
   Native lead molybdate occurring in tetragonal crystals,
   usually tabular, and of a bright orange-yellow to red, gray,
   or brown color; -- also called {yellow lead ore}.

Source : WordNet®

wulfenite
     n : a yellow to orange or brown mineral used as a molybdenum ore