Source : Webster's Revised Unabridged Dictionary (1913)

Molybdenite \Mo*lyb"de*nite\, n. [Cf. F. molybd['e]nite. See
   {Molybdena}.] (Min.)
   A mineral occurring in soft, lead-gray, foliated masses or
   scales, resembling graphite; sulphide of molybdenum.

Source : WordNet®

molybdenite
     n : a mineral resembling graphite that is valued as the chief
         source of molybdenum and its compounds