Source : Webster's Revised Unabridged Dictionary (1913)

Uraninite \U*ran"i*nite\, n. (Min.)
   A mineral consisting chiefly of uranium oxide with some lead,
   thorium, etc., occurring in black octahedrons, also in masses
   with a pitchlike luster; pitchblende.

Source : WordNet®

uraninite
     n : a mineral consisting of uranium oxide and trace amounts of
         radium and thorium and polonium and lead and helium;
         uraninite in massive form is called pitchblende which is
         the chief uranium ore [syn: {pitchblende}]