'Uraninite' definitions:

Definition of 'uraninite'

From: WordNet
noun
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: uraninite, pitchblende]

Definition of 'Uraninite'

From: GCIDE
  • 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. [1913 Webster]