noun Mineralogy.

  1. a massive variety of uraninite, occurring in black pitchlike masses: a major ore of uranium and radium.


  1. a blackish mineral that is a type of uraninite and occurs in veins, frequently associated with silver: the principal source of uranium and radium. Formula: UO 2

n.also pitch-blende, 1770, a loan-translation of German Pechblende; see pitch (n.2) + blende.

  1. A brown to black, often crusty, cubic mineral that is a principal ore of uranium. It is highly radioactive. Chemical formula: UO2.
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