- a massive variety of uraninite, occurring in black pitchlike masses: a major ore of uranium and radium.
- 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.
- A brown to black, often crusty, cubic mineral that is a principal ore of uranium. It is highly radioactive. Chemical formula: UO2.