a blackish heavy radioactive mineral consisting of uranium oxide in cubic crystalline form together with radium, lead, helium, etc: occurs in coarse granite. Formula: UO2
Word origin
C19: see uranium, -in, -ite1
uraninite in American English
(jʊˈreɪnəˌnaɪt; juˈrænəˌnaɪt)
noun
a hard, very heavy, dark-colored, radioactive mineral, UO2, the chief ore of uranium; uranium oxide