uraninite

views updated May 08 2018

uraninite (pitchblende) Mineral, UO2; sp. gr. from 8.5 when massive to 10 for unaltered crystals; hardness 5–6; cubic; it is brownish-black or grey-black; brownish-black streak; sub-metallic, greasy lustre; crystals very rare, the mineral is usually found as botryoidal masses; no cleavage; radioactive; occurs in pegmatites, and in association with monazite, zircon, and tourmaline, in hydrothermal veins together with cassiterite, pyrite, chalcopyrite, and galena, and as a detrital material in alluvials. It is a major ore mineral for uranium metal.

uraninite

views updated May 14 2018

uraninite (pitchblende) Dense radioactive mineral form of uranium oxide, UO2, the chief ore of uranium and the most important source for uranium and radium. The blackish, lustrous ore occurs as a constituent of quartz veins. Hardness 5–6; r.d. 6.5–8.5.