• WordNet 3.6
    • n uraninite 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
    • ***
Webster's Revised Unabridged Dictionary
    • n Uraninite (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.
    • ***
Century Dictionary and Cyclopedia
    • n uraninite This mineral, in its different varieties (the crystallized kinds called cleveite, bröggerite, nivenite, etc., and the more abundant amorphous and impure pitchblende), has become of much importance as being the chief source of radium. See radium and radioactivity. From the investigation of it also has been derived a large part of our present knowledge of the transformation of uranium into radium and the further successive changes of the latter element with lead as the probable final step: all analyses have shown a small amount of this element whose presence was hitherto unexplained. It has also been found that many varieties of uraninite yield the gas helium, which is one of the early transformation products of radium.
    • n uraninite A mineral of a pitch-black color and very heavy, having when unaltered a specific gravity of 9.5. It usually occurs massive, rarely in regular octahedrons, and is commonly met with in granitic rocks. Its exact chemical composition is uncertain, but it consists essentially of the oxids of uranium (UO3,UO2), also thorium, lead, and other elements in small amount, with, further, from 1 to 2.5 per cent. of nitrogen. It is the chief source of uranium; and it is also the only mineral in the primitive crust of the earth in which the element nitrogen is known to exist. Also called pitch-blende.
    • ***


In literature:

There were two other mines that produced the same uraninite ore as the one at which Hanlon was stationed.
"Man of Many Minds" by E. Everett Evans
On the occurrence of nitrogen in uraninite, and on the composition of uraninite in general.
"United States Government Publications, v. 8 Jan-Jun 1892" by Compiled