Pitchblende form Niederschlema-Alberoda deposit, Germany
General Category Oxide minerals Chemical formula Uranium dioxide or uranium(IV) oxide (UO2) Strunz classification 04.DL.05 Identification Color Black or brownish Crystal habit Massive, botryoidal, granular. Crystals uncommon. Crystal system Isometric Cleavage Indistinct Fracture Conchoidal to uneven Mohs scale hardness 5 - 6 Luster Submetallic, greasy Streak Same as colour, black or brownish Specific gravity 7.8 - 10 Refractive index Opaque Pleochroism None Solubility Soluble in sulfuric, nitric, and hydrofluoric acids. Major varieties Pitchblende Massive
Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO2, but also contains UO3 and oxides of lead, thorium, and rare earth elements. It is most commonly known as pitchblende (from pitch, because of its black color, and blende, a term used by German miners to denote minerals whose density suggested metal content, but whose exploitation was, at the time they were named, either impossible or not economically feasible). The mineral has been known at least since the 15th century from silver mines in the Erzgebirge Mountains, Germany. However, the type locality is Jáchymov in the Czech Republic, from where F.E.Brückmann described the mineral in 1727. Pitchblende from the Johanngeorgenstadt deposit in Germany was used by M. Klaproth in 1789 to discover the element uranium.
All uraninite minerals contain a small amount of radium as a radioactive decay product of uranium. Uraninite also always contains small amounts of the lead isotopes Pb-206 and Pb-207, the end products of the decay series of the uranium isotopes U-238 and U-235 respectively. Small amounts of helium are also present in uraninite as a result of alpha decay. Helium was first found on Earth in uraninite after having been discovered spectroscopically in the Sun's atmosphere. The extremely rare element technetium can be found in uraninite in very small quantities (about 0.2 ng/kg), produced by the spontaneous fission of uranium-238.
Uraninite is a major ore of uranium. Some of the highest grade uranium ores in the world were found in the Shinkolobwe mine in the Democratic Republic of the Congo (the initial source for the Manhattan Project) and in the Athabasca Basin in northern Saskatchewan, Canada. Another important source of pitchblende is at Great Bear Lake in the Northwest Territories of Canada, where it is found in large quantities associated with silver. It also occurs in Australia, Germany, England, and South Africa. In the United States it can be found in the states of New Hampshire, Connecticut, North Carolina, Wyoming, Colorado, Arizona and New Mexico.
Uranium ore is generally processed close to the mine into yellowcake, which is an intermediate step in the processing of uranium.
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URANINITE — L’uraninite est le principal minerai d’uranium et de radium et doit son nom au premier de ces métaux. C’est un dioxyde d’uranium, mais, dans la nature, celui ci est plus ou moins oxydé, et, de ce fait, sa composition varie entre deux pôles: UO2… … Encyclopédie Universelle
Uraninite — U*ran i*nite, n. (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. [1913 Webster] … The Collaborative International Dictionary of English
uraninite — [yoo rā′nə nīt΄, yo͞oran′ənīt΄] n. [< URANIUM + IN1 + ITE1] a hard, very heavy, dark colored, radioactive mineral, UO2, the chief ore of uranium; uranium oxide: cf. PITCHBLENDE … English World dictionary
uraninite — /yoo ran euh nuyt , ray neuh /, n. a mineral, probably originally uranium dioxide, UO2, but altered by radioactive decay, and usually containing uranium trioxide, lead, radium, and helium, occurring in several varieties, including pitchblende:… … Universalium
uraninite — noun Etymology: German Uranin uraninite (from New Latin uranium) + English ite Date: 1879 a a black octahedral mineral that consists of an oxide of uranium which usually contains thorium, lead, and rare earth elements and is the chief ore of… … New Collegiate Dictionary
uraninite — uraninitas statusas T sritis chemija apibrėžtis UO₂ ir UO₃ mišinys, oksidų klasės mineralas. atitikmenys: angl. uraninite rus. уранинит … Chemijos terminų aiškinamasis žodynas
uraninite — noun 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 • Syn: ↑pitchblende • Hypernyms: ↑uranium ore •… … Useful english dictionary
Uraninite — Pechblende Pechblende Catégorie III : oxydes et hydroxydes Général … Wikipédia en Français
uraninite — noun Any of several brownish black forms of uranium dioxide, UO, (especially pitchblende) that is the chief ore of uranium; it is isomorphous with thorianite … Wiktionary
uraninite — SYN: pitchblende. * * * ura·ni·nite yu̇ rā nə .nīt n a mineral that is basically a black octahedral or cubic oxide of uranium containing lead, thorium, and rare earth elements and that is the chief ore of uranium … Medical dictionary