Brannerite

brannerite

[′bran·ə‚rīt]
(mineralogy)
A complex, black, opaque titanite of uranium and other elements in which the weight of uranium exceeds the weight of titanium; monoclinic and possibly (U,Ca,Fe,Y,Th)3Ti5O6·

Brannerite

 

(named after the American geologist John Branner, 1850–1922), a mineral; a composite of uranium titanate, thorium, and rare earths of an approximate composition of UTi2O6 where U may be replaced by Th, rare earth elements, Ca, and Pb; and Ti by Fe; it frequently contains adsorbed water.

Brannerite is crystallized into a monoclinal (rhombic) system; the crystals are prismatic. A black mineral, after weathering it is covered with a brownish yellow film. Its sheen is glassy to resinous; the density is 4,020–5,880 kg/m3; and the hardness on the mineralogical scale is 4.5–6.5. Brannerite is very brittle. Usually it is formed in magmatic and pneumatolytic stages of the intrusion process as an accessory mineral of granites, in skarns, pegmatites, greisens, and rarely in quartz and quartz-carbonate formations. Brannerite is an ore for the extraction of uranium.

References in periodicals archive ?
The main U minerals at the Olympic Dam are coffinite, brannerite, and uraninite-pitchblende, with minor to trace amounts of U hosted in hematite, thorite-uranothorite, thorianite, crandallite, xenotime-(Y), zircon, REE-group minerals, pyrite, chalcopyrite, bornite, and chalcocite [36].
Similarly, in samples dominated by brannerite, U distribution appears to overprint early ore textures (Figure 1(c)); this is consistent with textural observations by Macmillan et al., [38] indicating a secondary origin for the majority of coffinite and brannerite.
Coffinite and brannerite are both more abundant than uraninite (the only U mineral predicted to precipitate in our model).
Brannerite similarly appears to be a late mineral, forming at least in part via interaction of U-bearing fluids with preexisting Ti minerals [38].
Mineralogical work completed by the company indicated that a wide variety of rare-earth element-bearing minerals have been identified, including apatite, iimoriite, kainosite, gadolinite, allanite, bastnaesite, parisite, brannerite, thalenite, xenotime, fergusonite, synchysite (Y), and monazite.
Brannerite, a highly radioactive oxide, is common in some minor veins in the mining center at Bou Azzer, where it is associated with native gold.
In the district's western part, gold occurs commonly with the uranium oxide brannerite; here the gold content of the ore reaches 45 grams per ton.
Bultemann (1957) described the uranyl arsenate novacekite from Vein 5 + 7, Bou Azzer, as small, straw-yellow to yellow tabular crystals, more weakly fluorescent in ultraviolet light than the associated pale yellow to yellow-green uranospinite (some of these specimens also showed associated brannerite).
Smoky quartz has been found in small veins around Bou Azzer, its smokiness possibly having been induced by radiation from brannerite.
The most common uranium mineral is pitchblende, with lesser concentrations of coffinite and brannerite. Uranium is widely dispersed among gangue minerals and is not generally associated with sulphides, although it can occur in bornite/hematite composites.
Collecting crystals is a popular Swiss hobby, and many displays include minerals -- such as zircon, coffinite, carnotite, monazite, brannerite, titanite and pitchblende -- containing radon-emitting uranium or thorium.
Vinals had also two specimens of a Spanish classic: large (more than 10 cm) brannerite crystals from Sierra Albarrana.