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·

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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.