Three borides are known: UBr2 , UBr3 , and UBr4 . The
most attention has been paid to the tetraboride, the properties of which
are: melting point, >2,100 degrees C (but oxidizes rapidly above 600
degrees C); sp gr# = 9.38 g/mL; thermal expansion, 7.1 X 10-6 (20
to 1,000 degrees C); modulus of rupture (20 degrees C), 60,000 psi (414
MPa); electrical resistivity, 3 X 10-5 ohm.cm. Dodd
The series of nuclides resulting from the decay of uranium-238. The mass
numbers of all members of the series are given by 4n+2, where n is an
integer; therefore, the sequence is also known as the 4n+2 series. It is
also known as the uranium-radium series. Glasstone
Galena containing Pb 206, the lead isotope produced by radioactive decay
of U 238.
See:radium G
More than 150 uranium-bearing minerals are known to exist, but only a few
are common. The five primary uranium-ore minerals are pitchblende,
uraninite, davidite, coffinite, and brannerite. These were formed by
deep-seated hot solutions and are most commonly found in veins or
pegmatites. The secondary uranium ore minerals, altered from the primary
minerals by weathering or other natural processes, are carnotite,
tyuyamunite and metatyuyamunite (both very similar to carnotite),
torbemite and metatorbernite, autunite and metaautunite, and uranophane.
Pearl
The important oxides of uranium are UO2 , UO3 , and U (sub
3) O8 . The dioxide (melting point 2,880 degrees C) is used as a
nuclear-fuel element. Uranium oxide has been used to produce red and
yellow glazes and ceramic colors. Dodd
Red, orange, and yellow; UO3 ; an intermediate product in the
refining of uranium.
See:torbernite; uranite.
See:uran
A tetragonal mineral, Ba(UO2 )2 (PO4 )2 .10H
2 O ; autunite group; yellow-green.
A meteorite. Fay
A monoclinic mineral, Ca(UO2 )2 [(SiO3 )(OH)]2
.5H2 O ; dimorphous with uranophane-beta; radioactive; soft;
yellow; as secondary coatings, commonly associated with autunite and
torbernite around uranium deposits; a source of uranium.
A monoclinic mineral, (UO2 )6 (SO4 )(OH)10
.13H2 O ; radioactive; yellow; secondary on uraninite; associated
with gypsum and metauranopilite.
A variety of thorium silicate; thorite containing a small percentage of
oxide of uranium. Fay
A monoclinic mineral, BiUO3 (OH)3 ; radioactive; orange to
red; an oxidation product of pitchblende. Also spelled uranospherite.
See:samarskite
See:liebigite
Thorianite with uranium in partial substitution for thorium.
Crosby
A uranian variety of thorite.
See:uranophane
See:torbernite