A soft, yellow, radioactive mineral (see radioactivity),
potassium uranyl vanadate (K2[UO2]2[VO4]2.nH2O),
a major ore of uranium and vanadium.
It is found in Colorado, Wyoming, South Dakota, Pennsylvania, Siberia, Zaire,
and Australia as yellow-green crusts or cavity fillings in sandstone and
in fossilized wood. It is finely crystalline (monoclinic), dull or earthy.
Relative density 3–5.
AND PLANETARY SCIENCE