Primary minerals like uraninite
, coffinite, pitchblende are found below water table while secondary minerals like uranophane, metatyuyamunite, carnotite are found in the the oxidized environments/above water table hosted by Vihowa group in Sulaiman, Manchar/Vihowa group in Kirthar and Potwar group in Kohat and Potwar basins.
At the deposit scale, the average proportions of U minerals are 56% coffinite, 31% brannerite, and 13% uraninite
; however, individual samples show large variations (; see Figure 1).
It occurs naturally in low concentrations of a few parts per million in soil, rock and water and is commercially extracted from uranium-bearing minerals such as uraninite
As mentioned before, China and the Soviet Union signed six agreements on nuclear science and technology and nuclear industry construction: two on uraninite
exploration and mining (1954 and 1956), one on nuclear physics (1955), two on nuclear industrial construction (1956 and 1958), and one on nuclear weapons research and production (1957).
In contrast, U dissolves in oxidizing environments, predominantly in the form of the uranyl ion (U[O.sub.2.sup.2+]), and precipitates in reducing environments as U[O.sub.2] (uraninite
) (Hem 1992).
Studies on drill core from Laramide's drilling have confirmed the high proportion of uraninite
in the Redtree ore, which responds favourably to conventional metallurgy.'
The invention further provides compositions produced according to the foregoing methods, including compositions comprising enriched uraninite
. (US 7,452,703)
An occurence of rhenium associated with uraninite
in Coconino Country, Arizona // Economic Geology.
, the solid reduced form of uranium, is not very stable in the presence of dissolved oxygen.
Other U-bearing minerals, such as uraninite
, may contain some initial Pb.
 A 1980 issue entitled 'Uranium Resources' shows the crystal structure of uranium oxide, [UO.sub.2], known in nature as uraninite
, which has a fluorite structure.
The observed paragenetic reaction tre nd; [UO.sub.2][greater than] uranyl oxide hydrates [greater than] uranlyl silicates [greater than] uranyl alkali + alkaline earth silicates, is identical to that observed in surficial weathering zones of natural uraninite
Thus, dissolved uranium settles out as uraninite
(uranium ore) and can be filtered from water.
Uranium minerals (uraninite
) generally occur as grape-like crystals imbedded in micritic kaolinite (Figures 5(c) and 5(d)).