Geochemical Characteristics of Uranium (U)
1-Atomic no:
92, atomic wt: 238.04
2- Igneous rocks:
ultramafics 0.03, mafics 0.53, Granite 3.9
3- Sedimentary rocks
l.st 2.2, s.st 1.7, shale 3.7 ,Soils: 1
4- Fresh water:
0.5 ppb, (0.05 in humid areas to 5 in arid areas)
5- Associations:
lithophile: V, As, P, Mo, Se, Pb and Cu in Colorado Plateau ores , Co & Ag in some sulfide ores , Au in the South Africa Rand , P in phosphoritite deposits , C in black shales.
6- Rock minerals:
zircon (ZrSiO4), apatite (Ca5 (PO4)3F), allanite complex (aluminosilicate)
7- Industrial sources:
uraninite (UO2), coffinite (USiO4), uraniferous organic matter, carnotite (K2 (UO2)2(VO4)2.3H2O) weathering products: complex carbonates, phosphates, vanadates and silicates, including carnotite, over uraninite ores, organic matter, and to a lesser extent limonite in normal soils: soluble U complexes.
8-Aqueous species:
UO22+, UO2 (CO3)34-, UO2 (CO2)22-, UO2 (HPO4)22-
9- Biological response:
in vegetation, most of the U in the nutrient solution is apparently precipitated in the root tips as autunite, Ca (UO2)2PO4. even so, some U gets through the upper parts of some plant species, where it is useful in biogeochemical prospecting. Because of the association of Se with U deposits of the Colorado plateau, Se indicator plants have successive fully been used in locating U rich areas.
10- Mobility:
mobile to slightly mobile under oxidizing conditions, especially acid or carbonate rich waters, immobile under reducing conditions, strongly sorbed to organic matter and Fe-oxides, may be mobile as organic complexes or colloidal particles.
2-4- Geochemical prospecting applications of uranium
: the content of U in normal soils is not used extensively because of the greater effectiveness of radioactivity and Rn as indicators. U in organic soils and bogs and particularly in organic lake sediments has been shown to be highly effective under specialized conditions. U in stream sediments, especially extractable U, is a useful ore guide, particularly in sediments containing some organic matter. Strong enrichments can occur in organic rich environments; however, U in surface waters is useful but is affected by very large temporal variations and by very low background values in humid regions. U in ground water seems to be good guide if samples can be obtained. Analysis of plants for U has been used successfully in the Colorado Plateau, where it has been known to give an indication of ore through thickness of as much as 15 m of barren cover. Experiments in the swamps of the Arctic taiga country of northern European Russia shown that although both plants and soils shown an anomalies over U ore, soil sampling is generally more satisfactory. U has been used as a guide to U bearing phosphorites.
1-Atomic no:
92, atomic wt: 238.04
2- Igneous rocks:
ultramafics 0.03, mafics 0.53, Granite 3.9
3- Sedimentary rocks
l.st 2.2, s.st 1.7, shale 3.7 ,Soils: 1
4- Fresh water:
0.5 ppb, (0.05 in humid areas to 5 in arid areas)
5- Associations:
lithophile: V, As, P, Mo, Se, Pb and Cu in Colorado Plateau ores , Co & Ag in some sulfide ores , Au in the South Africa Rand , P in phosphoritite deposits , C in black shales.
6- Rock minerals:
zircon (ZrSiO4), apatite (Ca5 (PO4)3F), allanite complex (aluminosilicate)
7- Industrial sources:
uraninite (UO2), coffinite (USiO4), uraniferous organic matter, carnotite (K2 (UO2)2(VO4)2.3H2O) weathering products: complex carbonates, phosphates, vanadates and silicates, including carnotite, over uraninite ores, organic matter, and to a lesser extent limonite in normal soils: soluble U complexes.
8-Aqueous species:
UO22+, UO2 (CO3)34-, UO2 (CO2)22-, UO2 (HPO4)22-
9- Biological response:
in vegetation, most of the U in the nutrient solution is apparently precipitated in the root tips as autunite, Ca (UO2)2PO4. even so, some U gets through the upper parts of some plant species, where it is useful in biogeochemical prospecting. Because of the association of Se with U deposits of the Colorado plateau, Se indicator plants have successive fully been used in locating U rich areas.
10- Mobility:
mobile to slightly mobile under oxidizing conditions, especially acid or carbonate rich waters, immobile under reducing conditions, strongly sorbed to organic matter and Fe-oxides, may be mobile as organic complexes or colloidal particles.
2-4- Geochemical prospecting applications of uranium
: the content of U in normal soils is not used extensively because of the greater effectiveness of radioactivity and Rn as indicators. U in organic soils and bogs and particularly in organic lake sediments has been shown to be highly effective under specialized conditions. U in stream sediments, especially extractable U, is a useful ore guide, particularly in sediments containing some organic matter. Strong enrichments can occur in organic rich environments; however, U in surface waters is useful but is affected by very large temporal variations and by very low background values in humid regions. U in ground water seems to be good guide if samples can be obtained. Analysis of plants for U has been used successfully in the Colorado Plateau, where it has been known to give an indication of ore through thickness of as much as 15 m of barren cover. Experiments in the swamps of the Arctic taiga country of northern European Russia shown that although both plants and soils shown an anomalies over U ore, soil sampling is generally more satisfactory. U has been used as a guide to U bearing phosphorites.