Uranium is a relatively common element in the crust of the Earth. It is a metal approximately as common as tin or zinc, and it is a constituent of most rocks.
Some typical concentrations .....
Very high-grade ore (Canada) greater than 20% U, (or 200,000 ppm U)
High-grade ore ... 2% U, (or 20,000 ppm U)
Low-grade ore ... 0.1% U, (or 1,000 ppm U)
Very low-grade ore (Namibia) ... 0.01% U, (or 100 ppm U)
Granite ... 3-5 ppm U
Sedimentary rock ... 2-3 ppm U
Earth continental crust (av) ... 2.8 ppm U
Seawater .... 0.003 ppm U
Groundwater ....variable (depends on proximity to U mineralization)
Where uranium is at low levels in rock or sands (certainly less than 1,000 ppm) it needs to be in a form which is easily separated for those concentrations to be called ore – that is, implying that the uranium can be recovered economically. This means that it needs to be in a mineral form that can easily be dissolved by sulfuric acid, sodium carbonate, or induced by application of CO2 for leaching and converting from solid to solution.
An orebody is, by definition, an occurrence of mineralisation from which the metal is economically recoverable. It is therefore relative to both costs of extraction and market prices. At present neither the oceans nor any granites are orebodies, but conceivably either could become so if prices were to rise sufficiently.
Measured resources of uranium, the amount known to be economically recoverable from orebodies, are thus also relative to costs and prices. They are also dependent on the intensity of past exploration effort, and are basically a statement about what is known rather than what is present in the Earth crust, epistemology rather than geology.
Changes in costs or prices, or further exploration, may alter measured resource figures markedly. At ten times the current price, seawater might become a potential source of vast amounts of uranium.
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Managed & Built by I2M Consulting, LLC | © 2010-