Low-grade carnotite material in the Morrison Formation on the Colorado Plateau
The Geological survey has used three grade classes in calculating reserves on the Colorado Plateau. The highest grade cut-off was 0.1 percent U3O8 or 1.0 percent V2O5, as this was essentially the cutoff being used by the mills. Although the tonnage calculated at the lowest grade cut-off (0.02 percent U3O8 or 0.2 percent V2O5) is nearly twice the tonnage of the second grade class (0.05 percent U3O8 or 0.5 percent V2O5), the amount of contained metal is only about 14 percent greater. The increment of reserves gained by using the lowest grade cut-off contains only about 0.8 pounds of U3O8 and 6 ...
(For more, see "View full record.")