Correction (June 22, 2009)

In our article on uranium in Niger (T. N. M. , June 15-21/09), the reserve numbers for the Arlit, Akouta and Imouraren mines, and the projected annual production for Imouraren should be in tonnes of uranium, not tonnes of uranium oxide as stated. The corrected figures are: for Akouta, reserves of 24,300 tonnes uranium; for Arlit, reserves of 23,000 tonnes uranium, plus resources of 24,000 tonnes uranium and resources of 20,000 tonnes uranium from heap leaching; and for Imouraren, reserves of 180,000 tonnes uranium, and projected production of 5,000 tonnes uranium per year.

The text in the paragraph on the geology of the Tim Mersoi basin should be:

The geological setting of the basin is Devonian to Cretaceous. Production at Arlit and Akouta is from Carboniferous age rocks, and the setting at Azelik and Madouela is also Carboniferous, while at Imouraren, it is Jurassic. The age of mineralization remains controversial, with some arguing for uranium emplacement during or shortly after deposition of the host rocks, and others claiming it is younger.