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Mechanism of Saleeite Formation at the Koongarra Secondary Ore Deposit

  • Takashi Murakami (a1), Hiroshi Isobe (a2), Toshihiko Ohnuki (a2), Tsutomu Sato (a2), Nobuyuki Yanase (a2) and Junko Kiyoshige (a3)...

Abstract

Rock samples in the secondary ore deposit at Koongarra, Australia, were examined mineralogically to clarify the formation mechanism of saléeite (Mg(UO2)2(PO4)2.10H2O), a major secondary uranium mineral in the secondary ore deposit. Sklodowskite (MgSi2U2O11.7H2O) veinlets, present upstream of the ore deposit, are partially replaced by saléeite. Most grains of apatite (Ca5(P04)3F), an accessory mineral of the host rock, are also replaced by saléeite. Thermodynamic calculations by EQ3NR showed that the present Koongarra ground waters are undersaturated with respect to saléeite and also suggested that saléeite can be precipitated under the condition of higher U or P concentrations. Such conditions can be created at the reaction interfaces of dissolving sklodowskite, which releases U, or dissolving apatite, which releases P. The present study indicates that saléeite is formed by local microscale saturation upstream of the secondary ore deposit, which is different from the formation mechanism of saléeite downstream of the ore deposit, where saléeite microcrystals of 1 – 20 nm in size form by catalysis on iron minerals, the weathering products of the host rock.

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Mechanism of Saleeite Formation at the Koongarra Secondary Ore Deposit

  • Takashi Murakami (a1), Hiroshi Isobe (a2), Toshihiko Ohnuki (a2), Tsutomu Sato (a2), Nobuyuki Yanase (a2) and Junko Kiyoshige (a3)...

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