Carnotite mineral

Carnotite is the potassium uranyl vanadate mineral K2(UO2)2(VO4)2·3H2O. The September 2026 IMA-CNMNC list recognizes it with grandfathered status G; 1899 is the original-description year, not an IMA approval accession. This mineral-species owner is distinct from the broader carnotite group, elemental uranium or vanadium, mixed uranium ore and dissolved uranyl or vanadate salts. Glasauer et al. (2022) identified K-carnotite together with metatyuyamunite by X-ray diffraction in the final fine fraction of a natural uranium-vanadium sandstone incubated with living Shewanella putrefaciens CN32. The starting assemblage was identified as metatyuyamunite and fritzscheite, rather than a pure carnotite feed. Figure 1b and sections 3.1 and 3.3 support this bounded phase-occurrence comparison. Increased K and decreased Ca in the final fine fraction are consistent with interlayer-cation exchange. The study does not isolate a uniquely biological cause of carnotite formation: the authors recognize both biotic and abiotic pathways, and do not provide a matched final abiotic diffraction series. Section 3.2 describes tyuyamunite-to-carnotite conversion whereas the conclusion names fritzscheite as the precursor; this record assigns neither unique precursor. The shared laboratory experiment used 1.6 g of mixed sandstone in 80 mL defined medium with 10 mM sodium lactate and 1 mM phosphate, nitrogen degassing and autoclaving before inoculation, followed by an anoxic glovebox incubation extending to ten months. Treatments were in triplicate. These three mineral records refer to the same experiment, not independent replications. Bacteria-free solution controls were included, but do not isolate each phase's fate. The mixed-ore spectra support partial V reduction while U remained predominantly U(VI); results from the separate soluble-salt arm must not be transferred to this mineral. Dissolved U was low, rather than established to be exactly zero. Section 3.2 gives a V plateau time of 120 days while Figure 2 labels the time axes in hours, so no exact kinetic endpoint is adopted. The species identity and culture-associated phase occurrence are curated here without a mineral-specific mechanism assertion. Carnotite formation is not established as obligatory, exclusively biological, a pure recovered product or an industrial process. No criticality designation is inherited from its constituent elements.

Record source: data/records/carnotite.yaml