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Uramphite mineral

Uramphite is a hydrated ammonium uranyl phosphate mineral with formula (NH4)(UO2)(PO4)·3H2O in the September 2026 IMA compilation. Its status G denotes a grandfathered species and 1957 is the original-description year, not a modern approval number. The mineral is distinct from elemental uranium, dissolved uranyl salts and the U(IV)-phosphate product ningyoite. The experiment below concerns an abiotic precipitate assigned to uramphite within laboratory growth medium, not a natural mineral specimen or ore. No uranium criticality designation is inherited.

Microbial & Biochemical Mechanisms (1)

Culture-associated reduction of a precipitated uramphite analogue

redox transformation Microbial

Associated Organisms: Carboxydothermus ferrireducens (NCBITaxon:54265)

The organism reported as Thermoterrabacterium ferrireducens grew while reducing U(VI) in a medium whose uranium was predominantly in a solid assigned to uramphite. A gray product was assigned to ningyoite by XRD, with X-ray absorption evidence for U(IV) and coordinated phosphate. Noninoculated medium retained the starting precipitate and U(VI). These observations support culture-associated transformation of this precipitated feed; they do not identify an electron-transfer protein or distinguish direct mineral reduction from a pathway involving dissolved uranium. This is the same experiment represented from the product perspective in the ningyoite record, not independent replication.

Experimental Context & Analytical Limits:
Fumarate-grown cultures were transferred at 5% by volume into anaerobic bicarbonate-buffered medium initially pH 7.0. The standard assay used 2.5 mM U(VI), injected as uranyl acetate from a 50 mM stock, and 2.4 mM medium phosphate; a yellow precipitate formed immediately before microbial growth. The experiment used 10 mL medium in 27 mL Balch tubes at 65 degrees C in darkness without agitation, 0.2 g/L yeast extract and glycerol. Methods specify 3 mL/L glycerol whereas Figure 3 specifies 30 mmol/L; equivalence is not assumed. No reducing agent was added in the base assay; separate growth comparisons included Na2S. The article refers the remaining medium recipe to an earlier paper and does not explicitly name a strain accession for this assay. Supernatant U(VI) and U(VI) in centrifuged solids dissolved in 1 M HCl were measured separately by a colorimetric method. Duplicate sample preparation does not clearly establish the number of independent biological cultures. Cells were counted microscopically. Figure 2 separately examines 1, 2.5, 5 and 10 mM starting U(VI).
Curated Evidence Points:
Pages 6423-6424 and Figure 1A identify the starting yellow precipitate, both immediately after preparation and after 68 h without cells, as uramphite using XRD characteristic lines. The association is therefore not based on a formula alone, although quantitative phase purity is unreported. Figures 1B-C and accompanying XANES discussion support a reduced phosphate product assigned to ningyoite. Figure 2 and the text report approximately 80-90% U(VI) reduction within 68 h at 1 or 2.5 mM initial U(VI). This percentage concerns the U(VI) assay, not a uramphite dissolution yield, ningyoite phase fraction or isolated uranium recovery.
No reduction or growth was detected at 5 or 10 mM U(VI), so the favorable lower-loading result does not apply to all concentrations. Figure 3 compares growth with and without U(VI), with additional sulfide and other-acceptor arms, but its kinetics are a separate comparison from Figure 2. The authors infer growth coupled to U(VI) reduction; small dissolved U(VI) pools and the lack of pathway-specific tests prevent an exclusive direct-contact interpretation. Figure 1D describes a mixture of crystals in the uninoculated medium; neither it nor the diffraction patterns establishes a pure natural-mineral feed. The glycerol discrepancy, incomplete replication detail and absent mineral-specific mass balance limit extrapolation. The study does not demonstrate ore treatment, long-term product stability or industrial recovery.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Uramphite row, PDF page 224; status and year definitions on page 1, distribution terms on page 2. Retained official original rechecked on the access date; the official URL was also opened live.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-11)
  2. khijniak2005: Khijniak et al. (2005). Reduction of Uranium(VI) Phosphate during Growth of the Thermophilic Bacterium Thermoterrabacterium ferrireducens. Applied and Environmental Microbiology 71(10), 6423-6426. DOI 10.1128/AEM.71.10.6423-6426.2005. Entire original article and Figures 1-3 rechecked in the Strathclyde repository PDF.
    https://doi.org/10.1128/AEM.71.10.6423-6426.2005 (accessed 2026-10-11)
  3. ncbi_ferrireducens: NCBI Taxonomy. Datasets API resolution of Thermoterrabacterium ferrireducens to Carboxydothermus ferrireducens, species taxon 54265. Species identity does not identify the experimental strain.
    https://api.ncbi.nlm.nih.gov/datasets/v2/taxonomy/taxon/Thermoterrabacterium%20ferrireducens (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T22:18:47Z codex created Added IMA-grounded uramphite identity and the source-specific laboratory reduction of its precipitated analogue, explicitly reusing the ningyoite study while retaining phase, control, concentration, pathway and recovery limitations.

Record source: data/records/uramphite.yaml