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Ningyoite mineral

Ningyoite is an approved mineral species listed as (U,Ca,Ce)2(PO4)2·1-2H2O in the September 2026 IMA compilation, with status A and special-procedure entry 1962 s.p. Experimental papers use the calcium U(IV)-phosphate formulations CaU(PO4)2·H2O or CaU(PO4)2 for their assigned products; those formulas do not establish every natural specimen's composition. The mineral is distinct from elemental uranium, uramphite, uraninite and molecular U(IV)-phosphate complexes. The observations below concern laboratory products, not a natural ore feed or an industrial recovery process. No criticality designation is inherited from uranium.

Microbial & Biochemical Mechanisms (2)

Ningyoite formation during thermophilic U(VI)-phosphate reduction

redox transformation Microbial

Associated Organisms: Carboxydothermus ferrireducens (NCBITaxon:54265)

Cultures reported as Thermoterrabacterium ferrireducens converted a largely precipitated U(VI)-phosphate feed into a gray U(IV) product assigned to ningyoite by XRD, supported by X-ray absorption and electron microscopy. Growth increased in U(VI)-containing cultures compared with U(VI)-free controls. This supports the reported culture-associated reduction and mineral formation, without establishing a particular electron transfer protein, a direct-contact pathway, or a ningyoite recovery yield. The article names the species without explicitly specifying a strain accession for this experiment.

Experimental Context & Analytical Limits:
Khijniak et al. inoculated 5% by volume fumarate-grown culture into anaerobic bicarbonate-buffered medium initially pH 7.0, with 0.2 g/L yeast extract and glycerol. Methods specify 3 mL/L glycerol, whereas Figure 3 specifies 30 mmol/L; these source expressions are retained without assuming equivalence. Standard assays used 2.5 mM U(VI) added as uranyl acetate, 10 mL medium in 27 mL Balch tubes, 65 degrees C, darkness and no agitation. The medium contained 2.4 mM phosphate and immediately produced a yellow precipitate assigned to uramphite. The base assay had no added reducing agent; separate growth comparisons included Na2S. Figure 2 examines 1, 2.5, 5 and 10 mM initial U(VI). Supernatant and HCl-dissolved centrifuged solids were assayed separately for U(VI), with duplicate sample preparations; biological replication is not clearly distinguished. Cells were counted microscopically.
Curated Evidence Points:
Pages 6423-6424 and Figure 1 identify the initial U(VI) solid as uramphite and the culture-associated gray solid as ningyoite. XANES indicates U(IV), EXAFS supports coordinated phosphate, and cryostage microscopy checks the observed rounded particles against drying artifacts. Noninoculated medium retained the initial precipitate and U(VI). 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 is not a measured ningyoite phase fraction or isolated-product yield.
The reported reduction and growth were absent at 5 and 10 mM U(VI), limiting concentration generalization. Figure 3 includes U(VI)-free growth controls with and without added sulfide; the authors interpret increased cell yields as growth coupled to U(VI) reduction. These comparisons do not identify an enzyme or exclude every dissolved-intermediate pathway. The glycerol discrepancy, incompletely specified culture replication and lack of quantitative mineral purity or persistence measurements limit process extrapolation. No field treatment is demonstrated.

Minority ningyoite in MI-1 spore-associated U(VI) reduction products

biomineralization Microbial

Associated Organisms: Desulforamulus reducens MI-1 (NCBITaxon:349161)

A spore preparation of the organism reported as Desulfotomaculum reducens MI-1 yielded biomass-associated reduced uranium that included a small crystalline fraction assigned to ningyoite. Most uranium was interpreted as molecular U(IV) associated with biomass, and another U(IV)-phosphate phase co-occurred. The observation does not establish ningyoite as the dominant or universally produced phase. Proposed calcium release from damaged spores is a hypothesis, not a demonstrated mineralization pathway.

Experimental Context & Analytical Limits:
Bernier-Latmani et al. sample I used 300 micromolar U(VI) as uranyl acetate, 1.6 x 10^8 spores/mL, 20 mM H2 and spent Widdel low-phosphate medium from pyruvate-grown cultures. Table SI-1 describes the basal WLP formulation with 0.68 mM CaCl2·2H2O, 0.22 mM KH2PO4, 30 mM bicarbonate and 20 mM PIPES, initially pH 7.3; amended growth media were reported as pH 7.0 +/- 0.3. Spent-medium phosphate was measured as 48 +/- 0.6 mg/L and exceeded the recipe contribution because of yeast extract. Sporulation was induced in a fermentative culture with acetate and sulfate for several weeks, followed by one oxic-water and three anoxic-water washes. Sample I is a spore-preparation assay, not a vegetative-growth assay. The article does not clearly give its incubation temperature or a mineral-specific harvest time. Aqueous U(VI) time courses and endpoint phase characterization are different measurements; no ningyoite mass yield is reported.
Curated Evidence Points:
Table 1 assigns sample I to D. reducens spores. Figure SI-3A contains the SAED pattern interpreted as CaU(PO4)2 and additional nanoparticles assigned to U2O(PO4)2. Figure SI-4, sample I, shows associated U, P and Ca signals, supporting but not independently proving the diffraction assignment. XANES in Figure SI-2 supports reduced uranium. Neither aqueous U(VI) loss nor elemental colocalization alone is used here to identify ningyoite.
The Crystalline U(IV)-Orthophosphates section notes that the expected U-Ca contribution was not observed in bulk EXAFS, consistent with minority ningyoite. Figures SI-3A/SI-4 and section SI-1 do not quantify its fraction; fits to the predominant molecular U(IV) permit both P and C neighbors. The authors did not detect ningyoite in the C. acetobutylicum systems despite their higher medium Ca concentration, so calcium concentration alone does not explain formation. Spore-integrity loss and Ca-dipicolinate release were proposed explanations, not independently tested causes. The phase comparison does not establish an abiotic nucleation baseline, long-term stability or a recoverable mineral yield.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Ningyoite row, PDF page 155; column definitions on pages 1-2. Retained original rechecked on the access date.
    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, 6423-6426. DOI 10.1128/AEM.71.10.6423-6426.2005. Full article including Figures 1-3, read in the Strathclyde repository copy.
    https://doi.org/10.1128/AEM.71.10.6423-6426.2005 (accessed 2026-10-11)
  3. bernier_latmani2010: Bernier-Latmani et al. (2010). Non-uraninite Products of Microbial U(VI) Reduction. Environmental Science & Technology 44, 9456-9462. DOI 10.1021/es101675a. D. reducens methods, Tables 1-2, Figure 1, Crystalline U(IV)-Orthophosphates; original Supporting Information section SI-1, Table SI-1, Figures SI-1/SI-2, SI-3A and SI-4 sample I.
    https://doi.org/10.1021/es101675a (accessed 2026-10-11)
  4. ncbi_ferrireducens: NCBI Taxonomy 54265, Carboxydothermus ferrireducens, species. The live Datasets API resolves Thermoterrabacterium ferrireducens to this current name and species node; no strain ID is inferred.
    https://api.ncbi.nlm.nih.gov/datasets/v2/taxonomy/taxon/Thermoterrabacterium%20ferrireducens (accessed 2026-10-11)
  5. ncbi_mi1: NCBI Taxonomy 349161, Desulforamulus reducens MI-1. Datasets API identifies the strain node; the taxonomy browser lists Desulfotomaculum reducens strain MI-1 as an equivalent name.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=349161 (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T21:40:23Z codex created Added IMA-grounded ningyoite identity and two source-specific laboratory observations, retaining taxon scope, controls, source discrepancies, minority-phase evidence and recovery limits.

Record source: data/records/ningyoite.yaml