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Natroboltwoodite mineral

Natroboltwoodite is a sodium-bearing uranyl silicate hydrate mineral, distinct from potassium-bearing boltwoodite and elemental uranium. The September 2026 IMA list gives Na(UO2)(SiO3OH)(H2O), status Rn and the special-procedure entry 2007 s.p.; that entry records renaming, not an ordinary approval accession. Historical sodium boltwoodite and Na-boltwoodite terminology is retained for the experimental material below. Ilton and colleagues used synthetic material represented as Na(UO2)(SiO3OH)·1.5H2O. Its measured bulk U/Si and U/Na ratios were approximately one, but minor impurities could not be excluded and its hydration was not reconciled with the current IMA one-water formula. The laboratory dissolution results therefore describe that characterized synthetic preparation, not a universal composition or behavior of natural natroboltwoodite. No criticality, microbial mechanism or industrial recovery claim is inferred.

Microbial & Biochemical Mechanisms (1)

Abiotic bicarbonate-associated dissolution of synthetic sodium boltwoodite

other

The seven-day series was nonmonotonic at low added bicarbonate: filtered aqueous uranium initially fell from 3.4 micromolar at zero to 1.4 micromolar at 0.1 mM, and silicon from 40.1 micromolar at zero to 8.0 micromolar at 0.6 mM. Higher-bicarbonate arms showed enhanced U and Si concentrations with accompanying higher pH; this does not establish a monotonic response over the entire series. Pretreatment altered uranium release and improved apparent congruence in selected arms. The experiments did not separate carbonate-complexation effects from pH-dependent surface reactions, or demonstrate isolated-product recovery.

Experimental Context & Analytical Limits:
Ilton et al. prepared material from uranyl acetate and sodium metasilicate at pH 10.5, followed by heating and a seven-day 150 degrees C hydrothermal treatment. Dissolution used 0.25 g synthetic solid in 100 mL solution, 250 mL HDPE bottles, an orbital shaker, atmospheric carbon dioxide and 23 ± 2 degrees C for seven days. Added NaHCO3 ranged from zero to 50 mM; NaNO3 maintained sodium near 50 mM. The once-sampled seven-day series was duplicated. Separate kinetic arms and higher-loading arms were sampled over time. Solution aliquots passed 0.2 micrometre Teflon filters, with the first 1 mL discarded; ICP-AES measured U and Si. Pretreated arms used solid preleached in 50 mM bicarbonate for 24 hours.
Curated Evidence Points:
Table 1 reports duplicate-average seven-day U concentrations of 3.4 micromolar at zero added bicarbonate and final pH 6.76, 28.7 micromolar at 1.2 mM and pH 8.06, and 774.2 micromolar at 50 mM and pH 9.63. Corresponding Si values are 40.1, 11.9 and 648.1 micromolar. Figures 4-8 support the distinction between once-sampled endpoints, time courses and pretreated material. At 1.2 mM the pretreated and untreated kinetic arms ended at 8.3 and 32.7 micromolar U, respectively, with similar Si concentrations (17.2 and 17.4 micromolar). These are filtered solution concentrations, not recovery percentages or intrinsic dissolution-rate constants.
Figures 6 and 10 and Sections 4.1-4.3 limit the broad near-congruent dissolution claim. Untreated low-bicarbonate arms lost aqueous U after initial release, and several higher-bicarbonate arms had excess U relative to Si. A minor U-rich, Si-poor contaminant and secondary precipitation were proposed without identifying those phases directly. Near-congruent behavior was stronger after pretreatment at 6 and 50 mM. Some seven-day endpoints had not attained steady state. Derived equilibrium constants and proposed molecular causes are model-dependent; no one value is imposed on all arms or on the natural mineral.
Context_only Source: pnnl_ilton2006
The institutional landing abstract gives a different interpretation of calculated solubility constants from the final paper. This is retained as a source-version discrepancy, not treated as an independent conflicting experiment or proof of a published correction. The accepted measured endpoints above come from the final paper's Table 1.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Natroboltwoodite row, PDF page 152; status and special-procedure definitions, page 1. Official PDF freshly acquired and row visually inspected. The row cites Doklady Akademii Nauk SSSR 221 (1975), 195 and Crystal Growth and Design 22 (2022), 1202. The latter primary article was located as DOI 10.1021/acs.cgd.1c01152, but its complete main text was unavailable; its experimental and structural claims are not accepted here from indexed excerpts or supplements alone.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-16)
  2. ilton2006: Ilton ES, Liu C, Yantasee W, Wang Z, Moore DA, Felmy AR, Zachara JM (2006). The dissolution of synthetic Na-boltwoodite in sodium carbonate solutions. Geochimica et Cosmochimica Acta 70:4836-4849. DOI 10.1016/j.gca.2006.06.1553. Complete published 14-page PDF, Tables 1-4 and Figures 1-12 inspected. Methods pages 4837-4838; characterization pages 4838-4840; arm-specific measurements Table 1 and Figures 4-8; limitations pages 4843-4848. The powder XRD data used for phase assignment are explicitly not shown in the article.
    https://doi.org/10.1016/j.gca.2006.06.1553 (accessed 2026-10-16)
  3. pnnl_ilton2006: PNNL publication landing record for Ilton et al. (2006), PNNL-SA-46902. Its abstract reports a bicarbonate-dependent solubility-constant range and speciation-model concern differing from the final published paper. Metadata confirms the same DOI; this landing abstract is not substituted for the complete article.
    https://www.pnnl.gov/publications/dissolution-synthetic-na-boltwoodite-sodium-carbonate-solutions (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T03:45:49.222845Z codex (GPT-6; codex) CREATE Added current mineral identity and synthetic bicarbonate dissolution with distinct experimental arms, hydration and source-version limits.
2026-10-16T03:50:23.077196Z codex (GPT-6; codex) EDIT Corrected the nonmonotonic low-bicarbonate trend and scoped higher-range enhancement after independent review issue 446.

Record source: data/records/natroboltwoodite.yaml