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Andersonite mineral

Andersonite is the sodium calcium uranyl carbonate hydrate mineral with the September 2026 IMA formula Na2Ca(UO2)(CO3)3(H2O)6. Its grandfathered status G and original-description year 1951 are not an approval accession. A natural Cane Springs Canyon specimen studied in 2018 was refined in trigonal R-3m with 5.3 H2O per formula unit, distinct from the ideal six-water formula and from synthetic preparations. The authors proposed variable channel-water occupancy and a (5+x)H2O formulation; that proposal does not replace the current IMA formula here. This mineral is distinct from elemental uranium and a uranium commodity. No criticality designation, microbial process or industrial recovery is inferred.

Microbial & Biochemical Mechanisms (1)

Laboratory thermal alteration of natural andersonite

other

In-air powder X-ray diffraction showed loss of andersonite crystallinity around 100 degrees C: unit-cell trends changed after 95 degrees C and the last diffraction relicts occurred at 105 degrees C. Subsequent heating produced diffraction peaks assigned to other uranium-bearing phases. Cooling did not reverse the reported transformation. Water release and framework collapse are the authors' structural interpretation; this study did not directly measure water loss by simultaneous thermogravimetry or evolved-gas analysis. These are laboratory phase observations, not a uranium extraction yield or a demonstrated recovery process.

Experimental Context & Analytical Limits:
Natural sample 1272 in the University of Notre Dame collection came from Cane Springs Canyon, San Juan County, Utah, USA. Ground crystalline material was heated on a platinum strip in air from 25 to 800 degrees C at 2 degrees C/min, with 5-25 degree C increments and approximately 30 minutes of diffraction collection per step. PXRD and EDX indicated minor quartz inclusions; the sample was not asserted to be perfectly pure. Single-crystal refinement at 100 K gave 5.3 H2O per formula unit with disordered water sites and some restrained O-H distances. Powder loading, particle-size distribution and independent replicate counts were not specified.
Curated Evidence Points:
Section 2.4 describes the heating and cooling protocol. Section 3.2 and Figure 4 show the nearly unchanged initial powder pattern, changes after 95 degrees C and the last andersonite relicts at 105 degrees C. Residual platinum-holder and quartz peaks are distinguished from andersonite. These temperatures describe this stepped experiment, not universal equilibrium or kinetic decomposition thresholds.
Sections 3.1 and 4 connect refined channel-water occupancy and anisotropic thermal expansion with inferred dehydration. Direct gravimetric water-loss curves are absent from this experiment. The structural estimate of 5.3 H2O is not an independent bulk water-content measurement, and the authors' molecular explanation remains distinct from observed PXRD.
Context_only Source: gurzhiy2018
Section 3.2 assigns Na4(UO2)(CO3)3 near 340 degrees C, CaUO4 at 575 degrees C, Na2U2O7 above 600 degrees C and NaUO3 beginning at 700 degrees C. NaUO3 is described as the only distinguishable phase at 800 degrees C, with a quartz peak overlapped; this is not a quantified pure-product yield or a direct uranium-valence determination. The methods specify CoKalpha radiation, whereas Figure 4 labels its horizontal axis CuKalpha. That unresolved discrepancy precludes reconstructing exact peak positions here.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Andersonite row, PDF page 10; status and year definitions page 1. Fresh official PDF and row inspected.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-16)
  2. gurzhiy2018: Gurzhiy VV, Krzhizhanovskaya MG, Izatulina AR, Sigmon GE, Krivovichev SV, Burns PC (2018). Structure Refinement and Thermal Stability Studies of the Uranyl Carbonate Mineral Andersonite, Na2Ca[(UO2)(CO3)3]·(5+x)H2O. Minerals 8:586. DOI 10.3390/min8120586. Complete 12-page publisher v2 PDF inspected, including methods sections 2.1-2.4, Tables 1-3, Figures 1-4 and sections 3.2-4. Earlier publisher PDF retained separately. Supplementary crystallographic files were not acquired, and no deposited structure was re-refined.
    https://doi.org/10.3390/min8120586 (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T08:06:50Z codex (GPT-6; codex) CREATE Added verified andersonite identity and scoped primary laboratory evidence with natural/synthetic distinctions and source limitations.

Record source: data/records/andersonite.yaml