Metatorbernite mineral
Metatorbernite is the copper uranyl phosphate mineral Cu(UO2)2(PO4)2(H2O)4·4H2O in the September 2026 IMA list, with grandfathered status G. The year 1916 is a historical description year, not a numbered IMA approval. Its ideal eight-water composition is distinct from twelve-water torbernite, arsenate metazeunerite, calcium meta-autunite, uranyl ions and elemental uranium or copper. Locock and Burns grew synthetic metatorbernite in copper-bearing silica gel at room temperature over three weeks and refined an epoxy-coated, merohedrally twinned crystal in P4/n. Its 88.3(6)% fitted copper-site occupancy and constrained hydrogen model are specimen-specific; proposed oxonium charge compensation was not directly established. The 2023 natural Cornwall crystal instead gave the preferred P4/nmm model with a smaller c repeat. These are source-specific structural models, not grounds to replace all specimens with one symmetry or transfer occupancy between them. Thermal behavior below is abiotic laboratory evidence; neither criticality nor microbial extraction, isolated-product recovery or industrial deployment is inferred.
Microbial & Biochemical Mechanisms (1)
Specimen-dependent abiotic dehydration and thermal structural change
other
Heating changes the interlayer geometry and diffraction of natural metatorbernite and its synthetic analogue. The natural powder experiment reports stepwise dehydration, whereas a separate sealed-capillary synthetic experiment becomes poorly crystalline or X-ray amorphous at its high-temperature endpoint and recrystallizes on cooling. These observations have different specimen preparation and environmental conditions and do not establish a universal dehydration threshold or uranium recovery process.
Experimental Context & Analytical Limits:
Nazarchuk et al. used natural sample 1 from Old Gunnislake Mine, Cornwall, UK; semiquantitative EDS gave Cu:U:P = 0.89:2.11:1.99 with no detected As admixture, not a quantitative water assay. Single-crystal measurements covered 100-300 K. Ground powder was prepared from heptane suspension on Pt; the metatorbernite plot is the air-heating arm. Methods specify 293-673 K, 10 K steps, 2 K/min and approximately 30 min collection per step; Figure 4 caption starts at 313 K while the plot also labels 303 K. Several runs are stated without a numerical replicate count. Separately, Kulaszewska et al. precipitated the synthetic phosphate end member from uranyl nitrate, copper chloride and phosphoric acid, settled it for 48 h, vacuum-filtered and washed it, then dried it at 40 degrees C to constant weight. High-resolution synchrotron diffraction used a 0.5-mm borosilicate capillary secured with Kapton tape, described as sealed in Discussion, initially at 293 K, cooled to 105 K and subsequently heated. Methods give nominal 50 K steps and 30 min collections; the plotted temperatures are not uniformly 50 K apart. The mixed phosphate-arsenate member and natural South Terras spoil samples are separate arms.
Nazarchuk et al. used natural sample 1 from Old Gunnislake Mine, Cornwall, UK; semiquantitative EDS gave Cu:U:P = 0.89:2.11:1.99 with no detected As admixture, not a quantitative water assay. Single-crystal measurements covered 100-300 K. Ground powder was prepared from heptane suspension on Pt; the metatorbernite plot is the air-heating arm. Methods specify 293-673 K, 10 K steps, 2 K/min and approximately 30 min collection per step; Figure 4 caption starts at 313 K while the plot also labels 303 K. Several runs are stated without a numerical replicate count. Separately, Kulaszewska et al. precipitated the synthetic phosphate end member from uranyl nitrate, copper chloride and phosphoric acid, settled it for 48 h, vacuum-filtered and washed it, then dried it at 40 degrees C to constant weight. High-resolution synchrotron diffraction used a 0.5-mm borosilicate capillary secured with Kapton tape, described as sealed in Discussion, initially at 293 K, cooled to 105 K and subsequently heated. Methods give nominal 50 K steps and 30 min collections; the plotted temperatures are not uniformly 50 K apart. The mixed phosphate-arsenate member and natural South Terras spoil samples are separate arms.
Curated Evidence Points:
Support
Source:
nazarchuk2023
Sections 3.2 and 4 and Figure 4 report diffraction changes attributed to dehydration at approximately 353, 373 and 483 K for natural sample 1 in air, with strongest expansion normal to its autunite-type layers. Table 1 and Section 2.3 support the P4/nmm refinement of this natural crystal; the authors explicitly tested alternative models and did not obtain an equivalent satisfactory P4/n refinement. The geometric thermal-expansion fits and powder patterns are complementary measurements, not independent metal-recovery trials.
Partial
Source:
nazarchuk2023
The extra transitions in mixtures of pristine and partly dehydrated metatorbernite are given as 313 and 463 K in Section 3.2 but 303 and 473 K in Section 4; neither pair is adopted as a corrected threshold. The article does not provide a matched water mass balance for these diffraction arms, and instability can begin during handling or irradiation. Its fitted bond-length changes and proposed interlayer explanation do not identify every dehydration product. The cited crystallographic deposits remain unacquired, so no independent re-refinement is claimed.
Support
Source:
kulaszewska2019
Section 3 and Figure 4 show the synthetic phosphate end member retaining tetragonal indexing on cooling, expanding anisotropically on heating, and developing a high-temperature amorphous signature followed by an unidentified crystalline product on cooling. The source distinguishes this sealed-capillary behavior from earlier natural specimens heated in open systems. Its room-temperature synthetic solid-solution series supports phosphate-arsenate substitution as another experimental variable; it does not prove all natural samples are pure end members.
Support
Source:
kulaszewska2019_si
Figure S5 displays distinct synthetic metatorbernite traces through 423 K, a largely diffuse 473 K trace, and a changed 293 K trace after cooling; S6 shows departure from the preceding a/c trend above approximately 373 K. These figures support the qualitative sequence, without assigning a sharp transition temperature from coarse sampling.
Partial
Source:
kulaszewska2019
The abstract places amorphization at 473 K, Results says greater than 473 K, a later discussion says greater than 423 K, and Conclusion says above 373 K. Those wordings are retained as inconsistent bounds, not combined into one precise threshold; S5 distinguishes the plotted 423 and 473 K states. The study does not directly establish water stoichiometry at every temperature, and the high-temperature and cooled products are not completely identified. Its natural spoil compositions were inferred from a synthetic lattice-parameter calibration after 80-degree-C drying; they are not direct assays of untreated in-situ hydration or mineral-specific uranium retention.
Sources & References
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ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Metatorbernite row, PDF page 142: Cu(UO2)2(PO4)2(H2O)4·4H2O, G, 1916; definitions on page 1. Current authority PDF acquired and row visually checked.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15) -
locock2003: Locock AJ and Burns PC (2003). Crystal structures and synthesis of the copper-dominant members of the autunite and meta-autunite groups: torbernite, zeunerite, metatorbernite and metazeunerite. Canadian Mineralogist 41:489-502. DOI 10.2113/gscanmin.41.2.489. Complete 14-page original; synthesis pages 490-491, refinement page 492, Tables 1, 4-5, 8-9 and 12-13, Figures 1-4, natural-equivalence qualification page 497. Retained round103 PDF rechecked; cited CISTI reflection deposit remains unacquired.
https://www.rruff.net/doclib/cm/vol41/CM41_489.pdf (accessed 2026-10-15) -
nazarchuk2023: Nazarchuk EV et al. (2023). High-Temperature Crystal Chemistry of Meta-Autunite Group Minerals: Metatorbernite, Cu(UO2)2(PO4)2(H2O)8 and Metazeunerite, Cu(UO2)2(AsO4)2(H2O)8. Crystals 13, 1688. DOI 10.3390/cryst13121688. Complete 13-page publisher PDF: Sections 2.1-2.4, Table 1, Figures 1-5 and Sections 3.2, 4-5. Cited CSD/ICSD deposit numbers 2307946-2307947 were not retrieved; the access service returned an access notice.
https://doi.org/10.3390/cryst13121688 (accessed 2026-10-15) -
kulaszewska2019: Kulaszewska J, Dann S, Warwick P and Kirk C (2019). Solid solution formation in the metatorbernite-metazeunerite system (Cu(UO2)2(PO4)2-x(AsO4)x.nH2O) and their stability under conditions of variable temperature. Philosophical Transactions A 377, 20180242. DOI 10.1098/rsta.2018.0242. Complete published PMC HTML, Methods 2b-c, Results 3, Table 1, Figures 1-5 and Conclusion 4 inspected. Publication is 2019 despite the DOI year and the 2023 paper reference. Institutional 23-page PDF is visibly marked For Review Only and is not treated as the final version.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6501896/ (accessed 2026-10-15) -
kulaszewska2019_si: Royal Society supplementary material for Kulaszewska et al. (2019), DOI 10.1098/rsta.2018.0242. Figshare article 7867979, file 14651870, rsta20180242_si_001.doc. Original DOC acquired and its seven-page PDF conversion visually inspected: Figures S1-S9. This is dependent evidence from the same experiment, not an independent replication or a raw diffraction dataset.
https://doi.org/10.6084/m9.figshare.7867979 (accessed 2026-10-15)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-15T22:14:36.174369Z |
codex (GPT-6; codex) | CREATE | Added current-IMA identity and separately scoped natural and synthetic abiotic thermal evidence; retained specimen, symmetry, hydration, deposit-access and conflicting-temperature limits without inferred criticality or microbial recovery. |
Record source: data/records/metatorbernite.yaml