Metazeunerite mineral
Metazeunerite is the copper uranyl arsenate mineral Cu(UO2)2(AsO4)2(H2O)4·4H2O in the September 2026 IMA list, with grandfathered status G. The year 1937 is a historical description year, not a numbered IMA approval. Its ideal eight-water composition is distinct from twelve-water zeunerite, phosphate metatorbernite, calcium meta-autunite and elemental uranium, arsenic or copper. Locock and Burns synthesized its analogue hydrothermally at 220(1) degrees C for 24 h after controlled heating, then refined an epoxy-coated, twinned crystal in P4/n at room temperature. The hydrogen model was constrained; metatorbernite copper deficiency is not a metazeunerite result. A later natural German specimen gave a preferred P4/nmm model with a smaller c repeat, while synthetic low-temperature powder data were indexed orthorhombically. These specimen- and condition-specific models are preserved rather than merged. The thermal evidence is laboratory and abiotic; no criticality, microbial mechanism, isolated-product recovery or industrial deployment is inherited from composition.
Microbial & Biochemical Mechanisms (1)
Condition-dependent abiotic structural change and dehydration
other
Natural metazeunerite undergoes diffraction changes interpreted as dehydration during vacuum heating, while a separate synthetic end-member sample shows a reversible low-temperature symmetry change and a distinct high-temperature transformation in a sealed capillary. Phosphate substitution, sample hydration, pressure, atmosphere and thermal history prevent direct transfer of a temperature or product assignment between these arms.
Experimental Context & Analytical Limits:
Nazarchuk et al. studied natural sample 2a from Weisser Hirsch Mine, Saxony, Germany, and 2b from Melekhinskaya Sopka, Sherlovaya Gora, Russia. Semiquantitative EDS ratios Cu:U:As:P were 0.88:2.04:1.81:0.23 and 0.96:1.99:1.97:0.06, respectively; these are slightly phosphate-bearing natural specimens, not chemically verified pure synthetic end members. Single-crystal data explicitly use 2a over 100-300 K. Powder Methods include both specimens, ground from heptane suspension on Pt, and specify a vacuum chamber over 100-573 K, 10 K steps, 2 K/min and approximately 30 min per pattern. Figure 5 and Results label the plotted vacuum experiment 93-573 K and call its sample only 2, leaving its exact 2a/2b assignment unresolved. Separately, Kulaszewska et al. synthesized the arsenate end member with uranyl nitrate, copper chloride and arsenic acid, using 48 h settling, vacuum filtration, washing and 40-degree-C drying to constant weight. Their synchrotron sample was in a 0.5-mm borosilicate capillary secured with Kapton tape and described as sealed, measured initially at 293 K, cooled to 110 K and heated; nominal 50 K intervals and 30 min collections are stated, but plotted steps vary. The mixed-anion member is a separate material arm.
Nazarchuk et al. studied natural sample 2a from Weisser Hirsch Mine, Saxony, Germany, and 2b from Melekhinskaya Sopka, Sherlovaya Gora, Russia. Semiquantitative EDS ratios Cu:U:As:P were 0.88:2.04:1.81:0.23 and 0.96:1.99:1.97:0.06, respectively; these are slightly phosphate-bearing natural specimens, not chemically verified pure synthetic end members. Single-crystal data explicitly use 2a over 100-300 K. Powder Methods include both specimens, ground from heptane suspension on Pt, and specify a vacuum chamber over 100-573 K, 10 K steps, 2 K/min and approximately 30 min per pattern. Figure 5 and Results label the plotted vacuum experiment 93-573 K and call its sample only 2, leaving its exact 2a/2b assignment unresolved. Separately, Kulaszewska et al. synthesized the arsenate end member with uranyl nitrate, copper chloride and arsenic acid, using 48 h settling, vacuum filtration, washing and 40-degree-C drying to constant weight. Their synchrotron sample was in a 0.5-mm borosilicate capillary secured with Kapton tape and described as sealed, measured initially at 293 K, cooled to 110 K and heated; nominal 50 K intervals and 30 min collections are stated, but plotted steps vary. The mixed-anion member is a separate material arm.
Curated Evidence Points:
Support
Source:
nazarchuk2023
Table 1 and Sections 2.3 and 3.2 support P4/nmm for natural crystal 2a at 100 K and strongly anisotropic thermal expansion. Section 3.2 and Figure 5 report powder diffraction changes at approximately 283 and 543 K in vacuum, interpreted as two dehydration steps, and a separate 100-333 K experiment reaching a partially dehydrated state. These are source-assigned events for the specified natural material, not fixed species-wide decomposition temperatures or a metal extraction result.
Partial
Source:
nazarchuk2023
Figure 5c-d caption incorrectly calls its material metatorbernite while the figure introduction, equations and surrounding text refer to metazeunerite, sample 2. The 93 K plotted start differs from the 100 K method boundary; no precise 2a/2b assignment is supplied for Figure 5. The study does not directly measure the water content of each intermediate by a paired mass-loss assay; its suggested greater flexibility of the arsenate layer and delayed water loss remain a structural interpretation. The cited CSD/ICSD files remain unacquired, precluding independent diffraction re-refinement.
Support
Source:
kulaszewska2019
Section 3 and Figure 5 describe the synthetic arsenate end member as tetragonal initially, orthorhombic on cooling to 110 K, mixed orthorhombic/tetragonal at 293 K during reheating, and tetragonal again at 323 K. The authors call the orthorhombic indexing preliminary and identify the high-temperature product as unknown. This observed synthetic sequence differs from the 2023 natural-crystal model and vacuum powder behavior, rather than independently confirming their exact transition temperatures.
Support
Source:
kulaszewska2019_si
Figure S9 gives the synthetic arsenate end-member cooling/heating sequence, including the 110 K, 293 K reheating, 323 K, 373 K, 423 K, 473 K and final cooled 293 K patterns. S7 and S8 instead belong to the mixed phosphate-arsenate composition and are not assigned to pure metazeunerite.
Partial
Source:
kulaszewska2019
The abstract places the new high-temperature phase at 473 K, Results says above 373 K, and the later comparison says 150 degrees C (about 423 K); Figure S9 provides sampled states rather than a unique transition onset. The paper also prints an arsenate-only formula in a sentence calling the composition mixed phosphate-arsenate. Neither that wording nor the mixed-member transition is used as an end-member measurement. Water content at each temperature, the high-temperature product and the causal origin of the low-temperature symmetry change remain unresolved. No quantitative uranium or arsenic recovery, microbial causality or durable field immobilization is demonstrated.
Sources & References
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ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Metazeunerite row, PDF page 143: Cu(UO2)2(AsO4)2(H2O)4·4H2O, G, 1937; 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/metazeunerite.yaml