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Metazellerite mineral

Metazellerite (IMA 1965-032) is an IMA-accepted lower-hydrate calcium uranyl carbonate mineral with IMA September 2026 Master List formula Ca(UO2)(CO3)2·3H2O. Described by Coleman, Ross, and Meyrowitz (1966) from the oxidized zone of the Lucky Mc uranium mine, Gas Hills district, Fremont County, Wyoming, USA (and recognized in additional western United States deposits), where it forms as the chalky yellow dehydration product of zellerite (Ca(UO2)(CO3)2·5H2O; Table 2, p. 1571 raw analysis: CaO 10.8, UO3 56.6, CO2 17.7, H2O+ 13.0, SiO2+insol. 0.5, R2O3 1.0, K2O 0.2, Na2O 0.4, total 100.2 wt%, with H2O- 6.9 wt% determined separately at 110 ± 5 °C [normalized H2O- = 6.6 wt%]) associated with gypsum, limonite, and iron disulfides. Orthorhombic (space group Pbn21 or Pbnm), with a = 9.718(5) Å, b = 18.226(9) Å, c = 4.965(4) Å, V = 879.5(7) Å3, Z = 4, Dcalc = 3.414 g/cm3, and Gladstone-Dale calculated mean refractive index ncalc = 1.626.

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Identifiers & Classification

System Identifier Label
IMA IMA:1965-032 Metazellerite

Microbial & Biochemical Mechanisms (1)

Metazellerite other Abiotic topotactic dehydration of zell

Abiotic topotactic dehydration of zellerite to parallel-oriented metazellerite

other

Topotactic dehydration of orthorhombic zellerite (Ca(UO2)(CO3)2·5H2O, V = 1065.4 Å3, Z = 4) into parallel-oriented crystallites of metazellerite (Ca(UO2)(CO3)2·3H2O, V = 879.5 Å3, Z = 4), contracting unit-cell volume by 186 Å3 while preserving the orientation of crystallographic axes a, b, and c; from the 186 Å3 volume contraction (~19–23 Å3 per water molecule), the authors infer loss of 8 or 10 H2O molecules per unit cell and favor the 8 H2O (5-to-3 hydrate) formula interpretation pending further verification, whereas the 6.9 wt% H2O- loss at 110 ± 5 °C is a separate chemical-analysis determination on zellerite (with part of H2O- treated as structural).

Experimental Context & Analytical Limits:
Abiotic dehydration observed during X-ray beam exposure in Buerger precession single-crystal photography, storage in laboratory air (with low ambient relative humidity proposed as a stability condition), and separate 110 ± 5 °C chemical drying; no microbial, enzymatic, or bioleaching mechanism was tested or reported in Coleman, Ross, and Meyrowitz (1966).
Curated Evidence Points:
Buerger precession X-ray single-crystal photography demonstrates that orthorhombic zellerite (Ca(UO2)(CO3)2·5H2O, V = 1065.4 Å3, Z = 4) dehydrates topotactically under X-ray exposure and during laboratory-air storage (with low humidity discussed as a stability condition) into parallel-oriented crystallites of metazellerite (Ca(UO2)(CO3)2·3H2O, V = 879.5 Å3, Z = 4), contracting the unit-cell volume by 186 Å3 while preserving crystallographic axes a, b, and c; the authors infer a loss of 8 or 10 H2O per unit cell from the 186 Å3 volume change and favor the 8 H2O (3H2O hydrate) formula pending further verification, while separately reporting 6.9 wt% H2O- lost on drying zellerite at 110 ± 5 °C in Table 2 (pp. 1570–1575).

Sources & References

  1. ima_2026_09: IMA-CNMNC (Pasero M., 2026), The New IMA List of Minerals – A Work in Progress (Updated: September 2026), PDF p. 143, Metazellerite row: status A, IMA 1965-032, formula Ca(UO2)(CO3)2·3H2O, reference Coleman R.G., Ross D.R., Meyrowitz R. (1966) American Mineralogist 51, 1567-1578.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-24)
  2. coleman_1966_metazellerite: Coleman RG, Ross DR, and Meyrowitz R (1966), Zellerite and metazellerite, two new uranyl carbonates, American Mineralogist 51:1567-1578.
    https://www.rruff.net/doclib/am/vol51/AM51_1567.pdf (accessed 2026-10-24)

Curation History

Timestamp Curator Action Summary
2026-10-24T07:30:00Z antigravity CREATE Created mineral record for Metazellerite (IMA:1965-032) from the IMA September 2026 Master List and the primary type-description paper by Coleman, Ross, and Meyrowitz (1966) in American Mineralogist 51:1567-1578, including its abiotic topotactic dehydration mechanism.
2026-10-24T10:45:00Z antigravity EDIT Resolved CMM120-F2 (issue #838) by correcting the shifted Table 2 zellerite analysis (CO2 = 17.7, H2O+ = 13.0, separate H2O- = 6.9 wt%), qualifying the 8-or-10 H2O per unit-cell loss as inferred from the 186 Å3 volume contraction distinct from the 110 ± 5 °C chemical H2O- determination, and simplifying sources[1].title to a concise bibliographic citation.
2026-10-24T11:27:00Z antigravity EDIT Applied reviewed conservative correction for CMM120-F2 (issue #838): removed unsupported follow-up measurement protocol attribution from mechanisms[0] while retaining the volume-inferred 8-or-10 H2O vs separate 110 ± 5 °C chemical H2O- distinction.

Record source: data/records/metazellerite.yaml