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Widgiemoolthalite mineral

Widgiemoolthalite (IMA 1992-006) is an IMA-accepted hydrated nickel hydroxy-carbonate mineral, the nickel analogue of hydromagnesite, with IMA September 2026 Master List formula Ni5(CO3)4(OH)2·4-5H2O and empirical formula (Ni4.62Mg0.38)(CO3)4.15(OH)1.70·5.12H2O (Table 1, p. 820 electron microprobe and CHN elemental analysis: NiO 54.6, MgO 2.4, CO2 28.9, H2O 17.0, total 102.9 wt%). Described by Nickel, Robinson, and Mumme (1993) from the weathered zone of a nickel sulfide body at the 132 North nickel mine, 4 km southwest of Widgiemooltha, Western Australia, Australia (holotype Western Australian Museum M.1.1993), where it occurs as bluish-green fibrous crusts and spherulites lining cavities in weathered gaspeite along with kambaldaite, takovite, retgersite, and nickeloan paratacamite. Monoclinic unit-cell parameters indexed from X-ray powder diffraction by comparison with hydromagnesite give a = 10.06(17) Å, b = 8.75(5) Å, c = 8.32(4) Å, beta = 114.3(8)°; definitive crystallographic characterization was not obtained. SGmeas = 3.13(1), Dcalc = 3.24 g/cm3, and biaxial (+) optics with nmin = 1.630(5) and nmax = 1.640(5).

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Identifiers & Classification

System Identifier Label
IMA IMA:1992-006 Widgiemoolthalite

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. 234, Widgiemoolthalite row: status A, IMA 1992-006, formula Ni5(CO3)4(OH)2·4-5H2O, reference Nickel E.H., Robinson B.W., Mumme W.G. (1993) American Mineralogist 78, 819-821.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-24)
  2. nickel_1993_widgiemoolthalite: Nickel EH, Robinson BW, and Mumme WG (1993), Widgiemoolthalite: The new Ni analogue of hydromagnesite from Western Australia, American Mineralogist 78:819-821.
    https://www.rruff.net/doclib/am/vol78/AM78_819.pdf (accessed 2026-10-24)

Curation History

Timestamp Curator Action Summary
2026-10-24T07:30:00Z antigravity CREATE Created mineral record for Widgiemoolthalite (IMA:1992-006) from the IMA September 2026 Master List and the primary type-description paper by Nickel, Robinson, and Mumme (1993) in American Mineralogist 78:819-821.
2026-10-24T10:45:00Z antigravity EDIT Resolved CMM120-F15 (issue #838) by removing the unsupported definitive P21/c space-group and Z = 2 attribution to Nickel, Robinson, and Mumme (1993), noting that structural disorder/twinning and diffuse fiber patterns prevented definitive single-crystal space-group characterization, and simplifying sources[1].title to a concise bibliographic citation.
2026-10-24T11:27:00Z antigravity EDIT Applied reviewed conservative correction for CMM120-F15 (issue #838): omitted unsupported hellyerite from the assemblage and stated that definitive crystallographic characterization was not obtained.

Record source: data/records/widgiemoolthalite.yaml