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CMMMech > Mineral > Mckelveyite-(Y)

Mckelveyite-(Y) mineral

Hydrated sodium-calcium-barium-yttrium carbonate mineral of the mckelveyite (donnayite) group with current September 2026 IMA-CNMNC redefined formula NaCaBa3Y(CO3)6(H2O)3, status Rd, and approval number IMA 1964-025. Milton et al. (1965) originally described mckelveyite from four subsurface core and trona-mine localities in the Eocene Wilkins Peak Member of the Green River Formation, Sweetwater County, Wyoming, USA, proposing the uranium-bearing trigonal P-3 formula Na1.9Ba4.0Ca1.1Sr0.2RE1.5U0.3(CO3)9·5H2O after recalculating wet-chemical analyses of massive and crystal-aggregate fractions for 18.0-20.7 wt% acid-insoluble impurities (organic matter, authigenic biotite, acmite, and quartz). Subsequent studies cited by Demartin et al. (2008) showed that type mckelveyite-(Y) is triclinic P1 (mckelveyite-(Y)-1A) with formula NaBa3(Ca,U)Y(CO3)6·3H2O. Demartin et al. (2008) solved the first complete crystal structure on a uranium-free monoclinic Cc polytype, mckelveyite-(Y)-2M (a = 15.8213(7), b = 9.1364(4), c = 13.7522(6) A, beta = 112.44(1) degrees, Z = 4, R = 0.0283 for 4454 reflections with I > 2sigma(I)), from hydrothermal carbonate veins at the Cava Fabi talc quarry, Val Malenco, Sondrio, Lombardy, Italy, where CO2 and H2O were derived from structure solution rather than direct gas analysis. Following IMA-CNMNC guidance, the monoclinic Alpine material is a polytype (mckelveyite-(Y)-2M) of the species rather than a separate mineral species. Distinct from mckelveyite-(Nd), donnayite-(Y), ewaldite, and elemental yttrium or rare earths; no criticality designation, microbial mechanism, or extraction yield is asserted.

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Identifiers & Classification

System Identifier Label
IMA IMA:1964-025 Mckelveyite-(Y)

Sources & References

  1. ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026, PDF page 138, Mckelveyite-(Y) row: formula NaCaBa3Y(CO3)6(H2O)3, status Rd, IMA No. 1964-025, country USA, first reference American Mineralogist 50 (1965), 593, second reference Canadian Mineralogist 46 (2008), 195; column definitions on PDF page 1.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-18)
  2. milton_1965_mckelveyite: Milton C, Ingram B, Clark JR, Dwornik EJ (1965), Mckelveyite, a new hydrous sodium barium rare-earth uranium carbonate mineral from the Green River Formation, Wyoming, American Mineralogist 50:593-612. Complete 20-page primary PDF visually inspected: subsurface Green River Formation localities pp. 593-597; wet-chemical analyses of massive and crystal fractions and recalculation for 18.0-20.7 wt% acid-insoluble organic, biotite, acmite, and quartz inclusions in Tables 1-6 pp. 598-606; X-ray diffraction Table 7 p. 607 and rare-earth comparison with burbankite in Table 8 p. 609.
    https://www.rruff.net/doclib/am/vol50/AM50_593.pdf (accessed 2026-10-18)
  3. demartin_2008_mckelveyite2m: Demartin F, Gramaccioli CM, Campostrini I, Diella V (2008), The crystal structure of mckelveyite-(Y)-2M, a new monoclinic polytype from Val Malenco, Italian Alps, Canadian Mineralogist 46:195-203, DOI 10.3749/canmin.46.1.195. Complete 9-page primary PDF visually inspected: occurrence and IMA-CNMNC polytype nomenclature decision p. 196; WDS chemical analysis Table 1 p. 196; single-crystal refinement and unit- cell comparison with triclinic mckelveyite-(Y)-1A in Tables 2-6 pp. 197-199; XRPD comparison Table 7 and bond geometry Table 8 p. 202.
    https://www.rruff.net/doclib/cm/vol46/CM46_195.pdf (accessed 2026-10-18)

Curation History

Timestamp Curator Action Summary
2026-10-19T05:22:00Z antigravity CREATE Created mckelveyite-(Y) mineral record from the September 2026 IMA master list, the 1965 Green River Formation original description, and the 2008 Val Malenco mckelveyite-(Y)-2M crystal-structure determination, preserving impurity recalculations and polytype relationships.

Record source: data/records/mckelveyite-y.yaml