CMMMech
CMMMech > Mineral > Weloganite

Weloganite mineral

Hydrated sodium-strontium-zirconium carbonate mineral, archetype of the mckelveyite/weloganite group, with current September 2026 IMA-CNMNC approved formula Na2Sr3Zr(CO3)6(H2O)3, status A, and approval number IMA 1967-042. Sabina, Jambor, and Plant (1968) originally described weloganite from an alkaline dawsonite-bearing sill at the Francon quarry, St-Michel, Montreal Island, Quebec, Canada, initially proposing the Na-free trigonal formula Sr5Zr2(CO3)9·4H2O based on a partial analysis that overlooked essential sodium (Table 1, p. 471: SrO 41.0, ZrO2 19.4, CO2 32.2, H2O 6.6, sum 99.2 wt%). Following Chen and Chao's (1975) discovery of essential Na and triclinic symmetry, Grice and Perrault (1975) performed a complete chemical re-analysis on 2.0 g of pure Francon quarry weloganite (Table 1, p. 210: SrO 36.18, CaO 1.14, ZrO2 15.26, Na2O 7.75, K2O 0.02, CO2 30.70, H2O+ 7.65, H2O- 0.11, SiO2 0.25, Fe2O3 0.03, MgO <0.02, total 99.20 wt%, empirical formula (Sr2.8Ca0.2)ZrNa2(CO3)6·3H2O) and solved the crystal structure in non-centrosymmetric triclinic space group P1 (a = 8.966(1), b = 8.980(2), c = 6.730(1) A, alpha = 102.72(2), beta = 116.65(1), gamma = 60.06(1) degrees, V = 419.60 A3, Z = 1, R = 0.043 for 2354 observed reflections), showing ordered 9-coordinated [Zr(CO3)3O3] (3m symmetry), 6-coordinated [NaO4(H2O)2] and [NaO2(H2O)4] octahedra, and three 10-coordinated Sr2+ polyhedra. Distinct from mckelveyite-(Y), donnayite-(Y), bainbridgeite-(NdCe), strontianite, and elemental strontium or zirconium; no criticality designation, microbial mechanism, or industrial recovery yield is asserted.

Explore across X-Mech: MediaIngredientMech · CultureMech · CommunityMech · HabitatMech · TraitMech · CMMMech Network Graph

Identifiers & Classification

System Identifier Label
IMA IMA:1967-042 Weloganite

Microbial & Biochemical Mechanisms (1)

Weloganite other Laboratory multi-stage thermal dehydra

Laboratory multi-stage thermal dehydration and decarbonation of natural weloganite to SrCO3 and SrZrO3

other

Heating natural Francon quarry weloganite in air up to 1400 degrees C (tracked by DTA, TGA, and room-temperature X-ray powder diffraction of quenched products at 350, 500, 650, 740, 860, 1000, and 1400 degrees C) decomposed the mineral through three principal endothermic stages: (1) a sharp endotherm at 378 degrees C (300-440 degrees C, 17.05 wt% gravimetric loss) expelling H2O and part of the CO2 to form crystalline SrCO3 plus an amorphous, dilute-HCl-soluble Zr-bearing phase; (2) a second endotherm at 535 degrees C (440-650 degrees C, additional 2.26 wt% loss) crystallizing a cubic Zr-betafite-like oxide phase alongside SrCO3 at 650-740 degrees C; and (3) a third endotherm at 760 degrees C accompanied by solid-state reaction of the Zr-oxide intermediate with SrCO3 to form crystalline perovskite-type SrZrO3 plus residual SrCO3 at 860-1400 degrees C (with an additional 19.65 wt% mass loss between 650 and 1000 degrees C, totaling 38.96 wt%).

Experimental Context & Analytical Limits:
Thermal decomposition experiments in Sabina et al. (1968), pp. 473-475, Figure 4, and Tables 3-4, combined DTA at 12 degrees C/min up to 1000 degrees C, isothermal and dynamic TGA intervals (300-440, 440-650, and 650-1000 degrees C), dilute HCl leaching tests of the heated products, and X-ray powder diffraction + X-ray spectrographic analyses of residues quenched from 350, 500, 650, 740, 860, 1000, and 1400 degrees C.
Curated Evidence Points:
Pages 473-475, Figure 4, and Tables 3-4 document the three endotherms (378, 535, and 760 degrees C), the gravimetric losses of 17.05 wt% (300-440 degrees C), 2.26 wt% (440-650 degrees C), and 19.65 wt% (650-1000 degrees C; total 38.96 wt%), and the XRD phase progression from SrCO3 + HCl-soluble amorphous Zr phase (350-500 degrees C) to SrCO3 + cubic Zr-betafite-like oxide (650-740 degrees C) to SrZrO3 + SrCO3 (860-1400 degrees C).
Table 1 (p. 210) establishes that natural weloganite contains 7.75 wt% Na2O, 30.70 wt% CO2, and 7.65 wt% H2O+ (combined H2O + CO2 = 38.35 wt%, closely matching the 38.96 wt% total TGA loss), so the heated solid residues in Sabina et al. (1968) also retained sodium alongside Sr and Zr.

Sources & References

  1. ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026, PDF page 233, Weloganite row: formula Na2Sr3Zr(CO3)6(H2O)3, status A, IMA No. 1967-042, country Canada, first reference Canadian Mineralogist 9 (1968), 468, second reference Canadian Mineralogist 13 (1975), 209; column definitions on PDF page 1.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-22)
  2. sabina_1968_weloganite: Sabina AP, Jambor JL, Plant AG (1968), Weloganite, a new strontium zirconium carbonate from Montreal Island, Canada, Canadian Mineralogist 9:468-477. Complete 10-page primary PDF visually inspected: Francon quarry occurrence, physical/optical and X-ray data Table 2 pp. 468-473; DTA-TGA multi-stage thermal decomposition and heated-product phase identification Figure 4 and Tables 3-4 pp. 473-475.
    https://www.rruff.net/doclib/cm/vol9/CM9_468.pdf (accessed 2026-10-22)
  3. grice_1975_weloganite: Grice JD, Perrault G (1975), The crystal structure of triclinic weloganite, Canadian Mineralogist 13:209-216. Complete 8-page primary PDF visually inspected: complete wet/XRF/AAS chemical re-analysis Table 1 p. 210 and triclinic P1 single-crystal structure refinement Tables 2-6 and Figures 1-3 pp. 210-215.
    https://www.rruff.net/doclib/cm/vol13/CM13_209.pdf (accessed 2026-10-22)

Curation History

Timestamp Curator Action Summary
2026-10-22T07:20:00Z antigravity CREATE Created weloganite mineral record with verified IMA:1967-042 identity, 1968 Francon quarry description and multi-stage DTA-TGA thermal decomposition mechanism, and 1975 revised Na2Sr3Zr(CO3)6(H2O)3 chemistry and triclinic P1 crystal structure.

Record source: data/records/weloganite.yaml