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Burbankite mineral

A natural anhydrous carbonate mineral with the IMA-CNMNC September 2026 formula (Na,Ca)3(Sr,Ba,Ce)3(CO3)5. It is grandfathered; the listed 1953 value is an original-description year, not an IMA approval accession. This record denotes the mineral species, not the entire burbankite group, its constituent elements, or a carbonatite ore. Pecora and Kerr (1953) characterized natural hexagonal burbankite from calcite-rich veins at the Vermiculite Prospects, Big Sandy Creek, Bearpaw Mountains, Montana. Powder and single-crystal diffraction support the mineral characterization. Their chemical preparation remained about 96 percent burbankite by grain count, with about 3 percent ancylite and 1 percent other minerals; Table 2 separately gives the impure analysis and an impurity-adjusted calculation. The corrected chemistry is not a direct pure-phase measurement. The authors reported vigorous effervescence in cold dilute (1:5) HCl, but did not establish a leaching yield, rate or isolated rare-earth product. Observed weathering assemblages contained several minerals and do not resolve a unique reaction pathway. A later synthetic Na-Ca-La carbonate with burbankite structure is treated below as an experimental analogue, not as the measured composition of these natural specimens. No dated criticality designation or microbial mechanism is asserted.

Microbial & Biochemical Mechanisms (1)

High-pressure formation of a synthetic La-Ca carbonate with burbankite structure

other

Milani et al. synthesized a burbankite-structure carbonate from a nominal Na3Ca2La(CO3)5 mixture at 5 GPa and 1073 K for 24 h. The recovered laboratory assemblage also contained a Ca-rich La oxide, so it was not a demonstrated pure carbonate product. Electron microprobe analysis and single-crystal X-ray diffraction characterize the carbonate; its ambient structure was refined in P63mc. This establishes formation and La incorporation in a synthetic analogue. It does not demonstrate recovery from a natural ore, quantitative La capture, a species-wide compositional endmember or industrial deployment.

Experimental Context & Analytical Limits:
Carbonate powders in the stated stoichiometric proportions were sealed in a platinum capsule 3.5 mm long and 2 mm in diameter and heated in a multi-anvil apparatus at about 40 K/min. The reported temperature accuracy was ±20 K and assumed pressure uncertainty ±3 percent. Starting powder identities, purities and mass, phase yield and independent synthesis replication are not specified. Twenty microprobe points characterize the synthetic carbonate, not twenty independent synthesis runs. The nominal formula differs from its reported analytical composition; the prose and Table 1 state a five-oxygen normalization without explicitly distinguishing metal-oxide oxygen from the full carbonate formula. A metal-oxide-only basis could explain that wording, so it is not treated as proof of an erroneous formula. Na uncertainty is (14) in the prose/CIF and (13) in Table 1. No exact analytical formula is adopted here. Separate pressure and temperature diffraction arms must not be pooled with the synthesis. Thermal coverage and fitted coefficients conflict between abstract/methods and published tables/results: the reported 746 K maximum exceeds the 628 K maximum in Table 5 and Supplement Table S4, and the abstract and Results give different thermal-expansion coefficients. No disputed thermal coefficient, extrapolated mantle density or natural phase stability boundary is adopted.
Curated Evidence Points:
Experimental p.352 and Figure 1 establish the conditions and mixed recovered assemblage. Results pp.353–355 and Tables 1–3 characterize the synthetic carbonate and refined structure; they support the bounded laboratory formation claim, not natural-ore recovery or pure-product yield.
The CIF explicitly identifies a synthetic source made at 5 GPa and 1073 K. Tables S1–S4 and Figures S1–S3 provide structure and elastic context; Table S4 ends at 628 K. These files do not resolve all printed formula/thermal inconsistencies or provide a phase yield.

Sources & References

  1. ima2026: IMA-CNMNC, The New IMA List of Minerals, September 2026; field definitions PDF page 1 and Burbankite row page 32 (grandfathered, 1953).
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-16)
  2. pecora1953: Pecora WT and Kerr JH (1953), Burbankite and calkinsite, two new carbonate minerals from Montana. American Mineralogist 38:1169–1183. Full original; burbankite pp.1169–1176, Tables 1–3 and Figures 1–2; impurity accounting pp.1172–1174.
    https://www.rruff.net/doclib/am/vol38/AM38_1169.pdf (accessed 2026-10-16)
  3. milani2022: Milani S et al. (2022), High-pressure and high-temperature structure and equation of state of Na3Ca2La(CO3)5 burbankite. European Journal of Mineralogy 34:351–358. DOI 10.5194/ejm-34-351-2022; synthesis p.352/Figure 1, chemistry and structure pp.353–355/Tables 1–3.
    https://doi.org/10.5194/ejm-34-351-2022 (accessed 2026-10-16)
  4. milani2022supp: Milani et al. (2022), official supplement: seven-page Tables S1–S4/Figures S1–S3 and burbankite.cif. Synthetic composition and acquisition metadata; thermal data extend to 628 K in Table S4.
    https://doi.org/10.5194/ejm-34-351-2022-supplement (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T03:43:33.998046Z codex /root/round104_ree (GPT-6; codex) CREATE Added verified species identity and bounded primary characterization, distinguishing natural mineral, synthetic analogue and mixed-resource evidence; preserved source limitations and omitted unestablished criticality or microbial claims.

Record source: data/records/burbankite.yaml