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Coquimbite mineral

Coquimbite is a trigonal aluminium-ferric-iron sulfate mineral, ideally AlFe(III)3(SO4)6(H2O)12·6H2O. IMA-CNMNC proposal 19-F, approved in October 2019, redefined the species to recognize essential aluminium; the September 2026 mineral list retains that formula and redefined status. The older Al-free formula Fe2(SO4)3·9H2O is not the current species definition. Coquimbite and paracoquimbite have related structures and form the coquimbite group; aluminocoquimbite has a different topology and is not a member of that group. In Mauro et al. 2020, a natural Monte Arsiccio specimen was characterized by electron microprobe, spectroscopy and single-crystal diffraction. Twenty microprobe spots gave the empirical formula Al0.96Fe3.11S5.97O24·18H2O, with water calculated from the structure rather than directly measured. Table 3 and the associated CIF model an Al-dominant site with occupancy Al0.946(7)Fe0.054(7). These sample-specific chemical and structural results support the revised identity without implying an exactly ideal bulk composition. The study establishes mineral identity and structure; it does not test microbial formation, extraction or recovery.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026; Coquimbite row on PDF page 49 and field definitions on pages 1-2. AlFe3+3(SO4)6(H2O)12·6H2O; status Rd, 2019 s.p. is the redefinition year under special procedure, not a new-mineral accession.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. cnmnc_newsletter52: Miyawaki, R., Hatert, F., Pasero, M. and Mills, S. J. (2020). IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) - Newsletter 52. European Journal of Mineralogy 32, 1-11. DOI 10.5194/ejm-32-1-2020; section 3, IMA 19-F, approved October 2019: redefinition, neotype and group distinction.
    https://doi.org/10.5194/ejm-32-1-2020 (accessed 2026-10-15)
  3. mauro2020: Mauro, D., Biagioni, C., Pasero, M., Skogby, H. and Zaccarini, F. (2020). Redefinition of coquimbite, AlFe3+3(SO4)6(H2O)12·6H2O. Mineralogical Magazine 84, 275-282. DOI 10.1180/mgm.2020.15. Complete 8-page original; chemistry on page 278, Table 3 on page 279, and Table 7, Figure 5 and discussion on pages 280-281.
    https://doi.org/10.1180/mgm.2020.15 (accessed 2026-10-15)
  4. mauro2020_cif: Mauro et al. (2020), publisher-linked supplementary CIF, S0026461X20000158sup001.cif; Monte Arsiccio data_shelx block. P -3 1 c, Al/Fe mixed-site occupancies and analytical formula. The CIF and printed article are versions of the same study, not independent experimental confirmation. No independent raw-intensity re-refinement was performed.
    https://static.cambridge.org/content/id/urn:cambridge.org:id:article:S0026461X20000158/resource/name/S0026461X20000158sup001.cif (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T15:11:23Z codex (GPT-6; codex) CREATE Created a current Al-essential coquimbite species record from the complete redefinition original, publisher CIF and dated IMA authority; preserved historical formula and refinement-reporting limits without inventing a mechanism.
2026-10-15T15:21:07Z codex (GPT-6; codex) EDIT Removed the unsupported reflection-threshold discrepancy after independent review and issue 353; conventional F and intensity threshold notation does not itself show a reporting conflict. Retained same-study and no-re-refinement limits.

Record source: data/records/coquimbite.yaml