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Quenstedtite mineral

Quenstedtite is a triclinic ferric sulfate mineral, represented in the September 2026 IMA list as Fe(III)2(SO4)3(H2O)9·2H2O. It is distinct from other ferric-sulfate hydrates and from mixed-valence romerite. Thomas et al. (1974) refined a natural Chilean crystal of unknown exact locality in P-1, locating nine iron-coordinated water sites and two additional interlayer water sites. Eleven waters fit that specimen; earlier analyses indicating less water were retained as possible occupancy variability, with the lower limit untested. A separate 2012 MSc thesis refined a natural Alcaparrosa specimen and modeled hydrogen positions at 180 K. Its calcium-bearing surface grains were attributed to gypsum, rather than accepted as calcium intrinsic to quenstedtite. The thesis contains inconsistent comparison table angles, instrument descriptions and water-bonding prose; its CIF records mixed hydrogen treatment and geometrical H-site location. These qualifications prevent treating all hydrogen positions as direct unconstrained measurements or its proposed romerite conversion as an observed reaction. This is an identity and structure record, without a curated extraction, microbial mechanism, recovery yield or criticality designation.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026; Quenstedtite row on PDF page 181 and field definitions on pages 1-2. Fe3+2(SO4)3(H2O)9·2H2O; status G denotes grandfathered species, while 1889 is the original-description year, not an approval number.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. handbook_quenstedtite: Handbook of Mineralogy. Quenstedtite, version 1 (2001-2005), complete one-page entry; triclinic P-1, historical 10-11 water formula range and distinction between measured and calculated water contents.
    https://handbookofmineralogy.org/pdfs/quenstedtite.pdf (accessed 2026-10-15)
  3. thomas1974: Thomas, J. N., Robinson, P. D. and Fang, J. H. (1974). Crystal Structures and Mineral Chemistry of Hydrated Ferric Sulfates. IV. The Crystal Structure of Quenstedtite. American Mineralogist 59, 582-586. Complete five-page original; specimen/methods page 582, occupancy comparison and Tables 1-2 pages 583-584, Figure 1 and water-content discussion pages 585-586. Hydrogen coordinates were not resolved in this study; cited older water assays are not new measurements of the selected crystal.
    https://msaweb.org/AmMin/AM59/AM59_582.pdf (accessed 2026-10-15)
  4. westland2012: Westland, R. E. (2012). New Phases in the Hydrous Ferric Sulfate System, a Supporting Argument That the Mineral Lausenite is of Formula Fe2(SO4)3·5H2O and the Crystal Structure Refinement and Hydrogen Bonding Scheme of the Minerals Quenstedtite and Romerite. MSc thesis, Queen's University; August 2012 title page, repository issued September 4, 2012. Sections 2.2.1/2.2.5-2.2.7/2.3.1.2/2.4, Tables 2.11-2.20, Figures 2.4-2.8/2.12-2.14 and Appendices D-E. Table 2.11 angles conflict with Table 2.12 and the printed CIF; text names SMART CCD 1000 while CIF names APEX-II CCD. The checkCIF sheet says structure factors were not supplied, so its full test set was not run. No raw diffraction refinement reproduced.
    https://hdl.handle.net/1974/7411 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T17:14:40Z codex (GPT-6; codex) CREATE Created natural-mineral identity from original 1974 structure and 2012 thesis, retaining specimen, water-occupancy and contradictory refinement metadata without claiming an observed transformation.

Record source: data/records/quenstedtite.yaml