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Natrojarosite mineral

Natrojarosite is the sodium ferric hydroxysulfate mineral with ideal formula NaFe3(SO4)2(OH)6, all iron ferric. The September 2026 IMA list records the species as redefined, 1987 s.p. It is distinct from potassium jarosite, ammoniojarosite, hydroniumjarosite and a mixed industrial jarosite residue. Natural compositions can contain substitutions; the ideal formula is not an assay of every specimen. Gómez et al. (2024), sampling in May 2010, identified natrojarosite and quartz in an inner crust associated with a cyanobacteria-containing mixed microbial mat beneath a gypsum-rich outer layer at Río Tinto, Spain. Their field deposit measurements averaged pH 0.8, but pH across the thin cyanobacterial layer could not be measured. This is an association, without controlled evidence that the organisms precipitated or dissolved natrojarosite, without a verified cyanobacterial species or strain, and without an extraction or recovery measurement. No constituent-element criticality or industrial deployment is inferred.

Microbial & Biochemical Mechanisms (1)

Abiotic hydrothermal preparation of synthetic natrojarosite

other

Basciano and Peterson prepared synthetic members of the sodium-potassium and sodium-hydronium jarosite solid-solution series and characterized them by powder X-ray diffraction with Rietveld refinement, chemical analysis and infrared spectroscopy. A two-step treatment produced their near-endmember sodium sample P. This is laboratory abiotic synthesis and structural characterization, not microbial precipitation or metal recovery.

Experimental Context & Analytical Limits:
Initial sodium-hydronium preparations used ferric sulfate pentahydrate and variable sodium sulfate in water at 140 degrees C for 48 hours. For sample P, an initially approximately 87% sodium-occupied material was ground and treated at 200 degrees C for three days in sulfuric acid and sodium sulfate solution. The recipe prints 1.0 m for sulfuric acid and 0.5 before sodium sulfate without an explicit concentration unit for the latter; an executable complete recipe is not inferred. Annealing and homogenization treatments differ among members of the wider series, and are not assigned uniformly to every sample. No microorganisms were involved.
Curated Evidence Points:
Pages 854-856 describe the two-stage sodium-endmember preparation. Figure 1 and Tables 1-4 identify sample P through diffraction, chemistry and refinement. Table 1 reports approximately 97.7% Na site occupation from chemical analysis normalized to two sulfur atoms; Tables 2 and 4 use an idealized 100% Na model. Analytical uncertainty and model idealization preclude treating the difference as a precise deficit or reporting a quantitative product purity or yield.
Several original-text inconsistencies prevent reconstruction of an unambiguous protocol. Page 854 calls Figure 1 ammoniojarosite, whereas its caption and sample P identify natrojarosite. The Table 1 P asterisk footnote says chloride-medium synthesis, conflicting with the two-step sulfate-medium description and page 856 discussion. Table 3 prints Na occupancy 0.1 for P, inconsistent with Tables 2 and 4 and the endmember discussion. These values are retained as source conflicts, not silently corrected measurements. Table headings for the broader Na-K series also differ from the methods reagent names.
The structural series and infrared spectra demonstrate composition-dependent variation, but do not establish recovery efficiency, phase-specific dissolution kinetics or industrial treatment. Natural comparison samples were assessed through unit-cell parameters, with minor aluminium substitution noted; they were not all refined for atomic occupancies. Synthetic near-endmember results therefore do not establish universal stoichiometry or full iron occupancy for natural natrojarosite.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 152, Natrojarosite row; page 1 status definitions.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. handbook_natrojarosite: Handbook of Mineralogy. Natrojarosite, complete one-page entry; natural chemistry, ideal formula and jarosite solid-solution context. Secondary identity source.
    https://www.handbookofmineralogy.org/pdfs/natrojarosite.pdf (accessed 2026-10-15)
  3. basciano2008: Basciano LC and Peterson RC (2008). Crystal chemistry of the natrojarosite-jarosite and natrojarosite-hydronium jarosite solid-solution series: A synthetic study with full Fe site occupancy. American Mineralogist 93:853-862. Complete original, sample synthesis pages 854-856, Tables 1-5 and Figures 1-7. Print year 2008; publisher online date 2015 is not the study edition.
    https://doi.org/10.2138/am.2008.2731 (accessed 2026-10-15)
  4. basciano2008_fulltext: RRUFF archive of the complete ten-page Basciano and Peterson (2008) original.
    https://www.rruff.net/doclib/am/vol93/AM93_853.pdf (accessed 2026-10-15)
  5. gomez2024: Gómez et al. (2024). Association of Acidotolerant Cyanobacteria to Microbial Mats below pH 1 in Acidic Mineral Precipitates in Río Tinto River in Spain. Microorganisms 12:829. Complete publisher original, sections 2-4, Figures 1-11 and official Table S1 workbook; mixed-field association only.
    https://doi.org/10.3390/microorganisms12040829 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T08:36:10.615076+00:00 codex (GPT-6; codex) CREATE Added natrojarosite as a distinct mineral with qualified abiotic synthesis evidence and separately bounded field microbial association; preserved source conflicts and omitted unsupported microbial causation and criticality.

Record source: data/records/natrojarosite.yaml