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Ammoniojarosite mineral

Ammoniojarosite is the ammonium ferric hydroxysulfate mineral with ideal formula (NH4)Fe3(SO4)2(OH)6, with ferric iron. The September 2026 IMA list records it as redefined, 1987 s.p. It is distinct from potassium jarosite, natrojarosite, hydroniumjarosite and industrial jarosite residues. Wang et al. (2007) prepared diffraction-assigned ammoniojarosite during biological oxidation of ferrous sulfate in ammonium-containing laboratory media. Their products were nonstoichiometric, and low-ammonium experiments instead produced schwertmannite or mixed precipitates. Neither phase assignment nor bulk composition establishes absolute phase purity, a recovered-metal yield, microbial necessity or industrial deployment. No constituent-element criticality is inherited.

Microbial & Biochemical Mechanisms (1)

Ammonium-dependent precipitation during microbial ferrous-iron oxidation

biomineralization Microbial

Associated Organisms: Acidithiobacillus ferrooxidans (NCBITaxon:920), Sulfuracidifex metallicus (NCBITaxon:47303)

Iron-oxidizing cultures generated ferric iron from dissolved ferrous sulfate, with ammoniojarosite identified in the resulting precipitates at sufficient ammonium concentrations. The ammonium-concentration series used an enrichment dominated by A. ferrooxidans, not a verified pure strain. A separate temperature series used that enrichment, source-named Sulfolobus metallicus, or an unresolved thermophilic consortium. The demonstrated association with biological iron oxidation does not isolate a cell-specific nucleation mechanism.

Experimental Context & Analytical Limits:
Wang et al., section 2.1 and Table 1: aerobic 100 mL cultures in 250 mL shake flasks used 120 mM FeSO4.7H2O, 1.6 mM MgSO4.7H2O, 5.4 mM NH4H2PO4 and 4.05 mM H2SO4, initially pH 2.3-2.6, with added ammonium sulfate and no potassium nutrient salt. The 36 degrees C concentration series tested 5.4-805 mM ammonium. The separate 165 mM ammonium temperature series used the MAF enrichment at 22 and 36 degrees C, the source-named S. metallicus culture at 45 degrees C, and consortium MT at 65 degrees C. NCBI species mappings do not identify a deposited experimental strain; the MT composition after enrichment at 65 degrees C was not established, so no taxa are assigned to it. Carbon came from ambient CO2. Precipitates were generally aged for one week, but the 22 degrees C product required about two months. They were centrifuged, washed twice with 5 mM sulfuric acid and dried at 65 degrees C for ten hours; elemental-analysis aliquots were additionally dried at 110 degrees C. Inoculum fraction, shaking speed and independent culture replication were not specified in the inspected methods.
Curated Evidence Points:
Sections 2.1-3.1, Tables 1 and 3 and Figures 1-2 show schwertmannite as the only identified phase at 5.4 and 9.4 mM ammonium, mixed schwertmannite and ammoniojarosite at 11.5-85.4 mM, and ammoniojarosite as the only identified crystalline phase in the tested 165-805 mM arms at 36 degrees C. The abstract/conclusion says above 165 mM, whereas Table 3 already assigns sample 3.5.12 at 165 mM to ammoniojarosite. These are tested conditions, not a universal precipitation threshold or quantified purity measurement.
Section 3.2, Table 4 and Figures 4-8 identify the temperature-series ammoniojarosites by powder diffraction, unit-cell refinement and elemental chemistry. All products were nitrogen-deficient relative to the ideal endmember; hydronium substitution was inferred from composition and diffraction trends. Nitrogen retained in biomass could also contribute to bulk analysis. Mineral stoichiometry is therefore not assumed from the ideal formula, and neither fitted cell parameters nor bulk nitrogen quantify a microbial mineral-production yield.
Section 2.1 explicitly states that abiotic syntheses were not matched controls: ferric rather than ferrous sulfate, ammonium concentrations, temperature and contact time differed (36 degrees C for 27 days, 65 degrees C for eight days, and 95 degrees C for 24 hours). Sample 6.6 is 65 degrees C in Methods, Tables 1 and 4 and the Figure 4 plotted label, but 45 degrees C in Table 3 and Figures 4 and 9 captions. Figure 7 labels the low-temperature abiotic trace 35 degrees C although Tables 1 and 4 give 36 degrees C. No exact matched-temperature biological advantage is inferred across these inconsistent labels.
Sections 3.1-3.3 and Figure 9 retain causal limits: precipitation rates and ammonium consumption were not measured, proposed precipitation order was not demonstrated, and living-versus-inactive intact-cell comparisons were absent. Biological and chemical products could not consistently be distinguished by diffraction, chemistry, color or surface area. More rounded or aggregated biological particles do not establish a unique biosignature, extracellular-polymer mechanism or metabolic necessity.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 10, Ammoniojarosite row; page 1 definitions of Rd and special procedure.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. handbook_ammoniojarosite: Handbook of Mineralogy. Ammoniojarosite, complete one-page entry. Secondary identity and natural substituted-composition context.
    https://www.handbookofmineralogy.org/pdfs/ammoniojarosite.pdf (accessed 2026-10-15)
  3. wang2007: Wang H, Bigham JM, Jones FS and Tuovinen OH (2007). Synthesis and properties of ammoniojarosites prepared with iron-oxidizing acidophilic microorganisms at 22-65 degrees C. Geochimica et Cosmochimica Acta 71:155-164. Complete original, sections 2-3, Tables 1-4 and Figures 1-9; print year 2007, not copyright 2006.
    https://doi.org/10.1016/j.gca.2006.09.001 (accessed 2026-10-15)
  4. wang2007_original: Repository copy of the complete ten-page Wang et al. (2007) original, including all original tables and figures.
    https://repository.geologyscience.ru/server/api/core/bitstreams/c6323873-9c96-4835-b252-480cd5bd7d5b/content (accessed 2026-10-15)
  5. ncbi_taxonomy: NCBI Taxonomy. Species 920 Acidithiobacillus ferrooxidans and species 47303 Sulfuracidifex metallicus, including historical synonym Sulfolobus metallicus. Name mappings only, not verification of an experimental strain or consortium.
    https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id=920,47303&retmode=xml (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T11:37:59.122132Z codex (GPT-6; codex) CREATE Added ammoniojarosite with original microbial iron-oxidation-associated precipitation evidence, current mineral and taxon identity, low-ammonium nulls and mixed phases, and unmatched abiotic comparator and temperature-label limits.

Record source: data/records/ammoniojarosite.yaml