Kornelite mineral
Kornelite is a monoclinic ferric sulfate mineral, represented in the September 2026 IMA list as Fe(III)2(SO4)3(H2O)6·1.75H2O. Its additional channel water is variable; historical seven-water formulae are not exact hydration measurements for every specimen. This species is distinct from paracoquimbite, ferricopiapite and undifferentiated ferric-sulfate salts. The evidence below separates abiotic synthesis of a characterized crystalline product from provisional diffraction assignments in mixed bacterial-culture solids. Neither experiment establishes a recovered iron product from ore or waste, industrial deployment or a criticality designation.
Microbial & Biochemical Mechanisms (2)
Kornelite crystallization during cooling of a ferric-sulfate preparation
other
An aqueous ferric-sulfate preparation first produced an XRD-assigned ferricopiapite precipitate at 75 degrees C. After further heating, opening the vessel and slow cooling, pale-violet kornelite crystals appeared. Single-crystal and powder diffraction support the final product identity. The sequence does not establish a direct solid-state ferricopiapite-to-kornelite pathway or a mass-balanced iron recovery.
Experimental Context & Analytical Limits:
Ackermann et al., page 1621: 2.5 g of analytical-grade, X-ray-amorphous ferric sulfate was dissolved in 1.17 mL deionized water. Closed polyethylene flasks were held at 75 degrees C for 48 hours, then nine additional days. The oven was switched off, the vessel lid removed and the contents cooled slowly in the oven to room temperature. Cooling duration, exact final temperature, solution pH, replicate synthesis count and product yield are not reported. This is a chemical laboratory synthesis; no organism or biological treatment is involved. The source also supports the existing paracoquimbite record through a different preparation; two material records do not constitute independent replication.
Ackermann et al., page 1621: 2.5 g of analytical-grade, X-ray-amorphous ferric sulfate was dissolved in 1.17 mL deionized water. Closed polyethylene flasks were held at 75 degrees C for 48 hours, then nine additional days. The oven was switched off, the vessel lid removed and the contents cooled slowly in the oven to room temperature. Cooling duration, exact final temperature, solution pH, replicate synthesis count and product yield are not reported. This is a chemical laboratory synthesis; no organism or biological treatment is involved. The source also supports the existing paracoquimbite record through a different preparation; two material records do not constitute independent replication.
Curated Evidence Points:
Support
Source:
ackermann2009
Page 1621 describes the preparation, and Figure 1a/page 1622 shows the resulting elongated crystals. Table 1 reports a monoclinic P21/n single-crystal refinement at 293 K. The electron microprobe Fe/S ratio, 0.62(5), averages 35 spots rather than 35 independent syntheses; the authors acknowledge measurement difficulty and compare it with theoretical 0.66.
Partial
Source:
ackermann2009
Pages 1622-1625 and Tables 2/4 distinguish model-dependent channel water from fixed stoichiometry. Single-crystal models yield 1.71(5) or 1.75(5) channel waters per formula unit, compared with 1.55(2) from powder refinement; thermogravimetry gives total hydration estimates of 7.47 or 7.98 depending on the plateau endpoint. Disordered and incommensurate water arrangements were not distinguished. Deposit AM-09-052 could not be acquired, so detailed-coordinate reproducibility remains unchecked.
Partial
Source:
ackermann2009
Figure 6/pages 1626-1627 demonstrates strong sensitivity of calculated phase boundaries to estimated entropies. These are not measured universal stability fields. Table 6 prints a 6.53-water coefficient in the kornelite Hess-cycle expression, inconsistent with the 6.75 implied by its adopted 7.75-water formula and Table 5 reaction; no formation-enthalpy value is adopted here. Thermal-peak labels also do not establish an isolated product or an ore-treatment yield.
Provisional kornelite assignment in mixed AY5 culture precipitates
biomineralization
Microbial
Associated Organisms:
Desulfovibrio desulfuricans (NCBITaxon:876)
Karnachuk et al. label some peaks in precipitates from living Desulfovibrio desulfuricans AY5 cultures as kornelite using a powder diffraction database match. This is a provisional culture-associated phase observation, not proof that sulfate-reducing metabolism directly precipitates ferric sulfate. The mineral products are mixed, and neither kornelite abundance nor a recovered iron fraction was measured.
Experimental Context & Analytical Limits:
Sections 2.1-2.4 describe glycerol-fed Widdel-Bak medium with sulfate, phosphate, nutrients and reductant; the one-litre bioreactor received 100 mg/L iron as FeSO4 and operated at 28 degrees C, 100 rpm and 25 mL/min nitrogen sparging. Its pH was progressively decreased from 7 using HCl or NaHCO3, with medium replacement and transfers to closed, dark batch bottles at 28 degrees C. Thus the successive pH arms share a reactor history rather than independent fresh inoculations. Solids were centrifuged at 13,100 g for 15 minutes at 15 degrees C and washed in distilled water for 10 minutes before powder XRD. Oxygen exclusion during washing, any drying conditions and an uninoculated mineralogical control are not reported. These are laboratory observations, without clinical or industrial inference.
Sections 2.1-2.4 describe glycerol-fed Widdel-Bak medium with sulfate, phosphate, nutrients and reductant; the one-litre bioreactor received 100 mg/L iron as FeSO4 and operated at 28 degrees C, 100 rpm and 25 mL/min nitrogen sparging. Its pH was progressively decreased from 7 using HCl or NaHCO3, with medium replacement and transfers to closed, dark batch bottles at 28 degrees C. Thus the successive pH arms share a reactor history rather than independent fresh inoculations. Solids were centrifuged at 13,100 g for 15 minutes at 15 degrees C and washed in distilled water for 10 minutes before powder XRD. Oxygen exclusion during washing, any drying conditions and an uninoculated mineralogical control are not reported. These are laboratory observations, without clinical or industrial inference.
Curated Evidence Points:
Partial
Source:
karnachuk2021
Figure 5A/page 6 labels kornelite peaks in the day-two pH-7 bioreactor pattern; Figure 6A/page 7 labels them at days three and four for pH 6. Supplementary Figure S2A labels kornelite at days two/four for pH 6.5, and S3A at days one/two for pH 5.5. These are mixed patterns with broad backgrounds and other phases; no kornelite-specific refinement, hydration analysis or isolated crystal chemistry is supplied. The database's seven-water formula in captions is not a measured hydration value.
Partial
Source:
karnachuk2021
Later bioreactor patterns and the displayed batch patterns do not carry the same kornelite labels; absence of a label is not a quantified disappearance or a detection-limit-based absence. Section 3.2 calls the pH-6.5 bioreactor phases unpronounced, while supplementary Figure S2A assigns small peaks. Phase identity and timing therefore remain qualified. No matched sterile or killed-cell arm separates biological effects from solution chemistry or sample-workup oxidation/precipitation. Fe/S maps in Figure 4/S1 identify elements, not kornelite or Fe(III).
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026; Kornelite row on PDF page 115 and field definitions on pages 1-2. Fe3+2(SO4)3(H2O)6·1.75H2O; G denotes grandfathered species, and 1888 is an original-description year, not an approval accession.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15) -
handbook_kornelite: Handbook of Mineralogy. Kornelite, version 1 (2001-2005), complete one-page entry; monoclinic P21/n and historical Fe3+2(SO4)3·7-8H2O formula range.
https://handbookofmineralogy.org/pdfs/kornelite.pdf (accessed 2026-10-15) -
ackermann2009: Ackermann, S., Lazic, B., Armbruster, T., Doyle, S., Grevel, K.-D. and Majzlan, J. (2009). Thermodynamic and crystallographic properties of kornelite [Fe2(SO4)3·~7.75H2O] and paracoquimbite [Fe2(SO4)3·9H2O]. American Mineralogist 94, 1620-1628. DOI 10.2138/am.2009.3179. Complete nine-page original; synthesis and Table 1 page 1621, Figure 1a and composition page 1622, hydration/refinement pages 1622-1625, model limits pages 1626-1627.
https://doi.org/10.2138/am.2009.3179 (accessed 2026-10-15) -
karnachuk2021: Karnachuk et al. (2021). Desulfovibrio desulfuricans AY5 Isolated from a Patient with Autism Spectrum Disorder Binds Iron in Low-Soluble Greigite and Pyrite. Microorganisms 9, 2558. DOI 10.3390/microorganisms9122558. Complete eleven-page original, methods sections 2.1-2.4, Figures 5-6 and original three-page supplementary Figures S1-S3; only laboratory mineral observations are used, without adopting clinical extrapolations.
https://doi.org/10.3390/microorganisms9122558 (accessed 2026-10-15) -
ncbi_desulfuricans: NCBI Taxonomy 876, Desulfovibrio desulfuricans, species rank. This species identifier does not itself authenticate isolate AY5.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=876 (accessed 2026-10-15)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-15T17:14:40Z |
codex (GPT-6; codex) | CREATE | Created ferric-sulfate identity, characterized abiotic synthesis and explicitly provisional AY5 culture-phase association, preserving hydration, source-model, control and workup limitations. |
Record source: data/records/kornelite.yaml