Chukanovite mineral
Chukanovite is the iron(II) hydroxide-carbonate mineral species Fe2(CO3)(OH)2, approved as IMA 2005-039 in the September 2026 IMA-CNMNC list. It is distinct from siderite, mixed-valence green rusts, elemental iron and mixed culture products. The curated experiments concern source-assigned laboratory precipitates, not a pure recovered commodity or an industrial process. No constituent iron criticality designation is inherited.
Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| IMA |
IMA:2005-039
|
Chukanovite |
Microbial & Biochemical Mechanisms (1)
Chukanovite-assigned secondary solids during culture-associated goethite reduction
biomineralization
Microbial
Associated Organisms:
Shewanella putrefaciens CN-32 (NCBITaxon:319224)
Cultures reported as Shewanella putrefaciens CN32 accumulated acid-extractable Fe(II) during long-term incubation with synthetic goethite and formate. Selected solids from cultures with no added phosphate, with or without AQDS, were assigned to mixtures of residual goethite and chukanovite by fitted Mossbauer spectra, with limited diffraction and morphological support. This supports conditional culture-associated formation of an iron(II) carbonate phase. It does not establish a unique biological precipitation pathway, universal production by the strain, pure-product yield or isolated iron recovery.
Experimental Context & Analytical Limits:
O'Loughlin2021 Section 2.1 synthesized goethite by aging ferrihydrite under alkaline conditions at 70 degrees C for 60 hours, followed by repeated washing, drying at 60 degrees C and grinding through a 200-mesh sieve; pXRD checked starting phase identity. Duplicate 160 mL serum bottles contained 100 mL defined mineral medium, 80 mM Fe(III) as goethite and 75 mM formate. The basal medium was adjusted to pH 7.5 before sterilization; this is not a constant-pH experiment. Bottles were argon-sparged and late-log cells added to approximately 5 x 10^9 cells/mL as printed, then rolled at 30 degrees C in darkness. Complete basal-medium and inoculum recipes are delegated to earlier references and were not reconstructed. Arms were no added phosphate without or with 100 micromolar AQDS, and 500 micromolar phosphate with 100 micromolar AQDS; there was no phosphate-amended, AQDS-free comparator. Table 2 and Figure 7 associate final phosphate-free observations with day 1060 and the phosphate arm with day 744, not a common endpoint. Suspension Fe(II) was measured after one-week HCl extraction by ferrozine and is not dissolved Fe(II) alone. Filtered solids were protected with Kapton for ambient pXRD; SEM samples were dried anoxically and briefly exposed during transfer. Mossbauer analyses used protected samples and fitted spectral components. Figure 7 includes a sterile-control diffraction trace, but does not supply a matched sterile time series and full amendment/harvest details for each culture arm. Both papers print ATCC BAA-543 beside CN32, whereas the authority assigns CN-32 to BAA-453 and BAA-543 to Cellulomonas sp. ES5. The organism identifier records the reported strain name; the actual experimental stock remains unauthenticated.
O'Loughlin2021 Section 2.1 synthesized goethite by aging ferrihydrite under alkaline conditions at 70 degrees C for 60 hours, followed by repeated washing, drying at 60 degrees C and grinding through a 200-mesh sieve; pXRD checked starting phase identity. Duplicate 160 mL serum bottles contained 100 mL defined mineral medium, 80 mM Fe(III) as goethite and 75 mM formate. The basal medium was adjusted to pH 7.5 before sterilization; this is not a constant-pH experiment. Bottles were argon-sparged and late-log cells added to approximately 5 x 10^9 cells/mL as printed, then rolled at 30 degrees C in darkness. Complete basal-medium and inoculum recipes are delegated to earlier references and were not reconstructed. Arms were no added phosphate without or with 100 micromolar AQDS, and 500 micromolar phosphate with 100 micromolar AQDS; there was no phosphate-amended, AQDS-free comparator. Table 2 and Figure 7 associate final phosphate-free observations with day 1060 and the phosphate arm with day 744, not a common endpoint. Suspension Fe(II) was measured after one-week HCl extraction by ferrozine and is not dissolved Fe(II) alone. Filtered solids were protected with Kapton for ambient pXRD; SEM samples were dried anoxically and briefly exposed during transfer. Mossbauer analyses used protected samples and fitted spectral components. Figure 7 includes a sterile-control diffraction trace, but does not supply a matched sterile time series and full amendment/harvest details for each culture arm. Both papers print ATCC BAA-543 beside CN32, whereas the authority assigns CN-32 to BAA-453 and BAA-543 to Cellulomonas sp. ES5. The organism identifier records the reported strain name; the actual experimental stock remains unauthenticated.
Curated Evidence Points:
Support
Source:
oloughlin_2021
Section 3.3, Figures 6-8 and Tables 2-3 support the narrow phosphate-free culture-product assignment. At 140 K, Table 3 fits chukanovite relative spectral areas of 20.0 percent without AQDS and 27.4 percent with AQDS, alongside goethite. The AQDS sample's fitted chukanovite areas are 21.6 percent at 270 K and 29.0 percent at 77 K; these temperature-dependent spectral areas are not mass fractions or whole-feed recovery yields. Section 3.3 calls the pXRD evidence inconclusive, while noting a small peak near 34 degrees 2theta at day 1060. Figure 8's bladed crystallites provide compatible morphology, not independent chemical or phase proof. Residual goethite is explicitly retained.
Partial
Source:
oloughlin_2021
The phosphate-arm assignment is internally inconsistent: Section 3.3 says no secondary mineral formation was evident with AQDS plus 500 micromolar phosphate, whereas Table 2 labels its SEM outcome Chuk and Section 4.3 states chukanovite formed with or without that phosphate addition. Table 2 calls its XRD inconclusive and its Mossbauer result not determined. No confident phosphate-arm chukanovite assignment or phosphate-specific yield is accepted here. Section 3.3 also prints initial goethite rates in micromolar/day where Table 2 gives the same numbers in millimolar/day; no exact rate is adopted.
Partial
Source:
oloughlin_2021
Section 4.1 proposes a secondary product of goethite reduction because no intermediate phase was observed. The absence of a detected intermediate does not establish a unique direct pathway. Bicarbonate production is estimated from Fe(II) and formate stoichiometry rather than measured. The reported sterile diffraction comparator, incomplete control metadata and fitted mixed-phase assignments do not establish metabolic necessity, direct enzymatic carbonate precipitation or industrial recovery. Separate feroxyhyte evidence in the corpus belongs to the same 2021 publication.
Partial
Source:
oloughlin_2019
Section 4.2 explicitly reports that chukanovite was not observed in any of that study's systems. These are distinct commercial lepidocrocite experiments, including an electron-donor survey with differing observation durations and focused 62-day formate/AQDS cultures in chloride or sulfate medium at initial pH 7.5 and 30 degrees C. Their products include green-rust phases and, in other donor arms, siderite. This bounded null result limits transfer of the 2021 goethite observation; it does not refute the latter's particular long-incubation assignment. The suggestion that the 2019 incubation was too short for chukanovite is a hypothesis, not an experimentally isolated time effect.
Context_only
Source:
ncbi_cn32
Resolves the repeated CN-32 strain name to NCBITaxon:319224; taxon mapping does not resolve the conflicting culture accession.
Context_only
Source:
atcc_cn32
The collection identifies CN-32 as BAA-453, preserving rather than silently correcting the papers' BAA-543 attribution.
Partial
Source:
atcc_es5
The printed BAA-543 accession resolves to Cellulomonas sp. ES5, so the provenance of the reported CN32 stock remains uncertain.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Page 45 Chukanovite row; pages 1-2 column/status definitions and terms. Previously acquired official PDF reinspected for this record.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14) -
oloughlin_2021: O'Loughlin EJ, Boyanov MI, Gorski CA, Scherer MM and Kemner KM (2021). Effects of Fe(III) Oxide Mineralogy and Phosphate on Fe(II) Secondary Mineral Formation during Microbial Iron Reduction. Minerals 11(2):149. DOI 10.3390/min11020149. Complete 43-page publisher PDF; Sections 2.1-2.3, 3.3 and 4.1-4.3, Tables 2-3 and Figures 6-8. Same study as the existing feroxyhyte record, with the present mechanism scoped to its separate goethite assays.
https://doi.org/10.3390/min11020149 (accessed 2026-10-14) -
oloughlin_2019: O'Loughlin EJ, Gorski CA, Flynn TM and Scherer MM (2019). Electron Donor Utilization and Secondary Mineral Formation during the Bioreduction of Lepidocrocite by Shewanella putrefaciens CN32. Minerals 9:434. DOI 10.3390/min9070434. Complete 29-page OSTI 1560537 copy; Sections 2.1-2.3, 3.1, 3.3 and 4.2, Tables 1-3, Figures 1 and 5-6. Separate study with no observed chukanovite; already used by the lepidocrocite owner, not new replication.
https://doi.org/10.3390/min9070434 (accessed 2026-10-14) -
ncbi_cn32: NCBI Taxonomy 319224, Shewanella putrefaciens CN-32. Live taxonomy XML and browser resolve the named strain; neither authenticates the experimental stock or its conflicting collection number.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=319224 (accessed 2026-10-14) -
atcc_cn32: ATCC BAA-453, Shewanella putrefaciens CN-32 [OCM 576, SMCC 576W]. Collection authority for the strain name reported in both studies.
https://www.atcc.org/products/baa-453 (accessed 2026-10-14) -
atcc_es5: ATCC BAA-543, Cellulomonas sp. ES5. This differs from CN-32 and exposes the collection-number conflict in both primary papers.
https://www.atcc.org/products/baa-543 (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T18:00:20.421680+00:00 |
codex (GPT-6; /root) | CREATE | Added the mineral identity and qualified goethite-culture product assignment, with a separate lepidocrocite null result, source contradictions and unresolved stock provenance retained. |
2026-10-14T18:12:06.841517Z |
codex (GPT-6; codex) | EDIT | Corrected the survey-wide 72-day wording after independent finding F1; retained differing donor-arm observation periods, the focused 62-day formate cultures and the bounded null result. |
Record source: data/records/chukanovite.yaml