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Siderite mineral

Siderite is the ferrous carbonate mineral species Fe(CO3), listed as approved through a 1962 special procedure in the September 2026 IMA list. The special-procedure year is not an approval-number CURIE. The selected culture experiment identifies siderite alongside dominant vivianite, rather than a pure carbonate product. It is distinct from elemental iron, iron-ore commodities and other iron-bearing phases. This is the same experiment curated under vivianite, not independent evidence or an inherited criticality designation.

Microbial & Biochemical Mechanisms (1)

Culture-associated siderite formation with vivianite from an Fe(II) medium

biomineralization Microbial

Associated Organisms: Tessaracoccus lapidicaptus (NCBITaxon:1427523)

Living Tessaracoccus lapidicaptus cultures formed a precipitate whose X-ray diffraction pattern was assigned to siderite together with dominant vivianite. Microscopy shows carbonate-bearing aggregates around cells and extracellular polymeric substances. Culture-associated precipitation is supported, while the proposed mineral sequence, surface nucleation and metabolic carbonate supply are not separately quantified causal pathways.

Experimental Context & Analytical Limits:
Living Tessaracoccus lapidicaptus CECT 8385 (= DSM 27266; type strain IPBSL-7) was cultured anaerobically at 30 degrees C in reported 100-mL bottles containing 100 mL FE medium, examined for mineral formation for up to 45 days. Inoculum OD600 was 0.5; inoculum volume and replicate count are not specified. FE medium was initially pH 6 and autoclaved at 121 degrees C for 20 min. Its reported w/v composition was 0.25% NaCl, 0.04% NH4Cl, 0.003% MgCl2.6H2O, 0.005% CaCl2.2H2O, 0.2% FeCl2.4H2O, 0.01% yeast extract, 0.085% NaNO3, 0.1% glucose, 0.1% succinic anhydride, 0.05% KH2PO4, 0.025% NaHCO3, 0.05% cysteine hydrochloride and 0.01% resazurin. Iron was supplied as Fe(II), so this selected experiment does not establish microbial Fe(III) reduction. The organism identifier is species-level; the paper and taxonomy authority link the culture collection strains. The paper also uses the spelling Tessarococcus, whereas NCBI and LPSN accept Tessaracoccus.
Curated Evidence Points:
Methods and Results on PDF pages 2-3 describe the live cultures and controls. Figure 1 on page 4 labels multiple siderite reflections in a pattern dominated by vivianite. Figure 4 on page 6 shows assigned siderite aggregates and Fe-C-O-bearing regions, including an EDX spectrum with a small phosphorus signal and a nearby vivianite crystal. The complementary bulk diffraction and microscopy support a siderite-containing mixture; EDX alone would not identify a carbonate mineral species.
Uninoculated and nonviable-cell controls reportedly showed neither mineral precipitation nor pH change; the nonviable-cell preparation and viability check are not specified. Live-culture final pH is approximately 7.5 in Results but 7.8 in Discussion. No matched-pH abiotic control or direct phosphatase/EPS perturbation isolates the proposed nucleation mechanism. Table 1 gives modelled initial supersaturation, not observed abiotic precipitation. Reported Fe(II) decline from 0.56 to 0.01 g/L has no specified filtration/fraction protocol and cannot be assigned to either mineral or converted to a recovery yield. Mixed-phase formation, without quantified phase abundance, product purity, isolated mass balance or fertilizer testing, is limited to this laboratory medium; no industrial deployment is established.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 199, Siderite row; page 1 column definitions and page 2 distribution terms.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-11)
  2. sanchez_roman_2015: Sánchez-Román, Puente-Sánchez, Parro and Amils (2015). Nucleation of Fe-rich phosphates and carbonates on microbial cells and exopolymeric substances. Frontiers in Microbiology 6:1024. DOI 10.3389/fmicb.2015.01024; Methods, Results, Figures 1-4, Table 1 and Discussion.
    https://doi.org/10.3389/fmicb.2015.01024 (accessed 2026-10-11)
  3. ncbi_tessaracoccus: NCBI Taxonomy 1427523 - Tessaracoccus lapidicaptus; species rank and type-material names CECT 8385, DSM 27266 and IPBSL-7 verified in taxonomy XML on 11 October 2026.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=1427523&mode=Info (accessed 2026-10-11)
  4. lpsn_tessaracoccus: LPSN - Tessaracoccus lapidicaptus; validly published name and equivalent type-strain designations CECT 8385, DSM 27266 and IPBSL-7.
    https://lpsn.dsmz.de/species/tessaracoccus-lapidicaptus (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T10:24:37.301663+00:00 codex (GPT-6; codex) CREATE Created siderite mineral identity and bounded culture-associated formation with mixed-phase and control limitations.

Record source: data/records/siderite.yaml