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Falottaite mineral

Falottaite is the manganese oxalate trihydrate mineral MnC2O4.3H2O, approved as IMA 2013-044 in the September 2026 IMA compilation. It is distinct from elemental manganese, manganese oxides and manganese oxalate dihydrates. Its identity does not confer a criticality designation from manganese. The experimental product below is a phase assigned in a mixed laboratory precipitate, not a natural ore or purified commodity.

Microbial & Biochemical Mechanisms (1)

Falottaite-assigned precipitation during fungal culture with synthetic hausmannite

biomineralization Microbial

Associated Organisms: Aspergillus niger (NCBITaxon:5061)

Laboratory cultures reported as Aspergillus niger CBS 140837 produced manganese oxalate precipitates assigned in part to falottaite by powder diffraction during incubation with synthetic hausmannite. Acidification, manganese release and subsequent extracellular oxalate precipitation are the authors' explanation. The assay supports culture-associated phase formation but does not isolate a particular enzyme, quantify a falottaite yield or demonstrate industrial recovery.

Experimental Context & Analytical Limits:
The synthetic hausmannite was made by alkaline precipitation of MnSO4, followed by shaking, five hours of reflux, washing and dry heating; it was heated again at 95 degrees C for one hour before use. In 100 mL flasks, 0.25 g solid was contacted with 50 mL commercial Sabouraud Dextrose Broth containing initially 9.1 mg/L As(V), supplied as sodium hydrogen arsenate heptahydrate. The medium and solid were shaken at 130 rpm for 24 hours before inoculation. A 0.1 mL suspension prepared from a ten-day culture and reported as approximately 10^6 CFU/mL inoculated each flask. Static cultivation lasted 25 days in triplicate under laboratory conditions; its temperature is not specified. The separately stated 25 degrees C concerns culture maintenance and should not be substituted for the assay temperature. Oxide-free and arsenic-free inoculated treatments were included, but a matched uninoculated, killed-biomass or oxalate-only formation series is not described.
Curated Evidence Points:
Section 3.5 and Figure 6 assign a trihydrate component to falottaite in the manganese-bearing solid products; the paper reports diffraction analysis of residual solids and biomass-associated material. Figure 6b displays reference positions for falottaite, a dihydrate labelled lindbergite, and hausmannite. These are mixed-phase assignments, without quantitative phase fractions, isolated falottaite mass or specimen-specific water analysis. Figures 7-8 concern the author's dihydrate assignment; their morphology and biomass localization are not falottaite-specific confirmations.
The onset is internally inconsistent: section 3.5 reports enough falottaite for identification after 20 days, while the Discussion says first XRD detection after 15 days and points to Figure 5a, a biomass plot. Figure 6a contains an additional unlabelled lowest trace, so its timepoint is not inferred. Methods describe a 20-80 degree 2-theta scan but the displayed patterns extend below 20. These limits preclude a precise onset, rate or complete phase-transition reconstruction. Partial dehydration to the later dihydrate is the authors' interpretation, not a directly measured falottaite mass balance.
Figures 2-5 show solution, mixed-residue and biomass-associated elemental changes during culture. They do not measure a falottaite-specific arsenic capacity or distinguish adsorption onto remaining hausmannite from incorporation in newly precipitated phases. The reported roughly 45 percent manganese redistribution includes solution and mineral-bearing mycelium; it is not a falottaite recovery yield or exclusively intracellular uptake. Oxalate excretion and hyphal nucleation are inferred rather than isolated by direct metabolite measurements or matched chemical controls. Stable environmental sequestration and field deployment were not tested.
Context_only Source: ncbi_niger
The authority confirms the species name and TaxID. CBS 140837 is the study's strain designation; this species node does not independently authenticate that strain or establish its mineral-forming phenotype.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Falottaite row on PDF page 67 and column definitions on pages 1-2.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-11)
  2. farkas2020: Farkas et al. (2020). Aspergillus niger Decreases Bioavailability of Arsenic(V) via Biotransformation of Manganese Oxide into Biogenic Oxalate Minerals. Journal of Fungi 6(4):270. Complete 12-page article, methods 2.2-2.5, results 3.1-3.5, Figures 1-8 and Tables 1-2.
    https://doi.org/10.3390/jof6040270 (accessed 2026-10-11)
  3. ncbi_niger: NCBI Taxonomy 5061. Aspergillus niger, species node.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=5061&mode=Info (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T22:57:00Z codex (GPT-6; codex) CREATE Added the distinct trihydrate mineral and a narrowly qualified fungal phase-formation observation, retaining onset conflicts, mixed products, control gaps and non-phase-specific elemental outcomes.

Record source: data/records/falottaite.yaml