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Katsarosite mineral

Katsarosite is the approved zinc oxalate dihydrate mineral, ideal Zn(C2O4).2H2O, IMA 2020-014, with monoclinic C2/c structure. It is distinct from zinc metal, dissolved zinc, zinc sulfate reagent and magnesium-dominant oxalates that can have a related diffraction pattern. No criticality designation is inherited from zinc.

Microbial & Biochemical Mechanisms (1)

Katsarosite-assigned formation during Aspergillus niger culture

biomineralization Microbial

Associated Organisms: Aspergillus niger (NCBITaxon:5061)

Zinc-dominant monoclinic oxalate assigned to katsarosite formed during laboratory culture of Aspergillus niger Ch4/07 with zinc sulfate. Fungal oxalate production and subsequent extracellular precipitation provide the proposed explanation. The experiment supports culture-associated mineral formation but does not establish a particular enzyme, an isolated zinc product yield, complete zinc removal or industrial deployment.

Experimental Context & Analytical Limits:
The source describes Ch4/07 isolated from damaged marble at Chersonesos Taurica and cites ITS accession KF768341. The verified KF768341.1 record labels Ch 4/07 and Aspergillus niger; this is not a strain-specific TaxID or independent authentication of the culture used in the experiment. Surface cultures used 30 mL liquid Czapek-Dox medium in cultivation mattresses at 25 degrees C for 28 days, initially pH 6.0, in triplicate. Medium composition in g/L was glucose 30, NaNO3 2.0, KH2PO4 1.0, MgSO4.7H2O 0.5, KCl 0.5 and FeSO4.7H2O 0.01. Methods specify ZnSO4.7H2O additions at 0, 250, 500, 1000 and 2000 micromol/L; the strongest species-level product assignment below concerns the 2000 micromol/L arm. Autoclaving at 121 degrees C is reported without a duration. Spore inoculum density and volume are not specified. Uninoculated syntheses at the zinc concentrations and zinc-free fungal cultures were examined. Matched killed-biomass, cell-free-metabolite, oxalate-only and pH-matched comparator series were not reported.
Curated Evidence Points:
Section 3.2.2 and Table 3 report the first katsarosite assignment at day 21 in the A. niger 2000 micromol/L arm. Day-28 powder diffraction in Figure 4a identifies the monoclinic oxalate using a calculated katsarosite pattern and PDF-2 reference data. Figure 5c-d shows zinc-rich oxalate crystals; the reported semiquantitative EDX Mg/Zn ratio is 0-0.04 at this loading. Together these support the source's zinc-dominant katsarosite assignment. There is no specimen-specific water-content measurement, quantitative phase fraction or isolated product mass. Diffraction of ground mycelium and associated crystals does not establish pure katsarosite or complete conversion.
Sections 3.1-3.2, Figures 3-5 and Tables 2-3 distinguish biogenic oxalates from hopeite that precipitated chemically before inoculation. Uninoculated zinc-containing medium formed hopeite, whereas zinc-free fungal controls did not form the reported oxalate or phosphate crystals. The Table 2 free-zinc values concern chemical precipitation before fungal growth and are not fungal zinc-removal yields. Native versus acid-treated organic-acid measurements define operational soluble and insoluble fractions, not a katsarosite-specific mass balance.
Lower-zinc cultures produced magnesium-rich or compositionally mixed oxalates, with minor orthorhombic glushinskite in some conditions; these are not all accepted as katsarosite merely because a monoclinic pattern is similar. The abstract's proposed alpha-to-beta transition at Mg/Zn greater than one is inconsistent with the body's reported monoclinic Mg-rich compositions and is not adopted as a universal structural threshold. Neither genetic nor enzyme-level causality was directly tested.
Source conditions contain unresolved numerical inconsistencies. Methods specify micromol/L, several headings shorten this to micromol, and Discussion 4.2 sometimes uses mmol. The Methods concentration basis is retained. For A. niger at 2000 micromol/L on day 28, Table 1 gives pH 2.8, Table 3 and Figure 2a approximately 2.5, while Discussion 4.1 states pH 5-6 at days 14 and 28. These values are not reconciled into a unique final pH or a universal precipitation threshold.
Context_only Source: genbank_ch407
The deposited sequence supports the published Ch4/07 strain label and marble isolation provenance, without proving that the deposited specimen and the experiment's inoculum were independently authenticated.
Context_only Source: ncbi_niger
The current species node verifies the organism identifier and name; species identity alone does not establish the mineral-forming trait.
The paper labels a companion culture Penicillium chrysogenum Cs/21 and cites OP758843. The actual accession OP758843.1 instead labels Penicillium granulatum isolate II47-8. Its companion assays are not admitted as an independently authenticated P. chrysogenum mechanism and are not reassigned to P. granulatum without resolving the mismatch.
Context_only Source: giester2023
The original mineral description and its diffraction/structure data establish the zinc oxalate dihydrate identity. Proposed lichen-related formation at the natural type locality is a geological interpretation, not a controlled organism-specific assay. Natural minor-element chemistry is not transferred into the cultured precipitate.
This is a laboratory mineral-formation study, not a demonstrated remediation or metal-recovery process. No closed zinc balance, product-purity measurement or deployment evidence is provided. The data-availability statement says no new data were created or analyzed despite the experimental report; no underlying assay dataset was inspected. A related 2023 report cited by the paper may overlap these strains and experiments and is not counted as independent replication.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Katsarosite row, PDF page 110, and introductory column definitions.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-11)
  2. giester2023: Giester et al. (2023). Katsarosite Zn(C2O4).2H2O, a new humboldtine-group mineral from the Lavrion Mining District, Greece. Mineralogy and Petrology 117:259-267. Complete article, Figures 1-5, Tables 1-5 and the two original natural/synthetic crystal-structure CIF supplements.
    https://doi.org/10.1007/s00710-023-00810-9 (accessed 2026-10-11)
  3. sazanova2025: Sazanova et al. (2025). Effect of Fungal Metabolism on Zn Minerals Formation: The Case of Aspergillus niger and Penicillium chrysogenum. Crystals 15(2):118. Complete 19-page publisher PDF and JATS; Methods, Results, Figures 1-7 and Tables 1-4.
    https://doi.org/10.3390/cryst15020118 (accessed 2026-10-11)
  4. 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)
  5. genbank_ch407: GenBank KF768341.1. Aspergillus niger strain Ch 4/07 ribosomal and ITS sequence; source qualifiers and taxon 5061.
    https://www.ncbi.nlm.nih.gov/nuccore/KF768341.1 (accessed 2026-10-11)
  6. genbank_op758843: GenBank OP758843.1. Penicillium granulatum isolate II47-8 ribosomal and ITS sequence; inconsistent with the companion strain cited by Sazanova 2025.
    https://www.ncbi.nlm.nih.gov/nuccore/OP758843.1 (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T23:34:39Z codex (GPT-6; codex) CREATE Added approved katsarosite identity and zinc-dominant fungal formation evidence, preserving mixed phases, control limitations, source conflicts and unresolved companion-strain provenance.

Record source: data/records/katsarosite.yaml