Hopeite mineral
Hopeite is the orthorhombic zinc phosphate tetrahydrate mineral, ideal Zn3(PO4)2.4H2O, distinct from its dimorph parahopeite, zinc metal, zinc sulfate reagent and zinc oxalates. The September 2026 IMA list records grandfathered status G and original-description year 1826; that year is not an approval accession. The curated experiment distinguishes chemically precipitated starting hopeite from fungal-associated surface alteration and secondary hopeite-assigned crystals. No criticality designation is inherited from zinc.
Microbial & Biochemical Mechanisms (1)
Hopeite alteration and secondary precipitation associated with Aspergillus niger culture
biomineralization
Microbial
Associated Organisms:
Aspergillus niger (NCBITaxon:5061)
During laboratory culture of Aspergillus niger Ch4/07, large chemically formed hopeite crystals showed rounded edges, while small hopeite-assigned crystals encrusted hyphae. The observations support culture-associated dissolution and secondary precipitation; they do not establish that fungi are necessary for hopeite formation or identify a specific biochemical pathway. Starting hopeite formed before inoculation. No isolated zinc or phosphate recovery yield is demonstrated.
Experimental Context & Analytical Limits:
Sazanova2025 used 30 mL Czapek-Dox surface cultures in cultivation mattresses at 25 degrees C for 28 days, in triplicate, initially pH 6.0. Medium contained, in g/L, glucose 30, NaNO3 2.0, KH2PO4 1.0, MgSO4.7H2O 0.5, KCl 0.5 and FeSO4.7H2O 0.01. ZnSO4.7H2O additions were 0, 250, 500, 1000 or 2000 micromol/L; the strongest secondary-hopeite observation is the 2000 micromol/L arm at day 14. Hopeite had already precipitated after autoclaving at 121 degrees C without spores; autoclave duration and inoculum density/volume were not specified. Uninoculated zinc-containing syntheses and zinc-free fungal cultures were included. Matched killed-cell, cell-free-metabolite and pH-matched control series were not reported. Microscopy was performed at days 7, 14, 21 and 28; PXRD used ground mycelium with crystals at day 28 and selectively at earlier times. Ch4/07 was reported from damaged marble; its deposited sequence is not an independent authentication of the culture used here.
Sazanova2025 used 30 mL Czapek-Dox surface cultures in cultivation mattresses at 25 degrees C for 28 days, in triplicate, initially pH 6.0. Medium contained, in g/L, glucose 30, NaNO3 2.0, KH2PO4 1.0, MgSO4.7H2O 0.5, KCl 0.5 and FeSO4.7H2O 0.01. ZnSO4.7H2O additions were 0, 250, 500, 1000 or 2000 micromol/L; the strongest secondary-hopeite observation is the 2000 micromol/L arm at day 14. Hopeite had already precipitated after autoclaving at 121 degrees C without spores; autoclave duration and inoculum density/volume were not specified. Uninoculated zinc-containing syntheses and zinc-free fungal cultures were included. Matched killed-cell, cell-free-metabolite and pH-matched control series were not reported. Microscopy was performed at days 7, 14, 21 and 28; PXRD used ground mycelium with crystals at day 28 and selectively at earlier times. Ch4/07 was reported from damaged marble; its deposited sequence is not an independent authentication of the culture used here.
Curated Evidence Points:
Support
Source:
sazanova2025
Section 3.2.2, Figure 6 and Table 3 identify hopeite-associated hyphal encrustations in the A. niger 2000 micromol/L culture. Figure 6 shows large rounded parent crystals beside small crystals and tubular hyphal structures, with a PXRD pattern of the mycelial fragments labelled hopeite; SEM/EDX and comparison to calculated alpha-hopeite diffraction support the assignment. Table 3 lists abiogenic and biogenic hopeite at days 14 and 21, with katsarosite also present at day 21. The spatially separate small crystals are the evidence for secondary formation, not proof that every phosphate crystal is biogenic.
Partial
Source:
sazanova2025
Section 3.2.1 and Figure 3 show that zinc-containing medium produces Mg-bearing hopeite before inoculation. Free-zinc values in Tables 1-2 are measured after this chemical precipitation, not after fungal removal. Zinc-free fungal cultures lacked the reported phosphate and oxalate crystals. Figure 4 and Table 3 concern mixed biomass/mineral preparations; no quantitative hopeite fraction, isolated product purity or closed Zn/P balance was measured. Reported absence of visible hopeite at day 28 does not establish complete conversion or extraction.
Partial
Source:
sazanova2025
The day-14 2000 micromol/L A. niger arm is reported at pH 6.0 in Tables 1 and 3. Later pH statements conflict: day 28 is 2.8 in Table 1, 2.5 in Table 3, whereas Discussion 4.1 describes days 14 and 28 as pH 5-6. Discussion 4.2 also substitutes mmol for the Methods micromol/L concentration basis. No unique late endpoint pH or universal hopeite precipitation threshold is inferred.
Context_only
Source:
genbank_ch407
KF768341.1 verifies the source strain label Ch 4/07, A. niger annotation and marble provenance; it does not prove that the experimental inoculum was independently re-identified.
Context_only
Source:
ncbi_niger
The current species node verifies the organism name and identifier without establishing the strain-level phenotype.
Context_only
Source:
genbank_op758843
The source companion culture is called P. chrysogenum Cs/21 with accession OP758843, but OP758843.1 is P. granulatum isolate II47-8. Those companion assays are not assigned a verified P. chrysogenum or P. granulatum mechanism here. The primary A. niger evidence is treated separately.
Partial
Source:
sazanova2025
The existing katsarosite owner describes another mineral product of this same experiment, not independent replication of the hopeite claim. A related 2023 report cited by the article may share strains and experiments. The paper reports no underlying assay dataset and says no new data were created or analyzed despite describing experiments. Laboratory surface cultures and proposed remediation uses do not demonstrate field or industrial deployment.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026: introductory definitions and Hopeite row, PDF page 95. Previously acquired original re-inspected on the access date.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14) -
handbook_hopeite: Handbook of Mineralogy, Hopeite, version 1 (2001-2005). Complete one-page identity, formula, orthorhombic Pnma structure and parahopeite dimorphism.
https://www.handbookofmineralogy.org/pdfs/hopeite.pdf (accessed 2026-10-14) -
sazanova2025: Sazanova et al. (2025). Effect of Fungal Metabolism on Zn Minerals Formation: The Case of Aspergillus niger and Penicillium chrysogenum. Crystals 15:118. Complete 19-page publisher PDF and JATS; Methods, Figures 1-7 and Tables 1-4. Shared experiment with the katsarosite record.
https://doi.org/10.3390/cryst15020118 (accessed 2026-10-14) -
ncbi_niger: NCBI Taxonomy 5061: Aspergillus niger, species node.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=5061&mode=Info (accessed 2026-10-14) -
genbank_ch407: GenBank KF768341.1: Aspergillus niger strain Ch 4/07 ribosomal/ITS sequence, marble isolation source and taxon 5061.
https://www.ncbi.nlm.nih.gov/nuccore/KF768341.1 (accessed 2026-10-14) -
genbank_op758843: GenBank OP758843.1: Penicillium granulatum isolate II47-8 ribosomal/ITS sequence, inconsistent with the companion culture name in Sazanova2025.
https://www.ncbi.nlm.nih.gov/nuccore/OP758843.1 (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T16:31:44.836542Z |
codex (GPT-6; codex) | CREATE | Added hopeite identity and narrowly scoped fungal-associated alteration/secondary precipitation, retaining chemically formed starting crystals, shared-study lineage, source inconsistencies and unresolved companion-culture identity. |
Record source: data/records/hopeite.yaml