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Willemite mineral

Willemite is the zinc orthosilicate mineral Zn2SiO4, listed by IMA-CNMNC in September 2026 with grandfathered status G and original-description year 1830. It is distinct from hemimorphite, zincite, elemental zinc and mixed zinc-bearing ores or slags. The evidence concerns willemite assigned within weathered smelting slag associated with a lichen, and a separate synthetic analogue in laboratory acid leaching. The field study does not establish the lichen's necessary causal contribution, and the synthetic feed has unresolved composition inconsistencies. No inherited criticality, phase-specific recovered-product yield or industrial deployment is asserted.

Microbial & Biochemical Mechanisms (2)

Lichen-associated alteration of willemite assigned within mixed slag

bioleaching Microbial

Associated Organisms: Stereocaulon exutum (NCBITaxon:373707)

Willemite-bearing portions of smelting slag beneath Stereocaulon exutum showed hyphal penetration, etch pits and Zn-depleted weathered material. These field observations support a biological association with alteration. They do not isolate a lichen-specific dissolution pathway from other microorganisms or abiotic weathering; organic-acid dissolution and chelation remain proposed explanations.

Experimental Context & Analytical Limits:
Sueoka et al. Sections 2.1-2.3 sampled an abandoned Cu-smelting mine site in eastern Okayama, Japan, between 21 April 2011 and 28 September 2013. The substrate was heterogeneous slag containing silicates, glass and metal/sulfide matte, not a purified willemite culture feed. Lichens were identified morphologically and by color reactions; no specimen sequence or collection accession is supplied. Reported XRD and SEM-EDS identify substrate phases, although the original does not display the XRD patterns. There is no matched sterile exposure, controlled incubation duration or mineral-specific dissolution mass balance. Collection dates are not reaction times.
Curated Evidence Points:
Sections 3.1-3.2, Figure 2 on printed page 1596 and Figures 4-5 on page 1597, show penetration, etch pits in source-assigned willemite pseudomorphs, and element distributions across altered slag and thalli. These support the stated field association and local alteration, not a phase-pure recovered mineral or metal.
Section 4.1, pages 1601-1602, explicitly cannot determine whether S. exutum or other microbes mainly caused acid-mediated decomposition and acknowledges that the detailed process was not clarified. Sections 3.3-4.3 and Table 2 concern bulk thallus and substrate elements; their correlations cannot be converted into a willemite-specific extraction efficiency. No mineralized oxalate product was found in this study (Section 4.2).

Laboratory acid dissolution of a synthetic willemite-assigned feed

other

Dilute sulfuric acid released Zn from a synthetic willemite-assigned powder, leaving a silica-rich residue with residual willemite. This is a chemical laboratory experiment. A fitted pore/product-layer diffusion model describes the reported kinetics but does not independently prove a unique molecular dissolution pathway.

Experimental Context & Analytical Limits:
Xu et al. Sections 2.1-2.2 synthesized the feed from stoichiometric ZnO and SiO2 pellets at 1473 K for 12 h, then cooled, ground and sieved it. Runs used 2.0 g solid and 1.6 L solution in a 2 L autoclave; pressurized air introduced the solid, with air partial pressure usually 1.2 MPa. The Figure 2 arm used 53-57 micrometre particles, 1.0 g/L sulfuric acid, 393 K and 800 rpm. Approximately 10 mL aliquots were analyzed by EDTA titration, with a volume-corrected extraction calculation. Independent replication and uncertainty are not specified for that series. The separate real-concentrate experiment in Table 3 uses different conditions and is not pooled with the synthetic arm.
Curated Evidence Points:
Support Source: xu2022
Section 3.1.1 and Figure 2 report 79.78% aqueous Zn extraction after 16 min for the stated synthetic-feed arm, relative to the feed-Zn basis in Equation 1. Figure 3 assigns residual willemite and cristobalite in that arm. This is dissolved Zn relative to assayed feed Zn, not isolated-metal recovery, a direct mineral-phase conversion fraction or an ore yield.
Partial Source: xu2022
Section 2.1 states that XRD detected only willemite, but Table 1 reports 48.7-49.5 wt% Zn and 34.8-36.5 wt% SiO2 across size fractions. Those values differ from approximately 58.7 wt% Zn and 27.0 wt% SiO2 calculated for ideal Zn2SiO4; Figure 1 EDS also does not establish stoichiometric purity. Consequently the source's pure-feed claim and a closed mineral mass balance are not adopted. The Figure 17 real-concentrate residue is assigned quartz under its separate conditions, and is not treated as the same silica product as Figure 3.

Sources & References

  1. ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026. Retained official original: definitions PDF page 1 and Willemite row page 235, Zn2(SiO4), G, 1830. This is a dated authority edition, not a claim that the live issuing-site index was accessible in this investigation.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. handbook_willemite: Handbook of Mineralogy, Willemite. Complete one-page version 1.2 datasheet, copyright 2001; formula, crystal data and natural occurrence.
    https://www.handbookofmineralogy.org/pdfs/willemite.pdf (accessed 2026-10-15)
  3. sueoka2015: Sueoka Y, Sakakibara M and Sera K (2015). Heavy Metal Behavior in Lichen-Mine Waste Interactions at an Abandoned Mine Site in Southwest Japan. Metals 5, 1591-1608. DOI 10.3390/met5031591. Complete eighteen-page original including Figures 1-10 and Tables 1-2 inspected.
    https://doi.org/10.3390/met5031591 (accessed 2026-10-15)
  4. xu2022: Xu H et al. (2022). Kinetics and Mechanisms of Artificial Willemite Leaching in Low-Sulfuric-Acid Solution at Elevated Temperature. Metals 12, 2031. DOI 10.3390/met12122031. Complete twenty-page original including Figures 1-17 and Tables 1-3 inspected.
    https://doi.org/10.3390/met12122031 (accessed 2026-10-15)
  5. ncbi_stereocaulon_exutum: NCBI Taxonomy 373707, Stereocaulon exutum, species. Current taxonomy XML inspected; this name mapping does not authenticate the field specimens or identify every lichen-associated organism.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=373707&mode=info (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T02:30:30.146882Z codex / GPT-6 CREATE Created a distinct mineral owner from verified primary originals and identity authorities, retaining experimental-form, microbial-association, denominator and source-access limitations without inherited criticality.

Record source: data/records/willemite.yaml