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Hemimorphite mineral

Hemimorphite is the orthorhombic hydrated zinc silicate mineral Zn4Si2O7(OH)2·H2O. The September 2026 IMA-CNMNC list records approved status A and 1962 s.p.; this special-procedure entry is not a numbered new-mineral approval. The record distinguishes crystalline hemimorphite from willemite, mixed zinc ores and a poorly ordered hemimorphite-like microbial precursor. It contains a natural-sample chemical-leaching experiment and narrowly scoped precursor-associated field evidence. It does not assert microbial production of phase-pure crystalline hemimorphite, inherited criticality or industrial recovery.

Microbial & Biochemical Mechanisms (2)

Chemical leaching of a natural hemimorphite-bearing specimen

other

Concentrated aqueous ammonium chloride released Zn from a hemimorphite-bearing natural specimen, while residue diffraction retained hemimorphite and showed silica. Ammoniacal Zn complexation is the authors' chemical interpretation; no organism participates in this experiment and no isolated recovered Zn product is measured.

Experimental Context & Analytical Limits:
Zhao et al. Sections 2.1-2.2 used a Yunnan, China specimen that was ground and wet-sieved. Figure 1 assigns hemimorphite by XRD. Table 1 assigns 99.20% of the specimen's total Zn to hemimorphite; this is not a 99.20 wt% mineral-purity measurement. Total Zn is 42.24 wt%, with minor Zn assigned to sulfate, sulfide and ferrite phases. The Figure 5 comparison used 5 g solid per 1000 mL solution, 45-61 micrometre particles, 95 degrees C and 350 rpm in a condenser-equipped 2 L flask. Five-millilitre slurry samples were filtered and aqueous Zn measured by atomic absorption. Replicate counts, error bars and a reagent-free blank series are not reported.
Curated Evidence Points:
Section 3.3 and Figure 5 report 92.95% aqueous Zn extraction after 150 min at 5.0 mol/L NH4Cl, compared with 47.28% at 3.5 mol/L under the stated conditions. Equation 1 divides dissolved Zn by total feed Zn; the outcome is neither phase-specific hemimorphite dissolution nor isolated-product recovery. Figure 3 assigns residual hemimorphite and SiO2.
Equation 1 assumes constant solution volume despite serial sampling, so its reported percentages are retained with that limitation. Methods list five stirring speeds including 200 rpm, whereas Section 3.2/Figure 4 display four; the accepted Figure 5 arm is consistently labelled 350 rpm. Section 3.6 and Figure 12 show silica associated with some residual surfaces but do not show a continuous product layer on the polished cross sections. Elovich fits and inferred rate-controlling steps are interpretations, not direct demonstrations of a unique molecular pathway.

Field association of a cyanobacterium with a hemimorphite-like precursor

biomineralization Microbial

Associated Organisms: Stenomitos frigidus (NCBITaxon:1886765)

White-mud material from Rio Naracauli, Sardinia, contained nanoparticulate zinc silicate associated with cyanobacterial filaments assigned by the source to Leptolyngbya frigida. Main-paper spectroscopy supports a locally hemimorphite-like structure with low long-range order. This contextual precursor observation does not establish formation of crystalline hemimorphite or demonstrate the necessity of the assigned organism.

Experimental Context & Analytical Limits:
Medas et al. Materials and methods, page 712, studied natural material collected between summer 1995 and summer 2010, alongside crystalline hemimorphite and hydrozincite reference minerals. These are field collections and structural comparisons, not a controlled pure-culture precipitation assay. The source provides no strain accession or matched sterile precipitation control. Its prior-study water chemistry, seasonal behavior and aging experiments are not adopted as newly verified experiments here. The unacquired supplement includes the comparative XRD patterns; no supplemental phase-purity, organic-mass or fit-statistics claim is accepted. The current taxon name maps the historical species label only, not an independently authenticated field isolate.
Curated Evidence Points:
Context_only Source: medas2018
Figure 1, page 713, shows particles associated with filaments and polymeric material; panels a-b are explicitly modified from Medas et al. 2012 and are not independent new microscopy. Figures 2-3, page 714, and Figures 5-6, page 715, compare the precursor with crystalline reference material using FTIR, silicon NMR and Zn X-ray absorption. These support local structural similarity and limited order, not unambiguous crystalline-species identity or a mineral yield.
Discussion, pages 716-717, leaves template and metabolic contributions unresolved. Organic-matrix binding and Zn-mediated silica condensation are proposed explanations; Table 1 fixes the first-shell coordination in its fitting model, and Table 2 provides comparison chemical shifts. Neither establishes the organism's causal necessity. The missing AM-18-56128 supplement and unacquired earlier aging paper prevent a stronger claim about crystallization, quantitative conversion or preservation of this precursor.

Sources & References

  1. ima_2026_09: IMA-CNMNC, The New IMA List of Minerals, September 2026. Retained official original: definitions PDF page 1 and Hemimorphite row page 92, Zn4(Si2O7)(OH)2·H2O, A, 1962 s.p. This dated edition is not a claim that the live issuing-site index was accessible here.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15)
  2. handbook_hemimorphite: Handbook of Mineralogy, Hemimorphite. Complete one-page version 1.2 datasheet, copyright 2001; formula, orthorhombic crystal data and occurrence in oxidized zinc-bearing deposits.
    https://www.handbookofmineralogy.org/pdfs/hemimorphite.pdf (accessed 2026-10-15)
  3. zhao2017: Zhao D, Yang S, Chen Y, Tang C, He J and Li H (2017). Leaching Kinetics of Hemimorphite in Ammonium Chloride Solution. Metals 7, 237. DOI 10.3390/met7070237. Complete ten-page original including Figures 1-13 and Table 1 inspected.
    https://doi.org/10.3390/met7070237 (accessed 2026-10-15)
  4. medas2018: Medas D et al. (2018). Structure of low-order hemimorphite produced in a Zn-rich environment by cyanobacterium Leptolingbya frigida. American Mineralogist 103, 711-719. DOI 10.2138/am-2018-6128. Complete nine-page original, Figures 1-6 and Tables 1-2 inspected. Deposit AM-18-56128 supplement was not acquired; its diffraction figures and additional fitting/chemistry data are not verified here.
    https://doi.org/10.2138/am-2018-6128 (accessed 2026-10-15)
  5. ncbi_stenomitos_frigidus: NCBI Taxonomy 1886765, Stenomitos frigidus, species, including Leptolyngbya frigida as a synonym and former TaxID 268127. Current XML inspected. This taxonomic mapping does not authenticate a source-specific Naracauli strain or the causality of its association.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=1886765&mode=info (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T02:30:36.477614Z 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/hemimorphite.yaml