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Sphalerite mineral

Sphalerite is the mineral species with IMA-approved formula ZnS. The September 2026 IMA list records status A (approved) and the IMA No./Year entry 1980 s.p., denoting special procedure rather than a sequential approval identifier or the year of original discovery. This species is distinct from elemental zinc, the zinc commodity, other ZnS phases and a flotation concentrate. The curated experiments used an iron-bearing Gamsberg concentrate; they are the same studies represented under cmmmech:zinc, not additional independent replications. No constituent-element criticality is inherited.

Microbial & Biochemical Mechanisms (1)

Conditional bacterial enhancement of sphalerite dissolution

bioleaching Microbial

Associated Organisms: Acidithiobacillus ferrooxidans (NCBITaxon:920)

Living Thiobacillus ferrooxidans FC1, using its published name, enhanced sphalerite-concentrate dissolution under selected elevated ferrous-ion conditions relative to chemical controls with matched bulk iron chemistry. The authors interpret surface analyses and kinetic fits as support for removal of a sulfur product layer. The experiments do not demonstrate direct enzymatic oxidation of the ZnS lattice or a particular sulfur-oxidation enzyme.

Experimental Context & Analytical Limits:
Both studies used Gamsberg flotation concentrate reported as 98% sphalerite by XRD, with 53.3% Zn, 7.84% Fe, 32.5% S, 1.19% Mn and 0.24% Pb. The authors interpret Fe as solid solution in sphalerite rather than a separate mineral; this is not a pure ideal-ZnS reagent. Concentrate was milled and screened to 45-53 micrometres and washed in 0.5 M sodium sulfide to remove flotation agents and sulfidize its surface. The stirred, aerated two-compartment electrolysis cell had 2 L working volume, 5 g concentrate/L, 10% v/v living FC1 inoculum, pH 1.6, 35 +/- 0.1 degrees C and 5.9 mg/L dissolved oxygen. Electrolytic redox control maintained bulk iron concentrations during biotic and chemical runs; uninoculated controls were checked microscopically for bacteria. The 1999 series varied Fe(II) with Fe(III) held at 1 g/L. Zinc was measured by atomic spectrophotometry in 0.45-micrometre filtrate. Ten analytical replicates describe assay repeatability, not biological reactor replication. NCBITaxon:920 maps the published species name, not a verified accession or modern genomic reassignment of strain FC1. The apparatus controlled solution chemistry; it did not demonstrate downstream zinc-product recovery or industrial deployment.
Curated Evidence Points:
Figures 2-3 show later divergence of zinc dissolution after an initial approximately 8-12 h interval with similar dissolution. Figures 5-6 compare surfaces at Fe(II) 4 g/L after 100 h and 8 g/L after 69 h, respectively. SEM/EDAX and shrinking-core fits support the authors' sulfur-layer explanation, without a sulfur mass balance or enzyme assay. These surface endpoints are distinct from the shorter Figure 2 dissolution time course. No recovery percentage is estimated from the figures.
The 1 g/L Fe(II) series in Figures 2-3 also departs from equal dissolution, in tension with the Discussion's sharp low-ferrous null boundary. A universal 1 g/L threshold is therefore not asserted. Figure 10 reanalyzes earlier 1998 data and is not new independent replication.
Methods and Figures 4-6 report similar zinc dissolution in inoculated and chemical runs with Fe(II) fixed at 1 g/L and varied Fe(III), despite bacterial growth and attachment. This conditional null limits a universal enhancement claim. Figure 3's illustrative current caption gives different iron concentrations from the Methods; no quantitative current-based claim is taken from that panel.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 203, Sphalerite row; page 1, column definitions; page 2, distribution terms.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-11)
  2. fowler_crundwell_1999: Fowler TA and Crundwell FK (1999). Leaching of Zinc Sulfide by Thiobacillus ferrooxidans: Bacterial Oxidation of the Sulfur Product Layer Increases the Rate of Zinc Sulfide Dissolution at High Concentrations of Ferrous Ions. Applied and Environmental Microbiology 65:5285-5292. DOI 10.1128/AEM.65.12.5285-5292.1999. Methods; Figures 2-6 and 8-10; Discussion.
    https://doi.org/10.1128/AEM.65.12.5285-5292.1999 (accessed 2026-10-11)
  3. fowler_crundwell_1998: Fowler TA and Crundwell FK (1998). Leaching of Zinc Sulfide by Thiobacillus ferrooxidans: Experiments with a Controlled Redox Potential Indicate No Direct Bacterial Mechanism. Applied and Environmental Microbiology 64:3570-3575. DOI 10.1128/AEM.64.10.3570-3575.1998. Methods; Figures 4-6; Discussion.
    https://doi.org/10.1128/AEM.64.10.3570-3575.1998 (accessed 2026-10-11)
  4. taxonomy_ferrooxidans: NCBI Taxonomy 920, Acidithiobacillus ferrooxidans, species; Thiobacillus ferrooxidans listed as homotypic synonym.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=920&mode=Info (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T04:56:10Z codex (GPT-6) CREATE Added IMA-grounded sphalerite identity and controlled dissolution of iron-bearing concentrate, preserving null results, source tensions, organism resolution and recovery limits. Distinguished the mineral from zinc and identified the already represented shared experiments.

Record source: data/records/sphalerite.yaml