Wurtzite mineral
Wurtzite is the hexagonal zinc sulfide mineral, ideally ZnS, distinct from cubic sphalerite, elemental zinc and unspecified ZnS particles. The September 2026 IMA list gives grandfathered status and the original-description year 1861, not an approval accession. The accepted primary experiment assigned wurtzite together with sphalerite in dried precipitates from unresolved sulfate-reducing bacterial consortia; it did not isolate pure wurtzite or measure a phase-specific recovery yield. No criticality claim is inherited from zinc or sulfur.
Microbial & Biochemical Mechanisms (1)
Wurtzite-bearing mixed ZnS precipitation in sulfate-reducing cultures
biomineralization
Microbial
Three living, enriched sulfate-reducing consortia produced mixed ZnS precipitates assigned to wurtzite and sphalerite while filtered zinc and sulfate concentrations decreased. The supported interpretation is consortium-associated sulfide precipitation in a laboratory synthetic medium. Neither a specific causal organism nor microbial necessity for the hexagonal polymorph was established.
Experimental Context & Analytical Limits:
Chapter 2 compares mine-stream sediment inocula from Cueva de la Mora (CM) and Mina Esperanza (ME), Spain, with a previously maintained mixed culture originating from Montenegro wastewater-treatment sludge (SS), Algarve, Portugal. No strain or sequence identification is reported, so no taxon identifier is assigned. Separate 35-day enrichment used 100 mL modified Postgate B, five-percent inoculum, nitrogen and a paraffin cover. Cells were centrifuged at 4000 rpm for ten minutes and washed with the same culture medium before transfer. The 42-day zinc experiment used 200 mL basal medium containing sodium lactate, yeast extract and sulfate salts, nominally 260 mg/L Zn added as zinc sulfate heptahydrate. Medium was adjusted to pH 7, nitrogen purged, paraffin covered and incubated at room temperature in a nitrogen-purged glove box. The zinc-assay inoculum dose is not given; the enrichment dose is not transferred to this assay. Weekly 10 mL samples were centrifuged and filtered at 0.2 micrometres before acid-preserved ICP-OES Zn/total-S analysis. Final centrifuged solids were frozen and lyophilized before microscopy and diffraction.
Chapter 2 compares mine-stream sediment inocula from Cueva de la Mora (CM) and Mina Esperanza (ME), Spain, with a previously maintained mixed culture originating from Montenegro wastewater-treatment sludge (SS), Algarve, Portugal. No strain or sequence identification is reported, so no taxon identifier is assigned. Separate 35-day enrichment used 100 mL modified Postgate B, five-percent inoculum, nitrogen and a paraffin cover. Cells were centrifuged at 4000 rpm for ten minutes and washed with the same culture medium before transfer. The 42-day zinc experiment used 200 mL basal medium containing sodium lactate, yeast extract and sulfate salts, nominally 260 mg/L Zn added as zinc sulfate heptahydrate. Medium was adjusted to pH 7, nitrogen purged, paraffin covered and incubated at room temperature in a nitrogen-purged glove box. The zinc-assay inoculum dose is not given; the enrichment dose is not transferred to this assay. Weekly 10 mL samples were centrifuged and filtered at 0.2 micrometres before acid-preserved ICP-OES Zn/total-S analysis. Final centrifuged solids were frozen and lyophilized before microscopy and diffraction.
Curated Evidence Points:
Support
Source:
castillo_thesis2013
Chapter 2 Results 3.2, printed pages 31-33 / PDF pages 55-57, Figures 2.5-2.6, identifies Zn and S by SEM-EDS and assigns the final solids from all three cultures to mixed sphalerite and wurtzite by synchrotron micro-XRD. With wavelength 0.443 angstrom, the authors identify a wurtzite-specific (103) feature near 14.5 degrees 2theta; Figure 2.6b displays the SS fit over 7.5-9 degrees as sphalerite (111) plus wurtzite (100), (002) and (101). Its reported fit agreement is not a phase-purity or abundance measurement. The Scherrer estimate of 3-6 nm describes the mixed ZnS crystallites rather than a measured wurtzite-only particle-size distribution.
Support
Source:
castillo_thesis2013
Results 3.1 and Figure 2.3d, printed pages 29-30 / PDF pages 53-54, report filtered Zn falling from approximately 260 mg/L to below detection after 14, 35 and 42 days for SS, ME and CM, respectively. The unspecified detection threshold is not zero. Decreasing sulfate, changing redox potential and eventual increases in most-probable-number estimates support active sulfate-reducing cultures. These are solution-removal observations, not an isolated Zn product, wurtzite yield or industrial AMD trial.
Partial
Source:
castillo_thesis2013
Complete Chapter 2 Methods and Results do not describe matched uninoculated, killed-biomass or chemically sulfided precipitation controls. Figures 2.4, 2.5 and 2.7 show close association of ZnS aggregates, cells and organic material, but do not establish exclusive biological nucleation or distinguish individual polymorphs in each imaged particle. Growth and metabolic activity were inferred at community level. The initial SS population was higher than the mine inocula, limiting intrinsic-tolerance comparisons. Figure captions describe duplicate means without defining independent-reactor replication; the separate MPN n=3 does not resolve that experimental unit.
Partial
Source:
castillo_thesis2013
Methods 2.2 states approximately 3000 mg/L sulfate, whereas Results 3.1, Discussion and Figure 2.3c give approximately 1400 mg/L initially. The nominal pH-7 adjustment differs from the approximately 6.3 initial values plotted in Figure 2.3a. Figure 2.3's caption calls panel c zinc although zinc is plotted in panel d. The Spanish summary on printed page 23 gives aggregates smaller than 2.5 nm, whereas Results 3.2 and the microscopy describe micrometre-scale spheroids; the inconsistent summary unit is not used as a measurement.
Partial
Source:
castillo_thesis2013
Discussion 4 infers reduced sulfur from the difference between measured total sulfur and sulfate; direct dissolved-sulfide speciation and volatile-sulfur measurements are not reported. The authors also consider biosorption and organic complexation, so Zn depletion is not apportioned quantitatively to precipitation. Washing in culture medium leaves carryover unresolved, and dried end-point diffraction does not establish the exact wet-culture phase history. No purified product mass balance, stable long-term sequestration, organism-specific pathway or industrial deployment is demonstrated.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026, Wurtzite row, PDF page 236; page 1 defines grandfathered status G. Complete retained original rechecked: ZnS, G, 1861.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-15) -
handbook_wurtzite: Handbook of Mineralogy. Wurtzite, version 1 (2001-2005), complete one-page entry: hexagonal (Zn,Fe)S, synthetic 2H P63mc structure and powder pattern; Fe-bearing formula accommodates substitution rather than changing the IMA ideal ZnS formula.
https://www.handbookofmineralogy.org/pdfs/wurtzite.pdf (accessed 2026-10-15) -
castillo_thesis2013: Castillo Hernandez, Julio Cesar (2013). Procesos biogeoquimicos de sulfato-reduccion involucrados en la remediacion de los drenajes acidos de mina y las balsas de fosfoyeso. Doctoral thesis, Universidad Internacional de Andalucia and Universidad de Huelva, ISBN 978-84-7993-915-1. Complete 143-page institutional original; accepted Chapter 2, printed pages 18-39 / PDF pages 42-63, Methods 2.1-2.3, Results 3.1-3.2, Discussion 4 and Figures 2.1-2.7. Chapter explicitly based on Castillo et al. (2012), DOI 10.1016/j.scitotenv.2012.02.013; these are one experimental lineage. Appendix PDF page 139 contains only the journal first page, not its complete nine-page original.
https://hdl.handle.net/10334/2563 (accessed 2026-10-15)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-15T01:19:33Z |
codex (GPT-6; codex) | CREATE | Created wurtzite from a complete institutional primary experiment supporting mixed ZnS precipitation in sulfate-reducing cultures, preserving unresolved community identity, controls, source conflicts and the distinction between filtered removal and phase-specific recovery. |
Record source: data/records/wurtzite.yaml