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Greenockite mineral

Greenockite is the hexagonal CdS mineral species, distinct from cubic hawleyite, unspecified cadmium-sulfide nanoparticles, elemental cadmium and mixed ores. The September 2026 IMA-CNMNC list gives grandfathered status and original-description year 1840; that year is not a unique approval accession. The curated mechanism concerns a synthetic greenockite-assigned component of mixed CdS produced in a defined microbial laboratory experiment, not a demonstrated origin or extraction pathway for every natural greenockite occurrence. No cadmium criticality designation is inherited.

Microbial & Biochemical Mechanisms (1)

X513-associated formation of a greenockite-assigned CdS component

biomineralization Microbial

Associated Organisms: Thermoanaerobacter sp. X513 (NCBITaxon:573062)

Thermoanaerobacter sp. X513 cultures supplied with oxidized sulfur sources formed mixed synthetic CdS whose diffraction and electron-imaging data were assigned to greenockite and hawleyite. The results support culture-associated formation of the hexagonal component after an initially cubic product, with sulfur-source and incubation dependence. They do not establish pure greenockite recovery or transformation of a pre-existing natural greenockite feed.

Experimental Context & Analytical Limits:
Moon2013 Materials and methods, Synthesis of CdS NP, and Results, Mechanism of CdS NP formation: the displayed experiments used Thermoanaerobacter sp. X513, not the separately mentioned TOR-39. Anaerobic modified TOR-39 medium at 65 degrees C contained 10 mM glucose, 10 mM thiosulfate or sulfite and normally 2% by volume mid-log culture. Bicarbonate was kept low to limit otavite, but the complete modified medium recipe is not reproduced. The duplicate 10-mL time course used 24 h pre-growth with thiosulfate, then 0.4 mM CdCl2 per day for ten days, sampling from 5 min through 240 h after dosing began. Separate phase comparisons used total nominal Cd doses of 4.45 or 8.90 mM over ten days. These are supplied soluble cadmium salts, not leaching of natural CdS ore. General methods add 24 h after the final dose before harvest; this is not substituted for the explicitly sampled time-course endpoints. XRD samples were repeatedly washed/centrifuged, with cell pellets scraped off, then mixed with methanol on a silicon plate. Some suspensions received dithionite during preparation/storage. Live cells are present during production, but washing does not prove a sterile product. NCBITaxon:573062 is the X513-labelled entry at species rank, not a general species-level claim about all Thermoanaerobacter or an authentication assay on this experimental culture.
Curated Evidence Points:
Results, Effect of microbes and sulfur sources, and Figure 1 compare X513 with thiosulfate, sulfite or cysteine against sodium-sulfide abiotic and G20-sulfate reference preparations. XRD and HRTEM/FFT support a hexagonal greenockite-assigned component alongside cubic hawleyite in the thiosulfate/sulfite products. The displayed cysteine, G20 and sodium-sulfide comparisons are reported as cubic, not hexagonal. Figure 4 and the time-course text report the later appearance and increasing relative abundance of the hexagonal component through 240 h. These are shared experiments with the hawleyite record, not independent replications.
Materials and methods and Figures 2–3 distinguish an abiotic medium comparison from the separate Cd-salt plus sodium-sulfide reference, which can itself produce cubic CdS. The no-microbe thiosulfate/sulfite controls showed negligible precipitation; the control-method sentence also says the same medium was incubated with X513 for 24 h, leaving preparation/conditioning wording ambiguous. In the room-temperature comparison, 24-h pristine and two-hour-autoclaved cultures gave fluorescence, while 0.2-micrometre filtration removed most protein and roughly half the sulfide. Thus filtration is not a sulfide-matched test of cell-surface catalysis. Dead biomass can support the optical signal; the proposed nucleation role is not an identified enzyme, a uniquely proven pathway, or proof that live metabolism is required at the moment of precipitation.
Characterization and Figure 4 use profile fitting without structural parameters, reference-intensity-ratio semi-quantification, and Scherrer crystallite sizes. They do not provide a structural refinement, raw diffraction dataset or a phase-specific isolated recovery balance. TEM object sizes exceed XRD coherent-domain estimates; the source interprets aggregation, so a universal sub-10-nm particle diameter is not adopted. The prose assigns 0.672 nm to greenockite (002), whereas the Handbook c value 0.6713 nm implies d002 about 0.3357 nm; the printed 28.1-degree (102) assignment is also not treated as an independently validated index. These unresolved labels limit detailed crystallographic interpretation without erasing the broader mixed-phase XRD/FFT observation.
Context_only Source: handbook
The structure entry supports the distinction between cubic hawleyite and hexagonal greenockite. Greenockite cell dimensions permit checking the printed lattice-spacing assignment in Moon2013; this reference is not another biosynthesis experiment.
Table 1 and the scale-up section describe washed, freeze-dried mixed CdS material and tests from 10 mL to two parallel 24-L reactors. The 1-L yield and conversion values concern bulk CdS nanoparticles, not either pure polymorph; reported conversion is not accompanied by a closed dissolved/solid cadmium balance or a detailed analytical calculation. Similar fluorescence across volumes does not establish identical phase fractions or phase purity at every scale. These are controlled experimental scale-up demonstrations, not industrial deployment, an independently audited cost comparison, or recovered elemental cadmium. The source conclusion calls the process near room temperature, but synthesis methods specify 65 degrees C; only the separate nucleation comparison is explicitly at room temperature.

Sources & References

  1. ima202609: IMA-CNMNC (September 2026). The New IMA List of Minerals. Definitions p.1; Greenockite row p.86: CdS, G (grandfathered), original-description year 1840.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14)
  2. handbook: Handbook of Mineralogy. Greenockite. Mineral Data Publishing version 1 (2001–2005); complete one-page identity/structure entry. Historical secondary context, not microbial evidence.
    https://www.handbookofmineralogy.org/pdfs/greenockite.pdf (accessed 2026-10-14)
  3. moon2013: Moon, J.-W. et al. (2013). Scalable economic extracellular synthesis of CdS nanostructured particles by a non-pathogenic thermophile. Journal of Industrial Microbiology and Biotechnology 40(11):1263–1271. DOI 10.1007/s10295-013-1321-3. Complete publisher HTML, Materials and methods, Results, Figures 1–6 and Table 1.
    https://doi.org/10.1007/s10295-013-1321-3 (accessed 2026-10-14)
  4. taxonomy_x513: NCBI Taxonomy 573062 — Thermoanaerobacter sp. X513; species-rank X513-labelled entry. Thermoanaerobacter ethanolicus X513 is listed as a misspelling.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=573062&mode=Info (accessed 2026-10-14)

Curation History

Timestamp Curator Action Summary
2026-10-14T07:25:28.960419+00:00 codex (GPT-6; codex) CREATE Created a distinct CdS mineral record from official mineral identity and newly acquired complete Moon2013 publisher evidence, separating polymorphs, preserving phase/control/scale conflicts, and linking actual curation history.

Record source: data/records/greenockite.yaml