Carrollite mineral
Carrollite is the CuCo2S4 mineral species, listed as grandfathered with original-description year 1852 in the September 2026 IMA list. It is distinct from elemental cobalt or copper, dissolved metal ions, mixed cobalt-bearing ores and mine tailings. The evidence below concerns laboratory surface alteration of source-identified natural carrollite crystals in an acidophile culture system. It does not establish an isolated-metal recovery yield or industrial deployment. No criticality designation is inherited from constituent elements.
Microbial & Biochemical Mechanisms (1)
Culture-associated corrosion of natural carrollite crystals
bioleaching
Microbial
Natural carrollite crystals exposed in the reported ZY101 mixed-acidophile culture system developed surface pits, cracks and deposits. At 96 hours, the directly exposed specimen showed more pronounced corrosion than a specimen placed behind a membrane intended to restrict cell contact; the membrane-separated specimen also corroded. These observations are consistent with contact-associated promotion in an iron-bearing acidic system, but do not isolate a unique biological cause, establish a species-specific contribution or quantify a dissolution-rate advantage. The study supplies no dissolved-cobalt or dissolved-copper yield for these crystal experiments and no isolated recovery product.
Experimental Context & Analytical Limits:
The natural crystal was supplied by Luanshya Mine, Zambia, and assigned to carrollite using chemical analysis and X-ray diffraction. Table 1 reports 3.23 mass percent unspecified other constituents, so the source's description as pure is not treated as proof of perfect bulk purity. ZY101 is reported as a mixture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans; authenticated strain accessions, culture proportions and individual causal roles are not provided. Section 2.2 combines 300 mL culture with 2700 mL 9K medium in a 4 L 316L stainless-steel tank at 45 degrees C. The 9K formulation includes 44.3 g/L FeSO4.7H2O. After culturing, the reported solution potential was about 650 mV against a calomel reference. Two crystals, each 10 by 10 by 3 mm, were introduced at initial pH 1.5. One was placed in a plexiglass container covered with a 1.0 micrometer-pore membrane; the other was directly exposed. Sterile distilled water replaced evaporation losses. Figure 2 compares the arrangements after 96 hours; Figure 4 presents the surface series from 0 through 144 hours. Mixing, gas supply, surface pretreatment, inoculum cell density and independent experimental replicate counts are not specified. These are laboratory crystal experiments, separate from mixed-ore or mixed-tailings yields in other publications.
The natural crystal was supplied by Luanshya Mine, Zambia, and assigned to carrollite using chemical analysis and X-ray diffraction. Table 1 reports 3.23 mass percent unspecified other constituents, so the source's description as pure is not treated as proof of perfect bulk purity. ZY101 is reported as a mixture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans; authenticated strain accessions, culture proportions and individual causal roles are not provided. Section 2.2 combines 300 mL culture with 2700 mL 9K medium in a 4 L 316L stainless-steel tank at 45 degrees C. The 9K formulation includes 44.3 g/L FeSO4.7H2O. After culturing, the reported solution potential was about 650 mV against a calomel reference. Two crystals, each 10 by 10 by 3 mm, were introduced at initial pH 1.5. One was placed in a plexiglass container covered with a 1.0 micrometer-pore membrane; the other was directly exposed. Sterile distilled water replaced evaporation losses. Figure 2 compares the arrangements after 96 hours; Figure 4 presents the surface series from 0 through 144 hours. Mixing, gas supply, surface pretreatment, inoculum cell density and independent experimental replicate counts are not specified. These are laboratory crystal experiments, separate from mixed-ore or mixed-tailings yields in other publications.
Curated Evidence Points:
Support
Source:
yang2015
Section 2.1, Table 1 and Figure 1 establish the source-assigned natural carrollite substrate. Sections 2.2 and 3.1 and Figure 2 specify the culture, conditions and the 96-hour comparison. The original SEM panels show corrosion in both arrangements and more pronounced pits on the directly exposed surface. Figure 4 shows progressive surface alteration and deposits over the reported exposure series. This supports the bounded observation of mineral surface corrosion in the stated culture system, not a measured metal-extraction yield.
Partial
Source:
yang2015
The membrane-separated specimen shares the cultured leaching system; it is not an independently sterile abiotic control. Bacterial exclusion by the 1.0 micrometer membrane is not experimentally verified, and membrane-associated differences in mass transfer are not controlled. No matched sterile membrane experiment, quantitative surface-cell count, replicated corrosion measurement or dissolved-metal balance is reported. Thus selected SEM fields and the two exposure arrangements do not prove that cell attachment alone caused the difference or establish a statistically significant dissolution-rate enhancement.
Partial
Source:
yang2015
Section 3.1 proposes ferric-ion concentration within extracellular polymeric substances and microbial iron recycling. The EPS iron value cited there comes from earlier literature, not a measurement in this crystal experiment. Neither EPS composition nor specimen-specific iron-reoxidation activity is measured. Figure 5 labels a deposited surface layer as passivation, but no paired rate experiment demonstrates inhibition by that layer. These remain interpretations rather than separately demonstrated molecular mechanisms or product identities.
Partial
Source:
yang2015
The proposed obligatory sulfur sequence and polysulfide pathway are not adopted as established outcomes. In Figure 3 and Table 2, peaks near 161.5-161.8 eV are assigned to sulfide at 0-48 hours, whereas 161.641 eV at 72 hours and 161.606 eV at 96 hours are assigned to elemental sulfur. Oxidized-sulfur assignments already appear at 24 hours. These assignments and sparse time points do not establish the asserted temporal sequence from sulfide through elemental sulfur and sulfite to sulfate. Resolving the sulfur species requires the underlying spectra and fitting assumptions; this uncertainty does not erase the separately observed surface alteration.
Sources & References
-
ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. Carrollite row, PDF page 38; column definitions and distribution terms on pages 1-2. Retained original re-inspected on the access date, not freshly downloaded.
https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-14) -
yang2015: Yang, Liu, Chen, Liu, Tong, Jin and Liu (2015). Function of microorganism and reaction pathway for carrollite dissolution during bioleaching. Transactions of Nonferrous Metals Society of China 25, 2718-2724. Complete seven-page publisher PDF; Sections 2-3, Figures 1-5 and Tables 1-2. The original pagination corrects Crossref's 2718-2754.
https://doi.org/10.1016/S1003-6326(15)63896-1 (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T04:40:05.305919+00:00 |
codex (GPT-6; codex) | CREATE | Created carrollite mineral identity and qualified natural-crystal corrosion evidence, retaining membrane-control, culture-resolution, sulfur-assignment and recovery-yield limitations. Separate mixed-tailings and author-chapter sources remain contextual research evidence. |
Record source: data/records/carrollite.yaml