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Scheelite mineral

Scheelite is the Ca(WO4) mineral species in the September 2026 IMA list, with grandfathered status G and original-description year 1821. It is distinct from elemental tungsten, tungstate ions, wolframite and impure tungsten concentrates. The experiment below reuses the Blazevic 2019 study also represented under tungsten, with a scheelite-bearing mixed feed; it is not an independent replicate or evidence for a pure-mineral yield. No constituent-element criticality is inherited.

Microbial & Biochemical Mechanisms (1)

Culture-enhanced tungsten release from scheelite concentrate

bioleaching Microbial

Associated Organisms: Metallosphaera sedula (NCBITaxon:43687)

Aerobic M. sedula cultures released more tungsten into clarified, filtered medium than corresponding uninoculated controls during incubation with an impure scheelite concentrate. This supports a microbial contribution to W mobilization in this system. The actual growth-supporting energy source and the relative contributions of direct mineral contact, microbially altered chemistry and abiotic acid dissolution remain unresolved. No enzyme-specific or tungsten-oxidation mechanism is established.

Experimental Context & Analytical Limits:
The study used M. sedula DSM5348, represented here by a species-level identifier, in DSMZ88 Sulfolobus medium initially adjusted to pH 2.0 with sulfuric acid and not further adjusted. Aerobic cultures at 73 degrees C received CO2 and 10 g/L scheelite concentrate of average particle size 1 mm from the Serido Scheelite Province, Brazil. The feed was heated at 180 degrees C for at least 24 h and autoclaved at 121 degrees C for 20 min. It was not pure CaWO4: methods report Fe- and Mn-oxide impurities, while Table 1 reports multiple elements. The methods' 19.0% Fe-oxide statement and Table 1's 22.6 wt% Fe value are not reconciled; no pure-mineral or feed-normalized yield is inferred. Uninoculated medium with identically sterilized concentrate supplied the abiotic comparison. During the 21-day experiment, centrifuged supernatants were filtered at 0.44 micrometres and analyzed by ICP-OES. Figure 3 reports three biological replicates with standard-deviation error bars. This operational filtrate measurement does not identify aqueous W species or count W retained in cells and solids. No isolated product yield or complete tungsten mass balance is reported.
Curated Evidence Points:
Materials and Methods (Strain, Media Composition and Cultivation Setup; Metal Analysis), the first Results subsection and Figure 3A support a higher W signal in inoculated cultures than corresponding abiotic controls, with appreciable abiotic release also present. Figure 1 supports growth and mineral attachment in the tested impure concentrate. Figure 3's plotted x-axis is in days although its caption says hours; the y-axis describes log10 soluble metals with mg/L units. No exact concentration, fold change or recovery percentage is extracted from this ambiguously labeled graph.
The intracellular Mn/Fe discussion explicitly states that the actual energy source and an oxidizable-substrate balance sufficient to explain growth could not be confirmed. The proposed Fe/Mn oxidation-driven mineral disruption is therefore a hypothesis; the Conclusion also allows indirect chemistry and acid dissolution. These limits prevent treating growth on the concentrate as proof of energy conservation from tungsten or pure scheelite.
Figures 4-7 and the tungsten-deposit discussion support W-bearing surface encrustation in processed cells, so filtrate W alone is not total mobilized W. The microscopy preparation included 30 days of oxic dehydration after 21 days of culture and focused-ion-beam preparation. The authors describe the deposits as carbide-like and call for further W-environment spectroscopy; no pure WC phase, resolved W redox route, in-vivo product stoichiometry or useful material yield is accepted here. This associated observation does not convert the bioleaching result into demonstrated recovery.

Sources & References

  1. ima_2026_09: IMA-CNMNC. The New IMA List of Minerals, September 2026. PDF page 194, Scheelite row; page 1 column definitions and page 2 distribution terms.
    https://cnmnc.units.it/files/editor/IMA_Master_List_(2026-09).pdf (accessed 2026-10-11)
  2. blazevic2019: Blazevic et al. (2019). Biotransformation of Scheelite CaWO4 by the Extreme Thermoacidophile Metallosphaera sedula: Tungsten-Microbial Interface. Frontiers in Microbiology 10:1492; Materials and Methods, Results and Discussion, Figures 1-7 and Table 1.
    https://doi.org/10.3389/fmicb.2019.01492 (accessed 2026-10-11)
  3. ncbi_metallosphaera: NCBI Taxonomy 43687 - Metallosphaera sedula; species, with DSM5348 listed among type-strain designations.
    https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id=43687&retmode=xml (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T09:26:54.239859+00:00 codex (GPT-6; codex) CREATE Created scheelite species identity with qualified mixed-concentrate archaeal leaching evidence.

Record source: data/records/scheelite.yaml