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Tungsten element Critical Material

The element W, distinct from tungstate ions, scheelite and wolframite, tungsten carbides, experimental concentrates and mining wastes. The dated US designation concerns the named tungsten mineral commodity rather than every W-bearing material. A laboratory study supports enhanced tungsten release from an impure scheelite concentrate in Metallosphaera sedula cultures; it does not establish an isolated tungsten product, a specific tungsten redox pathway or industrial recovery.

Identifiers & Classification

System Identifier Label
CHEBI CHEBI:27998 tungsten atom

Criticality Designations

Jurisdiction List Name Edition / Document Classification Source
United States of America USGS Final List of Critical Minerals 2025; Federal Register 90:50494-50497, 7 November 2025 critical usgs2025

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. chebi_tungsten: ChEBI CHEBI:27998 - tungsten atom; formula W, net charge 0
    https://www.ebi.ac.uk/chebi/CHEBI:27998 (accessed 2026-10-11)
  2. usgs2025: USGS (2025). Final 2025 List of Critical Minerals. Federal Register 90:50494-50497, document 2025-19813; tungsten row on page 50497.
    https://www.govinfo.gov/content/pkg/FR-2025-11-07/html/2025-19813.htm (accessed 2026-10-11)
  3. 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)
  4. 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
2026-10-11T05:42:49Z Codex (GPT-6; Codex) CREATE Added verified elemental identity, dated US criticality and controlled laboratory tungsten-release evidence from scheelite concentrate, preserving feed, mechanism, analytical and recovery limitations.

Record source: data/records/tungsten.yaml