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Copper element Critical Material

Copper is the element Cu, grounded by the ChEBI copper-atom identifier. The United States 2025 designation names the copper commodity; it does not designate every copper-bearing mineral or waste. Experimental copper released from chalcopyrite concentrate is distinct from elemental copper metal and from a recovered, purified product.

Identifiers & Classification

System Identifier Label
CHEBI CHEBI:28694 copper atom

Criticality Designations

Jurisdiction List Name Edition / Document Classification Source
United States of America U.S. Department of the Interior Final List of Critical Minerals 2025 (published November 7, 2025; 90 FR 50494-50497) critical usgs_2025

Microbial & Biochemical Mechanisms (1)

Acidophile-dependent copper release from chalcopyrite concentrate

bioleaching Microbial

Associated Organisms: Acidithiobacillus caldus (NCBITaxon:33059), Sulfobacillus thermosulfidooxidans (NCBITaxon:28034), Leptospirillum ferriphilum (NCBITaxon:178606)

Defined acidophile cultures promoted copper release from chalcopyrite concentrate in laboratory flasks. The Acidithiobacillus caldus plus Sulfobacillus thermosulfidooxidans combination produced the largest reported copper concentration in the initial experiment. Adding the strong iron oxidizer Leptospirillum ferriphilum did not maximize copper release: all binary combinations outperformed the three-species mixture. This is a conditional leaching result, not isolated copper recovery or demonstrated deployment of a designed consortium at industrial scale.

Experimental Context & Analytical Limits:
Aitik-mine flotation concentrate, reported as 29.5% Cu, sieved to 50-100 micrometres; EDTA/NaOH and acetone washes, overnight drying at 60 degrees C and 10 hours at 120 degrees C under nitrogen preceded inoculation. The source notes accompanying bornite may occur at the deposit; this is not an assay on an elemental copper feed. Living A. caldus DSM 8584, S. thermosulfidooxidans DSM 9293 and L. ferriphilum DSM 14647 were tested singly and in all two- and three-species combinations, with uninoculated controls. Species-level identifiers below do not replace these experimental strain designations. Four flasks per treatment contained 100 mL MAC medium, initially pH 1.8, and 2% w/v concentrate in 250 mL vessels; inocula were 10^7 cells per mL per species. Incubation was at 38 +/- 2 degrees C and 120 rpm. Inoculated runs ended 14 days after the onset of iron oxidation (redox potential above 400 mV versus Ag/AgCl), giving 14-20 days total incubation. Endpoints are therefore not a common elapsed-time rate. AAS after heated HCl digestion of slurry measured total released copper, including dissolved and precipitated fractions.
Curated Evidence Points:
Methods and Bioleaching of Chalcopyrite Concentrate results, Figure 1C, support composition-dependent copper release. The initial A. caldus/S. thermosulfidooxidans treatment reached 14.2 +/- 0.3 mM total released Cu; Figure 1 identifies means +/- SD with n=4. Uninoculated controls released 2.4 +/- 0.3 mM Cu after 15 days. The record preserves the authors' concentration assay, without converting it to a recovery percentage or a purified metal yield.
The same results section reports marginal leaching by A. caldus alone and attributes its late iron oxidation to possible surviving environmental contaminants. It also reports variable run lengths and lower performance of the three-species mixture than the binary mixtures. These observations limit generalization to arbitrary acidophile mixtures and unsterilized ores. Low-redox and cell- attachment explanations, candidate iron-oxidation genes and scale-up feasibility remain interpretations or future tests, not demonstrated molecular causes or industrial performance.

Sources & References

  1. chebi_copper: ChEBI:28694, copper atom; elemental identity, Cu, charge 0.
    https://www.ebi.ac.uk/chebi/CHEBI:28694 (accessed 2026-10-11)
  2. usgs_2025: U.S. Department of the Interior. Final 2025 List of Critical Minerals. Federal Register 90 FR 50494-50497, November 7, 2025; copper row.
    https://www.govinfo.gov/content/pkg/FR-2025-11-07/html/2025-19813.htm (accessed 2026-10-11)
  3. christel_2018: Christel et al. (2018). Weak Iron Oxidation by Sulfobacillus thermosulfidooxidans Maintains a Favorable Redox Potential for Chalcopyrite Bioleaching. Frontiers in Microbiology 9:3059. DOI 10.3389/fmicb.2018.03059; Methods, Bioleaching of Chalcopyrite Concentrate results, and Figure 1.
    https://doi.org/10.3389/fmicb.2018.03059 (accessed 2026-10-11)
  4. taxonomy_sulfobacillus: NCBI Taxonomy 28034, Sulfobacillus thermosulfidooxidans; species record lists DSM 9293 as type strain.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=28034 (accessed 2026-10-11)
  5. taxonomy_leptospirillum: NCBI Taxonomy 178606, Leptospirillum ferriphilum; species record lists DSM 14647 as type strain.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=178606 (accessed 2026-10-11)
  6. taxonomy_acidithiobacillus: NCBI Taxonomy 33059, Acidithiobacillus caldus; species record lists DSM 8584 as type strain.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=33059 (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T04:02:09Z Codex (GPT-6) CREATE Added a copper element record with verified ChEBI identity, the final United States 2025 commodity designation, and bounded laboratory chalcopyrite-concentrate bioleaching evidence from Christel et al. 2018. Retained controls, unequal endpoints, assay fractions, possible contamination and unestablished industrial deployment.

Record source: data/records/copper.yaml