Aluminium element Critical Material
Aluminium (Al), the chemical element, distinct from its ions, alumina, bauxite ores and red-mud wastes. The dated US designation maps the named aluminum commodity to this element without assigning criticality to every Al-bearing material. The curated mechanism concerns laboratory aluminium mobilization from a mixed red-mud sample, not production of aluminium metal.
Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| CHEBI |
CHEBI:28984
|
aluminium 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)
Aspergillus-associated aluminium leaching from red mud
bioleaching
Microbial
Associated Organisms:
Aspergillus niger (NCBITaxon:5061)
Growing fungal isolate G-10 mobilized aluminium from red mud while acidifying the medium and accumulating organic acids. Synthetic acid mixtures also leached aluminium, supporting a contribution from extracellular chemistry without demonstrating that live fungal contact is required or resolving a specific enzyme mechanism.
Experimental Context & Analytical Limits:
G-10 was assigned to Aspergillus niger using morphology and a 612-bp ITS sequence with 99% similarity; the species identifier does not independently authenticate the strain. Red mud collected at the Ajka spill site in October 2010 was air-dried, disaggregated and sieved below 0.2 mm. The selected laboratory assay used 0.2 g red mud in 45 mL Sabouraud dextrose broth plus 5 mL suspension of approximately 10^6 spores/mL, in 250-mL flasks. Medium was autoclaved before inoculation; growing cultures were incubated statically in darkness at 25 degrees C for seven days, in triplicate. Aluminium was measured by ICP-OES in 0.45-micrometre filtrate; this is a filter-passing total-Al measurement, not a free Al3+ speciation assay. Table 1 reports 6.97% total Al in the dry feed. Its Al-host phases were unresolved by XRD, so no particular aluminium mineral is assigned to the experiment.
G-10 was assigned to Aspergillus niger using morphology and a 612-bp ITS sequence with 99% similarity; the species identifier does not independently authenticate the strain. Red mud collected at the Ajka spill site in October 2010 was air-dried, disaggregated and sieved below 0.2 mm. The selected laboratory assay used 0.2 g red mud in 45 mL Sabouraud dextrose broth plus 5 mL suspension of approximately 10^6 spores/mL, in 250-mL flasks. Medium was autoclaved before inoculation; growing cultures were incubated statically in darkness at 25 degrees C for seven days, in triplicate. Aluminium was measured by ICP-OES in 0.45-micrometre filtrate; this is a filter-passing total-Al measurement, not a free Al3+ speciation assay. Table 1 reports 6.97% total Al in the dry feed. Its Al-host phases were unresolved by XRD, so no particular aluminium mineral is assigned to the experiment.
Curated Evidence Points:
Support
Source:
urik2015
Sections 2.3, 2.5 and 3.3 with Figure 3 report approximately 141 mg/L Al after seven days for G-10 at the selected loading. No-fungus controls gave undetected or below-detection Al; a numerical Al detection limit is not supplied. Section 3.4 and Figure 7a report final pH 2.3 with oxalic and citric acids at 16.0 and 28.6 mmol/L. These results establish mobilization into the filtrate, without demonstrating an isolated aluminium product or industrial operation.
Partial
Source:
urik2015
Sections 2.4 and 3.4 with Figure 8 report approximately 142 mg/L Al for synthetic mixture B, formulated from the day-five fungal acid profile. Mixtures used sodium salts and HCl-adjusted pH, 0.2 g red mud in 50 mL and two days at 25 degrees C. This chemically mediated result is comparable in concentration to fungal leaching, but unequal incubation periods and media prevent a matched kinetic comparison. Acidification alone does not identify its physiological cause, and these experiments do not isolate proton effects from ligand complexation or other metabolites.
Sources & References
-
chebi_aluminium: ChEBI CHEBI:28984 - aluminium atom; formula Al, net charge 0
https://www.ebi.ac.uk/chebi/CHEBI:28984 (accessed 2026-10-11) -
usgs2025: US Department of the Interior, US Geological Survey (2025). Final 2025 List of Critical Minerals. Federal Register 90:50494-50497, 7 November 2025, document 2025-19813; Aluminum row.
https://www.govinfo.gov/content/pkg/FR-2025-11-07/html/2025-19813.htm (accessed 2026-10-11) -
urik2015: Urik, Bujdos, Milova-Ziakova, Mikusova, Slovak and Matus (2015). Aluminium leaching from red mud by filamentous fungi. Journal of Inorganic Biochemistry 152:154-159. DOI 10.1016/j.jinorgbio.2015.08.022; Sections 2.1-2.5, 3.1, 3.3-3.5, Table 1 and Figures 3, 7-8.
https://doi.org/10.1016/j.jinorgbio.2015.08.022 (accessed 2026-10-11) -
urik2017_fulltext: Urik (2017). Interactions of toxic metals and metalloids with fungi, habilitation thesis, Comenius University in Bratislava. Official Brno University of Technology copy, Attachment E, PDF pages 80-85 reproduce Urik et al. (2015), journal pages 154-159; same experiment, not new evidence.
https://www.vut.cz/uredni-deska/habilitace?action=priloha&priloha=226417 (accessed 2026-10-11) -
ncbi_aspergillus: NCBI Taxonomy 5061 - Aspergillus niger; species
https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=taxonomy&id=5061&retmode=xml (accessed 2026-10-11)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-11T05:38:07Z |
Codex (GPT-6; Codex) | CREATE | Added verified aluminium identity and dated US designation with a bounded fungal red-mud leaching experiment, preserving analytical, taxonomic and chemical-control limits; independent review is separate. |
Record source: data/records/aluminium.yaml