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Borates commodity Critical Material

Commercial borate raw materials, encompassing borate ores and refined borate products rather than a single ion or mineral species. USGS distinguishes natural borates such as colemanite and ulexite from refined borax and the associated boric-acid product stream. The commodity is distinct from elemental boron and from the separately qualified metallurgy-grade boron designation. The criticality entry records the named BGS/CMIC assessment, whose cover states that it does not constitute government policy. The microbial experiment below concerns one colemanite-bearing ore, not every borate or a purified product.

Criticality Designations

Jurisdiction List Name Edition / Document Classification Source
United Kingdom British Geological Survey / CMIC UK 2024 Criticality Assessment, Table 11 2024; Open Report OR/24/059 critical bgs-uk2024-or24059

Microbial & Biochemical Mechanisms (1)

Fungal leaching of a colemanite-bearing borate ore

bioleaching Microbial

Associated Organisms: Aspergillus niger (NCBITaxon:5061)

Aspergillus niger cultures released soluble boron from a colemanite-bearing ore while producing organic acids. This laboratory observation supports fermentation-associated leaching; it does not establish an exclusive molecular cause, an isolated boric-acid product or industrial performance.

Experimental Context & Analytical Limits:
Bayat et al. used growing A. niger, reported as ATCC 11414, and mixed Kütahya-Emet ore reported as 28.05 wt% B2O3-equivalent. Nominal particle size was below 0.075 mm. Methods specify autoclaved ore and sucrose medium, 150 mL in 250-mL flasks, 1 mL of a 3 x 10^7 spores/mL suspension, 150 rpm and 30 +/- 2 C; 1-10% w/v pulp densities were followed for 21 days. Abstract/optimum-condition text instead gives 25 +/- 2 C, and initial pH is inconsistently stated as 5.5 or about 7. Boron was assayed volumetrically in filtrate and acids by HPLC. Replication was at least duplicate. These reporting conflicts prevent treating the protocol as an unambiguous optimum.
Curated Evidence Points:
Methods pp. 3-4, Table 3 and Figures 1-3 support soluble-boron release during culture, acid production and culture-associated acidification relative to the stated no-microorganism control. The species identifier does not independently authenticate the reported strain.
Table 1 reports twelve oxide wt% cells that sum to 126.8%, leaving the bulk composition unresolved. The reported 28.05 wt% B2O3 cell is not normalized or treated as a validated recovery denominator. Table 3 gives no corresponding abiotic boron-release series, so the microbial increment in dissolution is unresolved. Its 5% endpoint pH differs from the Results and optimum-condition text. Figure 4's fitted slope differs from the kinetic coefficient reported in the text. Extraction percentages and kinetic constants are not adopted. The chemical comparison used a different temperature and duration; no isolated-product purity or recovery mass balance was demonstrated.

Sources & References

  1. usgs-mcs2025-boron: US Geological Survey, Mineral Commodity Summaries 2025, Boron, printed pp. 48-49: natural and refined borate commodities and boric-acid production
    https://pubs.usgs.gov/periodicals/mcs2025/mcs2025-boron.pdf (accessed 2026-10-11)
  2. bgs-uk2024-or24059: Mudd et al., UK 2024 Criticality Assessment, BGS/CMIC Open Report OR/24/059: cover disclaimer; Table 1, printed p. vii; Table 11, printed p. 44
    https://nora.nerc.ac.uk/id/eprint/539735/1/OR24059.pdf (accessed 2026-10-11)
  3. bayat2011-colemanite: Bayat, Arslan and Bayat (2011), Use of Aspergillus niger in the bioleaching of colemanite for the production of boric acid, Electronic Journal of Biotechnology 14(3), DOI 10.2225/vol14-issue3-fulltext-7: Methods pp. 3-4, Tables 1 and 3, Figures 1-4
    https://www.scielo.cl/pdf/ejb/v14n3/a07.pdf (accessed 2026-10-11)
  4. ncbi-aspergillus-niger: NCBI Taxonomy 5061, Aspergillus niger; species context, not strain authentication
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=5061 (accessed 2026-10-11)

Curation History

Timestamp Curator Action Summary
2026-10-11T08:30:19Z codex (GPT-6; codex) create Created a borates commodity record with a narrowly qualified colemanite bioleaching experiment.
2026-10-11T08:37:48Z codex (GPT-6; codex) EDIT Qualified the reported ore composition and retained the unresolved 126.8 wt% source total without normalization or a validated recovery denominator.

Record source: data/records/borates.yaml