Antimony element Critical Material
Antimony (Sb), represented as an element distinct from antimonate feed, sorbed antimonite and sulfide-bearing products. A sediment-inoculated laboratory experiment supports transformation through coupled microbial and chemical reactions under sulfidogenic conditions. The United States 2025 critical-mineral designation names the antimony commodity; it does not designate every Sb compound, host mineral or secondary resource.
Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| CHEBI |
CHEBI:30513
|
antimony 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)
Antimonate transformation coupled to microbial sulfur and iron cycling
redox transformation
Microbial
In wetland-sediment-inoculated microcosms containing antimonate, ferrihydrite, sulfate and lactate, solids-associated Sb(V) was progressively reduced to Sb(III). X-ray absorption spectroscopy supported both oxygen- and sulfur-coordinated Sb(III). Microbial sulfate reduction and formation of reactive sulfide species provide an indirect route: separate pasteurized-biogenic-material and mackinawite experiments also reduced Sb(V). Direct enzymatic reduction may contribute but was not demonstrated or excluded. This is a laboratory transformation observation, without an isolated-product yield or demonstrated industrial deployment.
Experimental Context & Analytical Limits:
Johnson et al. system D: duplicate 240 mL serum bottles containing 200 mL final suspension, with 2 mM Sb(V) added as KSb(OH)6, 50 mM Fe(III) as ferrihydrite, sulfate reported as 10 mM, and lactate in defined mineral medium adjusted to pH 7.2 before assembly. The abstract gives 10 mM lactate, whereas Methods 2.3 specifies 2 mL of 2 M lactate in 200 mL, arithmetically 20 mM; this loading discrepancy is unresolved. Bottles were argon-sparged for 20 min and incubated in the dark at 30 degrees Celsius with roller mixing. Each received 1 mL of an anoxic slurry made from 10 g of the top 5 cm of a Typha-dominated wetland sediment at Argonne National Laboratory in 150 mL medium. No pure strain or individual taxon's causal contribution is assigned. System D pH was reported as 7.11 initially, 6.87 at day 3 and 7.44 at day 21. ICP-OES measured total Sb in the 0.2 micrometre nylon filtrate, with a 5 micromolar detection limit; filter-retained solids were preserved anoxically for Sb K-edge XANES/EXAFS. Solution depletion and solids-associated redox speciation are distinct analytical outcomes. The experiment used defined laboratory feed, not ore, waste leachate or a field treatment installation.
Johnson et al. system D: duplicate 240 mL serum bottles containing 200 mL final suspension, with 2 mM Sb(V) added as KSb(OH)6, 50 mM Fe(III) as ferrihydrite, sulfate reported as 10 mM, and lactate in defined mineral medium adjusted to pH 7.2 before assembly. The abstract gives 10 mM lactate, whereas Methods 2.3 specifies 2 mL of 2 M lactate in 200 mL, arithmetically 20 mM; this loading discrepancy is unresolved. Bottles were argon-sparged for 20 min and incubated in the dark at 30 degrees Celsius with roller mixing. Each received 1 mL of an anoxic slurry made from 10 g of the top 5 cm of a Typha-dominated wetland sediment at Argonne National Laboratory in 150 mL medium. No pure strain or individual taxon's causal contribution is assigned. System D pH was reported as 7.11 initially, 6.87 at day 3 and 7.44 at day 21. ICP-OES measured total Sb in the 0.2 micrometre nylon filtrate, with a 5 micromolar detection limit; filter-retained solids were preserved anoxically for Sb K-edge XANES/EXAFS. Solution depletion and solids-associated redox speciation are distinct analytical outcomes. The experiment used defined laboratory feed, not ore, waste leachate or a field treatment installation.
Curated Evidence Points:
Support
Source:
johnson_2021
Methods 2.3-2.4, 2.8 and 2.11; Results 3.1; Figures 13-16: system D lost more than 99% of solution-phase Sb within 5 days, while its day-5 EXAFS remained similar to the uninoculated control. Later XANES/EXAFS showed reduction and changing O/S coordination. Early solution removal therefore does not itself establish reduction. Spectral components are model-based assignments, not isolated product quantities or recovery yields.
Partial
Source:
johnson_2021
Methods 2.3 and Results 3.1 define uninoculated system A as containing Sb(V), ferrihydrite and sulfate. It removed about 98% of solution-phase Sb within 5 days without detected Sb(V) reduction, supporting substantial abiotic sorption. Abbreviated Figure 3/4 captions omit Sb from A; the explicit methods and Sb results ground this control assignment. Community sequencing and sulfate consumption support microbial activity, but do not identify an Sb reductase or prove direct Sb respiration.
Partial
Source:
johnson_2021
Methods 2.7, Results 3.2, Figure 18 and Discussion 4.3: material from the Sb-free biotic system B at day 21 was pasteurized for 1 hour at 70 degrees Celsius, amended with 2 mM Sb(V), and examined after a further 21 days. Sb(III) formation in this material and in separate abiotic mackinawite assays supports a chemical reduction route involving biogenic sulfide. This is a mechanistic comparison, not a matched killed-cell replicate of D or a quantitative microbial-effect estimate. Attempts to enrich direct Sb(V)-reducing bacteria failed, but do not rule out their contribution in D.
Partial
Source:
johnson_2021
Results 3.1 and Discussion 4.3 do not uniquely identify all system D products: fits using sorbed Sb(III) and amorphous Sb2S3 standards describe O/S coordination, but a mixed-ligand phase such as kermesite could not be resolved from those alternatives. No crystalline Sb mineral is assigned here. The paper also cautions that acid-extraction Fe(II) assays can overestimate in-situ Fe reduction in sulfide-bearing samples.
Sources & References
-
johnson_2021: Johnson, Antonopoulos, Boyanov, Flynn, Koval, Kemner and O'Loughlin (2021). Reduction of Sb(V) by coupled biotic-abiotic processes under sulfidogenic conditions. Heliyon 7(2), e06275. DOI 10.1016/j.heliyon.2021.e06275; PMID 33681496; PMC7930292.
https://doi.org/10.1016/j.heliyon.2021.e06275 (accessed 2026-10-11) -
usgs_2025: U.S. Geological Survey (2025). Final 2025 List of Critical Minerals. Federal Register 90 FR 50494-50497, November 7, 2025; antimony row in the final commodity table, page 50496.
https://www.govinfo.gov/content/pkg/FR-2025-11-07/html/2025-19813.htm (accessed 2026-10-11) -
chebi_antimony: ChEBI:30513 - antimony atom; Sb, net charge zero
https://www.ebi.ac.uk/chebi/CHEBI:30513 (accessed 2026-10-11)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-11T04:57:40Z |
Codex (GPT-6; Codex) | create_record | Curated elemental antimony, the US 2025 designation and a sediment microcosm transformation with chemical controls, uncertain lactate loading and nonunique product speciation. Kept incomplete BES Sb sample and microbial attribution in the research handoff. |
Record source: data/records/antimony.yaml