Osmium element Critical Material
Osmium (Os), distinct from osmium chlorides, oxides, coordination complexes and platinum-group ores or commodities. Australia's 20 February 2024 critical-minerals list includes osmium through its explicitly enumerated platinum-group-elements entry; this grouped designation is not a separate unqualified listing of every osmium-bearing material. Curated microbial evidence is a historical cell-extract experiment with qualified product assignments, not a demonstrated industrial recovery process.
Identifiers & Classification
| System | Identifier | Label |
|---|---|---|
| CHEBI |
CHEBI:30687
|
osmium atom |
Criticality Designations
| Jurisdiction | List Name | Edition / Document | Classification | Source |
|---|---|---|---|---|
| Australia | Department of Industry, Science and Resources Critical Minerals List (platinum-group-elements entry, including osmium by footnote 16) | 2024 (updated 20 February 2024) | critical |
australia_2024
|
Microbial & Biochemical Mechanisms (1)
Hydrogen-coupled osmium transformation in bacterial crude extracts
redox transformation
Microbial
Crude cell-free extracts reported as Micrococcus lactilyticus consumed molecular hydrogen in separate assays with OsO4, OsO2 or Os(III) chloride. The authors interpreted the products as osmate from OsO4 and elemental osmium from OsO2 or Os(III) chloride. The stoichiometry supports redox transformation under the assay conditions, but the product identities and biological necessity remain less well resolved than an independently characterized phase or purified-enzyme result.
Experimental Context & Analytical Limits:
The paper uses the historical organism name Micrococcus lactilyticus and notes classification as Veillonella alcalescens; no strain or culture accession is provided. No modern strain identifier is inferred. Cells grown in a cited complex lactate medium were harvested, washed with water, sonicated for 20-45 min and centrifuged cold at 25000 g for 20 min; the supernatant was the crude extract. Warburg assays were run at 30 degrees C under oxygen-scrubbed hydrogen, routinely in 2.2 mL with 150 micromol Tris buffer pH 7.0 and 1 mL extract containing approximately 30 mg protein. Stoichiometry endpoints were taken after hydrogen uptake ceased; Os-specific elapsed times are not supplied. Table 4 reports 15.6 micromol OsO4 with 12.0 micromol H2 uptake, 12.7 micromol OsO2 with 25.0 micromol H2 uptake, and 7.3 micromol Os(III) chloride with 10.7 micromol H2 uptake. These are source substrate and gas-uptake amounts, not isolated osmium yields. OsO2 was added as a suspension; other relevant substrates were commercial. Os(III) solution titration assumed oxidation to OsO4.
The paper uses the historical organism name Micrococcus lactilyticus and notes classification as Veillonella alcalescens; no strain or culture accession is provided. No modern strain identifier is inferred. Cells grown in a cited complex lactate medium were harvested, washed with water, sonicated for 20-45 min and centrifuged cold at 25000 g for 20 min; the supernatant was the crude extract. Warburg assays were run at 30 degrees C under oxygen-scrubbed hydrogen, routinely in 2.2 mL with 150 micromol Tris buffer pH 7.0 and 1 mL extract containing approximately 30 mg protein. Stoichiometry endpoints were taken after hydrogen uptake ceased; Os-specific elapsed times are not supplied. Table 4 reports 15.6 micromol OsO4 with 12.0 micromol H2 uptake, 12.7 micromol OsO2 with 25.0 micromol H2 uptake, and 7.3 micromol Os(III) chloride with 10.7 micromol H2 uptake. These are source substrate and gas-uptake amounts, not isolated osmium yields. OsO2 was added as a suspension; other relevant substrates were commercial. Os(III) solution titration assumed oxidation to OsO4.
Curated Evidence Points:
Support
Source:
woolfolk_whiteley_1962
Table 4 and pages 651-652 establish substrate-associated H2 uptake with bacterial extract. The approximate two-H2-per-OsO2 and one-and-a-half-H2-per-Os(III) stoichiometries are consistent with the authors' Os(0) assignment. Table 5 separately summarizes OsO2-to-Os and OsO4-to-osmate reactions. The OsO4 endpoint must not be rewritten as complete reduction to metal.
Partial
Source:
woolfolk_whiteley_1962
Osmate was inferred from H2 uptake and the absence of the black appearance attributed to OsO2; the OsO4 uptake is below the stated one-H2-per-substrate stoichiometry. The inspected paper gives no Os-specific diffraction, spectroscopy, isolated-product assay, numerical uncertainty or replicate count. It also does not report an Os-specific no-extract, heat-inactivated-extract or no-H2 comparison. Thus quantitative product conversion, exclusive enzymatic causality and complete recovery are not established.
Context_only
Source:
woolfolk_whiteley_1962
Discussion on pages 655-656 explicitly considers nonspecific reactions of enzymes or electron carriers with other physiological functions. The Os assay does not identify a particular protein, gene or purified hydrogenase as necessary, and it does not show growth using osmium as an electron acceptor. Whole-cell respiration, natural-environment prevalence and industrial deployment remain outside this experiment's demonstrated scope.
Sources & References
-
chebi_osmium: ChEBI:30687 - osmium atom; Os, charge 0
https://www.ebi.ac.uk/chebi/CHEBI:30687 (accessed 2026-10-11) -
australia_2024: Australian Department of Industry, Science and Resources. Australia's Critical Minerals List and Strategic Materials List, updated 20 February 2024; Table 1 platinum-group-elements entry and footnote 16 explicitly enumerate osmium among the six group members.
https://www.industry.gov.au/publications/australias-critical-minerals-list-and-strategic-materials-list (accessed 2026-10-11) -
woolfolk_whiteley_1962: Woolfolk and Whiteley. Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactilyticus. I. Stoichiometry with compounds of arsenic, selenium, tellurium, transition and other elements. Journal of Bacteriology 84, 647-658 (1962). DOI 10.1128/jb.84.4.647-658.1962; Methods pages 648-649, Table 4 and osmium discussion pages 651-652, Table 5 and Discussion pages 654-656.
https://doi.org/10.1128/jb.84.4.647-658.1962 (accessed 2026-10-11)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-11T07:57:17Z |
Codex (GPT-6; Codex) | create | Verified element identity, explicit Australian grouped designation and historical crude-extract osmium transformation; preserved uncertain products and missing matched controls. Attached canonical CREATE history; independent scientific review is separate. |
Record source: data/records/osmium.yaml