{
  "spore": "profile",
  "id": "osmium",
  "spore_version": "0.2",
  "family": "precious-metals",
  "name": "Osmium",
  "abbreviation": "Os",
  "role": "dense platinum-group metal for hard alloys, wear-resistant contacts and a space-flown optical coating",
  "category": "metals",
  "type": "precious-metals",
  "summary": "Osmium is the metal Os, atomic number 76, a hard, brittle, blue-grey member of the platinum group. Goodfellow gives a density of 22.5 g/cm3 at 20 °C and a melting point of 3045 °C, and PubChem gives 3033 °C; the two sources differ by 12 °C. Its thermal conductivity is 87.6 W/(m·K) at 0 to 100 °C in one datasheet, and its bulk modulus is 410 GPa at zero temperature in a measured elastic study. Osmium is inert as a bulk metal but oxidises to volatile, highly toxic osmium tetroxide when heated in air or as a fine powder. An osmium-coated grating flew on the Spacelab 1 mission, and osmium coatings flown on early Shuttle test flights were lost to atomic oxygen.\n",
  "best_for": "Hard, dense alloys and wear-resistant electrical contacts where hardness and durability matter (Goodfellow, Tanaka)",
  "weakest_at": "Oxidation when heated in air or as a fine powder, which forms osmium tetroxide, a volatile and highly toxic compound (PubChem, Dartmouth); coatings were lost to atomic oxygen in orbit (NASA NTRS)",
  "identity": {
    "formula": "Os (element, atomic number 76); hexagonal close-packed metal",
    "cas": "7440-04-2",
    "crystal_system": "hexagonal close-packed",
    "designations": [],
    "source": "pubchem-os",
    "where": "Names and Identifiers, Other Identifiers, CAS (CID 23937); crystal structure from Goodfellow, Atomic Properties table"
  },
  "tags": {
    "environments": [
      "low-earth-orbit"
    ],
    "stresses": [],
    "applications": [
      "optics-and-cameras",
      "electronics-and-chips"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density of osmium powder at 20 °C (Goodfellow)",
      "value": 22.5,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "form": "99.9% powder, as listed on the product page"
      },
      "method": "Value printed in the physical properties table of a manufacturer's datasheet",
      "status": "ground",
      "source": "goodfellow-os",
      "where": "Physical Properties table, Density row",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of solid osmium (WebElements)",
      "value": 22610,
      "bound": "exact",
      "unit": "kg/m3",
      "scope": "material",
      "conditions": {
        "state": "solid",
        "temperature": "not stated in the source"
      },
      "method": "Value printed in the density properties of a reference database",
      "status": "ground",
      "source": "webelements-os",
      "where": "Density properties, Density of solid row",
      "source_detail": {
        "title": "WebElements, Osmium: physical properties",
        "id": "WebElements, element 76",
        "url": "https://webelements.co.uk/osmium/physics.html",
        "year": 2026,
        "kind": "database",
        "license": "WebElements (reference, linked not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point (PubChem experimental)",
      "value": 3033,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "experimental value listed in PubChem"
      },
      "method": "Value printed in the experimental properties of the PubChem compound record",
      "status": "ground",
      "note": "Goodfellow prints 3045 °C for the same metal; the two sources disagree.",
      "source": "pubchem-os",
      "where": "Chemical and Physical Properties, Experimental Properties, Melting Point",
      "source_detail": {
        "title": "PubChem compound record, Osmium (CID 23937)",
        "id": "CID 23937; CAS 7440-04-2",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23937/JSON",
        "year": 2026,
        "kind": "database",
        "license": "public domain (NCBI)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point (Goodfellow)",
      "value": 3045,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "powder datasheet value"
      },
      "method": "Value printed in the thermal properties table of a manufacturer's datasheet",
      "status": "ground",
      "note": "PubChem prints 3033 °C; the two sources disagree.",
      "source": "goodfellow-os",
      "where": "Thermal Properties table, Melting point row",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point (PubChem experimental)",
      "value": 5012,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "760 mm Hg, as printed by PubChem"
      },
      "method": "Value printed in the experimental properties of the PubChem compound record",
      "status": "ground",
      "note": "Goodfellow prints 5027 °C; the two sources disagree.",
      "source": "pubchem-os",
      "where": "Chemical and Physical Properties, Experimental Properties, Boiling Point",
      "source_detail": {
        "title": "PubChem compound record, Osmium (CID 23937)",
        "id": "CID 23937; CAS 7440-04-2",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23937/JSON",
        "year": 2026,
        "kind": "database",
        "license": "public domain (NCBI)"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point (Goodfellow)",
      "value": 5027,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "powder datasheet value"
      },
      "method": "Value printed in the physical properties table of a manufacturer's datasheet",
      "status": "ground",
      "note": "PubChem prints 5012 °C; the two sources disagree.",
      "source": "goodfellow-os",
      "where": "Physical Properties table, Boiling point row",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat of osmium (Goodfellow)",
      "value": 131,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "temperature": "25 (printed as @25, no unit given)"
      },
      "method": "Value printed in the thermal properties table of a manufacturer's datasheet, unit printed as J K-1 kg-1",
      "status": "ground",
      "source": "goodfellow-os",
      "where": "Thermal Properties table, Specific heat row",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, 0 to 100 °C (Goodfellow)",
      "value": 87.6,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "0 to 100 (printed as 0-100@, no unit given)"
      },
      "method": "Value printed in the thermal properties table of a manufacturer's datasheet, unit printed as W m-1 K-1",
      "status": "ground",
      "source": "goodfellow-os",
      "where": "Thermal Properties table, Thermal conductivity row",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity (WebElements)",
      "value": 88,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the source"
      },
      "method": "Value printed in the thermal properties of a reference database, unit printed as W m-1 K-1",
      "status": "ground",
      "source": "webelements-os",
      "where": "Thermal properties, Thermal conductivity row",
      "source_detail": {
        "title": "WebElements, Osmium: physical properties",
        "id": "WebElements, element 76",
        "url": "https://webelements.co.uk/osmium/physics.html",
        "year": 2026,
        "kind": "database",
        "license": "WebElements (reference, linked not reproduced)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion, 0 to 100 (Goodfellow)",
      "value": 4.57,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "temperature": "0 to 100 (printed as 0-100, no unit given)"
      },
      "method": "Value printed as x10-6 K-1 in a manufacturer's thermal properties table; 4.57 x10-6 K-1 is 4.57 ppm/K",
      "status": "ground",
      "source": "goodfellow-os",
      "where": "Thermal Properties table, Coefficient of thermal expansion row",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of linear thermal expansion (WebElements)",
      "value": 5.1,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the source"
      },
      "method": "Printed as 5.1 x 10-6 K-1 in a reference database; 5.1 x 10-6 K-1 is 5.1 ppm/K. The two CTE values differ and both are kept.",
      "status": "ground",
      "source": "webelements-os",
      "where": "Thermal properties, Coefficient of linear thermal expansion row",
      "source_detail": {
        "title": "WebElements, Osmium: physical properties",
        "id": "WebElements, element 76",
        "url": "https://webelements.co.uk/osmium/physics.html",
        "year": 2026,
        "kind": "database",
        "license": "WebElements (reference, linked not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Tensile (Young's) modulus (Goodfellow)",
      "value": 559,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "material_condition": "as listed in the mechanical properties table, soft and hard rows show the same value"
      },
      "method": "Value printed in the mechanical properties table of a manufacturer's datasheet",
      "status": "ground",
      "source": "goodfellow-os",
      "where": "Mechanical Properties table, Tensile modulus row",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    },
    {
      "benchmark": "shear_modulus",
      "label": "Rigidity (shear) modulus (WebElements)",
      "value": 222,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the source"
      },
      "method": "Value printed in the elastic properties of a reference database",
      "status": "ground",
      "source": "webelements-os",
      "where": "Density and elastic properties, Rigidity modulus row",
      "source_detail": {
        "title": "WebElements, Osmium: physical properties",
        "id": "WebElements, element 76",
        "url": "https://webelements.co.uk/osmium/physics.html",
        "year": 2026,
        "kind": "database",
        "license": "WebElements (reference, linked not reproduced)"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus at zero temperature (measured, Pantea et al. 2009)",
      "value": 410,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "0 K (zero-temperature value extrapolated from the elastic constants)",
        "form": "monocrystal and polycrystal measured by ultrasound and resonance ultrasound"
      },
      "method": "Value stated in the abstract of a measured elastic-constant study",
      "status": "ground",
      "note": "Contested in the literature. Earlier work reported a value above that of diamond. The 2009 study finds it does not exceed diamond at any temperature.",
      "source": "pantea2009",
      "where": "Abstract",
      "source_detail": {
        "title": "Elastic constants of osmium between 5 and 300 K",
        "id": "doi:10.1103/PhysRevB.80.024112 (Phys. Rev. B 80, 024112)",
        "url": "https://impact.ornl.gov/en/publications/elastic-constants-of-osmium-between-5-and-300-k/",
        "year": 2009,
        "kind": "paper",
        "license": "publisher record (ORNL repository abstract)"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus at 300 K (measured, Pantea et al. 2009)",
      "value": 405,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "300 K"
      },
      "method": "Value stated in the abstract of a measured elastic-constant study",
      "status": "ground",
      "source": "pantea2009",
      "where": "Abstract",
      "source_detail": {
        "title": "Elastic constants of osmium between 5 and 300 K",
        "id": "doi:10.1103/PhysRevB.80.024112 (Phys. Rev. B 80, 024112)",
        "url": "https://impact.ornl.gov/en/publications/elastic-constants-of-osmium-between-5-and-300-k/",
        "year": 2009,
        "kind": "paper",
        "license": "publisher record (ORNL repository abstract)"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "label": "Poisson's ratio (WebElements)",
      "value": 0.25,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the source"
      },
      "method": "Printed without a unit in a reference database",
      "status": "ground",
      "source": "webelements-os",
      "where": "Density and elastic properties, Poisson's ratio row",
      "source_detail": {
        "title": "WebElements, Osmium: physical properties",
        "id": "WebElements, element 76",
        "url": "https://webelements.co.uk/osmium/physics.html",
        "year": 2026,
        "kind": "database",
        "license": "WebElements (reference, linked not reproduced)"
      }
    },
    {
      "benchmark": "vickers_hardness",
      "label": "Vickers hardness, soft material condition (Goodfellow)",
      "value": 300,
      "value_high": 350,
      "bound": "range",
      "unit": "kgf/mm2",
      "scope": "material",
      "conditions": {
        "material_condition": "soft"
      },
      "method": "Range printed in the mechanical properties table of a manufacturer's datasheet",
      "status": "ground",
      "source": "goodfellow-os",
      "where": "Mechanical Properties table, Hardness Vickers row, soft column",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    },
    {
      "benchmark": "vickers_hardness",
      "label": "Vickers hardness, hard material condition (Goodfellow)",
      "value": 670,
      "value_high": 1000,
      "bound": "range",
      "unit": "kgf/mm2",
      "scope": "material",
      "conditions": {
        "material_condition": "hard"
      },
      "method": "Range printed in the mechanical properties table of a manufacturer's datasheet",
      "status": "ground",
      "source": "goodfellow-os",
      "where": "Mechanical Properties table, Hardness Vickers row, hard column",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    },
    {
      "benchmark": "mohs_hardness",
      "label": "Mineral (Mohs) hardness",
      "value": 7,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "basis": "Mohs scale, printed without a unit"
      },
      "method": "Value printed in the hardness section of a reference database",
      "status": "ground",
      "source": "webelements-os",
      "where": "Hardnesses, Mineral hardness row",
      "source_detail": {
        "title": "WebElements, Osmium: physical properties",
        "id": "WebElements, element 76",
        "url": "https://webelements.co.uk/osmium/physics.html",
        "year": 2026,
        "kind": "database",
        "license": "WebElements (reference, linked not reproduced)"
      }
    },
    {
      "benchmark": "brinell_hardness",
      "label": "Brinell hardness (WebElements)",
      "value": 3920,
      "bound": "exact",
      "unit": "MN/m2",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the source"
      },
      "method": "Value printed in the hardness section of a reference database",
      "status": "ground",
      "source": "webelements-os",
      "where": "Hardnesses, Brinell hardness row",
      "source_detail": {
        "title": "WebElements, Osmium: physical properties",
        "id": "WebElements, element 76",
        "url": "https://webelements.co.uk/osmium/physics.html",
        "year": 2026,
        "kind": "database",
        "license": "WebElements (reference, linked not reproduced)"
      }
    },
    {
      "benchmark": "debye_temperature",
      "label": "Debye temperature from zero-temperature elastic constants",
      "value": 477,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "basis": "from zero-temperature elastic constants"
      },
      "method": "Value stated in the abstract of a measured elastic-constant study (not in the property canon)",
      "status": "ground",
      "source": "pantea2009",
      "where": "Abstract",
      "source_detail": {
        "title": "Elastic constants of osmium between 5 and 300 K",
        "id": "doi:10.1103/PhysRevB.80.024112 (Phys. Rev. B 80, 024112)",
        "url": "https://impact.ornl.gov/en/publications/elastic-constants-of-osmium-between-5-and-300-k/",
        "year": 2009,
        "kind": "paper",
        "license": "publisher record (ORNL repository abstract)"
      }
    },
    {
      "benchmark": "gruneisen_parameter",
      "label": "Gruneisen parameter from Gruneisen's first rule",
      "value": 2.1,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "basis": "from Gruneisen's first rule, using the measured elastic constants"
      },
      "method": "Value stated in the abstract of a measured elastic-constant study (not in the property canon)",
      "status": "ground",
      "source": "pantea2009",
      "where": "Abstract",
      "source_detail": {
        "title": "Elastic constants of osmium between 5 and 300 K",
        "id": "doi:10.1103/PhysRevB.80.024112 (Phys. Rev. B 80, 024112)",
        "url": "https://impact.ornl.gov/en/publications/elastic-constants-of-osmium-between-5-and-300-k/",
        "year": 2009,
        "kind": "paper",
        "license": "publisher record (ORNL repository abstract)"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity at 20 °C (Goodfellow)",
      "value": 8.8,
      "bound": "exact",
      "unit": "µΩ·cm",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C"
      },
      "method": "Value printed in the electrical properties table of a manufacturer's datasheet, unit printed as µOhmcm",
      "status": "ground",
      "source": "goodfellow-os",
      "where": "Electrical Properties table, Electrical resistivity row",
      "source_detail": {
        "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
        "id": "Goodfellow osmium powder, CAS 7440-04-2",
        "url": "https://www.goodfellow.com/m-f/osmium-powder",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier datasheet, linked not reproduced"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Atomic oxygen in low Earth orbit (osmium samples on early Shuttle test flights)",
      "headline": "Osmium coatings flown on early Shuttle test flights disappeared, which the authors attribute to oxidation in the atomic oxygen environment.",
      "effect": "On the return of the samples the osmium coating was found to have disappeared. The authors attribute this to oxidation of the material in the atomic oxygen atmosphere in orbit. The abstract gives no flight duration or coating thickness.",
      "rating": "severe",
      "conditions": {
        "exposure": "early Shuttle test flights; flight duration not stated in the abstract",
        "coating": "osmium coating on samples flown in orbit"
      },
      "source": "torr1985",
      "where": "Abstract, first sentence"
    },
    {
      "environment": "Heated in air or as a finely divided powder",
      "headline": "Osmium metal is inert at room temperature but oxidises to osmium tetroxide when heated in air or as a fine powder.",
      "effect": "PubChem summarises that metallic osmium is inert, but when heated in air or in a finely divided form it oxidises to osmium tetroxide. The Dartmouth guideline says osmium tetroxide sublimes readily at room temperature.",
      "rating": "moderate",
      "conditions": {
        "temperature": "heated, temperature not given in the summary",
        "form": "bulk metal heated in air, or fine powder"
      },
      "source": "pubchem-os",
      "where": "Stability and Reactivity, Hazardous Reactivities and Incompatibilities"
    },
    {
      "environment": "Mineral acids and aqua regia",
      "headline": "Osmium is insoluble in acids and aqua regia, and the manufacturer describes its corrosion resistance against acids and oxidising agents as remarkable.",
      "effect": "PubChem lists the metal as insoluble in acids and aqua regia. Goodfellow describes remarkable corrosion resistance, particularly against acids and oxidising agents. Tanaka describes osmium alloy pen points as having high acid resistance.",
      "rating": "low",
      "conditions": {
        "basis": "solubility statement and manufacturer descriptions; no concentration or temperature given"
      },
      "source": "pubchem-os",
      "where": "Chemical and Physical Properties, Experimental Properties, Solubility"
    },
    {
      "environment": "Fused alkalis",
      "headline": "Molten alkali attacks osmium.",
      "effect": "PubChem lists the metal as attacked by fused alkalis. The source does not give the alkali, temperature or time.",
      "rating": "moderate",
      "conditions": {
        "basis": "statement in PubChem; no temperature or alkali given"
      },
      "source": "pubchem-os",
      "where": "Chemical and Physical Properties, Experimental Properties, Solubility"
    },
    {
      "environment": "Fluorine at elevated temperature",
      "headline": "Osmium ignites when heated with fluorine.",
      "effect": "PubChem reports that osmium ignites when heated to 100 °C with fluorine, and that it reacts incandescently with phosphorus vapour.",
      "rating": "severe",
      "conditions": {
        "temperature": "100 °C",
        "reagent": "fluorine"
      },
      "source": "pubchem-os",
      "where": "Stability and Reactivity, Hazardous Reactivities and Incompatibilities"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem aggregates the notified classifications for elemental osmium: flammable solid (H228, 97.4% of reports), skin irritation (H315, 96.7%), serious eye damage (H318, 96.1%), respiratory irritation (H335, 96.7%) and long-lasting harmful effects to aquatic life (H413, 69.1%). The signal word is Danger.",
        "ghs": [
          "H228",
          "H315",
          "H318",
          "H335",
          "H413"
        ],
        "source": "pubchem-os",
        "where": "Safety and Hazards, GHS Classification (CID 23937)"
      },
      {
        "text": "A supplier safety data sheet for osmium powder classifies it as a flammable solid under H228 and gives the precautionary statements P210 (keep away from heat, sparks and open flames) and P241 (use explosion-proof equipment). It is a single supplier document, so check the sheet for the lot you handle.",
        "ghs": [
          "H228"
        ],
        "source": "chemicalbook-os-sds",
        "where": "Sections 2 (Hazard statements and GHS label elements)"
      },
      {
        "text": "Osmium tetroxide, the oxide formed when osmium is heated in air, is a volatile, highly toxic solid. The guideline gives an oral rat LD50 of 14 mg/kg and says it sublimes readily at room temperature. This is a different compound from the metal, but the metal can produce it.",
        "ghs": [],
        "source": "dartmouth-osu",
        "where": "Page 1, hazard summary and Highly toxic section"
      }
    ],
    "failure_risks": [
      {
        "mode": "Dust fire",
        "trigger": "Finely divided osmium exposed to heat or flame",
        "consequence": "Flammable in the form of dust when exposed to heat or flame, according to PubChem. Fire response uses water spray, alcohol-resistant foam, dry chemical or carbon dioxide.",
        "severity": "moderate",
        "source": "pubchem-os",
        "where": "Safety and Hazards, Fire Potential"
      },
      {
        "mode": "Volatile oxide release in hot air",
        "trigger": "Metal or fine powder heated in air",
        "consequence": "Oxidation to osmium tetroxide, which sublimes at room temperature and is highly toxic. The PubChem summary says workers must be protected from the osmium tetroxide vapour produced when metallic osmium is handled hot.",
        "severity": "high",
        "source": "dartmouth-osu",
        "where": "Page 1, Highly toxic and sublimation sections"
      },
      {
        "mode": "Coating loss in orbit",
        "trigger": "Osmium surface exposed to the atomic oxygen environment of orbit",
        "consequence": "Osmium coatings flown on early Shuttle test flights were found to have disappeared, which the authors attribute to oxidation in the atomic oxygen atmosphere.",
        "severity": "high",
        "source": "torr1985",
        "where": "Abstract"
      }
    ],
    "side_effects": [
      {
        "text": "Aggregated GHS notifications list skin irritation, serious eye damage and respiratory irritation for the metal. Dust or hot vapour can reach the eyes and airways of people working with it.",
        "affects": "Eyes, skin and airways of people handling the powder or hot metal",
        "source": "pubchem-os",
        "where": "Safety and Hazards, GHS Classification (hazard statements H315, H318 and H335)"
      },
      {
        "text": "The guideline describes osmium tetroxide vapour as causing severe eye and respiratory irritation, with possible chemical burns and organ damage.",
        "affects": "Eyes and airways of people exposed to vapour from heated osmium",
        "source": "dartmouth-osu",
        "where": "Page 1, Highly toxic section"
      }
    ],
    "handling": [
      {
        "text": "PubChem: avoid dust formation and provide local exhaust ventilation where dust or fumes form. Metallic osmium should be handled with adequate ventilation to keep osmium tetroxide vapour out of the work area.",
        "source": "pubchem-os",
        "where": "Accidental Release Measures, Preventive Measures"
      },
      {
        "text": "Keep away from heat, sparks and open flames, and use explosion-proof equipment (P210 and P241). Avoid dust formation. Sweep up spills with a vacuum that is electrically protected, or wet-brush them.",
        "source": "chemicalbook-os-sds",
        "where": "Sections 2 and 7 (precautionary statements and handling)"
      },
      {
        "text": "Do not let osmium meet fluorine or chlorine trifluoride. PubChem records ignition with fluorine at 100 °C and violent reactions with chlorine trifluoride.",
        "source": "pubchem-os",
        "where": "Stability and Reactivity, Hazardous Reactivities and Incompatibilities"
      }
    ],
    "mitigations": [
      {
        "text": "PubChem: workers dealing with metallic osmium should be protected from osmium tetroxide vapour by adequate ventilation.",
        "source": "pubchem-os",
        "where": "Safety and Hazards, Accidental Release Measures, Preventive Measures"
      }
    ]
  },
  "uses": [
    {
      "application": "optics-and-cameras",
      "device": "Osmium-coated reflective grating in an extreme-ultraviolet spectrometer on Spacelab 1 (flown)",
      "example": "On the ten-day Spacelab 1 mission the osmium-coated reflective grating stayed stable, relative to a spectrometer with an MgF2 coating. The calibration ratio did not change in any major way over the two years from laboratory calibration to flight.",
      "source": "torr1985",
      "where": "Abstract"
    },
    {
      "application": "electronics-and-chips",
      "device": "Wear-resistant electrical contacts and high-reliability switch contact points",
      "example": "Goodfellow lists osmium powder for hardening platinum alloys, creating wear-resistant electrical contacts and contact points in high-reliability switches.",
      "source": "goodfellow-os",
      "where": "Product description, Applications paragraph"
    }
  ],
  "supply": [
    {
      "subject": "Osmium in the Earth's crust",
      "abundance": "0.0015 ppm in the continental crust (USGS PP 1802-A Table A1, crustal abundances, citing Jefferson Science Associates, 2014)",
      "producers": [],
      "critical_lists": [
        {
          "list": "EU critical raw materials list, entry 'Platinum group metals' (group entry; osmium is not named on its own)",
          "listed": true
        }
      ],
      "recycling": "No osmium-specific recycling figure found. USGS gives about 140,000 kg of palladium and platinum recovered from scrap globally in 2025 (see the next entry).",
      "substitutes": [],
      "source": "usgs-pp1802a",
      "where": "Table A1, Os row; EU list on the European Commission critical raw materials page (ec-crm)"
    },
    {
      "subject": "Platinum-group metals (platinum mine production used as the group proxy; USGS does not break out osmium)",
      "producers": [
        {
          "country": "South Africa",
          "share_percent": 70.6,
          "year": 2025
        },
        {
          "country": "Russia",
          "share_percent": 11.8,
          "year": 2025
        },
        {
          "country": "Zimbabwe",
          "share_percent": 10.6,
          "year": 2025
        },
        {
          "country": "Canada",
          "share_percent": 2.9,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "EU critical raw materials list, entry 'Platinum group metals'",
          "listed": true
        }
      ],
      "recycling": "USGS: about 140,000 kg of palladium and platinum were recovered globally from new and old scrap in 2025, including about 8,600 kg of platinum from automobile catalytic converters in the United States.",
      "substitutes": [
        "USGS: for some industrial end uses one platinum-group metal can substitute for another, with losses in efficiency. No osmium-specific substitute is named."
      ],
      "source": "usgs-mcs2026-pgm",
      "where": "World Mine Production and Reserves table, Platinum 2025e column (world total 170,000 kg; shares calculated by Space Mushroom); Recycling; Substitutes"
    },
    {
      "subject": "Osmium imports to the United States",
      "abundance": "57 kg imported in 2025e and 1 kg in 2024 (USGS salient statistics)",
      "producers": [],
      "critical_lists": [],
      "recycling": "See the platinum-group entry above.",
      "substitutes": [],
      "source": "usgs-mcs2026-pgm",
      "where": "Salient Statistics, Imports for consumption, Osmium row"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "PubChem: Osmium (CID 23937), GHS classification and experimental properties",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23937/JSON",
      "year": 2026
    },
    {
      "title": "Goodfellow: Osmium Powder, product datasheet with material properties",
      "type": "datasheet",
      "url": "https://www.goodfellow.com/m-f/osmium-powder",
      "year": 2026
    },
    {
      "title": "WebElements: Osmium physical properties",
      "type": "database",
      "url": "https://webelements.co.uk/osmium/physics.html",
      "year": 2026
    },
    {
      "title": "Elastic constants of osmium between 5 and 300 K (Phys. Rev. B 80, 024112)",
      "type": "paper",
      "url": "https://impact.ornl.gov/en/publications/elastic-constants-of-osmium-between-5-and-300-k/",
      "year": 2009
    },
    {
      "title": "Osmium coated diffraction grating in the Space Shuttle environment (Applied Optics 24)",
      "type": "paper",
      "url": "https://ntrs.nasa.gov/citations/19850066910",
      "year": 1985
    },
    {
      "title": "NIST: Atomic Weights and Isotopic Compositions for Osmium",
      "type": "database",
      "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Os&ascii=html",
      "year": 2026
    },
    {
      "title": "Dartmouth College guidelines for safe use of osmium tetroxide",
      "type": "report",
      "url": "https://ehs.dartmouth.edu/sites/ehs/files/2024-05/dartmouth-college-guidelines-for-safe-use-of-osmium-tetroxide.pdf",
      "year": 2024
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Platinum-Group Metals",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-platinum-group.pdf",
      "year": 2026
    },
    {
      "title": "USGS Professional Paper 1802-A: Critical Mineral Resources of the United States, Table A1",
      "type": "report",
      "url": "https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf",
      "year": 2017
    }
  ],
  "gaps": [
    "No flight or qualification test of an osmium structural part or contact was found. The only space results are an optical coating on one Spacelab 1 instrument, which the abstract describes as stable over a ten-day mission, and early Shuttle samples that lost their coating.",
    "No osmium-specific mine production or country shares were found. The USGS platinum-group chapter gives platinum and palladium only, so the supply entry uses platinum mine production as a proxy and says so.",
    "The USGS 2025 List of Critical Minerals page could not be opened (blocked), so the US critical-mineral status of osmium is not recorded. Only the EU group entry for platinum-group metals was read.",
    "Density, melting point and boiling point disagree between sources (22.5 g/cm3 from Goodfellow against 22610 kg/m3 from WebElements; 3045 against 3033 °C melting; 5027 against 5012 °C boiling). Both values are kept, each with its source.",
    "Bulk modulus: Goodfellow prints 373 GPa, which is not entered because it conflicts with the measured 405 to 410 GPa from Pantea et al. (2009). Earlier work reported a value above diamond; that claim was not entered.",
    "Electrical resistivity: WebElements prints it only in scientific notation, so it was not entered. The Goodfellow value of 8.8 µΩ·cm at 20 °C is the only one included.",
    "Hazard data rest on the PubChem aggregated notifications and one supplier SDS. American Elements and Thermo Fisher SDS pages could not be opened (blocked), so their hazard codes are not used.",
    "No designation (UNS, EN or ASTM code) was added: osmium is sold as an element, powder or alloy component, not as a graded alloy, and no source printed a grade code for it.",
    "The properties debye_temperature, gruneisen_parameter, vickers_hardness, mohs_hardness and brinell_hardness are not in spores/property-canon.yaml, so snake_case names are used for them.",
    "Wikipedia was used only for history and composition (discovery and isotopes). No Wikipedia value is used as a property.",
    "No image was added to the media list."
  ],
  "story": {
    "why": "Osmium is a hard, dense platinum-group metal, and its value comes from hardness and durability. Goodfellow describes its powder as having the highest density of any naturally occurring element, and it is used to harden platinum alloys and to make wear-resistant electrical contacts. The metal is inert in bulk, but heating it in air produces osmium tetroxide, which is volatile and highly toxic, so handling and ventilation matter.",
    "uses": [
      {
        "where": "Spacecraft optics",
        "line": "An osmium-coated reflective grating flew in the extreme-ultraviolet spectrometer of the Spacelab 1 instrument array. Over a ten-day mission the coating stayed stable, relative to a spectrometer with an MgF2 coating. The abstract is the only space-flight source found for the metal."
      },
      {
        "where": "Electrical contacts and switches",
        "line": "Goodfellow lists osmium powder for hardening platinum alloys, creating wear-resistant electrical contacts and making contact points in high-reliability switches."
      }
    ],
    "can_do": [
      {
        "label": "Density",
        "line": "Goodfellow gives 22.5 g/cm3 at 20 °C, and WebElements gives 22610 kg/m3 for the solid. Goodfellow describes osmium as the highest-density naturally occurring element.",
        "benchmark": "density",
        "scope": "material",
        "value": "22.5 g/cm3"
      },
      {
        "label": "Melting point",
        "line": "The metal melts at 3045 °C in Goodfellow's datasheet and at 3033 °C in PubChem. The two sources differ by 12 °C.",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "3045 °C"
      },
      {
        "label": "Hardness",
        "line": "Goodfellow prints a Vickers hardness of 300 to 350 kgf/mm2 for the soft condition and 670 to 1000 kgf/mm2 for the hard condition.",
        "benchmark": "vickers_hardness",
        "scope": "material",
        "value": "670 to 1000 kgf/mm2"
      },
      {
        "label": "Thermal conductivity",
        "line": "Goodfellow gives 87.6 W/(m·K) at 0 to 100 °C, close to the 88 W/(m·K) printed by WebElements.",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "87.6 W/(m·K)"
      }
    ],
    "compare": "Within this profile, the platinum-group comparison is limited. Goodfellow and PubChem give different melting and boiling points, and both are kept. The sources collected here do not compare osmium with other platinum-group metals, so no ranking is claimed.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "handling": [
      "The powder is a flammable solid. Keep it away from heat, sparks and open flames.",
      "Avoid dust. Use local exhaust ventilation where dust forms.",
      "Heating the metal in air can produce osmium tetroxide, which is volatile and highly toxic. Ventilate the work area.",
      "Keep it away from fluorine and chlorine trifluoride."
    ],
    "good_for": [
      "Hard, wear-resistant contacts. Goodfellow lists use in electrical contacts and high-reliability switches.",
      "Acid resistance. PubChem lists the metal as insoluble in acids and aqua regia.",
      "Thin reflective coatings in a space instrument. The Spacelab 1 grating stayed stable over a ten-day mission."
    ],
    "watch_out": [
      "Heated in air, it oxidises to volatile osmium tetroxide, which is highly toxic. PubChem and the Dartmouth guideline both describe this.",
      "Coatings are vulnerable to atomic oxygen in orbit. Early Shuttle samples lost their osmium coating.",
      "The sources disagree on density, melting point and boiling point. Check the datasheet used for a design."
    ],
    "verdict": "Osmium is a hard, dense platinum-group metal used for wear-resistant contacts and fountain-pen tips. It is inert as a bulk metal, but heat, fine powder and atomic oxygen each cause trouble, and the only space result found is one flight of an optical coating.",
    "recipe": {
      "line": "Osmium is a single element, Os, with atomic number 76. It is a hard, brittle, blue-grey metal of the platinum group that crystallises in the hexagonal close-packed structure. Wikipedia says it is separated from the other platinum-group metals by distillation or extraction of the volatile tetroxide.",
      "parts": [
        {
          "name": "Osmium",
          "symbol": "Os",
          "role": "The whole metal. Goodfellow describes it as the metal with the highest density of any naturally occurring element, and it is used to harden platinum alloys.",
          "atoms": 1,
          "atomic_weight": 190.23
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The metal itself is a flammable solid when it is a fine powder. Heating it in air can produce osmium tetroxide, which is highly toxic.",
        "points": [
          {
            "label": "The powder",
            "line": "A supplier safety data sheet classifies osmium powder as a flammable solid (H228). PubChem's aggregated notifications list skin irritation, serious eye damage and respiratory irritation for the metal."
          },
          {
            "label": "Heated metal",
            "line": "Metallic osmium is inert, but when heated in air or as a fine powder it oxidises to osmium tetroxide. That oxide is volatile and sublimes readily at room temperature. The guideline gives an oral rat LD50 of 14 mg/kg."
          },
          {
            "label": "Fire",
            "line": "In a fire, use water spray, alcohol-resistant foam, dry chemical or carbon dioxide. Keep away from heat and sparks."
          }
        ],
        "level": 0,
        "verdict": "Flammable powder and toxic vapour when heated"
      },
      {
        "title": "If a coating or part is heated or left in orbit",
        "lead": "These results come from one laboratory description and one flight, not from routine use.",
        "points": [
          {
            "label": "Orbit",
            "line": "Osmium-coated samples flown on early Shuttle test flights were found to have disappeared, attributed to oxidation in the atomic oxygen of orbit."
          },
          {
            "label": "Flight that worked",
            "line": "An osmium-coated reflective grating in the extreme-ultraviolet spectrometer on the Spacelab 1 mission stayed stable over the ten-day flight, relative to an MgF2-coated spectrometer."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Dust",
            "line": "Avoid dust formation and use local exhaust ventilation where dust forms, as PubChem and the supplier sheet both advise."
          },
          {
            "label": "Incompatible gases",
            "line": "Keep osmium away from fluorine, which ignites it at 100 °C, and from chlorine trifluoride, which reacts violently."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 23,
    "unreachable": 3,
    "caveats": 3,
    "note": "Read by an AI assistant on 2026-10-26 from the pages named in each entry. Three pages could not be opened (American Elements SDS and product page, Thermo Fisher product page, USGS 2025 critical list page). Caveats: the density, melting point and boiling point sources disagree; the bulk modulus values differ between a datasheet and a measured study; the hazard codes come from PubChem aggregates and one supplier SDS."
  },
  "sources": {
    "pubchem-os": {
      "title": "PubChem compound record, Osmium (CID 23937)",
      "id": "CID 23937; CAS 7440-04-2",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23937/JSON",
      "year": 2026,
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "goodfellow-os": {
      "title": "Goodfellow, Osmium Powder, 99.9% (3N) product datasheet with material properties",
      "id": "Goodfellow osmium powder, CAS 7440-04-2",
      "url": "https://www.goodfellow.com/m-f/osmium-powder",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier datasheet, linked not reproduced"
    },
    "webelements-os": {
      "title": "WebElements, Osmium: physical properties",
      "id": "WebElements, element 76",
      "url": "https://webelements.co.uk/osmium/physics.html",
      "year": 2026,
      "kind": "database",
      "license": "WebElements (reference, linked not reproduced)"
    },
    "pantea2009": {
      "title": "Elastic constants of osmium between 5 and 300 K",
      "id": "doi:10.1103/PhysRevB.80.024112 (Phys. Rev. B 80, 024112)",
      "url": "https://impact.ornl.gov/en/publications/elastic-constants-of-osmium-between-5-and-300-k/",
      "year": 2009,
      "kind": "paper",
      "license": "publisher record (ORNL repository abstract)"
    },
    "torr1985": {
      "title": "Osmium coated diffraction grating in the Space Shuttle environment: performance (Applied Optics 24)",
      "id": "NTRS 19850066910; doi not listed; Applied Optics 24, 1985",
      "url": "https://ntrs.nasa.gov/citations/19850066910",
      "year": 1985,
      "kind": "paper",
      "license": "NASA NTRS record (public domain)"
    },
    "nist-os": {
      "title": "NIST, Atomic Weights and Isotopic Compositions for Osmium",
      "id": "NIST physical reference data",
      "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Os&ascii=html",
      "year": 2026,
      "kind": "database",
      "license": "public domain (NIST)"
    },
    "chemicalbook-os-sds": {
      "title": "ChemicalBook, Osmium safety data sheet (supplier SDS aggregator)",
      "id": "CAS 7440-04-2",
      "url": "https://www.chemicalbook.com/msds/osmium.htm",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "dartmouth-osu": {
      "title": "Dartmouth College guidelines for safe use of osmium tetroxide",
      "id": "Dartmouth EHS, May 2024",
      "url": "https://ehs.dartmouth.edu/sites/ehs/files/2024-05/dartmouth-college-guidelines-for-safe-use-of-osmium-tetroxide.pdf",
      "year": 2024,
      "kind": "report",
      "license": "institutional guideline, linked not reproduced"
    },
    "usgs-mcs2026-pgm": {
      "title": "Mineral Commodity Summaries 2026, Platinum-Group Metals",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-platinum-group.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-pp1802a": {
      "title": "Critical Mineral Resources of the United States: An Introduction (Professional Paper 1802-A), Table A1",
      "id": "USGS PP 1802-A",
      "url": "https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf",
      "year": 2017,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "ec-crm": {
      "title": "Critical raw materials (European Commission, list under Regulation (EU) 2024/1252)",
      "id": "Regulation (EU) 2024/1252",
      "url": "https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en",
      "year": 2024,
      "kind": "web",
      "license": "European Commission web page"
    },
    "wikipedia-os": {
      "title": "Wikipedia, Osmium (history and composition only)",
      "id": "Discovery section; isotopes section; lead paragraph (discovered in 1803 by Smithson Tennant)",
      "url": "https://en.wikipedia.org/wiki/Osmium",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0"
    },
    "tanaka-os": {
      "title": "Tanaka Precious Metals, Precious Metals Guide: Osmium",
      "id": "Tanaka element data, Os",
      "url": "https://tanaka-preciousmetals.com/en/guide/element/os.html",
      "year": 2026,
      "kind": "web",
      "license": "manufacturer web page, linked not reproduced"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/osmium/"
}