{
  "spore": "profile",
  "id": "iridium",
  "spore_version": "0.2",
  "family": "precious-metals",
  "name": "Iridium",
  "abbreviation": "Ir",
  "role": "high-temperature oxidation-resistant metal",
  "category": "metals",
  "type": "heavy-metals",
  "summary": "Iridium is the pure metal Ir, one of the densest elements (22.56 g/cm3 in the Heraeus datasheet) and one of the most corrosion-resistant metals known. Its melting point is 2446 °C. Industry uses it for crucibles that grow oxide crystals at high temperature, and space propulsion groups have used it as an oxidation-barrier coating on rhenium thrust chambers, where it raised the operating temperature to 2200 °C in a NASA Lewis paper. It is not ductile at room temperature and must be formed hot.\n",
  "best_for": "Surviving hot oxidising gas and corrosive liquids: oxidation resistance to 800 °C in the datasheet and attack by no acid, including aqua regia, in the Wikipedia summary",
  "weakest_at": "Cold forming and machining (not ductile, hardly formable, limited machinability), and cost (USGS 2025 estimated price 4,400 dollars per troy ounce)",
  "identity": {
    "formula": "Ir (element, atomic number 77); pure metal sold as refined sponge and powder under ASTM B671, grades 99.80 and 99.90",
    "cas": "7439-88-5",
    "designations": [
      {
        "system": "UNS",
        "code": "PO6100",
        "note": "grade 99.80, sponge and powder; the page prints the code with the letter O",
        "source": "astm-b671",
        "where": "UNS number line under the title of the ASTM B671 listing"
      },
      {
        "system": "ASTM",
        "code": "B671",
        "note": "Standard Specification for Refined Iridium, sponge and powder, grades 99.80 and 99.90",
        "source": "astm-b671",
        "where": "Title and designation line of the ASTM B671 listing"
      }
    ],
    "source": "pubchem-ir",
    "where": "Other Identifiers section of the PubChem record, CAS entry 7439-88-5 (CID 23924, Iridium)"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "propulsion-and-tanks"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, iridium (Heraeus datasheet)",
      "value": 22.56,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the datasheet"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "heraeus-ir",
      "where": "General information table, row Density",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, iridium (Wikipedia infobox)",
      "value": 22.562,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C"
      },
      "method": "Value printed in the infobox of the Wikipedia article on iridium",
      "status": "ground",
      "note": "PubChem gives 22.42 at 17 °C and 21.56 at 25 °C from other sources; those two values are not entered here.",
      "source": "wikipedia-ir",
      "where": "Infobox, Physical properties, density row",
      "source_detail": {
        "title": "Iridium (Wikipedia, English)",
        "url": "https://en.wikipedia.org/wiki/Iridium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, iridium (Wikipedia infobox)",
      "value": 2446,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "unit_in_source": "2719 K (2446 °C, 4435 °F)",
        "pressure": "not stated"
      },
      "method": "Value printed in the infobox of the Wikipedia article on iridium",
      "status": "ground",
      "source": "wikipedia-ir",
      "where": "Infobox, Physical properties, melting point row",
      "source_detail": {
        "title": "Iridium (Wikipedia, English)",
        "url": "https://en.wikipedia.org/wiki/Iridium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, iridium (PubChem experimental property)",
      "value": 2446,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "element, CAS 7439-88-5",
        "pressure": "not stated"
      },
      "method": "Experimental value listed in the PubChem record for iridium",
      "status": "ground",
      "source": "pubchem-ir",
      "where": "Chemical and Physical Properties, Experimental Properties, Melting Point (2,446 °C)",
      "source_detail": {
        "title": "PubChem compound record: Iridium (CID 23924), experimental properties, GHS classification, CAS",
        "id": "CAS 7439-88-5",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23924/JSON",
        "kind": "database",
        "license": "PubChem (NCBI), public domain; sections attributed to ECHA, HSDB and the DOE PAC database"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, iridium (PubChem experimental property)",
      "value": 4428,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "760 mm Hg"
      },
      "method": "Experimental value listed in the PubChem record for iridium, attributed to the U.S. DOE PAC Chemical Database",
      "status": "ground",
      "source": "pubchem-ir",
      "where": "Chemical and Physical Properties, Experimental Properties, Boiling Point, entry 4428 °C @760 mm Hg",
      "source_detail": {
        "title": "PubChem compound record: Iridium (CID 23924), experimental properties, GHS classification, CAS",
        "id": "CAS 7439-88-5",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23924/JSON",
        "kind": "database",
        "license": "PubChem (NCBI), public domain; sections attributed to ECHA, HSDB and the DOE PAC database"
      }
    },
    {
      "benchmark": "electrical_conductivity",
      "label": "Electrical conductivity, iridium (min)",
      "value": 24,
      "value_high": 26,
      "bound": "range",
      "unit": "%IACS",
      "scope": "material",
      "conditions": {
        "temper": "not stated",
        "temperature": "not stated"
      },
      "method": "Range printed in a manufacturer datasheet",
      "status": "ground",
      "note": "electrical_conductivity is not in the canonical property list; the range is entered as printed in % IACS.",
      "source": "heraeus-ir",
      "where": "Physical properties, rows Conductivity, min. and Conductivity, max.",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity, iridium at 20 °C",
      "value": 47.1,
      "bound": "exact",
      "unit": "nΩ·m",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "unit_in_source": "47.1 nΩ⋅m (at 20 °C)"
      },
      "method": "Value printed in the infobox of the Wikipedia article on iridium",
      "status": "ground",
      "source": "wikipedia-ir",
      "where": "Infobox, Electrical resistivity row",
      "source_detail": {
        "title": "Iridium (Wikipedia, English)",
        "url": "https://en.wikipedia.org/wiki/Iridium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, iridium at 20 °C (Heraeus)",
      "value": 59,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "note": "The Wikipedia infobox gives 147 W/(m·K) with no condition; the two values differ and both are recorded.",
      "source": "heraeus-ir",
      "where": "Physical properties, row Thermal Conductivity at 20 °C",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, iridium (Wikipedia infobox)",
      "value": 147,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated"
      },
      "method": "Value printed in the infobox of the Wikipedia article on iridium",
      "status": "ground",
      "source": "wikipedia-ir",
      "where": "Infobox, Thermal conductivity row",
      "source_detail": {
        "title": "Iridium (Wikipedia, English)",
        "url": "https://en.wikipedia.org/wiki/Iridium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion at 20 °C",
      "value": 6.47,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "unit_in_source": "6.47×10−6 K−1 (at 20 °C)"
      },
      "method": "Value printed in the infobox of the Wikipedia article on iridium",
      "status": "ground",
      "source": "wikipedia-ir",
      "where": "Infobox, Thermal expansion coefficient row",
      "source_detail": {
        "title": "Iridium (Wikipedia, English)",
        "url": "https://en.wikipedia.org/wiki/Iridium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, iridium",
      "value": 130.58,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated"
      },
      "method": "Value printed in the infobox of the Wikipedia article on iridium",
      "status": "ground",
      "source": "wikipedia-ir",
      "where": "Infobox, Specific heat capacity row",
      "source_detail": {
        "title": "Iridium (Wikipedia, English)",
        "url": "https://en.wikipedia.org/wiki/Iridium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, iridium",
      "value": 528,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated",
        "temper": "not stated"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "heraeus-ir",
      "where": "Physical properties, row Young's Modulus, GPa",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "shear_modulus",
      "label": "Modulus of rigidity (shear modulus), iridium",
      "value": 210,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "heraeus-ir",
      "where": "Physical properties, row Modulus of Rigidity, GPa",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus, iridium",
      "value": 320,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated"
      },
      "method": "Value printed in the infobox of the Wikipedia article on iridium",
      "status": "ground",
      "source": "wikipedia-ir",
      "where": "Infobox, Bulk modulus row",
      "source_detail": {
        "title": "Iridium (Wikipedia, English)",
        "url": "https://en.wikipedia.org/wiki/Iridium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "label": "Poisson's ratio, iridium",
      "value": 0.26,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "temperature": "not stated"
      },
      "method": "Value printed in the infobox of the Wikipedia article on iridium, with no unit or condition",
      "status": "ground",
      "source": "wikipedia-ir",
      "where": "Infobox, Poisson ratio row",
      "source_detail": {
        "title": "Iridium (Wikipedia, English)",
        "url": "https://en.wikipedia.org/wiki/Iridium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "vickers_hardness",
      "label": "Vickers hardness, iridium annealed",
      "value": 210,
      "bound": "exact",
      "unit": "HV",
      "scope": "material",
      "conditions": {
        "temper": "annealed"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "note": "vickers_hardness is not in the canonical property list.",
      "source": "heraeus-ir",
      "where": "Hardness, HV row, column Annealed",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "vickers_hardness",
      "label": "Vickers hardness, iridium work hardened",
      "value": 453,
      "bound": "exact",
      "unit": "HV",
      "scope": "material",
      "conditions": {
        "temper": "work hardened"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "note": "vickers_hardness is not in the canonical property list.",
      "source": "heraeus-ir",
      "where": "Hardness, HV row, column Work Hardened",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "mohs_hardness",
      "label": "Mohs hardness, iridium",
      "value": 6.5,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "temperature": "not stated"
      },
      "method": "Value printed in the infobox of the Wikipedia article on iridium, with no unit or condition",
      "status": "ground",
      "note": "mohs_hardness is not in the canonical property list.",
      "source": "wikipedia-ir",
      "where": "Infobox, Mohs hardness row",
      "source_detail": {
        "title": "Iridium (Wikipedia, English)",
        "url": "https://en.wikipedia.org/wiki/Iridium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, iridium annealed",
      "value": 93,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temper": "annealed",
        "measure": "not stated"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "heraeus-ir",
      "where": "Yield Strength, MPa row, column Annealed",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, iridium work hardened",
      "value": 1618,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temper": "work hardened",
        "measure": "not stated"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "heraeus-ir",
      "where": "Yield Strength, MPa row, column Work Hardened",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, iridium annealed",
      "value": 450,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temper": "annealed"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "heraeus-ir",
      "where": "Tensile Strength, MPa row, column Annealed",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, iridium work hardened",
      "value": 1632,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temper": "work hardened"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "heraeus-ir",
      "where": "Tensile Strength, MPa row, column Work Hardened",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation, iridium annealed",
      "value": 7,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "temper": "annealed"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "heraeus-ir",
      "where": "Elongation, % row, column Annealed",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation, iridium work hardened",
      "value": 1,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "temper": "work hardened"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "heraeus-ir",
      "where": "Elongation, % row, column Work Hardened",
      "source_detail": {
        "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
        "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer datasheet (cited, not reproduced)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Oxidising gas at high temperature (datasheet)",
      "headline": "Iridium resists oxidation to about 800 °C according to the Heraeus datasheet.",
      "effect": "The datasheet comment reads oxidation resistant to 800°C. The datasheet gives no rate or atmosphere.",
      "rating": "low",
      "conditions": {
        "temperature": "up to 800 °C",
        "atmosphere": "not stated"
      },
      "source": "heraeus-ir",
      "where": "Chemical Properties, Comment row"
    },
    {
      "environment": "Very high temperature, air or corrosive gas (Wikipedia summary)",
      "headline": "Iridium is one of the most corrosion-resistant metals even at temperatures as high as 2000 °C.",
      "effect": "The Wikipedia lead states that iridium is one of the most corrosion-resistant metals, even at temperatures as high as 2,000 °C (3,600 °F). No rate is given.",
      "rating": "low",
      "conditions": {
        "temperature": "up to 2000 °C",
        "basis": "encyclopaedia summary; no measured rate"
      },
      "source": "wikipedia-ir",
      "where": "Lead section"
    },
    {
      "environment": "Rocket exhaust on an iridium-coated rhenium chamber",
      "headline": "The iridium coating acts as an oxidation barrier on rhenium, and iridium forms volatile oxides more slowly than rhenium.",
      "effect": "IrO2 formation was observed at temperatures as low as 600 C. Significant Ir-Re interdiffusion was observed at 1000 C. Below 1350 C the dominant diffusion path is along grain boundaries. The Ir-Re reaction gives an Ir solid solution in the hexagonal rhenium structure.",
      "rating": "moderate",
      "conditions": {
        "specimen": "magnetron-sputtered Ir on Re substrates",
        "test": "Raman spectroscopy and X-ray diffraction"
      },
      "source": "stulen-1990",
      "where": "Abstract, sentences on oxidation rate, interdiffusion onset and diffusion mechanism"
    },
    {
      "environment": "Acids, aqua regia and hydrochloric acid",
      "headline": "Iridium is not attacked by acids, including aqua regia, but it dissolves in concentrated hydrochloric acid with sodium perchlorate.",
      "effect": "The Wikipedia summary gives this as the chemical resistance of the metal. No rate is given.",
      "rating": "low",
      "conditions": {
        "basis": "encyclopaedia summary; concentrations not stated"
      },
      "source": "wikipedia-ir",
      "where": "Characteristics, Chemical properties"
    },
    {
      "environment": "Sulfur, cyanide salts and halogens",
      "headline": "Iridium reacts with sulfur to form iridium disulfide, with cyanide salts in the presence of oxygen, and with halogens and oxygen at higher temperatures.",
      "effect": "These are the reactions named in the Wikipedia summary. Iridium also reacts with the halogens and oxygen at higher temperatures.",
      "rating": "moderate",
      "conditions": {
        "basis": "encyclopaedia summary; temperatures not stated for the halogen and sulfur reactions"
      },
      "source": "wikipedia-ir",
      "where": "Characteristics, Chemical properties, bullet on cyanide and sulfur reactions"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem reports ECHA C&L notifications for iridium from 249 company reports: 92 say the substance does not meet GHS criteria (36.9 %). Codes given: H228 flammable solid (18.1 %), H319 causes serious eye irritation (20.1 %), H413 may cause long lasting harmful effects to aquatic life (41.8 %). Signal word Danger.",
        "ghs": [
          "H228",
          "H319",
          "H413"
        ],
        "source": "pubchem-ir",
        "where": "Safety and Hazards, GHS Classification, ECHA C&L Notifications Summary"
      },
      {
        "text": "Powdered iridium may ignite spontaneously in air. Violent reaction or ignition occurs on contact with interhalogens such as bromine pentafluoride and chlorine trifluoride (HSDB, as cited by PubChem).",
        "ghs": [],
        "source": "pubchem-ir",
        "where": "Stability and Reactivity, Hazardous Reactivities and Incompatibilities"
      }
    ],
    "failure_risks": [
      {
        "mode": "Brittle cold forming",
        "trigger": "Forming iridium at room temperature",
        "consequence": "The datasheet says the metal is not ductile and hardly formable, and that it is formed hot. Elongation is 7 % annealed and 1 % work hardened.",
        "severity": "moderate",
        "source": "heraeus-ir",
        "where": "Forming Processes rows and Physical properties, Elongation row"
      },
      {
        "mode": "Powder ignition",
        "trigger": "Powdered or sponge iridium exposed to air or to interhalogens",
        "consequence": "May ignite spontaneously in air, with violent reaction on contact with interhalogens.",
        "severity": "moderate",
        "source": "pubchem-ir",
        "where": "Stability and Reactivity, Hazardous Reactivities and Incompatibilities"
      },
      {
        "mode": "Oxide growth and Ir-Re interdiffusion in a rocket chamber",
        "trigger": "Iridium-coated rhenium exposed to hot oxidising exhaust, at 600 C or above for oxides and 1000 C or above for interdiffusion",
        "consequence": "Iridium forms volatile oxides more slowly than rhenium. Interdiffusion at 1000 C and above is significant. The paper gives no life values.",
        "severity": "moderate",
        "source": "stulen-1990",
        "where": "Abstract"
      }
    ],
    "side_effects": [
      {
        "text": "Iridium price averaged 4,810.40 dollars per troy ounce in 2024 and an estimated 4,400 dollars per troy ounce in 2025, according to the USGS price table.",
        "affects": "Cost of crucibles, coatings and thruster chambers",
        "source": "usgs-pgm-2026",
        "where": "Salient Statistics, Price, dollars per troy ounce, Iridium row"
      }
    ],
    "handling": [
      {
        "text": "Form it hot. The datasheet says the metal is hardly formable, with limited machinability.",
        "source": "heraeus-ir",
        "where": "Forming Processes rows"
      },
      {
        "text": "Treat powder and sponge as able to ignite in air, and keep them away from interhalogens such as bromine pentafluoride and chlorine trifluoride.",
        "source": "pubchem-ir",
        "where": "Stability and Reactivity, Hazardous Reactivities and Incompatibilities"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "propulsion-and-tanks",
      "device": "Iridium-coated rhenium thrust chamber, 22 N stationkeeping engine class",
      "example": "Stationkeeping class 22 N engines made from iridium-coated rhenium showed steady-state specific impulses 20 to 25 seconds higher than niobium chambers, and the material raised operating temperature to 2200 C against 1400 C for silicide-coated niobium.",
      "source": "schneider-1991",
      "where": "Text of the paper, sentences on stationkeeping specific impulse and operating temperature"
    },
    {
      "application": "propulsion-and-tanks",
      "device": "Iridium-coated rhenium rocket chamber, 22 N and 440 N classes",
      "example": "Iridium-coated rhenium rockets showed nominally 20 seconds higher specific impulse than niobium rockets in the 22 N class and nominally 10 seconds higher in the 440 N class.",
      "source": "schneider-1992",
      "where": "Abstract, sentence beginning Specific impulse iridium-coated rhenium rockets"
    },
    {
      "application": "propulsion-and-tanks",
      "device": "Thruster cone chamber of rhenium coated with iridium on the inside surface",
      "example": "Aerojet Technical Systems built a thruster cone chamber of rhenium coated inside with iridium, which faces the rocket exhaust; the iridium is applied as an oxidation barrier.",
      "source": "stulen-1990",
      "where": "Abstract, chamber design sentence"
    }
  ],
  "supply": [
    {
      "subject": "Iridium output as a by-product of platinum-group metal mining",
      "producers": [],
      "critical_lists": [],
      "recycling": "No iridium recovery figure is given in the USGS 2026 platinum-group summary, which gives 140,000 kg of palladium and platinum recovered globally in 2025.",
      "substitutes": [
        "USGS: for some industrial end uses one platinum-group metal can substitute for another, but with losses in efficiency."
      ],
      "source": "usgs-pgm-2026",
      "where": "Recycling paragraph and Substitutes paragraph of the 2026 platinum-group metals summary"
    },
    {
      "subject": "World iridium output",
      "producers": [],
      "critical_lists": [],
      "substitutes": [],
      "source": "wikipedia-ir",
      "where": "Lead section (2023 production) and Production section (2018 production, platinum to iridium ratio)"
    },
    {
      "subject": "United States iridium imports",
      "producers": [],
      "critical_lists": [],
      "substitutes": [],
      "source": "usgs-pgm-2026",
      "where": "Salient Statistics, Imports for consumption, Iridium row (kilograms)"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Wikipedia: Iridium",
      "type": "database",
      "url": "https://en.wikipedia.org/wiki/Iridium",
      "year": 2026
    },
    {
      "title": "Iridium datasheet, Heraeus Precious Metals, document number 02, status 09/2021",
      "type": "datasheet",
      "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
      "year": 2021
    },
    {
      "title": "PubChem compound record for iridium (CID 23924)",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Iridium"
    },
    {
      "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": "ASTM B671 Standard Specification for Refined Iridium, ASTM store listing",
      "type": "standard",
      "url": "https://store.astm.org/b0671-81r17.html"
    },
    {
      "title": "Schneider, High temperature thruster technology for spacecraft propulsion, IAF 1991, NASA NTRS 19920005907",
      "type": "paper",
      "url": "https://ntrs.nasa.gov/citations/19920005907",
      "year": 1991
    },
    {
      "title": "Schneider, Advanced liquid rockets, JANNAF 1992, NASA NTRS 19920015317",
      "type": "paper",
      "url": "https://ntrs.nasa.gov/citations/19920015317",
      "year": 1992
    },
    {
      "title": "Stulen et al., Characterization of Iridium Coated Rhenium Used in High-Temperature, Radiation-Cooled Rocket Thrusters, JANNAF 1990, NASA NTRS 19910014954",
      "type": "paper",
      "url": "https://ntrs.nasa.gov/citations/19910014954",
      "year": 1990
    }
  ],
  "gaps": [
    "Iridium country shares of world output were not found. The USGS 2026 platinum-group summary gives only palladium and platinum mine production and no iridium mine figure, and the Wikipedia production table was not read as numbers. The producers list is empty.",
    "The Heraeus datasheet melting point of 2447 is printed without a unit, so it is not entered. The melting point comes from Wikipedia (2446 °C) and PubChem (2,446 °C).",
    "Density is not settled across sources. PubChem gives 22.42 at 17 °C and 21.56 at 25 °C from other records; those are not entered. Only the Heraeus and Wikipedia values are.",
    "Thermal conductivity differs: Heraeus gives 59 W/(m·K) at 20 °C and the Wikipedia infobox gives 147 W/(m·K) with no condition. Both are kept and the difference is not resolved.",
    "Designations: no EN, DIN, JIS, AISI or trade-name designation for pure iridium was found in a fetched source. The UNS code PO6100 belongs to ASTM B671 grade 99.80 sponge and powder; grade 99.90 has no code on the page, and no wrought-iridium UNS or ASTM number was found. The page prints the UNS with a letter O, which is kept as printed.",
    "Critical-mineral status is not stated for iridium in the fetched pages, so no critical_lists entry is given.",
    "Canonical names are missing for electrical_conductivity, vickers_hardness and mohs_hardness; they are used as short snake_case names as noted on each row. The speed of sound (4825 m/s at 20 °C, Wikipedia infobox) is not entered because no canonical name exists.",
    "Crucible, electrode, spark-plug and thermocouple uses are described in story.uses only, because the application enum has no matching value. Crucibles for oxide crystal growth at up to 2,100 °C come from Wikipedia; the Heraeus datasheet lists crucibles, thermocouples, spark plug electrodes and probe needles.",
    "Iridium-rhenium chamber life, firing count, and the Space Shuttle vernier thruster were not found in fetched text; the abstracts give specific impulse and temperature only.",
    "No environment tag is set, because no fetched source names low Earth orbit, GEO or another environment for an iridium part.",
    "Atomic oxygen erosion, outgassing, radiation effects and cold welding were not searched.",
    "The Johnson Matthey product page was not reached; a search showed only a third-party datasheet, so no Johnson Matthey value is recorded."
  ],
  "story": {
    "why": "Iridium is one of the densest and most corrosion-resistant metals. The Heraeus datasheet gives a density of 22.56 g/cm3 and a melting point of 2447 with no unit, and Wikipedia gives 2446 °C, which PubChem also lists. It resists oxidation to about 800 °C in the datasheet and is described as one of the most corrosion-resistant metals up to about 2,000 °C in the Wikipedia summary. That is why it is used for crucibles and as an oxidation-barrier coating on rhenium thrust chambers. Iridium is not ductile at room temperature and must be formed hot.",
    "uses": [
      {
        "where": "Space propulsion",
        "line": "A NASA Lewis paper reports that iridium-coated rhenium thrust chambers raised operating temperature to 2200 C, against 1400 C for silicide-coated niobium, and gave stationkeeping engines of the 22 N class specific impulses 20 to 25 seconds higher than niobium chambers."
      },
      {
        "where": "Crucibles",
        "line": "Wikipedia says iridium's high melting point, hardness and corrosion resistance make it suitable for crucibles, used in the Czochralski process to grow oxide single crystals at up to 2,100 °C. The Heraeus datasheet also lists crucibles."
      },
      {
        "where": "Electrodes and spark plugs",
        "line": "Wikipedia names electrodes for producing chlorine as the main industrial use, and high-performance spark plugs. The Heraeus datasheet lists spark plug electrodes, thermocouples and probe needles."
      }
    ],
    "can_do": [
      {
        "label": "Stay solid and stiff at high heat",
        "line": "The melting point is 2446 °C in Wikipedia and PubChem. The Heraeus datasheet gives a Young's modulus of 528 GPa.",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "2446 °C melting point"
      },
      {
        "label": "Resist oxidation",
        "line": "The Heraeus datasheet says the metal is oxidation resistant to 800 °C. Wikipedia describes it as one of the most corrosion-resistant metals, even at temperatures as high as 2,000 °C.",
        "scope": "material",
        "value": "800 °C oxidation resistance"
      },
      {
        "label": "Conduct heat and current",
        "line": "The thermal conductivity is 59 W/(m·K) at 20 °C in the Heraeus datasheet and 147 W/(m·K) in the Wikipedia infobox. Electrical conductivity is 24 to 26 % IACS in the datasheet, and electrical resistivity is 47.1 nΩ·m at 20 °C in Wikipedia.",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "59 or 147 W/(m·K)"
      },
      {
        "label": "Weight",
        "line": "Density is 22.56 g/cm3 in the datasheet and 22.562 g/cm3 at 20 °C in Wikipedia.",
        "benchmark": "density",
        "scope": "material",
        "value": "22.56 g/cm3"
      },
      {
        "label": "Strength",
        "line": "Annealed iridium has a tensile strength of 450 MPa and a yield strength of 93 MPa, and it stretches 7 % before breaking. Work hardened iridium reaches 1632 MPa tensile and 1618 MPa yield, but stretches only 1 %.",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material",
        "value": "450 MPa tensile, annealed"
      }
    ],
    "compare": "Compared inside this profile, iridium's annealed and work-hardened rows differ widely: yield strength is 93 MPa annealed and 1618 MPa work hardened, and elongation is 7 % against 1 %. The two thermal conductivity figures, 59 and 147 W/(m·K), differ by about a factor of 2.5 and are not resolved. The Heraeus rows and the Wikipedia infobox are both recorded, and each row names its own source.",
    "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": [
      "Specify the temper, because annealed and work-hardened iridium differ in strength and elongation by a wide margin.",
      "Form the metal hot; it is not ductile at room temperature.",
      "Keep powder and sponge away from air-borne ignition sources and interhalogens."
    ],
    "good_for": [
      "High-temperature crucibles: oxidation resistance to 800 °C in the datasheet, and corrosion resistance to about 2,000 °C in Wikipedia.",
      "Oxidation-barrier coatings on rhenium rocket chambers: 2200 C operating temperature against 1400 C for silicide-coated niobium.",
      "Corrosive chemistry: not attacked by acids, including aqua regia, according to Wikipedia."
    ],
    "watch_out": [
      "Not ductile at room temperature, hardly formable, and limited in machinability.",
      "Powder can ignite spontaneously in air, and reacts violently with interhalogens.",
      "Iridium is very scarce: about 6,800 kg a year worldwide in 2023, and about 1 tonne of iridium for every 25 tonnes of platinum from ores.",
      "Iridium and rhenium interdiffuse significantly at 1000 C, and no life value is given in the fetched abstracts.",
      "The two thermal conductivity figures disagree (59 and 147 W/(m·K)), and this is not resolved."
    ],
    "verdict": "Iridium is the pure metal Ir, very dense and corrosion-resistant, with a melting point of 2446 °C. It is used for high-temperature crucibles and as an oxidation-barrier coating on rhenium rocket chambers, but it is not ductile at room temperature, its powder can ignite in air, and it is scarce and costly. This profile lacks EN, DIN and JIS designations, per-country production shares, and any life or flight data for thrusters.",
    "recipe": {
      "line": "Iridium is a single-element metal (Ir) with a face-centred cubic crystal structure (Wikipedia infobox). It is found in nature as the uncombined element or in the natural alloys osmiridium and iridosmium (Wikipedia, Occurrence). It is refined from platinum-group ore, usually by dissolving the ore and reducing an iridium chloride salt with hydrogen to a powder or sponge (Wikipedia, Production).",
      "parts": [
        {
          "name": "Iridium",
          "symbol": "Ir",
          "role": "The whole material. PubChem prints the molecular weight of the element as 192.22.",
          "atoms": 1,
          "atomic_weight": 192.22
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The hazard entries come from ECHA notifications in PubChem. The sources do not describe health effects of iridium metal in the body.",
        "points": [
          {
            "label": "Iridium as a substance",
            "line": "Of 249 company reports to the European chemicals agency, 92 say the metal does not meet GHS criteria. Among reports that give codes, 41.8 % list H413 (long lasting harmful effects to aquatic life) and 20.1 % list H319 (serious eye irritation). The signal word is Danger."
          },
          {
            "label": "Powder",
            "line": "Powdered iridium may ignite spontaneously in air, and reacts violently with interhalogens such as bromine pentafluoride."
          }
        ],
        "level": 1,
        "verdict": "Mixed notifications"
      },
      {
        "title": "If it fails",
        "lead": "These are failure routes found in the sources. The thruster results come from 1990 to 1992 abstracts and are not flight data.",
        "points": [
          {
            "label": "Cold forming",
            "line": "The datasheet says the metal is not ductile and hardly formable, with 7 % elongation annealed and 1 % work hardened. It is formed hot."
          },
          {
            "label": "Oxide and interdiffusion",
            "line": "On a rhenium chamber, iridium forms oxides at 600 C and above and interdiffuses with rhenium significantly at 1000 C. The abstract gives no life value."
          },
          {
            "label": "Cost",
            "line": "The USGS price table puts iridium at 4,810.40 dollars per troy ounce in 2024 and an estimated 4,400 dollars in 2025."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Form hot",
            "line": "The datasheet says iridium is hardly formable and has limited machinability, and it is formed hot."
          },
          {
            "label": "Powder",
            "line": "Treat powder and sponge as able to ignite in air, and keep them away from interhalogens."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 24,
    "unreachable": 2,
    "caveats": 6,
    "note": "Values were read by an AI assistant on 2026-10-26 from the pages named in each entry. Unreachable: the PubChem record page (captcha) and the Johnson Matthey product page (404); PubChem values came from its REST record. Caveats: the thermal conductivity sources disagree (59 against 147 W/(m·K)); the Heraeus melting point has no unit and is left out; the UNS code is printed with a letter O on the ASTM page; the rocket-chamber values come from 1990 to 1992 abstracts; the USGS summary has no iridium mine output figure."
  },
  "sources": {
    "wikipedia-ir": {
      "title": "Iridium (Wikipedia, English)",
      "url": "https://en.wikipedia.org/wiki/Iridium",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0 (cited, not reproduced)"
    },
    "heraeus-ir": {
      "title": "Iridium datasheet, Heraeus Precious Metals (document number 02, status 09/2021)",
      "url": "https://pim.heraeus.com/datasheets/HPM/FM/Contact%20Materials/Iridium_Datasheet_EN_(Heraeus_Precious_Metals).pdf",
      "year": 2021,
      "kind": "datasheet",
      "license": "Manufacturer datasheet (cited, not reproduced)"
    },
    "pubchem-ir": {
      "title": "PubChem compound record: Iridium (CID 23924), experimental properties, GHS classification, CAS",
      "id": "CAS 7439-88-5",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23924/JSON",
      "kind": "database",
      "license": "PubChem (NCBI), public domain; sections attributed to ECHA, HSDB and the DOE PAC database"
    },
    "usgs-pgm-2026": {
      "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)"
    },
    "astm-b671": {
      "title": "ASTM B671 Standard Specification for Refined Iridium (ASTM store listing, designation B671-81(2017))",
      "url": "https://store.astm.org/b0671-81r17.html",
      "kind": "standard",
      "license": "ASTM listing page (cited, not reproduced)"
    },
    "schneider-1991": {
      "title": "High temperature thruster technology for spacecraft propulsion (Schneider, NASA Lewis, IAF 1991)",
      "id": "NASA NTRS 19920005907",
      "url": "https://ntrs.nasa.gov/citations/19920005907",
      "year": 1991,
      "kind": "paper",
      "license": "public domain (NASA)"
    },
    "schneider-1992": {
      "title": "Advanced liquid rockets (Schneider, NASA Lewis, JANNAF Propulsion Meeting 1992)",
      "id": "NASA NTRS 19920015317",
      "url": "https://ntrs.nasa.gov/citations/19920015317",
      "year": 1992,
      "kind": "paper",
      "license": "public domain (NASA)"
    },
    "stulen-1990": {
      "title": "Characterization of Iridium Coated Rhenium Used in High-Temperature, Radiation-Cooled Rocket Thrusters (Stulen, Boehme, Clift, McCarty, Sandia, JANNAF 1990)",
      "id": "NASA NTRS 19910014954",
      "url": "https://ntrs.nasa.gov/citations/19910014954",
      "year": 1990,
      "kind": "paper",
      "license": "public domain (NASA)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/iridium/"
}