Iridium Ir

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.
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
  source: pubchem-ir
  where: Other Identifiers section of the PubChem record, CAS entry 7439-88-5 (CID 23924, Iridium)
  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
tags:
  applications:
    - propulsion-and-tanks
properties:
  - benchmark: density
    label: Density, iridium (Heraeus datasheet)
    value: 22.56
    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
  - benchmark: density
    label: Density, iridium (Wikipedia infobox)
    value: 22.562
    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
  - benchmark: melting_point
    label: Melting point, iridium (Wikipedia infobox)
    value: 2446
    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
  - benchmark: melting_point
    label: Melting point, iridium (PubChem experimental property)
    value: 2446
    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)
  - benchmark: boiling_point
    label: Boiling point, iridium (PubChem experimental property)
    value: 4428
    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
  - 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.
  - benchmark: electrical_resistivity
    label: Electrical resistivity, iridium at 20 °C
    value: 47.1
    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
  - benchmark: thermal_conductivity
    label: Thermal conductivity, iridium at 20 °C (Heraeus)
    value: 59
    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
  - benchmark: thermal_conductivity
    label: Thermal conductivity, iridium (Wikipedia infobox)
    value: 147
    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
  - benchmark: cte
    label: Coefficient of thermal expansion at 20 °C
    value: 6.47
    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
  - benchmark: specific_heat
    label: Specific heat capacity, iridium
    value: 130.58
    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
  - benchmark: elastic_modulus
    label: Young's modulus, iridium
    value: 528
    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
  - benchmark: shear_modulus
    label: Modulus of rigidity (shear modulus), iridium
    value: 210
    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
  - benchmark: bulk_modulus
    label: Bulk modulus, iridium
    value: 320
    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
  - benchmark: poissons_ratio
    label: Poisson's ratio, iridium
    value: 0.26
    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
  - benchmark: vickers_hardness
    label: Vickers hardness, iridium annealed
    value: 210
    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
  - benchmark: vickers_hardness
    label: Vickers hardness, iridium work hardened
    value: 453
    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
  - benchmark: mohs_hardness
    label: Mohs hardness, iridium
    value: 6.5
    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
  - benchmark: yield_strength
    label: Yield strength, iridium annealed
    value: 93
    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
  - benchmark: yield_strength
    label: Yield strength, iridium work hardened
    value: 1618
    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
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, iridium annealed
    value: 450
    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
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, iridium work hardened
    value: 1632
    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
  - benchmark: elongation
    label: Elongation, iridium annealed
    value: 7
    unit: '%'
    scope: material
    conditions:
      temper: annealed
    method: Value printed in a manufacturer datasheet
    status: ground
    source: heraeus-ir
    where: Elongation, % row, column Annealed
  - benchmark: elongation
    label: Elongation, iridium work hardened
    value: 1
    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
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: []
    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: []
    total: Wikipedia gives an estimated annual production of 6,800 kilograms in 2023 and about 7,300 kilograms in 2018; for every 190 tonnes of platinum from ores only 7.5 tonnes of iridium is isolated.
    source: wikipedia-ir
    where: Lead section (2023 production) and Production section (2018 production, platinum to iridium ratio)
  - subject: United States iridium imports
    producers: []
    total: 2,200 kg imported in 2025 (estimated), 1,360 kg in 2024, 2,040 kg in 2023, as imports for consumption.
    source: usgs-pgm-2026
    where: Salient Statistics, Imports for consumption, Iridium row (kilograms)
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.
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
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.'
story:
  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.
      level: 1
      verdict: Mixed notifications
      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.
    - 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.
  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
      value: 2446 °C melting point
      benchmark: melting_point
      line: The melting point is 2446 °C in Wikipedia and PubChem. The Heraeus datasheet gives a Young's modulus of 528 GPa.
    - label: Resist oxidation
      value: 800 °C oxidation resistance
      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.
    - label: Conduct heat and current
      value: 59 or 147 W/(m·K)
      benchmark: thermal_conductivity
      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.
    - label: Weight
      value: 22.56 g/cm3
      benchmark: density
      line: Density is 22.56 g/cm3 in the datasheet and 22.562 g/cm3 at 20 °C in Wikipedia.
    - label: Strength
      value: 450 MPa tensile, annealed
      benchmark: ultimate_tensile_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 %.
  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
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  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
        atoms: 1
        atomic_weight: 192.22
        role: The whole material. PubChem prints the molecular weight of the element as 192.22.