spore: profile
id: cerium
spore_version: 0.2
family: rare-earth-metals
name: Cerium
abbreviation: Ce
role: rare-earth metal for alloys and lighter flints; cerium oxide (ceria) used as a glass dopant
category: metals
type: heavy-metals
summary: |
  Cerium is the element Ce, a gray metal of the lanthanide series with a density of 6.77 g/cm3 and a melting point of 798 °C (Ames Laboratory SDS). It was first identified in 1803 (Wikipedia). USGS puts its crustal abundance at 66.5 ppm. Cerium is mined as part of the rare-earth group, where China produced 270,000 of 390,000 t in 2025 (USGS). The metal is a flammable solid: it sparks with friction, reacts with water and moist air, and needs a Class D extinguisher. In 1973 NASA Langley showed that cerium oxide (ceria) in solar-cell cover glass resisted radiation-induced discoloration under 1 MeV electrons, a laboratory test and not a flight result.
best_for: Ceria (cerium oxide) as a UV-blocking, radiation-resistant dopant in solar-cell cover glass (NASA 1973 laboratory test)
weakest_at: 'Handling: finely divided metal is pyrophoric, and the metal reacts with water and moist air (Ames SDS, CAMEO)'
identity:
  formula: Ce (element, atomic number 58, USGS PP 1802-A periodic table)
  cas: 7440-45-1
  source: pubchem-ce
  where: Compound record, CID 23974, molecular weight 140.116 and CAS 7440-45-1 (REST JSON)
tags:
  applications:
    - solar-arrays
    - structures
  stresses:
    - total-radiation-dose
properties:
  - benchmark: density
    label: Density, cerium (Ames Laboratory SDS)
    value: 6.77
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated
      unit_in_source: 6.77 g/cc (Relative Density, Specific Gravity)
      form: solid, various forms
    method: Value printed in a safety data sheet for cerium ingot, pieces, rod, foil, sheet and target (Ames Laboratory, 99 to 100 % cerium per section 3)
    status: ground
    source: ames-ce-sds
    where: Section 9, Physical and Chemical Properties, row Relative Density (Specific Gravity)
  - benchmark: density
    label: Density, cerium foil (Goodfellow)
    value: 6.75
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
      purity: 90 %
      form: foil/sheet, as rolled
      unit_in_source: 6.75@20°C
    method: Value printed in a supplier product datasheet for a 90 % purity foil
    status: ground
    note: The 90 % purity foil and the Ames 99 to 100 % metal differ by 0.02 g/cm3 in density, so both are recorded.
    source: goodfellow-ce-foil
    where: Physical Properties table, row Density (6.75@20°C)
  - benchmark: melting_point
    label: Melting point, cerium (Ames Laboratory SDS)
    value: 798
    unit: °C
    scope: material
    conditions:
      unit_in_source: 798 oC
    method: Value printed in a safety data sheet
    status: ground
    source: ames-ce-sds
    where: Section 9, Physical and Chemical Properties, row Melting Point
  - benchmark: melting_point
    label: Melting point, cerium foil (Goodfellow)
    value: 799
    unit: °C
    scope: material
    conditions:
      purity: 90 %
      form: foil/sheet, as rolled
    method: Value printed in a supplier product datasheet for a 90 % purity foil
    status: ground
    note: The Ames SDS gives 798 °C for the metal, so the two sources differ by 1 °C.
    source: goodfellow-ce-foil
    where: Thermal Properties table, row Melting point (799)
  - benchmark: boiling_point
    label: Boiling point, cerium (Ames Laboratory SDS)
    value: 3443
    unit: °C
    scope: material
    conditions:
      pressure: not stated
    method: Value printed in a safety data sheet
    status: ground
    source: ames-ce-sds
    where: Section 9, Physical and Chemical Properties, row Boiling Point
  - benchmark: boiling_point
    label: Boiling point, cerium foil (Goodfellow)
    value: 3426
    unit: °C
    scope: material
    conditions:
      purity: 90 %
      form: foil/sheet, as rolled
    method: Value printed in a supplier product datasheet for a 90 % purity foil
    status: ground
    note: The Goodfellow and Ames boiling points differ by 17 °C, which is not reconciled.
    source: goodfellow-ce-foil
    where: Physical Properties table, row Boiling point (3426)
  - benchmark: specific_heat
    label: Specific heat capacity, cerium foil (Goodfellow)
    value: 205
    unit: J/(kg·K)
    scope: material
    conditions:
      temperature: 25 °C
      purity: 90 %
      unit_in_source: 205@25°C in J K-1 kg-1
    method: Value printed in a supplier product datasheet for a 90 % purity foil
    status: ground
    source: goodfellow-ce-foil
    where: Thermal Properties table, row Specific heat (205@25°C)
  - benchmark: thermal_conductivity
    label: Thermal conductivity, cerium foil (Goodfellow)
    value: 11.3
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: 0 to 100 °C
      purity: 90 %
      unit_in_source: 11.3@0-100°C
    method: Value printed in a supplier product datasheet for a 90 % purity foil
    status: ground
    source: goodfellow-ce-foil
    where: Thermal Properties table, row Thermal conductivity (11.3@0-100°C)
  - benchmark: cte
    label: Coefficient of thermal expansion, cerium foil (Goodfellow)
    value: 8
    unit: ppm/K
    scope: material
    conditions:
      temperature: 0 to 100 °C
      purity: 90 %
      unit_in_source: 8 x10-6 K-1 at 0-100°C
    method: Value printed in a supplier product datasheet for a 90 % purity foil; 10-6 K-1 is the same unit as ppm/K
    status: ground
    source: goodfellow-ce-foil
    where: Thermal Properties table, row Coefficient of thermal expansion (8@0-100°C)
  - benchmark: electrical_resistivity
    label: Electrical resistivity, cerium foil (Goodfellow)
    value: 85.4
    unit: µOhm·cm
    scope: material
    conditions:
      temperature: 20 °C
      purity: 90 %
      unit_in_source: 85.4@20°C in µOhmcm
    method: Value printed in a supplier product datasheet for a 90 % purity foil; kept in the printed unit
    status: ground
    source: goodfellow-ce-foil
    where: Electrical Properties table, row Electrical resistivity (85.4@20°C)
  - benchmark: vickers_hardness
    label: Vickers hardness, cerium foil (Goodfellow)
    value: 25
    value_high: 30
    bound: range
    unit: kgf/mm2
    scope: material
    conditions:
      purity: 90 %
      form: foil/sheet, as rolled
      unit_in_source: 25-30 kgf mm-2
    method: Range printed in a supplier product datasheet for a 90 % purity foil
    status: ground
    note: No canonical name exists for hardness in the property file, so vickers_hardness is a new name and is listed in gaps. The unit is kept as printed.
    source: goodfellow-ce-foil
    where: Mechanical Properties table, row Hardness - Vickers (25-30)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, cerium foil as rolled (Goodfellow)
    value: 102
    unit: MPa
    scope: material
    conditions:
      temper: as rolled
      purity: 90 %
      form: foil/sheet
      unit_in_source: 102 MPa
    method: Value printed in a supplier product datasheet for a 90 % purity foil; the datasheet does not say whether this is a typical or minimum value
    status: ground
    source: goodfellow-ce-foil
    where: Mechanical Properties table, row Tensile strength (102)
  - benchmark: yield_strength
    label: Yield strength, cerium foil as rolled (Goodfellow)
    value: 91
    unit: MPa
    scope: material
    conditions:
      temper: as rolled
      purity: 90 %
      form: foil/sheet
      unit_in_source: 91 MPa
    method: Value printed in a supplier product datasheet for a 90 % purity foil; the datasheet does not say whether this is a typical or minimum value
    status: ground
    source: goodfellow-ce-foil
    where: Mechanical Properties table, row Yield strength (91)
corrosion:
  - environment: Water and moist air at room temperature
    headline: Cerium is readily oxidized by moist air and reacts vigorously with water, liberating flammable hydrogen.
    effect: CAMEO quotes a datasheet that says the metal is readily oxidized by moist air at room temperature and that it will react vigorously with water or moist air, generating flammable and toxic fumes. The Ames SDS lists water, moisture and air as incompatible and says cerium reacts with water under fire conditions to release hydrogen. PubChem gives H261, in contact with water releases flammable gas, from one notification.
    rating: severe
    conditions:
      temperature: room temperature
      atmosphere: moist air or water
      form: metal, not stated
    source: cameo-ce
    where: Reactivity and hazard text (datasheet quote and ERG Guide 170 entries); Ames SDS section 10
  - environment: Strong acids
    headline: Contact with acids may evolve hydrogen gas.
    effect: The Ames SDS lists strong acids among incompatible materials and says contact with acids may evolve hydrogen gas. No corrosion rate is printed.
    rating: moderate
    conditions:
      acid: strong acids, not named
      concentration: not stated
    source: ames-ce-sds
    where: Section 10, Stability and Reactivity (Incompatible Materials; Possibility of Hazardous Reactions)
risks:
  hazards:
    - text: 'PubChem aggregates ECHA C&L notifications for 502 company reports: H228 flammable solid (Danger) in 96.4% of reports; H302 and H312 at 100% (Warning); H261 and H370 from single notifications with no percentage printed; 11 of 502 reports (2.2%) say the substance does not meet GHS criteria.'
      ghs:
        - H228
        - H261
        - H302
        - H312
        - H370
      source: pubchem-ce
      where: GHS Classification, aggregated ECHA C&L summary and notification list
    - text: 'Ames Laboratory SDS for cerium ingot, pieces, rod, foil, sheet and target: GHS flammable solid, category 1, signal word Danger, H228. Handle under inert gas, protect from moisture, and use a Class D extinguisher.'
      ghs:
        - H228
      source: ames-ce-sds
      where: Sections 2 and 5
    - text: No OSHA or ACGIH exposure limit is established for cerium (Ames SDS). The SDS gives 'No data' for acute toxicity and says the toxicological characteristics are not fully known.
      ghs: []
      source: ames-ce-sds
      where: Section 8, Exposure Limits; Section 11, Toxicological Information
  failure_risks:
    - mode: Ignition by friction or in fire
      trigger: Friction or sparks on the metal, or a fire involving cerium; finely divided metal is more reactive
      consequence: The Ames SDS says cerium sparks with friction and will burn under fire conditions. CAMEO, citing Bretherick 1979, says finely divided metal powder is pyrophoric, and says reactivity is enhanced by high physical subdivision such as turnings or gritty powder.
      severity: critical
      source: ames-ce-sds
      where: Sections 2, 5 and 10; CAMEO reactivity text
    - mode: Hydrogen release on contact with water or moist air
      trigger: Exposure to water, moisture or moist air, or water used on a metal fire
      consequence: 'The Ames SDS says cerium reacts with water under fire conditions and liberates hydrogen gas. CAMEO quotes ERG Guide 170: dousing metallic fires with water will generate hydrogen gas, an extremely dangerous explosion hazard, particularly in confined spaces.'
      severity: critical
      source: cameo-ce
      where: Reactivity and hazard text; ERG Guide 170 entries
    - mode: Hydrogen evolution with acids
      trigger: Contact with strong acids
      consequence: Contact with acids may evolve hydrogen gas (Ames SDS section 10). The SDS does not give a rate.
      severity: moderate
      source: ames-ce-sds
      where: Section 10, Possibility of Hazardous Reactions
  side_effects:
    - text: Subsequent operations such as grinding, melting or welding may produce potentially hazardous dust or fumes that can be inhaled or contact skin and eyes. The Ames SDS says the product as shipped does not present an inhalation hazard.
      affects: Workers during machining, melting or welding
      source: ames-ce-sds
      where: Section 4, General Measures; Section 11, Likely Routes of Exposure
  handling:
    - text: Store under argon or mineral oil in tightly closed containers, away from water, moisture, acids and oxidizers, and away from sparks, heat and flame (Ames SDS section 7).
      source: ames-ce-sds
      where: Section 7, Conditions for Safe Storage
    - text: Handle in an enclosed, controlled process under dry argon, in a humidity-controlled atmosphere, with non-sparking tools (Ames SDS sections 7 and 8).
      source: ames-ce-sds
      where: Section 7, Precautions for Safe Handling; Section 8, Engineering Controls
    - text: Fight fires with a Class D dry powder agent. Do not use water (Ames SDS section 5).
      source: ames-ce-sds
      where: Section 5, Firefighting Measures
    - text: Sweep or scoop spills into a closed container and do not use water for spill clean-up (Ames SDS section 6).
      source: ames-ce-sds
      where: Section 6, Accidental Release Measures
  mitigations: []
uses:
  - application: solar-arrays
    device: Solar-cell cover glass made from 1.5% ceria-doped Micro-Sheet (cerium oxide dopant)
    example: NASA Langley irradiated 1.5% ceria-doped cover glass with 1 MeV electrons. The doped glass was much less sensitive to radiation-induced discoloration than undoped cover glass, and the report calls it comparable to synthetic fused silica for this application. This was a laboratory irradiation test, not a flight result.
    source: nasa-tn-d7245
    where: Abstract and Concluding Remarks (NASA TN D-7245, May 1973)
  - application: structures
    device: Metal alloys containing cerium, including mischmetal
    example: PubChem, citing Ullmann, says cerium is used in metal alloys, in polishing agents and in glass, and that mischmetal is used to make flints for cigarette lighters. The source does not name an aerospace alloy.
    source: pubchem-ce
    where: Use and Manufacturing, Sources/Uses (Ullmann, cited)
supply:
  - subject: Cerium crustal abundance
    abundance: 66.5 ppm of the Earth's crust (USGS PP 1802-A Table A1, citing Jefferson Science Associates 2014)
    producers: []
    critical_lists: []
    source: usgs-pp1802a
    where: Table A1, Crustal abundances of mineral commodities, row Cerium (Ce)
  - subject: Rare-earth mine production, 2025 (all rare earths together; cerium is not reported separately)
    producers:
      - country: China
        share_percent: 69.2
        year: 2025
      - country: United States
        share_percent: 13.1
        year: 2025
      - country: Australia
        share_percent: 7.4
        year: 2025
      - country: Burma
        share_percent: 5.6
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (cerium named individually)
        listed: true
    recycling: 'USGS: limited quantities of rare earths were recovered from batteries, permanent magnets and fluorescent lamps.'
    substitutes:
      - 'USGS: substitutes are available for many applications but generally are less effective.'
    source: usgs-mcs2026-rare-earths
    where: 'World Mine Production table, 2025 (China 270,000 t, United States 51,000 t, Australia 29,000 t, Burma 22,000 t, world total 390,000 t rounded). Shares are calculated by Space Mushroom from the printed values and are rare-earth oxide equivalent. Recycling; Substitutes. Critical list: usgs-crit2025.'
  - subject: U.S. imports of rare-earth compounds and metals (all rare earths; 2021 to 2024 combined)
    producers:
      - country: China
        share_percent: 71
        year: 2024
      - country: Malaysia
        share_percent: 13
        year: 2024
      - country: Japan
        share_percent: 5
        year: 2024
      - country: Estonia
        share_percent: 5
        year: 2024
    critical_lists: []
    source: usgs-mcs2026-rare-earths
    where: Import Sources (2021 to 2024) paragraph. The year field is the last year of the range. These are import shares, not production shares.
documents:
  - title: 'Safety Data Sheet: Cerium, ingot, pieces, rod, foil, sheet and target (Ames Laboratory, US DOE, Materials Preparation Center)'
    type: sds
    url: https://www.ameslab.gov/sites/default/files/inline-files/58_Cerium_SDS.pdf
    year: 2024
  - title: Goodfellow cerium foil/sheet, 50 x 50 mm, 0.25 mm (SKU 1000225237), product datasheet
    type: datasheet
    url: https://www.goodfellow.com/usa/cerium-foil-1000225237
  - title: 'PubChem compound record: Cerium (CID 23974), GHS classification and use summary'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23974
    year: 2026
  - title: 'Mineral Commodity Summaries 2026: Rare Earths (USGS)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
  - title: 'Critical Mineral Resources of the United States: An Introduction (USGS Professional Paper 1802-A), Table A1'
    type: report
    url: https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf
    year: 2017
  - title: 'NASA Technical Note D-7245: Effect of 1 MeV Electrons on Ceria-Doped Solar Cell Cover Glass (Haynes, Langley Research Center)'
    type: report
    url: https://ntrs.nasa.gov/citations/19730015355
    year: 1973
  - title: 'CAMEO Chemicals: Cerium, slabs, ingots or rods (NOAA)'
    type: database
    url: https://cameochemicals.noaa.gov/chemical/2844
  - title: 'Wikipedia: Cerium (history and mineral sources only)'
    type: database
    url: https://en.wikipedia.org/wiki/Cerium
    year: 2026
gaps:
  - 'Elastic constants: no Young''s modulus, shear modulus or Poisson''s ratio for cerium was read in a fetched source. Wikipedia prints a Young''s modulus, but the brief limits Wikipedia to composition and history, so it was not used.'
  - 'Purity: the Goodfellow properties are for a 90 % purity foil, and the Ames SDS covers the 99 to 100 % metal. The two sets are recorded separately and not reconciled. Goodfellow''s rod datasheet was not found.'
  - 'Hardness: Vickers hardness is printed in kgf/mm2 for the 90 % foil. The property file has no canonical name for hardness, so vickers_hardness is a new name.'
  - 'Strength: the tensile and yield values are for as-rolled 90 % foil. No grade, temper or minimum-value table for pure cerium was found, and Goodfellow does not say whether the values are typical or minimum.'
  - 'Corrosion rate: no quantitative oxidation or corrosion rate for cerium metal in air or humidity was read. A Corrosion Science paper on cerium oxidation in water vapour was seen only in search results and not opened.'
  - 'EU critical raw materials list: the European Commission page read here does not name cerium or the light rare earths, so no EU listing is recorded for cerium.'
  - 'Production route: no source read gives the reduction or metal-making process for cerium. The recipe names only the ore minerals (bastnaesite and monazite) from USGS and Wikipedia.'
  - Supply shares are for all rare earths together (USGS does not report cerium separately). They are rare-earth oxide equivalent and are not a cerium-only share.
  - 'Pyrophoric statement: the pyrophoric wording for finely divided metal comes from CAMEO, which cites Bretherick 1979. The Bretherick text was not opened and no measured ignition temperature was found.'
  - 'Hazard classification: PubChem gives H261 and H370 from single notifications and H228 in 96.4% of reports, while the Ames SDS gives only H228. The percentages for H261 and H370 are not printed.'
  - 'Space use: the only space-related source is a 1973 laboratory irradiation of ceria-doped cover glass (NASA TN D-7245). No flight result and no cerium metal space use was found. No environment tags are set because no source ties cerium to a specific environment.'
  - 'Mitigations: no source read gives a mitigation for the water, air or fire hazards beyond the handling steps above.'
  - 'Designations: no alloy or grade designation for cerium metal was found in a fetched source. UN 1333 is a transport number, not a designation in the list used for this profile.'
sources:
  ames-ce-sds:
    title: 'Safety Data Sheet: Cerium (Ames Laboratory, US DOE, Materials Preparation Center)'
    id: CAS 7440-45-1, UN 1333
    url: https://www.ameslab.gov/sites/default/files/inline-files/58_Cerium_SDS.pdf
    year: 2024
    kind: datasheet
    license: supplier safety data sheet, cited not reproduced
  goodfellow-ce-foil:
    title: Cerium foil/sheet, 50 x 50 mm, 0.25 mm, as rolled, 90 % purity (Goodfellow product datasheet)
    id: SKU 1000225237
    url: https://www.goodfellow.com/usa/cerium-foil-1000225237
    kind: datasheet
    license: supplier web page, cited not reproduced
  pubchem-ce:
    title: 'PubChem compound record: Cerium (CID 23974), GHS classification and use summary'
    id: CID 23974; CAS 7440-45-1
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23974/JSON
    year: 2026
    kind: database
    license: public domain (NCBI); sections attributed to ECHA, Ullmann and others
  usgs-mcs2026-rare-earths:
    title: 'Mineral Commodity Summaries 2026: Rare Earths (USGS)'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.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, crustal abundances'
    id: USGS PP 1802-A
    url: https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf
    year: 2017
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)
    id: Final 2025 List of Critical Minerals, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  nasa-tn-d7245:
    title: Effect of 1 MeV Electrons on Ceria-Doped Solar Cell Cover Glass (NASA Technical Note D-7245, Langley Research Center, Haynes)
    id: NASA TN D-7245; L-8785
    url: https://ntrs.nasa.gov/citations/19730015355
    year: 1973
    kind: report
    license: public domain (NASA)
  cameo-ce:
    title: 'CAMEO Chemicals: Cerium, slabs, ingots or rods (NOAA)'
    id: CAMEO chemical 2844; UN/NA 1333
    url: https://cameochemicals.noaa.gov/chemical/2844
    kind: database
    license: public domain (NOAA)
  wikipedia-ce:
    title: Cerium (Wikipedia)
    url: https://en.wikipedia.org/wiki/Cerium
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 13
  unreachable: 1
  caveats: 5
  note: 'Read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Unreachable: American Elements cerium page (HTTP 403). Caveats: the Goodfellow values are for a 90 % purity foil, not the 99 to 100 % metal in the Ames SDS; the supply shares are for all rare earths together; the strength values are as-rolled foil with no minimum stated; the boiling point and melting point differ between the Ames SDS and Goodfellow; no corrosion rate for cerium metal was found.'
story:
  recipe:
    line: Cerium is a single-element metal (Ce). It is not alloyed in the profile. Its ores are the minerals of the bastnaesite and monazite groups (Wikipedia); USGS reports bastnaesite mined at Mountain Pass, California, and monazite produced from heavy-mineral-sand concentrates in the southeastern United States. No source read gives the reduction process.
    parts:
      - name: Cerium
        symbol: Ce
        atoms: 1
        atomic_weight: 140.116
        role: The whole material. The Ames SDS lists cerium at 100 % in section 3 (ingot, pieces, rod, foil, sheet and target), and the Goodfellow foil is 90 % purity.
  risk_groups:
    - title: For people
      level: 1
      verdict: Flammable solid, category 1
      lead: The main hazard is fire and reaction with water, not toxicity. The sources give little toxicology data for the metal.
      points:
        - label: The metal
          line: The Ames SDS classes cerium as a flammable solid, category 1, with signal word Danger and H228. PubChem records H228 in 96.4% of reports, and 11 of 502 reports say the substance does not meet GHS criteria.
        - label: Dust and fumes
          line: Grinding, melting or welding can produce hazardous dust or fumes, and the SDS gives no exposure limit for cerium.
        - label: Toxicity
          line: The SDS gives 'No data' for acute toxicity and says the toxicological characteristics are not fully known.
    - title: If it fails
      lead: 'The sources give three failure routes: ignition by friction or in fire, hydrogen from water or moist air, and hydrogen from acids.'
      points:
        - label: Fire
          line: The metal sparks with friction and burns under fire conditions. CAMEO says finely divided metal is pyrophoric.
        - label: Water and moist air
          line: Cerium is readily oxidized by moist air and reacts vigorously with water, liberating hydrogen. The ERG guide quoted by CAMEO warns that water on a metal fire generates hydrogen, an extremely dangerous explosion hazard.
        - label: Acids
          line: Contact with acids may evolve hydrogen gas, according to the Ames SDS.
    - title: Handling and storage
      points:
        - label: Storage
          line: Store under argon or mineral oil in tightly closed containers, away from water, moisture, acids and oxidizers.
        - label: Fire
          line: Use a Class D dry powder agent on fires. Do not use water.
        - label: Spills
          line: Sweep or scoop spills into a closed container and do not use water for clean-up.
  why: 'Cerium is a reactive rare-earth metal. The SDS treats it as a flammable solid, so the metal is handled under argon and kept away from water. Its main uses in this profile are not as the metal: NASA tested cerium oxide (ceria) as a dopant in solar-cell cover glass in 1973, and it resisted radiation-induced discoloration. PubChem says the metal goes into alloys, polishing agents and glass, and into mischmetal flints for cigarette lighters. Cerium was first identified in 1803.'
  uses:
    - where: Solar-cell cover glass
      line: In the 1973 NASA Langley test, 1.5% ceria-doped cover glass was much less sensitive to electron-induced discoloration than undoped glass, and the report calls it comparable to synthetic fused silica. It was a laboratory test, not a flight result.
    - where: Alloys and lighter flints
      line: PubChem, citing Ullmann, says cerium is used in metal alloys, polishing agents and glass, and that mischmetal makes flints for cigarette lighters. The source names no aerospace alloy.
  can_do:
    - label: Density
      value: 6.77 g/cm3
      benchmark: density
      line: The Ames Laboratory SDS gives a relative density of 6.77 g/cc. Goodfellow's 90 % foil gives 6.75 g/cm3 at 20 °C.
    - label: Melting
      value: 798 °C
      benchmark: melting_point
      line: The Ames SDS gives a melting point of 798 °C, and Goodfellow's foil gives 799 °C.
    - label: Strength as rolled
      value: 102 MPa
      line: Goodfellow's 90 % purity foil, as rolled, gives 102 MPa tensile and 91 MPa yield. The datasheet does not say whether these are minimum values.
    - label: Abundance
      value: 66.5 ppm
      line: USGS PP 1802-A gives cerium a crustal abundance of 66.5 ppm.
  compare: Cerium is a reactive metal rather than a structural one. Its SDS treats it as a flammable solid, and it reacts with water and moist air, which sets it apart from the other metals in this collection. Its space record is as an oxide, ceria, in glass rather than as the metal. This profile has no other metal read in the same run, so the compare rows below give cerium's own values only.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Store under argon or mineral oil in tightly closed containers, away from water, moisture and acids (Ames SDS).
    - Handle under dry argon in a controlled process, with non-sparking tools (Ames SDS).
    - Use a Class D dry powder agent on a fire. Never use water (Ames SDS).
  good_for:
    - 'UV blocking in cover glass: 1.5% ceria in solar-cell cover glass resisted electron-induced discoloration in the 1973 NASA test.'
    - 'Alloys and lighter flints: PubChem says cerium is used in metal alloys and in mischmetal flints for cigarette lighters.'
  watch_out:
    - The metal is a flammable solid, reacts with water and moist air, and burns when finely divided (Ames SDS, CAMEO).
    - Property values differ between the Ames SDS and Goodfellow, and the Goodfellow values are for a 90 % purity foil.
    - Supply data are for all rare earths together, and China produced 270,000 of 390,000 t in 2025 (USGS).
  verdict: Cerium metal is a reactive, flammable solid that is handled under argon. Its most useful space-related result is the 1973 NASA test of ceria as a UV-blocking dopant in solar-cell cover glass, which is a laboratory test rather than a flight result. The metal's mechanical values come from one 90 % purity foil, so they should not be used for design without a grade-specific datasheet.