{
  "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.\n",
  "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",
    "designations": [],
    "source": "pubchem-ce",
    "where": "Compound record, CID 23974, molecular weight 140.116 and CAS 7440-45-1 (REST JSON)"
  },
  "tags": {
    "environments": [],
    "stresses": [
      "total-radiation-dose"
    ],
    "applications": [
      "solar-arrays",
      "structures"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, cerium (Ames Laboratory SDS)",
      "value": 6.77,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, cerium foil (Goodfellow)",
      "value": 6.75,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, cerium (Ames Laboratory SDS)",
      "value": 798,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, cerium foil (Goodfellow)",
      "value": 799,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, cerium (Ames Laboratory SDS)",
      "value": 3443,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, cerium foil (Goodfellow)",
      "value": 3426,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, cerium foil (Goodfellow)",
      "value": 205,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, cerium foil (Goodfellow)",
      "value": 11.3,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion, cerium foil (Goodfellow)",
      "value": 8,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity, cerium foil (Goodfellow)",
      "value": 85.4,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, cerium foil as rolled (Goodfellow)",
      "value": 102,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, cerium foil as rolled (Goodfellow)",
      "value": 91,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    }
  ],
  "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": [],
      "substitutes": [],
      "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": [],
      "substitutes": [],
      "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."
    }
  ],
  "media": [],
  "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."
  ],
  "story": {
    "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",
        "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.",
        "benchmark": "density",
        "scope": "material",
        "value": "6.77 g/cm3"
      },
      {
        "label": "Melting",
        "line": "The Ames SDS gives a melting point of 798 °C, and Goodfellow's foil gives 799 °C.",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "798 °C"
      },
      {
        "label": "Strength as rolled",
        "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.",
        "scope": "material",
        "value": "102 MPa"
      },
      {
        "label": "Abundance",
        "line": "USGS PP 1802-A gives cerium a crustal abundance of 66.5 ppm.",
        "scope": "material",
        "value": "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",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "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.",
    "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",
          "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.",
          "atoms": 1,
          "atomic_weight": 140.116
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "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."
          }
        ],
        "level": 1,
        "verdict": "Flammable solid, category 1"
      },
      {
        "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."
          }
        ]
      }
    ]
  },
  "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."
  },
  "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",
  "url": "https://spacemushroom.com/profiles/cerium/"
}