spore: profile
id: bismuth
spore_version: 0.2
family: low-melting-metals-and-solders
name: Bismuth
abbreviation: Bi
role: low-melting alloy metal and lead-free substitute
category: metals
type: heavy-metals
summary: |
  Bismuth is the element Bi (atomic number 83), a silver-white metal with a melting point of 271.3 °C according to the PubChem record. Its density is 9.78 g/cm3 at 20 °C, and it expands 3.32 % on solidifying. It is used mainly in low-melting (fusible) alloys, as an additive in brass, free-machining steels and aluminium alloys in place of lead, and in bismuth compounds for pharmaceuticals and pigments. The USGS puts world production at 16,000 t in 2025, with China at 88 % of it. Its weak points are its low thermal conductivity (8 W/(m·K) in WebElements), its low mineral hardness (2.25 in WebElements), and a powder form that PubChem lists as flammable.
best_for: 'Lead-free low-melting alloys and solders: melting point 271.3 °C and density 9.78 g/cm3, with no lead content'
weakest_at: 'Heat conduction and supply: 8 W/(m·K) thermal conductivity (WebElements), and China produced 88 % of world output in 2025 (USGS)'
identity:
  formula: Bi (element, atomic number 83)
  cas: 7440-69-9
  source: durham-sds
  where: Section 1 (Identification), CAS-No line of the bismuth granules SDS (Alfa Aesar cat. 44807, revision 14 Feb 2020)
tags:
  applications:
    - electronics-and-chips
    - mechanisms
    - propulsion-and-tanks
properties:
  - benchmark: density
    label: Density of bismuth at 20 °C (PubChem)
    value: 9.78
    unit: g/cm3
    scope: material
    conditions:
      form: solid metal
      temperature: 20 °C (reference 4 °C)
    method: Value printed in the Experimental Properties section of the PubChem record
    status: ground
    source: pubchem-bi
    where: Experimental Properties, Density, entry 9.78 @ 20 °C/4 °C
  - benchmark: density
    label: Density of bismuth at 25 °C (PubChem)
    value: 9.8
    unit: g/cm3
    scope: material
    conditions:
      form: solid metal
      temperature: 25 °C
    method: Value printed in the Experimental Properties section of the PubChem record
    status: ground
    source: pubchem-bi
    where: Experimental Properties, Density, entry 9.8 @25 °C
  - benchmark: density
    label: Density of solid bismuth (WebElements)
    value: 9780
    unit: kg/m3
    scope: material
    conditions:
      form: solid
      temperature: not stated on the page
    method: Value printed on a reference-database physical properties page
    status: ground
    source: webelements-bi
    where: Density properties, Density of solid row (9780 kg m-3)
  - benchmark: melting_point
    label: Melting point of bismuth
    value: 271.3
    unit: °C
    scope: material
    conditions:
      form: pure bismuth
      pressure: not stated
    method: Value printed in the Melting Point section of the PubChem record (PAC Chemical Database entry); the USGS text gives 271 °C
    status: ground
    source: pubchem-bi
    where: Experimental Properties, Melting Point, entry 271.3 °C
  - benchmark: boiling_point
    label: Boiling point of bismuth
    value: 1564
    unit: °C
    scope: material
    conditions:
      pressure: 760 mmHg
    method: Value printed in the Boiling Point section of the PubChem record (PAC Chemical Database entry)
    status: ground
    source: pubchem-bi
    where: Experimental Properties, Boiling Point, entry 1564 °C @760 [mm Hg]
  - benchmark: volume_change_on_solidification
    label: Volume expansion on solidification
    value: 3.32
    unit: '%'
    scope: material
    conditions:
      transition: liquid to solid at the melting point
    method: Value printed in the Other Experimental Properties section of the PubChem record
    status: ground
    source: pubchem-bi
    where: Experimental Properties, Other Experimental Properties, entry 'EXPANDS 3.32% ON SOLIDIFICATION'
  - benchmark: electrical_resistivity
    label: Electrical resistivity of solid bismuth (WebElements)
    value: 130
    unit: µΩ·cm
    scope: material
    conditions:
      unit_in_source: 130 × 10-8 Ω m
      temperature: not stated on the page
    method: Value printed on the WebElements page as 130 × 10-8 Ω m; converted by Space Mushroom to µΩ·cm (1 Ω·m = 10^8 µΩ·cm), which gives the same 130 µΩ·cm
    status: ground
    source: webelements-bi
    where: Electrical properties, Electrical resistivity row (130 × 10-8 Ω m; or mΩ cm)
  - benchmark: thermal_conductivity
    label: Thermal conductivity of bismuth (WebElements)
    value: 8
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed on a reference-database physical properties page
    status: ground
    source: webelements-bi
    where: Heat and conduction, Thermal conductivity row (8 W m-1 K-1)
  - benchmark: cte
    label: Coefficient of linear thermal expansion (WebElements)
    value: 13.4
    unit: ppm/K
    scope: material
    conditions:
      unit_in_source: 10-6 K-1
      temperature: not stated on the page
    method: Value printed on a reference-database physical properties page
    status: ground
    source: webelements-bi
    where: Heat and conduction, Coefficient of linear thermal expansion row (13.4 × 10-6 K-1)
  - benchmark: elastic_modulus
    label: Young's modulus of bismuth (WebElements)
    value: 32
    unit: GPa
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed on a reference-database physical properties page
    status: ground
    source: webelements-bi
    where: Elastic properties, Young's modulus row (32 GPa)
  - benchmark: shear_modulus
    label: Rigidity (shear) modulus of bismuth (WebElements)
    value: 12
    unit: GPa
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed on a reference-database physical properties page
    status: ground
    source: webelements-bi
    where: Elastic properties, Rigidity modulus row (12 GPa)
  - benchmark: bulk_modulus
    label: Bulk modulus of bismuth (WebElements)
    value: 31
    unit: GPa
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed on a reference-database physical properties page
    status: ground
    source: webelements-bi
    where: Elastic properties, Bulk modulus row (31 GPa)
  - benchmark: poissons_ratio
    label: Poisson's ratio of bismuth (WebElements)
    value: 0.33
    unit: '-'
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed on a reference-database physical properties page
    status: ground
    source: webelements-bi
    where: Elastic properties, Poisson's ratio row (0.33, no units)
  - benchmark: mineral_hardness
    label: Mineral hardness of bismuth (WebElements)
    value: 2.25
    unit: '-'
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed on a reference-database physical properties page; the page gives no scale name beyond 'mineral hardness'
    status: ground
    source: webelements-bi
    where: Hardnesses, Mineral hardness row (2.25, no units)
corrosion:
  - environment: Air at room temperature, then heated in air
    headline: Bismuth tarnishes in air, and heating in air forms bismuth trioxide.
    effect: PubChem records that bismuth is superficially oxidized by air, often becoming iridescent, and that when heated in air it forms bismuth trioxide and burns with a blue flame giving yellow oxide fumes. The record gives no oxidation rate, film thickness or humidity dependence.
    rating: low
    conditions:
      basis: qualitative statements in the stability and spectra sections of the record; no rate test
    source: pubchem-bi
    where: Experimental Properties, Stability/Shelf Life; Other Spectra
  - environment: Contact with copper and nickel alloys in a molten bismuth system
    headline: Molten bismuth appears to attack or alloy with copper and nickel.
    effect: NASA Marshall built a liquid-bismuth feed system and wrote that bismuth appears to attack or alloy with copper and nickel, so it used unplated stainless-steel gaskets and 316L stainless tubing to resist corrosion. The paper gives no corrosion rate.
    rating: moderate
    conditions:
      basis: design choice in a liquid-bismuth test rig at about 300 °C; no measured corrosion rate
      temperature: near 300 °C (liquid bismuth)
    source: nasa-tm-2007-214958
    where: Section 3 (VHITAL feed system), VCR fittings and tubing paragraph
risks:
  hazards:
    - text: PubChem reports that 324 of 382 company reports to the ECHA C&L Inventory say bismuth does not meet GHS hazard criteria. Four notifications from 58 reports give hazard codes H370 and H372 with the signal word Danger. The record says the information may vary between notifications depending on impurities and additives.
      ghs:
        - H370
        - H372
      source: pubchem-bi
      where: Hazards Identification, GHS Classification (ECHA C&L notifications summary; hazard statements and signal word)
    - text: 'Supplier SDS for bismuth granules (Alfa Aesar cat. 44807, revision 14 Feb 2020): the classification criteria under the 2012 OSHA Hazard Communication Standard are not met, and no label elements are given. The acute oral LD50 for bismuth in rats is printed as 5 g/kg.'
      ghs: []
      source: durham-sds
      where: Section 2 (Hazard identification); Section 11 (Toxicological information, acute toxicity table)
  failure_risks:
    - mode: Powder fire
      trigger: Bismuth in powder form, or in contact with gaseous or liquid chlorine
      consequence: PubChem records that powdered bismuth burns spontaneously in gaseous chlorine and that bismuth ignites in liquid chlorine at 80 °C. The record lists the powder as flammable.
      severity: moderate
      source: pubchem-bi
      where: Hazards Identification, Fire Potential
    - mode: Violent reaction with oxidizers
      trigger: Heating bismuth with perchloric acid at 110 °C, or with fused ammonium nitrate
      consequence: PubChem records that a brown coating forms that explodes violently on further heating, and that the fused-nitrate reaction is often violent and sometimes explosive.
      severity: moderate
      source: pubchem-bi
      where: Stability and Reactivity, Hazardous Reactivities and Incompatibilities
    - mode: Volume expansion on freezing
      trigger: Bismuth solidifying in a sealed or confined space
      consequence: The record gives a 3.32 % expansion on solidification. It gives no failure data for confined castings or sealed parts, so the effect on a given part is not assessed here.
      severity: low
      source: pubchem-bi
      where: Other Experimental Properties
  side_effects: []
  handling:
    - text: Avoid dust formation and ensure adequate ventilation, as the granule SDS advises for handling.
      source: durham-sds
      where: Section 7 (Handling and storage) and Section 6 (Accidental release, containment)
    - text: Keep bismuth away from perchloric acid and fused ammonium nitrate, which the PubChem stability section lists as hazardous mixtures.
      source: pubchem-bi
      where: Stability and Reactivity, Hazardous Reactivities and Incompatibilities
  mitigations:
    - text: NASA used 316L stainless steel tubing and unplated stainless-steel gaskets for liquid-bismuth lines, and a glass-mica ceramic (Macor) pump body that it calls stable and nonreactive with liquid bismuth near 300 °C.
      source: nasa-tm-2007-214958
      where: Section 3 (VHITAL feed system) and Section 4 (EM pump materials)
uses:
  - application: electronics-and-chips
    device: Bismuth-tellurium-oxide alloy film paste for semiconductor devices
    example: 'USGS: bismuth-tellurium-oxide alloy film paste is used in the manufacture of semiconductor devices. PubChem also lists thermoelectric materials and semiconductors among bismuth uses.'
    source: usgs-mcs2026-bismuth
    where: Domestic Production and Use paragraph (last sentence)
  - application: mechanisms
    device: 'Fusible alloys: fire-sprinkler triggers and holding devices for lens grinding'
    example: 'USGS: bismuth fusible alloys are used as a triggering mechanism for fire sprinklers and in holding devices for grinding optical lenses, where a low melting point is ideal.'
    source: usgs-mcs2026-bismuth
    where: Domestic Production and Use paragraph
  - application: propulsion-and-tanks
    device: Hall thruster propellant (ground development, not flown)
    example: NASA Marshall's 2007 technical memorandum describes a liquid bismuth feed system for a bismuth-fed anode-layer thruster. It cites bismuth at 8,000 s specific impulse at more than 70 % efficiency and gives a 2007 propellant cost of 75 dollars per kg against 2,000 dollars per kg for xenon.
    source: nasa-tm-2007-214958
    where: Section 1.1 (Motivation), first paragraph
supply:
  - subject: Bismuth (refinery production)
    producers:
      - country: China
        share_percent: 88
        year: 2025
      - country: Republic of Korea
        share_percent: 6.3
        year: 2025
      - country: Laos
        share_percent: 3.1
        year: 2025
      - country: Japan
        share_percent: 3.1
        year: 2025
    critical_lists: []
    recycling: 'USGS: recycled bismuth-containing alloy scrap was estimated to make up to 10 % of U.S. apparent consumption for 2021 to 2025.'
    substitutes:
      - 'USGS: cadmium, indium, lead and tin can partly replace bismuth in low-temperature solders. Bismuth itself is a nontoxic substitute for lead in plumbing, fishing weights, ammunition, greases and solders.'
    source: usgs-mcs2026-bismuth
    where: World Refinery Production and Capacity table, 2025 column (world total 16,000 t; China 88 % as printed in the text; the other shares are calculated by Space Mushroom from 1,000, 500 and 500 t over the 16,000 t world total); Recycling; Substitutes
    abundance: Bismuth reserves and resources were not reported by country (USGS). It is mostly a byproduct of lead ore processing; the USGS names two mines where bismuth was the primary product, the inactive Tasna Mine in Bolivia and one mine in China.
  - subject: Bismuth imports to the United States
    producers:
      - country: China
        share_percent: 56
        year: 2024
      - country: Republic of Korea
        share_percent: 22
        year: 2024
      - country: Germany
        share_percent: 13
        year: 2024
    critical_lists: []
    source: usgs-mcs2026-bismuth
    where: 'Import Sources (2021-24) paragraph: China 56 %, Republic of Korea 22 %, Germany 13 %; the year is the end of the 2021 to 2024 period as printed'
  - subject: Price and export controls
    demand: 'USGS: the 2025 average price of 99.99 % bismuth was 20 dollars per pound, almost four times the 2024 price and the highest annual average on record. China issued export controls on bismuth in 2025 after the United States imposed tariffs on Chinese goods.'
    critical_lists: []
    source: usgs-mcs2026-bismuth
    where: Events, Trends, and Issues paragraph; Salient Statistics (price, dollars per pound)
documents:
  - title: 'USGS Mineral Commodity Summaries 2026: Bismuth'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf
    year: 2026
  - title: 'PubChem compound record: Bismuth (CID 5359367), physical properties, GHS classification and uses'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Bismuth
    year: 2026
  - title: 'WebElements: bismuth physical properties'
    type: database
    url: https://www.webelements.com/bismuth/physics.html
    year: 2026
  - title: NIST Atomic Weights and Isotopic Compositions for All Elements (bismuth row)
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Bi&all=all&ascii=html
    year: 2026
  - title: 'NASA/TM-2007-214958: Liquid Bismuth Propellant Management System for the Very High Specific Impulse Thruster With Anode Layer'
    type: report
    url: https://ntrs.nasa.gov/api/citations/20070035081/downloads/20070035081.pdf
    year: 2007
  - title: Hall-Effect Thruster Utilizing Bismuth as Propellant (NASA NTRS 20080047186, Busek)
    type: report
    url: https://ntrs.nasa.gov/citations/20080047186
    year: 2008
  - title: Alfa Aesar bismuth granules safety data sheet, cat. 44807, revision 14 Feb 2020
    type: sds
    url: https://www.durhamtech.edu/sites/default/files/safety_data_sheets/Chemistry-and-Biology/Bismuth%20metal%20cas7440-69-9%20SDS.pdf
    year: 2020
  - title: 'Wikipedia: Bismuth (production as a lead byproduct, history, alloys)'
    type: database
    url: https://en.wikipedia.org/wiki/Bismuth
    year: 2026
gaps:
  - Specific heat, electrical conductivity in %IACS, and tensile, yield and elongation values for bismuth were not found in any fetched source, so none are recorded.
  - Abundance in the Earth's crust was not read in a fetched source.
  - Critical-mineral status of bismuth was not checked against the USGS 2025 list or the EU list in this run, so critical_lists is empty.
  - UNS, ASTM, EN and other standard designations were not found in a fetched source; the supplier catalogue number is not a designation and is not recorded.
  - Tarnish and oxidation rates at room temperature were not found in a fetched primary source. The 1979 bulk-oxidation paper (Tahboub, El Guindy and Merchant, Oxidation of Metals) was not opened because the publisher page required sign-in, so no values from it are used.
  - Radiation-shielding performance of bismuth was seen only in search snippets for open papers that were not opened (JBPE and DOAJ pages returned errors). No shielding value is recorded.
  - Supplier SDSs disagree on the flammability of bismuth powder (one search snippet names a flammable-solid classification); only the granule SDS was opened, so the powder classification is not recorded as a value.
  - The PubChem GHS notifications do not say which bismuth form each one covers. They are recorded as reported, not as the classification of the metal.
  - Outgassing, atomic oxygen, radiation and UV data for bismuth in space were not searched in this run.
  - Mineral hardness is recorded under the name mineral_hardness because WebElements does not name the scale, and the volume change on solidification is recorded under volume_change_on_solidification; neither name is in spores/property-canon.yaml.
  - The NASA 316L and Macor statements are design choices in one test rig, not corrosion rates.
sources:
  usgs-mcs2026-bismuth:
    title: 'Mineral Commodity Summaries 2026: Bismuth (U.S. Geological Survey)'
    id: USGS MCS 2026, prepared by Kateryna Klochko
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  pubchem-bi:
    title: 'PubChem compound record: Bismuth (CID 5359367), HSDB, PAC Chemical Database and ECHA GHS entries'
    id: CID 5359367
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5359367/JSON
    year: 2026
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to HSDB, PAC and ECHA
  webelements-bi:
    title: 'WebElements: Bismuth - 83 Bi, physical properties (Mark Winter, University of Sheffield)'
    url: https://www.webelements.com/bismuth/physics.html
    kind: database
    license: WebElements, cited not reproduced
  nist-bi-weights:
    title: NIST Atomic Weights and Isotopic Compositions for All Elements, bismuth (Bi)
    id: standard atomic weight 208.98040(1) (bismuth row)
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Bi&all=all&ascii=html
    kind: database
    license: US government data
  nasa-tm-2007-214958:
    title: NASA/TM-2007-214958, Liquid Bismuth Propellant Management System for the Very High Specific Impulse Thruster With Anode Layer (K.A. Polzin, T.E. Markusic, B.J. Stanojev)
    id: NASA/TM-2007-214958, NTRS 20070035081, May 2007
    url: https://ntrs.nasa.gov/api/citations/20070035081/downloads/20070035081.pdf
    kind: report
    license: NASA public technical report
  ntrs-busek-2008:
    title: Hall-Effect Thruster Utilizing Bismuth as Propellant (Szabo, Gasdaska, Hruby, Robin, Busek)
    id: NTRS 20080047186, report MFS-32440-1, November 2008
    url: https://ntrs.nasa.gov/citations/20080047186
    kind: report
    license: NASA public technical report
  durham-sds:
    title: Safety Data Sheet, Bismuth granules (Alfa Aesar cat. 44807), revision 2, 14 Feb 2020
    id: CAS 7440-69-9
    url: https://www.durhamtech.edu/sites/default/files/safety_data_sheets/Chemistry-and-Biology/Bismuth%20metal%20cas7440-69-9%20SDS.pdf
    kind: datasheet
    license: supplier document, cited not reproduced
  wikipedia-bismuth:
    title: Bismuth, Wikipedia (production, history and alloys)
    url: https://en.wikipedia.org/wiki/Bismuth
    kind: web
    license: CC BY-SA 4.0, linked not reproduced
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 14
  unreachable: 3
  caveats: 5
  note: 'Values were read by an AI assistant on 2026-10-26 from the pages and PDF named in each entry (USGS text extracted from the PDF; PubChem values from its JSON record; NASA values from the NTRS PDF text). Unreachable: a Springer article (sign-in required), an open shielding paper (JBPE, connection failed) and an Advent pellet page (no bismuth content in the fetched HTML). Caveats: PubChem density and melting values carry no test conditions beyond temperature; the GHS notifications do not say which bismuth form they cover; the WebElements resistivity was converted from Ω m; the USGS 2025 refinery shares other than China are calculated; the NASA corrosion statements are design choices, not rates.'
story:
  recipe:
    line: 'Bismuth is a single element (Bi, atomic number 83, group 15). Wikipedia says it is produced mainly as a byproduct of lead refining, from crude lead bullion that can contain up to 10 % bismuth. PubChem lists three refining routes for removing bismuth from lead bullion: fractional crystallization, electrolytic (Betts) refining, and the addition of calcium or magnesium (Betterton-Kroll process). The standard atomic weight is 208.98040(1) in the NIST table.'
    parts:
      - name: Bismuth
        symbol: Bi
        atoms: 1
        atomic_weight: 208.9804
        role: The whole material. The NIST standard atomic weight is 208.98040(1), printed in the bismuth entry of the NIST table.
  risk_groups:
    - title: For people
      level: 1
      verdict: Mixed notifications
      lead: The PubChem hazard codes come from company notifications, and the supplier SDS we read does not classify bismuth granules.
      points:
        - label: Bismuth as recorded in PubChem
          line: Of 382 company reports to the European chemicals agency, 324 say bismuth does not meet GHS criteria. Four notifications from 58 reports give H370 and H372 with the signal word Danger.
        - label: Supplier SDS
          line: The granule SDS we read (revision 14 Feb 2020) says the OSHA classification criteria are not met. It gives an oral LD50 of 5 g/kg in rats and advises avoiding dust.
    - title: If it fails
      lead: The failure routes in these sources are a powder fire in chlorine, violent reaction with some oxidizers, and expansion on freezing.
      points:
        - label: Powder
          line: PubChem records that powdered bismuth burns spontaneously in gaseous chlorine and that bismuth ignites in liquid chlorine at 80 °C.
        - label: Freezing
          line: Bismuth expands 3.32 % as it solidifies (PubChem). The record gives no failure data for confined castings.
    - title: Handling and storage
      points:
        - label: Dust
          line: Avoid dust formation and keep the area ventilated, as the granule SDS advises.
        - label: Incompatible mixtures
          line: PubChem records a violent reaction when bismuth is heated with perchloric acid and a violent or explosive reaction with fused ammonium nitrate.
  why: Bismuth is a silver-white, heavy, low-melting metal. It melts at 271.3 °C and has a density of 9.78 g/cm3 at 20 °C. It is mostly made as a byproduct of lead refining, and it is used in low-melting alloys, as a lead-free additive in brass and steel, and in bismuth compounds. A 2008 Busek report for NASA says bismuth has a larger atomic mass than xenon and is cheaper and more plentiful, which is why it was studied as a Hall-thruster propellant. The USGS puts 2025 world refinery output at 16,000 t, with China at 88 %. Its thermal conductivity of 8 W/(m·K) is low for a metal, and its powder is flammable.
  uses:
    - where: Low-melting and fusible alloys
      line: The USGS lists fusible bismuth alloys for fire-sprinkler triggers, lens-grinding holding devices, and other applications where a low melting point is ideal. Bismuth is also a nontoxic replacement for lead in brass, free-machining aluminium and steel, and solders.
    - where: Electronics
      line: The USGS notes that bismuth-tellurium-oxide alloy film paste is used in the manufacture of semiconductor devices.
    - where: Hall-effect thrusters (ground development, not flown)
      line: NASA Marshall described a liquid-bismuth feed system for an anode-layer thruster. The paper cites 8,000 s specific impulse at more than 70 % efficiency and gives a 2007 propellant cost of 75 dollars per kg against 2,000 dollars per kg for xenon.
  can_do:
    - label: Melt low
      value: 271.3 °C melting point
      benchmark: melting_point
      line: Bismuth melts at 271.3 °C, the PubChem value; the USGS text gives 271 °C.
    - label: Weight
      value: 9.78 g/cm3
      benchmark: density
      line: Density is 9.78 g/cm3 at 20 °C (PubChem). WebElements gives 9780 kg/m3 for the solid.
    - label: Conduct heat poorly
      value: 8 W/(m·K)
      benchmark: thermal_conductivity
      line: WebElements gives a thermal conductivity of 8 W/(m·K). This is a limit for parts that must spread heat.
    - label: Expand on freezing
      value: 3.32 %
      benchmark: volume_change_on_solidification
      line: Bismuth expands 3.32 % as it solidifies (PubChem), which affects castings and sealed volumes.
  compare: Bismuth is a dense metal (9.78 g/cm3) that melts at 271.3 °C and conducts heat at 8 W/(m·K). The sources read here give no values for other metals in this collection, so the compare rows show bismuth's own values, and the other profiles should be read against them, not as a ranking.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Avoid dust formation and keep the area ventilated, as the supplier SDS advises.
    - Keep bismuth away from perchloric acid and fused ammonium nitrate, which PubChem lists as violent mixtures.
    - Allow for the 3.32 % expansion on solidification in sealed or confined parts.
    - Use 316L stainless steel for liquid-bismuth lines, as NASA did, because bismuth appears to attack copper and nickel.
  good_for:
    - Lead-free low-melting alloys and solders, where the USGS names bismuth as a nontoxic substitute for lead.
    - Fusible holding and trigger devices with a melting point of 271.3 °C (USGS and PubChem).
  watch_out:
    - 'Low heat conduction for a metal: 8 W/(m·K) (WebElements).'
    - 'Supply is concentrated: China produced 88 % of world refinery output in 2025 (USGS), and 2025 prices averaged 20 dollars per pound, a record (USGS).'
    - Flammable as a powder, and violent reactions with some oxidizers (PubChem).
    - 'Hazard classifications conflict: PubChem''s notifications give H370 and H372, while the granule SDS does not classify the product.'
    - No outgassing, atomic oxygen or radiation data for bismuth in space were found in this run.
  verdict: Bismuth is a heavy, low-melting metal, with a melting point of 271.3 °C and a density of 9.78 g/cm3. Its main uses are lead-free low-melting alloys and solders, and it is a nontoxic substitute for lead in several products. Its weak points are its low heat conduction, the expansion on freezing, a flammable powder form, conflicting hazard classifications, and a concentrated supply that is mostly in China. The profile lacks specific heat, tensile strength and space-exposure data.