spore: profile
id: beryllium
spore_version: 0.2
family: refractory-metals
name: Beryllium
abbreviation: Be
role: structural and optical metal
category: metals
type: refractory-metals
summary: |
  Beryllium is the light alkaline-earth metal Be. Materion's S-65 pure grade has a density of 1.85 g/cm3, an elastic modulus of 290 GPa and a thermal conductivity of 216 W/(m·K) at 25 °C, which is why it is used for stiff, cold-stable structures and telescope mirrors. The metal and its dust are toxic: beryllium is classed as a carcinogen, inhaled dust and fume can cause chronic lung disease, and the S-65 grade has only 3.0 % minimum elongation at room temperature.
best_for: 'Stiff, light structures and mirrors that must hold their shape when cold: 290 GPa modulus at 1.85 g/cm3 in the pure S-65 grade'
weakest_at: 'Toxicity: inhaled dust or fume causes chronic beryllium disease, and the metal is hard and brittle with 3.0 % minimum elongation'
identity:
  formula: Be (element, atomic number 4); pure beryllium metal grade S-65 with Be 99.2 wt% minimum and BeO 0.90 wt% maximum
  cas: 7440-41-7
  crystal_system: hexagonal close-packed (hP2)
  source: pubchem-be
  where: Names and Identifiers > Other Identifiers > CAS 7440-41-7 (PubChem); composition from the Chemical Composition table of the S-65 data sheet (Be assay minimum 99.2, BeO maximum 0.90, carbon maximum 0.09, iron maximum 0.08, aluminum maximum 0.05, all wt%); crystal structure from the Wikipedia infobox
  designations:
    - system: Trade name
      code: S-65
      source: materion-s65
      where: Title of the data sheet, S-65 and S-65-H Nuclear-Grade Beryllium
tags:
  environments: []
  stresses:
    - extreme-cold
  applications:
    - structures
    - optics-and-cameras
    - thermal-control
properties:
  - benchmark: density
    label: Density, S-65 pure beryllium
    value: 1.85
    unit: g/cm3
    scope: material
    conditions:
      grade: S-65 (pure beryllium)
      form: pieces cut from a vacuum pressed block
      basis: minimum bulk density 99.0 % of theoretical, water displacement
      unit_in_source: 0.067 lb./in3
    method: Typical value printed in a manufacturer data sheet, with a footnote on the bulk density basis
    status: ground
    source: materion-s65
    where: Typical Physical Properties table, column Density
  - benchmark: density
    label: Density, element (HSDB)
    value: 1.85
    unit: g/cm3
    scope: material
    conditions:
      form: beryllium metal, CAS 7440-41-7
      unit_in_source: 1.85 g/cu cm
    method: Value printed in the Hazardous Substances Data Bank (HSDB) entry in the PubChem record, with no conditions stated
    status: ground
    note: NIOSH also lists a specific gravity of 1.85 for beryllium metal, the same value.
    source: pubchem-be
    where: Chemical and Physical Properties > Experimental Properties > Density (HSDB, reference 34)
  - benchmark: melting_point
    label: Solidus temperature, S-65
    value: 1287
    unit: °C
    scope: material
    conditions:
      grade: S-65
      unit_in_source: 2349 ˚F
    method: Typical value printed in a manufacturer data sheet
    status: ground
    source: materion-s65
    where: Typical Physical Properties table, column Solidus
  - benchmark: melting_point
    label: Melting point, element (HSDB)
    value: 1287
    unit: °C
    scope: material
    conditions:
      form: beryllium metal
      unit_in_source: 2349 °F (NIOSH, 2024)
    method: Value printed in the HSDB entry in the PubChem record
    status: ground
    source: pubchem-be
    where: Chemical and Physical Properties > Experimental Properties > Melting Point (HSDB, reference 34)
  - benchmark: boiling_point
    label: Boiling point, element (PAC Chemical Database)
    value: 2471
    unit: °C
    scope: material
    conditions:
      pressure: 760 mmHg
      form: beryllium metal
    method: Value printed in the boiling point section of the PubChem record, attributed to the U.S. DOE PAC Chemical Database
    status: ground
    source: pubchem-be
    where: Chemical and Physical Properties > Experimental Properties > Boiling Point, entry from PAC Chemical Database (reference 46)
  - benchmark: vapor_pressure
    label: Vapour pressure of beryllium metal, 10 kPa at 2054 °C
    value: 10
    unit: kPa
    scope: material
    conditions:
      temperature: 2054 °C
      form: beryllium metal
    method: One of six temperature points printed in the HSDB vapour pressure entry in the PubChem record
    status: ground
    note: Vapour pressure is not in the canonical property list, so this is a short snake_case name; see gaps.
    source: pubchem-be
    where: Chemical and Physical Properties > Experimental Properties > Vapor Pressure (HSDB, reference 34)
  - benchmark: elastic_modulus
    label: Elastic modulus, S-65
    value: 290
    unit: GPa
    scope: material
    conditions:
      grade: S-65
      temperature: not stated
      unit_in_source: 42 msi
    method: Typical value printed in a manufacturer data sheet
    status: ground
    source: materion-s65
    where: Typical Physical Properties table, column Elastic Modulus
  - benchmark: specific_heat
    label: Specific heat capacity, S-65
    value: 1.95
    unit: J/g/°C
    scope: material
    conditions:
      grade: S-65
      temperature: not stated
      unit_in_source: 0.46 BTU/lb./°F
    method: Typical value printed in a manufacturer data sheet
    status: ground
    source: materion-s65
    where: Typical Physical Properties table, column Specific Heat Capacity
  - benchmark: thermal_conductivity
    label: Thermal conductivity, S-65 at 25 °C
    value: 216
    unit: W/(m·K)
    scope: material
    conditions:
      grade: S-65
      temperature: 25 °C
      unit_in_source: 125 BTU/hr·ft·°F
    method: Typical value printed in a manufacturer data sheet
    status: ground
    source: materion-s65
    where: Typical Physical Properties table, column Thermal Conductivity @ 25°C
  - benchmark: cte
    label: Coefficient of thermal expansion, S-65 at 20 to 100 °C
    value: 11.3
    unit: ppm/°C
    scope: material
    conditions:
      grade: S-65
      temperature: 20 to 100 °C
      unit_in_source: 6.3 ppm/°F
    method: Typical value printed in a manufacturer data sheet
    status: ground
    source: materion-s65
    where: Typical Physical Properties table, column Thermal Expansion @ 20-100°C
  - benchmark: yield_strength
    label: Yield strength Rp0.2, S-65 minimum at room temperature
    value: 207
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: S-65
      form: pieces cut from a vacuum pressed block
      measure: 0.2 % offset
      temperature: room temperature
      standard_in_source: ASTM E8 and MAB-205 M
      unit_in_source: 30 ksi
    method: Minimum tensile property printed in a manufacturer data sheet; the table heading says Typical, the text says minimum
    status: ground
    source: materion-s65
    where: Typical Mechanical Properties table, row Yield Strength (0.2% offset), column S-65
  - benchmark: ultimate_tensile_strength
    label: Ultimate tensile strength, S-65 minimum at room temperature
    value: 290
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: S-65
      form: pieces cut from a vacuum pressed block
      temperature: room temperature
      standard_in_source: ASTM E8 and MAB-205 M
      unit_in_source: 42 ksi
    method: Minimum tensile property printed in a manufacturer data sheet
    status: ground
    source: materion-s65
    where: Typical Mechanical Properties table, row Ultimate Tensile Strength, column S-65
  - benchmark: elongation
    label: Elongation, S-65 minimum at room temperature
    value: 3
    bound: lower
    unit: '%'
    scope: material
    conditions:
      grade: S-65
      temperature: room temperature
      gauge_length: 4 diameters
      standard_in_source: ASTM E8 and MAB-205 M
    method: Minimum tensile property printed in a manufacturer data sheet
    status: ground
    source: materion-s65
    where: Typical Mechanical Properties table, row Elongation (% in 4 diameters), column S-65
corrosion:
  - environment: Strong mineral acids
    headline: Beryllium dissolves readily in sulfuric, hydrochloric and hydrofluoric acid; dilute nitric acid attacks it slowly.
    effect: PubChem (HSDB) says beryllium reacts readily with sulfuric, hydrochloric and hydrofluoric acids. Dilute nitric acid attacks the metal slowly, whereas concentrated nitric acid has little effect. Finely divided or amalgamated metal reacts with HCl, dilute HNO3 or dilute H2SO4.
    rating: severe
    conditions:
      basis: qualitative statements in the solubility and reactivity entries; no rate given
    source: pubchem-be
    where: Chemical and Physical Properties > Experimental Properties > Solubility (HSDB); Safety and Hazards > Stability and Reactivity > Reactivity Profile
  - environment: Strong alkali
    headline: Strong base attacks beryllium and releases hydrogen.
    effect: PubChem says beryllium is attacked by strong base with evolution of hydrogen gas. No rate, concentration or temperature is given.
    rating: unknown
    conditions:
      basis: qualitative statement only
    source: pubchem-be
    where: Safety and Hazards > Stability and Reactivity > Reactivity Profile
  - environment: Air at ordinary temperature
    headline: Beryllium resists oxidation in air at ordinary temperatures.
    effect: PubChem's stability entry says beryllium is resistant to oxidation at ordinary temperatures. Fine powder is a different case and can burn; see the failure risks.
    rating: low
    conditions:
      basis: qualitative statement only
    source: pubchem-be
    where: Chemical and Physical Properties > Experimental Properties > Stability/Shelf Life
risks:
  hazards:
    - text: PubChem's first GHS entry for beryllium, from Regulation (EC) No 1272/2008, lists H301 toxic if swallowed, H315, H317, H319, H330 fatal if inhaled, H335, H350i may cause cancer by inhalation and H372, with signal word Danger.
      ghs:
        - H301
        - H315
        - H317
        - H319
        - H330
        - H335
        - H350i
        - H372
      source: pubchem-be
      where: Safety and Hazards > Hazards Identification > GHS Classification, first entry (reference 49)
    - text: 'NIOSH Pocket Guide: OSHA PEL TWA 0.0002 mg/m3 (0.2 µg/m3) with a 15-minute STEL of 0.002 mg/m3; NIOSH REL is Ca, carcinogen, see Appendix A; IDLH 4 mg/m3 as Be.'
      ghs: []
      source: niosh-npg-be
      where: Exposure Limits field
    - text: PubChem's hazards summary still quotes an OSHA PEL and ACGIH TLV of a TWA of 2 ug/cu m, which conflicts with the 0.0002 mg/m3 printed by NIOSH. The NIOSH value is the one used in this profile.
      ghs: []
      source: pubchem-be
      where: Safety and Hazards > Hazards Identification > Hazards Summary
  failure_risks:
    - mode: Chronic beryllium disease after inhaling dust or fume
      trigger: Inhalation of beryllium dust, fume or mist; low concentrations over time are enough
      consequence: 'PubChem: exposure above about 100 ug/cu m causes acute beryllium disease (chemical pneumonitis). Low concentrations can cause chronic beryllium disease, a granulomatous lung disease, and beryllium is a human and animal carcinogen.'
      severity: high
      source: pubchem-be
      where: Toxicity > Toxicological Information > Toxicity Summary and Health Effects
    - mode: Fire of powder or finely divided metal
      trigger: Beryllium powder in a fire, or a mixture with carbon tetrachloride or trichloroethylene under heavy impact
      consequence: 'PubChem: beryllium powder will burn if involved in a fire, and the mixtures flash or spark on heavy impact. Bulk material does not burn or burns with difficulty.'
      severity: moderate
      source: pubchem-be
      where: Record Description (powder), Reactivity Profile and Fire Fighting Procedures
    - mode: Brittle failure of the bulk metal
      trigger: Mechanical loading of the S-65 grade, which has only 3.0 % minimum elongation
      consequence: NIOSH describes beryllium as a hard, brittle, gray-white solid. The S-65 data sheet gives a minimum yield strength of 207 MPa and a minimum elongation of 3.0 %.
      severity: moderate
      source: niosh-npg-be
      where: Physical Description field
  side_effects: []
  handling:
    - text: Use adequate local exhaust ventilation to prevent inhalation of, and skin contact with, beryllium dust, fume and mists.
      source: pubchem-be
      where: Safety and Hazards > Hazards Identification > Hazards Summary
    - text: In a fire, smother with dry sand, dry clay or dry ground limestone, or use Class D extinguishers. PubChem says not to use carbon dioxide, halogenated agents or water.
      source: pubchem-be
      where: Safety and Hazards > Fire Fighting > Fire Fighting Procedures
    - text: Read the safety data sheet before working with beryllium-containing material. Materion says processing beryllium-containing alloys poses a health risk and gives a product stewardship contact.
      source: materion-s65
      where: Health and Safety section
  mitigations:
    - text: Industry must carefully control the quantity of beryllium dust, fumes and mists in the workplace, under international, national and state guidelines.
      source: usgs-mcs2026-beryllium
      where: Events, Trends, and Issues
uses:
  - application: structures
    device: Aircraft and space-vehicle structures, instruments and x-ray equipment
    example: PubChem's record description says purified beryllium is used for nuclear weapons and reactors, aircraft and space vehicle structures, instruments, x-ray machines and mirrors.
    source: pubchem-be
    where: Names and Identifiers > Record Description
  - application: optics-and-cameras
    device: Space telescope primary mirror segments (James Webb Space Telescope)
    example: The program designed, manufactured, assembled and tested 21 flight beryllium mirrors for the James Webb Space Telescope Optical Telescope Element. The paper does not name the beryllium grade used, so the grade is not attributed here.
    source: nasa-jwst-ntrs
    where: Abstract and Section 1 (Introduction)
  - application: thermal-control
    device: Cryogenic telescope mirror segments
    example: Beryllium was chosen for its thermal conductivity and coefficient of thermal expansion at cryogenic temperatures, shown by AMSD-2 test data, and active thermal control was not needed.
    source: nasa-jwst-ntrs
    where: Mirror selection section, text around Figure 5
  - application: optics-and-cameras
    device: Optical-grade beryllium mirror blanks (I-70-H family grade)
    example: Materion sells high-purity beryllium metals for space and aerospace applications. Its optical grade I-70-H is made by hot isostatic pressing and has low oxide content for good polishing.
    source: materion-i70h
    where: Introduction paragraph and Chemical Composition table
  - application: structures
    device: Satellite and telescope structural parts (structural-grade beryllium family)
    example: Materion lists satellites, telescopes, reconnaissance systems and FLIR systems among the applications of its structural-grade beryllium (S-200-F, S-200-FC and S-200-FH).
    source: materion-s200f
    where: Introduction paragraph
  - application: structures
    device: Defense and aerospace parts
    example: USGS says aerospace and defense took about 24 % of beryllium products by sales revenue, and most unalloyed beryllium metal and composite products went to defense and scientific applications.
    source: usgs-mcs2026-beryllium
    where: Domestic Production and Use paragraph
supply:
  - subject: Beryllium (mine production)
    abundance: More than 100,000 tons of identified world resources, about 60 % of them in the United States (USGS 2026)
    producers:
      - country: United States
        share_percent: 53.5
        year: 2025
      - country: Brazil
        share_percent: 18.6
        year: 2025
      - country: China
        share_percent: 17.9
        year: 2025
      - country: Nigeria
        share_percent: 9.3
        year: 2025
    critical_lists: []
    recycling: 'USGS: recycling may account for as much as 20 % to 25 % of total beryllium consumption. The leading U.S. producer recovered about 40 % of the beryllium content of its alloy scrap.'
    substitutes:
      - 'USGS: certain metal matrix or organic composites, high-strength aluminum, pyrolytic graphite, silicon carbide, steel or titanium may be substituted for beryllium metal or beryllium composites.'
      - 'USGS: aluminum nitride or boron nitride may be substituted for beryllium oxide.'
    source: usgs-mcs2026-beryllium
    where: 'World Mine Production and Reserves table, 2025e: United States 230, Brazil 80, China 77, Nigeria 40 (world total rounded 430, beryllium content in tons; shares calculated by Space Mushroom as country value divided by 430). Also Recycling and Substitutes sections'
  - subject: Beryllium imports (sources 2021 to 2024)
    producers:
      - country: Kazakhstan
        share_percent: 31
        year: 2024
      - country: Latvia
        share_percent: 25
        year: 2024
      - country: Japan
        share_percent: 19
        year: 2024
      - country: Germany
        share_percent: 5
        year: 2024
    critical_lists: []
    source: usgs-mcs2026-beryllium
    where: Import Sources (2021-24) line; other sources make up 20 %
documents:
  - title: Materion S-65 and S-65-H Nuclear-Grade Beryllium data sheet (2023)
    type: datasheet
    url: https://hkvxni.files.cmp.optimizely.com/download/c2e44162f75e11eea40756b8ca9c2abc
    year: 2023
  - title: 'PubChem compound record: Beryllium (CID 5460467), with HSDB, PAC Chemical Database and ECHA GHS entries'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Beryllium
    year: 2026
  - title: 'NIOSH Pocket Guide to Chemical Hazards: beryllium metal'
    type: database
    url: https://www.cdc.gov/niosh/npg/npgd0054.html
  - title: 'USGS Mineral Commodity Summaries 2026: Beryllium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-beryllium.pdf
    year: 2026
  - title: Feinberg et al., James Webb Space Telescope Optical Telescope Element Mirror Development History and Results (NASA NTRS 20120013223)
    type: report
    url: https://ntrs.nasa.gov/api/citations/20120013223/downloads/20120013223.pdf
    year: 2012
  - title: Materion I-70-H and I-220-H Beryllium data sheet (2024)
    type: datasheet
    url: https://hkvxni.files.cmp.optimizely.com/download/a0b9e6e0f75f11eebf51367a729f0e29
    year: 2024
  - title: Materion S-200-F, S-200-FC and S-200-FH Structural-Grade Beryllium data sheet
    type: datasheet
    url: https://hkvxni.files.cmp.optimizely.com/download/c2eca2d0f75e11ee9aa0f6c265376dea
  - title: 'Wikipedia: Beryllium (crystal structure, history and name)'
    type: database
    url: https://en.wikipedia.org/wiki/Beryllium
    year: 2026
gaps:
  - Electrical conductivity or resistivity of beryllium metal was not found in any page opened in this run.
  - Poisson ratio, speed of sound and hardness were not opened for the S-65 grade. A Materion TDS2011 search result was not opened, so none of its figures are used.
  - The OSTI paper with S-65 design correlations for thermal conductivity, specific heat and expansion (osti.gov/biblio/212928) refused connection, so no cryogenic or temperature-dependent property is recorded.
  - The ASM Alloy Digest entry for Brush Wellman S-65B is paywalled and gives no numeric property table.
  - No UNS, EN, W.Nr. or AMS number for the S-65 grade was printed on any page opened. SAE AMS 7906 covers vacuum hot-pressed beryllium, but Materion prints it against S-200-F, a different grade, so it is not listed as a designation for S-65.
  - Tensile values are minimum values from one manufacturer data sheet at room temperature; no test-to-test spread or elevated-temperature tensile data were opened.
  - No outgassing, total mass loss, atomic oxygen, radiation or flight test result for beryllium metal was found in the sources read.
  - The NASA JWST paper describes 21 flight beryllium mirror segments but does not name the grade in the text read, so no S-65 property is attributed to the flight mirrors.
  - The OSHA chemical data page (osha.gov/chemicaldata/531) refused access. Exposure limits come from the NIOSH Pocket Guide page as read in this run. PubChem's older 2 ug/cu m PEL conflicts with it and is recorded as a note only.
  - Critical-mineral list status for beryllium was not stated in the USGS summary read, so the critical_lists field is empty.
  - Crustal abundance of beryllium was not found in a source opened for this profile.
  - Vapour pressure is not in the canonical property list, so it is recorded as vapor_pressure, a short snake_case name.
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 13
  unreachable: 1
  caveats: 3
  note: 'Values read by an AI assistant on 2026-10-26 from the Materion S-65 data sheet PDF, the PubChem JSON record and the USGS 2026 summary PDF. Unreachable: the NIOSH page (blocked to automated access in curl, read through a web-fetch summary). Caveats: S-65 mechanical values are minimums from one manufacturer; the vapour pressure row uses a non-canonical name; PubChem carries an older OSHA PEL that conflicts with the NIOSH value.'
story:
  recipe:
    line: Beryllium is the element Be, atomic number 4, used as a pure metal. Materion supplies S-65 as pieces cut from a vacuum pressed block. The crystal structure is hexagonal close-packed (Wikipedia). USGS reports that beryl and bertrandite ores are converted to beryllium hydroxide and then to metal, oxide and master alloy.
    parts:
      - name: Beryllium
        symbol: Be
        share_percent: 99.2
        share_note: minimum, wt%
        role: The metal itself. The S-65 grade has at least 99.2 wt% Be by assay.
        source: materion-s65
        where: Chemical Composition table, Beryllium (Be) Assay minimum
      - name: Beryllium oxide
        symbol: BeO
        share_percent: 0.9
        share_note: maximum, wt%
        role: Oxide present in the metal. The grade limits it to 0.90 wt%.
        source: materion-s65
        where: Chemical Composition table, Beryllium Oxide (BeO) maximum
      - name: Carbon
        symbol: C
        share_percent: 0.09
        share_note: maximum, wt%
        role: Impurity limited by the grade.
        source: materion-s65
        where: Chemical Composition table, Carbon (C) maximum
      - name: Iron
        symbol: Fe
        share_percent: 0.08
        share_note: maximum, wt%
        role: Impurity limited by the grade.
        source: materion-s65
        where: Chemical Composition table, Iron (Fe) maximum
      - name: Aluminum
        symbol: Al
        share_percent: 0.05
        share_note: maximum, wt%
        role: Impurity limited by the grade.
        source: materion-s65
        where: Chemical Composition table, Aluminum (Al) maximum
  risk_groups:
    - title: For people
      lead: Beryllium is classed as a carcinogen, and inhaled dust, fume or mist causes lung disease, so exposure is the main hazard.
      level: 4
      verdict: Toxic and carcinogenic
      points:
        - label: Classification
          line: PubChem's first GHS entry, from Regulation (EC) No 1272/2008, lists H301 toxic if swallowed, H330 fatal if inhaled and H350i may cause cancer by inhalation, with signal word Danger.
        - label: Exposure limit
          line: NIOSH gives a TWA of 0.0002 mg/m3 (0.2 µg/m3) and a 15-minute STEL of 0.002 mg/m3. The IDLH is 4 mg/m3 as Be.
        - label: Disease
          line: Above about 100 µg/m3 beryllium causes acute beryllium disease, a chemical pneumonitis. Low exposures can cause chronic beryllium disease, a lung disease that does not follow a clear dose-response.
    - title: If it burns or dissolves
      lead: The powder can burn, and strong acids dissolve the metal.
      level: 2
      verdict: Fire and acid risk
      points:
        - label: Powder fire
          line: The powder burns if it is involved in a fire, and mixtures with carbon tetrachloride or trichloroethylene can flash or spark under heavy impact. Use dry sand or Class D extinguishers, not water.
        - label: Acids
          line: Sulfuric, hydrochloric and hydrofluoric acids react readily with the metal. Dilute nitric acid attacks it slowly.
    - title: Handling and storage
      points:
        - label: Workplace control
          line: Use local exhaust ventilation and follow the safety data sheet. USGS notes that industry must carefully control beryllium dust, fume and mist in the workplace.
        - label: Form
          line: The minimum tensile values apply to the S-65 vacuum pressed form. Materion asks buyers to read the safety data sheet before working with the material.
  why: Beryllium is a light, stiff metal. The pure S-65 grade has a density of 1.85 g/cm3 and an elastic modulus of 290 GPa, so a structure of it can be stiff for its weight. Its thermal conductivity of 216 W/(m·K) at 25 °C and its expansion of 11.3 ppm/°C between 20 and 100 °C suit parts that must keep their shape. NASA's James Webb Space Telescope program chose beryllium for its primary mirror segments on the basis of its cryogenic thermal conductivity and expansion. The same metal and its dust are toxic, so its use depends on strict workplace control.
  uses:
    - where: Space telescope mirrors
      line: The James Webb Space Telescope's optical telescope element includes 21 light-weighted, cryogenic beryllium primary mirror segments, according to the NASA program history paper. The paper does not name the grade used.
    - where: Aircraft and space structures
      line: PubChem's record says purified beryllium is used for aircraft and space vehicle structures, instruments, x-ray machines and mirrors.
    - where: Defense and aerospace
      line: The USGS reports that aerospace and defense took about 24 % of beryllium products by sales revenue. Most unalloyed beryllium metal went to defense and scientific uses.
    - where: Reactor parts
      line: Materion lists reactor walls, reflector tiles, breeder pebbles and neutron reflectors among the uses of the S-65 grade, which has low neutron absorption.
  can_do:
    - label: Stiffness
      benchmark: elastic_modulus
      value: 290 GPa
      line: The elastic modulus of the S-65 grade is 290 GPa (42 msi), a measure of how strongly it resists elastic deformation.
    - label: Weight
      benchmark: density
      value: 1.85 g/cm3
      line: The density is 1.85 g/cm3 in the Materion data sheet, and PubChem prints the same value for the element.
    - label: Heat conduction
      benchmark: thermal_conductivity
      value: 216 W/(m·K)
      line: Thermal conductivity is 216 W/(m·K) at 25 °C, meaning heat flows through a one-metre slab at 216 W for each kelvin of difference per square metre.
    - label: Thermal expansion
      benchmark: cte
      value: 11.3 ppm/°C
      line: Between 20 and 100 °C the coefficient of thermal expansion is 11.3 ppm/°C, so a length changes by 11.3 millionths per kelvin.
    - label: Melting
      benchmark: melting_point
      value: 1287 °C
      line: The solidus of the S-65 grade is 1287 °C. PubChem's entry gives the same melting point for the element.
    - label: Strength
      benchmark: yield_strength
      value: 207 MPa minimum
      line: The S-65 data sheet gives minimum room-temperature values of 207 MPa yield strength, 290 MPa tensile strength and 3.0 % elongation. The metal is therefore hard and has limited ductility.
  compare: The USGS lists possible substitutes. Certain metal-matrix or organic composites, high-strength aluminum, pyrolytic graphite, silicon carbide, steel and titanium may replace beryllium metal, and aluminum nitride or boron nitride may replace beryllium oxide. The USGS also notes that beryllium is used where its properties are crucial, because its cost is high. The compare rows list three of this profile's own properties, because the sources read give no comparable figures for other metals.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Thermal expansion
      benchmark: cte
  handling:
    - 'Keep dust, fume and mists out of the workplace air: use local exhaust ventilation and follow the safety data sheet.'
    - In a fire, use dry sand, dry clay or Class D extinguishers, not water.
    - Use the grade and form stated on the data sheet, since the minimum tensile values apply to the S-65 vacuum pressed form.
  good_for:
    - 'Stiffness at low weight: 290 GPa modulus at 1.85 g/cm3 in the S-65 grade.'
    - 'Cold-stable optics: the JWST program chose beryllium for its cryogenic thermal conductivity and expansion.'
    - 'Neutron-sensitive reactor parts: low neutron absorption, according to Materion.'
  watch_out:
    - 'Toxicity: H330 fatal if inhaled, H350i may cause cancer by inhalation, and chronic lung disease at low exposure.'
    - 'Low ductility: 3.0 % minimum elongation in the S-65 grade, and the metal is described as hard and brittle.'
    - Strong acids such as hydrofluoric acid dissolve it readily.
    - No outgassing, atomic-oxygen or radiation test result for the metal was found in the sources read.
  verdict: 'Beryllium''s pure S-65 grade combines a 290 GPa modulus with a 1.85 g/cm3 density, which is why it appears in telescope mirrors and reactor parts. Toxicity is the main constraint: dust and fume need strict controls, and the sources read give no outgassing, cold-welding or atomic-oxygen data.'
sources:
  materion-s65:
    title: S-65 and S-65-H Nuclear-Grade Beryllium, Materion data sheet (2023)
    url: https://hkvxni.files.cmp.optimizely.com/download/c2e44162f75e11eea40756b8ca9c2abc
    year: 2023
    kind: datasheet
    license: Manufacturer data sheet (cited, not reproduced)
  pubchem-be:
    title: 'PubChem compound record: Beryllium (CID 5460467), including HSDB, PAC Chemical Database and ECHA GHS entries'
    id: CAS 7440-41-7; EC 231-150-7
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5460467/JSON
    year: 2026
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to HSDB, PAC, ECHA and others
  niosh-npg-be:
    title: 'NIOSH Pocket Guide to Chemical Hazards: Beryllium (metal)'
    url: https://www.cdc.gov/niosh/npg/npgd0054.html
    kind: database
    license: US government public domain
  usgs-mcs2026-beryllium:
    title: Mineral Commodity Summaries 2026, Beryllium
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-beryllium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  nasa-jwst-ntrs:
    title: Feinberg et al., James Webb Space Telescope Optical Telescope Element Mirror Development History and Results
    id: NASA NTRS 20120013223
    url: https://ntrs.nasa.gov/api/citations/20120013223/downloads/20120013223.pdf
    year: 2012
    kind: report
    license: public domain (NASA)
  materion-i70h:
    title: I-70-H and I-220-H Beryllium, Materion data sheet (2024)
    url: https://hkvxni.files.cmp.optimizely.com/download/a0b9e6e0f75f11eebf51367a729f0e29
    year: 2024
    kind: datasheet
    license: Manufacturer data sheet (cited, not reproduced)
  materion-s200f:
    title: S-200-F, S-200-FC and S-200-FH Structural-Grade Beryllium, Materion data sheet
    url: https://hkvxni.files.cmp.optimizely.com/download/c2eca2d0f75e11ee9aa0f6c265376dea
    kind: datasheet
    license: Manufacturer data sheet (cited, not reproduced)
  wiki-be:
    title: Beryllium (Wikipedia)
    url: https://en.wikipedia.org/wiki/Beryllium
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)