Beryllium Be
Be (element, atomic number 4) · CAS 7440-41-7 · hexagonal close-packed
Also known as S-65
Beryllium is the light alkaline-earth metal Be.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Stiffness
290 GPa
Weight
1.85 g/cm3
Heat conduction
216 W/(m·K)
Thermal expansion
11.3 ppm/°C
Melting
1287 °C
Recipe, share of the weight
- Be minimum, wt%Beryllium
- BeO maximum, wt%Beryllium oxide
- C maximum, wt%Carbon
- Fe maximum, wt%Iron
- Al maximum, wt%Aluminum
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
Risk at a glance
- People Severe. Toxic and carcinogenic
- If it fails High. Chronic beryllium disease after inhaling dust or fume
- Corrosion Severe. Beryllium dissolves readily in sulfuric, hydrochloric and hydrofluoric acid; dilute nitric acid attacks it slowly.
Quick facts: Be
| Property | Value | Basis |
|---|---|---|
| Density | 1.85 g/cm³ | 2 sourced values across conditions |
| Yield strength | at least 207 MPa | 1 sourced value |
| Tensile strength | at least 290 MPa | 1 sourced value |
| Young's modulus | 290 GPa | 1 sourced value |
| Thermal conductivity | 216 W/(m·K) | 1 sourced value |
| Thermal expansion (CTE) | 11.3 ppm/K | 1 sourced value |
| Melting point | 1,287 °C | 2 sourced values across conditions |
| Specific heat | 1.95 J/g/°C | 1 sourced value |
What is the density of Beryllium?
Beryllium has a density of 1.85 g/cm³. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the thermal conductivity of Beryllium?
Beryllium has a thermal conductivity of 216 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of Beryllium?
Beryllium has a coefficient of thermal expansion of 11.3 ppm/K. The source and test conditions are listed in the properties table on this page.
What is the melting point of Beryllium?
Beryllium has a melting point of 1,287 °C. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the yield strength of Beryllium?
Beryllium has a yield strength of at least 207 MPa. The source and test conditions are listed in the properties table on this page.
What is Beryllium used for?
Uses recorded in the sources include Aircraft and space-vehicle structures, instruments and x-ray equipment; Space telescope primary mirror segments (James Webb Space Telescope); Cryogenic telescope mirror segments.
Why it exists
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.
Where it's used
Space telescope mirrors
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.
Aircraft and space structures
PubChem's record says purified beryllium is used for aircraft and space vehicle structures, instruments, x-ray machines and mirrors.
Defense and aerospace
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.
Reactor parts
Materion lists reactor walls, reflector tiles, breeder pebbles and neutron reflectors among the uses of the S-65 grade, which has low neutron absorption.
Recipe
Be (element, atomic number 4); pure beryllium metal grade S-65 with Be 99.2 wt% minimum and BeO 0.90 wt% maximum
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.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Beryllium Be | minimum, wt% | The metal itself. The S-65 grade has at least 99.2 wt% Be by assay. |
| Beryllium oxide BeO | maximum, wt% | Oxide present in the metal. The grade limits it to 0.90 wt%. |
| Carbon C | maximum, wt% | Impurity limited by the grade. |
| Iron Fe | maximum, wt% | Impurity limited by the grade. |
| Aluminum Al | maximum, wt% | Impurity limited by the grade. |
Weight shares are as printed in the sources.
What it can do
Stiffness
290 GPa
measured
The elastic modulus of the S-65 grade is 290 GPa (42 msi), a measure of how strongly it resists elastic deformation.
Weight
1.85 g/cm3
measured
The density is 1.85 g/cm3 in the Materion data sheet, and PubChem prints the same value for the element.
Heat conduction
216 W/(m·K)
measured
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.
Thermal expansion
11.3 ppm/°C
measured
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.
Melting
1287 °C
measured
The solidus of the S-65 grade is 1287 °C. PubChem's entry gives the same melting point for the element.
Strength
207 MPa minimum
measured
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.
How it compares
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.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | Be | W | WC | Hf | Mo | Mo-Re | Mo-30W | TZM | Nb | Nb alloys | Re | W-Re | WHA | W-Cu | W-Ag | WT20 | V | V alloys | Zr | Zr alloys | TiH2 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Thermal behavior and safety | |||||||||||||||||||||
| Solidus temperature, S-65 | 1287 °C3 | 3695 K | no data | 2233 °C | 2623 °C | > 2610 °C | 2829 °C | no data | 2477 °C | 2350 °C | 3186 °C | 3350 °C | no data | no data | no data | 3695 K | 1910 °C | 1900 °C | 1852 °C | 1850 °C | > 400 °C |
| Melting point, element (HSDB) | 1287 °C4 | 3695 K | no data | 2233 °C | 2623 °C | > 2610 °C | 2829 °C | no data | 2477 °C | 2350 °C | 3186 °C | 3350 °C | no data | no data | no data | 3695 K | 1910 °C | 1900 °C | 1852 °C | 1850 °C | > 400 °C |
| Vapour pressure of beryllium metal, 10 kPa at 2054 °C | 10 kPa6 | no data | no data | no data | 1 Pa | no data | no data | no data | no data | no data | 1×10^-7 Pa | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data |
| Specific heat capacity, S-65 | 1.95 J/g/°C8 | no data | no data | 25.69 J/(g·K) | 0.25 J/(g·K) | no data | no data | 0.25 J/(g·K) | 264.8 J/(kg·K) | no data | no data | no data | no data | no data | no data | no data | no data | no data | 0.2847 kJ/(kg·K) | 0.285 J/g-°C | no data |
| Thermal conductivity, S-65 at 25 °C | 216 W/(m·K)9 | 174 W m-1 K-1 | 110 W/(m·K) | 23 W/(m·K) | 142 W/(m·K) | no data | no data | 130 W/(m·K) | 53.7 W/(m·K) | 38.1 W/(m·K) | 48 W/m·K | no data | no data | 235 W/(m·K) | no data | 174 W m-1 K-1 | 30.7 W/(m·K) | no data | 22 W/(m·K) | 21.5 W/m-K | no data |
| Physical and electrical | |||||||||||||||||||||
| Density, S-65 pure beryllium | 1.85 g/cm³1 | 19250 kg/m3 | 14.8 g/cm³ | 13.3 g/cm³ | 10.22 g/cm³ | 14.6 g/cm³ | 10.9 g/cm³ | 10.2 g/cm³ | 8.582 g/cm³ | 8.85 g/cm³ | 21.02 g/cm³ | 19.4 g/cm³ | 16.85 to 17.25 g/cc | 15.15 g/cm³ | 11.75 to 16.1 g/cm³ | 19250 kg m-3 | 6.11 g/cm³ | 6.05 g/cm³ | 6.51 g/cm³ | 6.55 g/cc | 3.91 g/cm³ |
| Density, element (HSDB) | 1.85 g/cm³2 | 19250 kg/m3 | 14.8 g/cm³ | 13.3 g/cm³ | 10.22 g/cm³ | 14.6 g/cm³ | 10.9 g/cm³ | 10.2 g/cm³ | 8.582 g/cm³ | 8.85 g/cm³ | 21.02 g/cm³ | 19.4 g/cm³ | 16.85 to 17.25 g/cc | 15.15 g/cm³ | 11.75 to 16.1 g/cm³ | 19250 kg m-3 | 6.11 g/cm³ | 6.05 g/cm³ | 6.51 g/cm³ | 6.55 g/cc | 3.91 g/cm³ |
| Other measurements | |||||||||||||||||||||
| Boiling point, element (PAC Chemical Database) | 2471 °C5 | 5828 K | no data | 4603 °C | 4639 °C | no data | no data | no data | 4744 °C | no data | 5596 °C | no data | no data | no data | no data | 5828 K | 3407 °C | no data | no data | no data | no data |
| Elastic modulus, S-65 | 290 GPa7 | 411 GPa | 530 to 700 GPa | 137 GPa | no data | no data | no data | 300 GPa | 105 GPa | 90 GPa | 460 GPa | no data | 340 GPa | 280 GPa | no data | 411 GPa | 128 GPa | 125.6 GPa | 99.2 GPa | 99.3 GPa | no data |
| Coefficient of thermal expansion, S-65 at 20 to 100 °C | 11.3 ppm/°C10 | 4.5×10^-6 K-1 | 5.5 μm/(m·K) | 5.9 ppm/K | 5.2 ppm/K | no data | no data | 5.3 to 5.7 ppm/K | 7.07 ppm/K | no data | no data | no data | no data | 8.3 ppm/K | no data | no data | 8.3 ppm/K | no data | 6.3 10-6/°C | 6 µm/(m·°C) | no data |
| Yield strength Rp0.2, S-65 minimum at room temperature | > 207 MPa11 | no data | no data | > 151 MPa | 265 MPa | 557 MPa | no data | 750 to 900 MPa | 276 MPa | 276 MPa | 200 to 500 MPa | no data | 517 MPa | no data | no data | no data | no data | 402 MPa | 321.1 MPa | 468 MPa | no data |
| Ultimate tensile strength, S-65 minimum at room temperature | > 290 MPa12 | no data | no data | > 400 MPa | 411 MPa | 719 MPa | 170 MPa | 800 to 1000 MPa | 386 MPa | 386 MPa | 400 to 700 MPa | 220 x 10^3 psi | 758 MPa | 620 to 689 MPa | no data | no data | no data | 488 MPa | 468.1 MPa | 541 MPa | no data |
| Elongation, S-65 minimum at room temperature | > 3 %13 | no data | no data | > 20 % | no data | 18 % | 10 % | 6 to 10 % | 20 % | 20 % | 30 to 50 % | 20 % | 5 % | 8.3 % | no data | no data | 35 % | 30.8 % | 28.9 % | 28 % | no data |
Why choose it, and why not
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 for
- 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.
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.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| Trade name | S-65 |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density, S-65 pure beryllium | Typical value printed in a manufacturer data sheet, with a footnote on the bulk density basis | grade S-65 (pure beryllium)form pieces cut from a vacuum pressed blockbasis minimum bulk density 99.0 % of theoretical, water displacementunit in source 0.067 lb./in3 | — |
| 2 | Density, element (HSDB) | Value printed in the Hazardous Substances Data Bank (HSDB) entry in the PubChem record, with no conditions stated | form beryllium metal, CAS 7440-41-7unit in source 1.85 g/cu cm | NIOSH also lists a specific gravity of 1.85 for beryllium metal, the same value. |
| 3 | Solidus temperature, S-65 | Typical value printed in a manufacturer data sheet | grade S-65unit in source 2349 ˚F | — |
| 4 | Melting point, element (HSDB) | Value printed in the HSDB entry in the PubChem record | form beryllium metalunit in source 2349 °F (NIOSH, 2024) | — |
| 5 | Boiling point, element (PAC Chemical Database) | Value printed in the boiling point section of the PubChem record, attributed to the U.S. DOE PAC Chemical Database | pressure 760 mmHgform beryllium metal | — |
| 6 | Vapour pressure of beryllium metal, 10 kPa at 2054 °C | One of six temperature points printed in the HSDB vapour pressure entry in the PubChem record | temperature 2054 °Cform beryllium metal | Vapour pressure is not in the canonical property list, so this is a short snake_case name; see gaps. |
| 7 | Elastic modulus, S-65 | Typical value printed in a manufacturer data sheet | grade S-65temperature not statedunit in source 42 msi | — |
| 8 | Specific heat capacity, S-65 | Typical value printed in a manufacturer data sheet | grade S-65temperature not statedunit in source 0.46 BTU/lb./°F | — |
| 9 | Thermal conductivity, S-65 at 25 °C | Typical value printed in a manufacturer data sheet | grade S-65temperature 25 °Cunit in source 125 BTU/hr·ft·°F | — |
| 10 | Coefficient of thermal expansion, S-65 at 20 to 100 °C | Typical value printed in a manufacturer data sheet | grade S-65temperature 20 to 100 °Cunit in source 6.3 ppm/°F | — |
| 11 | Yield strength Rp0.2, S-65 minimum at room temperature | Minimum tensile property printed in a manufacturer data sheet; the table heading says Typical, the text says minimum | grade S-65form pieces cut from a vacuum pressed blockmeasure 0.2 % offsettemperature room temperaturestandard in source ASTM E8 and MAB-205 Munit in source 30 ksi | — |
| 12 | Ultimate tensile strength, S-65 minimum at room temperature | Minimum tensile property printed in a manufacturer data sheet | grade S-65form pieces cut from a vacuum pressed blocktemperature room temperaturestandard in source ASTM E8 and MAB-205 Munit in source 42 ksi | — |
| 13 | Elongation, S-65 minimum at room temperature | Minimum tensile property printed in a manufacturer data sheet | grade S-65temperature room temperaturegauge length 4 diametersstandard in source ASTM E8 and MAB-205 M | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Strong mineral acids | severe | Beryllium dissolves readily in sulfuric, hydrochloric and hydrofluoric acid; dilute nitric acid attacks it slowly.1 |
| Strong alkali | not rated | Strong base attacks beryllium and releases hydrogen.2 |
| Air at ordinary temperature | low | Beryllium resists oxidation in air at ordinary temperatures.3 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Strong mineral acids | 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. | basis qualitative statements in the solubility and reactivity entries; no rate given |
| 2 | Strong alkali | PubChem says beryllium is attacked by strong base with evolution of hydrogen gas. No rate, concentration or temperature is given. | basis qualitative statement only |
| 3 | Air at ordinary temperature | 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. | basis qualitative statement only |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
Beryllium is classed as a carcinogen, and inhaled dust, fume or mist causes lung disease, so exposure is the main hazard.
- Classification
- 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.
- Exposure limit
- 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.
- Disease
- 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.
If it burns or dissolves
The powder can burn, and strong acids dissolve the metal.
- Powder fire
- 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.
- Acids
- Sulfuric, hydrochloric and hydrofluoric acids react readily with the metal. Dilute nitric acid attacks it slowly.
Handling and storage
- Workplace control
- 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.
- Form
- 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.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Chronic beryllium disease after inhaling dust or fumehigh severity | Inhalation of beryllium dust, fume or mist; low concentrations over time are enoughPubChem: 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. |
| Fire of powder or finely divided metalmoderate severity | Beryllium powder in a fire, or a mixture with carbon tetrachloride or trichloroethylene under heavy impactPubChem: 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. |
| Brittle failure of the bulk metalmoderate severity | Mechanical loading of the S-65 grade, which has only 3.0 % minimum elongationNIOSH 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 %. |
Handling and storage
- Use adequate local exhaust ventilation to prevent inhalation of, and skin contact with, beryllium dust, fume and mists.
- 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.
- 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.
Mitigations
- Industry must carefully control the quantity of beryllium dust, fumes and mists in the workplace, under international, national and state guidelines.
Supply and geography
How common the raw materials are and where they come from.
Beryllium (mine production)
More than 100,000 tons of identified world resources, about 60 % of them in the United States (USGS 2026)
- Top producers (2025)
- United States 53.5%, Brazil 18.6%, China 17.9%, Nigeria 9.3%
- 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.
Beryllium imports (sources 2021 to 2024)
- Top producers (2024)
- Kazakhstan 31%, Latvia 25%, Japan 19%, Germany 5%
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
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)
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| S-65 and S-65-H Nuclear-Grade Beryllium, Materion data sheet (2023) | datasheet | 2023 | 10 values | |
| PubChem compound record: Beryllium (CID 5460467), including HSDB, PAC Chemical Database and ECHA GHS entries | database | 2026 | 15 values | |
| NIOSH Pocket Guide to Chemical Hazards: Beryllium (metal) | database | 2 values | ||
| Mineral Commodity Summaries 2026, Beryllium | report | 2026 | 4 values | |
| Feinberg et al., James Webb Space Telescope Optical Telescope Element Mirror Development History and Results | report | 2012 | 2 values | |
| I-70-H and I-220-H Beryllium, Materion data sheet (2024) | datasheet | 2024 | 1 value | |
| S-200-F, S-200-FC and S-200-FH Structural-Grade Beryllium, Materion data sheet | datasheet | 1 value | ||
| Beryllium (Wikipedia) | web | 2026 | 0 values |