Steatite MgO-SiO2

spore: profile
id: steatite
spore_version: 0.2
family: oxide-ceramics
name: Steatite
abbreviation: MgO-SiO2
role: electrical insulator ceramic
category: ceramics
type: oxides
summary: |
  Steatite, also called magnesium silicate ceramic, is made mostly from talc (soapstone) that is shaped and fired at about 1300 °C into a white or brown, non-flammable electrical insulator. Kyocera's white grade SO210O has a density of 2.8 g/cm3, a flexural strength of 190 MPa and a dielectric strength of 18 kV/mm, and Du-Co rates steatite for safe operating temperatures up to 1000 °C. A 2016 study of talc-based steatite measured a dielectric constant of about 5 to 8 and losses of 0.001 to 0.003 at 1 MHz. Two related insulating ceramics are cordierite (Kyocera CO220O: density 2.5 g/cm3, dielectric constant 4.9, expansion 1.5 ppm/K from 40 to 400 °C) and forsterite (Kyocera F1023O: density 3.0 g/cm3, dielectric constant 6.5, expansion 10.1 ppm/K). No space, vacuum or flight result for steatite was found in a source we could open.
best_for: Low-cost electrical insulators and heater supports that must not burn and must hold their shape to about 930 °C (Farnell glazed standoff rating)
weakest_at: Shear and torsion loads, and sudden changes in temperature; steatite is weak in shear, as are glass-type materials (RIKO and Farnell sheet)
identity:
  formula: MgO SiO2 (magnesium silicate; the fired body is mostly protoenstatite, MgSiO3)
  source: kyocera-so210o
  where: 'Specifications table, Chemical formula: MgO SiO2; Chemical name: Steatite'
tags:
  environments: []
  stresses:
    - extreme-heat
  applications:
    - electronics-and-chips
    - thermal-control
properties:
  - benchmark: density
    label: Density, white thermal-insulator grade (SO210O)
    value: 2.8
    unit: g/cm3
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS R 1634
      form: dense sintered steatite, water absorption 0
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Density row
  - benchmark: density
    label: Density, dark brown light-shield grade (SO211O)
    value: 3.1
    unit: g/cm3
    scope: material
    conditions:
      grade: Kyocera SO211O, dark brown steatite
      test: JIS R 1634
      form: dense sintered steatite
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so211o
    where: Mechanical and physical characteristics (typ.) table, Density row
  - benchmark: density
    label: Density, grade L-3
    value: 2.5
    unit: g/cc
    scope: material
    conditions:
      grade: Du-Co steatite grade L-3
      form: off-white, impervious to water
    method: Typical value from a manufacturer product page
    status: ground
    source: du-co-steatite
    where: Material grade table, Density (g/cc) row, L-3 column
  - benchmark: density
    label: Density, grade L-5
    value: 2.7
    unit: g/cc
    scope: material
    conditions:
      grade: Du-Co steatite grade L-5
      form: off-white, impervious to water
    method: Typical value from a manufacturer product page
    status: ground
    source: du-co-steatite
    where: Material grade table, Density (g/cc) row, L-5 column
  - benchmark: flexural_strength
    label: Flexural strength, white grade (SO210O)
    value: 190
    unit: MPa
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS R 1601, three-point bending
      form: dense sintered steatite
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Flexural strength row
  - benchmark: flexural_strength
    label: Flexural strength, dark brown grade (SO211O)
    value: 220
    unit: MPa
    scope: material
    conditions:
      grade: Kyocera SO211O, dark brown steatite
      test: JIS R 1601, three-point bending
      form: dense sintered steatite
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so211o
    where: Mechanical and physical characteristics (typ.) table, Flexural strength row
  - benchmark: elastic_modulus
    label: Young's modulus, white grade (SO210O)
    value: 120
    unit: GPa
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS R 1602
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Young's modulus row
  - benchmark: poissons_ratio
    label: Poisson's ratio, white grade (SO210O)
    value: 0.22
    unit: '-'
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS R 1602
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Poisson's ratio row
  - benchmark: vickers_hardness
    label: Vickers hardness, white grade (SO210O)
    value: 5.8
    unit: GPa
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS R 1610, HV 9.807 N load
    method: Typical value from a manufacturer datasheet; not a canonical property name, so vickers_hardness is used (see gaps)
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Vickers hardness row
  - benchmark: cte
    label: Thermal expansion, white grade, 40 to 400 °C (SO210O)
    value: 7.7
    unit: ppm/K
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS R 1618
      temperature_range: 40 to 400 °C
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Coefficient of linear thermal expansion, 40 to 400 °C row
  - benchmark: cte
    label: Thermal expansion, white grade, 40 to 800 °C (SO210O)
    value: 8
    unit: ppm/K
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS R 1618
      temperature_range: 40 to 800 °C
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Coefficient of linear thermal expansion, 40 to 800 °C row
  - benchmark: cte
    label: Thermal expansion, dark brown grade, 40 to 400 °C (SO211O)
    value: 9.2
    unit: ppm/K
    scope: material
    conditions:
      grade: Kyocera SO211O, dark brown steatite
      test: JIS R 1618
      temperature_range: 40 to 400 °C
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so211o
    where: Mechanical and physical characteristics (typ.) table, Coefficient of linear thermal expansion, 40 to 400 °C row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, white grade (SO210O)
    value: 2
    unit: W/(m·K)
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS R 1611
      temperature: not printed
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Thermal conductivity row
  - benchmark: specific_heat
    label: Specific heat capacity, white grade (SO210O)
    value: 0.75
    unit: J/(g·K)
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS R 1611
      unit_in_source: J/(g*K)
    method: Typical value from a manufacturer datasheet; printed in J/(g*K) and left in that unit for import
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Specific heat capacity row
  - benchmark: dielectric_strength
    label: Dielectric strength, white grade (SO210O)
    value: 18
    unit: kV/mm
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS C 2141
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Dielectric strength row
  - benchmark: dielectric_constant
    label: Dielectric constant, white grade (SO210O)
    value: 6
    unit: '-'
    scope: material
    conditions:
      grade: Kyocera SO210O, white steatite
      test: JIS C 2141
      frequency: not printed
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-so210o
    where: Mechanical and physical characteristics (typ.) table, Dielectric constant row
  - benchmark: dielectric_constant
    label: Dielectric constant, talc-based steatite fired at 1275 to 1300 °C
    value: 5
    value_high: 8
    unit: '-'
    scope: material
    conditions:
      frequency: 1 MHz
      temperature: room temperature
      sintering: 2 h at 1275 °C (about 8) and 1300 °C (about 5)
      body: talc, clay and dolomite, dry pressed
    method: Range read from the abstract, not a single value; lower end is the 1300 °C firing
    status: ground
    source: makovsek2016
    where: Abstract, final sentences
  - benchmark: dissipation_factor
    label: Dielectric loss, talc-based steatite fired at 1275 to 1300 °C
    value: 0.001
    value_high: 0.003
    unit: '-'
    scope: material
    conditions:
      frequency: 1 MHz
      temperature: room temperature
      body: talc, clay and dolomite, dry pressed
    method: Range read from the abstract
    status: ground
    source: makovsek2016
    where: Abstract, final sentence
  - benchmark: max_service_temp
    label: Continuous safe operating temperature, glazed L-5 steatite standoff
    value: 930
    unit: °C
    scope: material
    conditions:
      grade: Grade L-5 steatite, glazed, threaded standoffs
      form: ceramic standoff
    method: Continuous safe operating rating printed on the distributor sheet
    status: ground
    source: farnell-standoff
    where: Product notes, bullet on continuous safe operating temperature rating
  - benchmark: max_service_temp
    label: Continuous use temperature, unglazed C 220 connector housing
    value: 200
    unit: °C
    scope: material
    conditions:
      grade: Steatite C 220, IEC 672-1, unglazed connector housing
      form: terminal block housing with brass inserts
    method: Maximum continuous use temperature printed on the connector sheet; a second RIKO sheet prints 350 °C for a different connector with a glazed or similar housing
    status: ground
    source: riko-steatite-connector
    where: Technical data table, continuous use temperature row
corrosion:
  - environment: Chemicals and corrosive media, no test conditions given
    headline: The steatite maker says it has very good corrosion resistance, but gives no test figures.
    effect: Kyocera describes steatite as having high insulating capacity, good mechanical strength and high chemical resistance, and says it is used in the chemical industry for its corrosion resistance. No acid, alkali or immersion test data were found for steatite in a source we could open.
    rating: low
    conditions:
      basis: qualitative manufacturer statement
      test: none stated
    source: kyocera-steatite-page
    where: Steatite section, description paragraph
  - environment: Moisture and water, dense steatite
    headline: Dense steatite absorbs almost no water, with water absorption of 0.00 to 0.02 per cent.
    effect: Du-Co lists steatite grades L-3 and L-5 as impervious to water, with water absorption of 0.00 to 0.02 per cent.
    rating: none
    conditions:
      grades: L-3 and L-5
      test: not printed
      basis: manufacturer typical value
    source: du-co-steatite
    where: Physical properties table, Water Absorption row
  - environment: Heat over long periods, dimensional stability
    headline: Steatite stays dimensionally stable up to about 1000 °C, according to two suppliers.
    effect: Du-Co gives safe operating temperatures up to 1000 °C for steatite in general, and the RIKO sheet says the material is dimensionally stable up to about 1000 °C. Neither source reports a long-term ageing test, and the RIKO sheet limits the surrounding temperature to 200 °C where brass inserts are used.
    rating: low
    conditions:
      basis: supplier statements
      duration: not stated
    source: riko-steatite-connector
    where: Other properties section, dimensional stability line
risks:
  hazards:
    - text: The steatite supplier sheet treats unfired steatite as an article with no health hazard under normal use, and classifies it as not a hazardous substance or mixture under GHS. Health effects are relevant only when dust is made during machining.
      ghs: []
      source: stc-sds-steatite
      where: Sections 2 and 4
    - text: The USGS summary of talc says that an ECHA committee in July 2025 recommended classifying talc as a Category 1B carcinogen (H350) and as STOT RE 1 (H372). This is an opinion, not an adopted classification, and it concerns talc, the main raw material of steatite.
      ghs:
        - H350
        - H372
      source: usgs-mcs2026-talc
      where: Domestic Production and Use section, final paragraph on the ECHA opinion
  failure_risks:
    - mode: Brittle failure under shear or torsion
      trigger: Shear or torsion load on a steatite part, such as a twisted standoff or a threaded insulator
      consequence: The distributor says steatite is strong in compression and tension but weak in shear (torsion), as are all glass-type materials, so the part can break without warning.
      severity: moderate
      source: farnell-standoff
      where: Product notes, first bullet
    - mode: Overheating past the rating
      trigger: Surrounding temperature above 200 °C in a connector with brass inserts
      consequence: The RIKO sheet says that above this limit the brass inserts reach their scaling temperature.
      severity: moderate
      source: riko-steatite-connector
      where: Other properties section
    - mode: Dust from machining
      trigger: Grinding or machining steatite without dust control
      consequence: The supplier sheet says the dust contains crystalline silica and can irritate the eyes, nose, throat and skin.
      severity: low
      source: stc-sds-steatite
      where: Section 4, general advice
  side_effects:
    - text: Metal inserts in a steatite connector housing (brass, nickel-plated) scale at high temperature; the RIKO sheet limits the surrounding temperature to 200 °C to keep them below their scaling temperature.
      affects: Brass or nickel-plated inserts in the housing
      source: riko-steatite-connector
      where: Other properties section
  handling:
    - text: Wet mop or dry vacuum dust from machining; the supplier sheet recommends local or general exhaust ventilation where dust is made.
      source: stc-sds-steatite
      where: Sections 6, 7 and 8
    - text: For the unfired powder the organic portion is combustible and the flash point is printed as 220 °C; the sheet lists a possible Class A fire hazard from vapour in the headspace above the product.
      source: stc-sds-steatite
      where: Sections 5 and 9
  mitigations:
    - text: Ask the supplier for specified values for critical parts; Kyocera prints its values as typical and says they vary with product configuration and manufacturing process.
      source: kyocera-so210o
      where: Footnote below the mechanical and physical characteristics table
uses:
  - application: electronics-and-chips
    device: Terminal-block housings and insulating connector bodies (ground use, not flown)
    example: RIKO Components sells steatite (C 220, IEC 672-1, unglazed) connector housings with nominal voltages printed as 250 V and 450 V, depending on the number of poles.
    source: riko-steatite-connector
    where: Electrical values table, nominal voltage column
  - application: thermal-control
    device: Band heater insulators, heater supports and thermocouple parts (ground use)
    example: Du-Co lists steatite for electrical heating equipment, insulators, thermocouples and sensors, with safe operating temperatures up to 1000 °C.
    source: du-co-steatite
    where: Steatite Ceramic page, introduction paragraph
  - application: thermal-control
    device: Threaded ceramic standoffs for heated assemblies (ground use)
    example: A distributor sells glazed grade L-5 steatite standoffs with a continuous safe operating temperature rating of 930 °C (1700 °F).
    source: farnell-standoff
    where: Product notes, bullet on continuous safe operating temperature
  - application: electronics-and-chips
    device: Various circuit parts, white thermal-insulator grade (ground industrial use)
    example: Kyocera lists its white steatite SO210O for various circuit parts and as a thermal insulator.
    source: kyocera-so210o
    where: Specifications table, Main applications
supply:
  - subject: Talc (steatite is about 90 per cent soapstone, which is talc)
    producers:
      - country: India (steatite)
        share_percent: 21.7
        year: 2025
      - country: China (unspecified minerals)
        share_percent: 18.8
        year: 2025
      - country: Brazil (crude and beneficiated)
        share_percent: 8.3
        year: 2025
      - country: United States (crude)
        share_percent: 7.1
        year: 2025
    critical_lists: []
    recycling: 'USGS: Recycling: Insignificant.'
    substitutes:
      - 'USGS: substitutes for talc in ceramics include bentonite, chlorite, feldspar, kaolin and pyrophyllite.'
    source: usgs-mcs2026-talc
    where: World Mine Production and Reserves table, 2025e (world total 6900 thousand t; shares calculated by Space Mushroom against that total, so they are not exact national shares of steatite alone); Salient Statistics; Recycling; Substitutes. Pakistan supplied 52 per cent of US talc imports in 2021 to 2024 (Import Sources).
documents:
  - title: Kyocera Fineceramics Europe SO210O steatite datasheet
    type: datasheet
    url: https://www.kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/steatit/Kyocera_Fineceramics_Europe_SO210O.pdf
    year: 2023
  - title: Kyocera Fineceramics Europe SO211O steatite datasheet
    type: datasheet
    url: https://www.kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/steatit/Kyocera_Fineceramics_Europe_SO211O.pdf
    year: 2023
  - title: Makovšek et al., Processing of steatite ceramic with a low dielectric constant and low dielectric losses (Informacije MIDEM)
    type: paper
    url: https://ojs.midem-drustvo.si/index.php/InfMIDEM/article/view/217
    year: 2016
  - title: 'Mineral Commodity Summaries 2026: Talc and pyrophyllite'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-talc.pdf
    year: 2026
  - title: 'Superior Technical Ceramics safety data sheet: Unfired Steatite (rev. 03/22/2024)'
    type: sds
    url: https://ceramics.net/wp-content/uploads/STC-SDS-Unfired-Steatite-Rev-03-22-2024.pdf
    year: 2024
  - title: Kyocera Fineceramics Europe CO220O cordierite datasheet (related ceramic)
    type: datasheet
    url: https://www.kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/cordierit/Kyocera_Fineceramics_Europe_CO220O.pdf
    year: 2023
  - title: Kyocera Fineceramics Europe F1023O forsterite datasheet (related ceramic)
    type: datasheet
    url: https://www.kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/forsterit/Kyocera_Fineceramics_Europe_F1023O.pdf
    year: 2023
  - title: Farnell ceramic standoffs, grade L-5 steatite (product 2621193)
    type: datasheet
    url: https://www.farnell.com/datasheets/2621193.pdf
    year: 2026
  - title: RIKO Components steatite connector technical data, C 220 (Farnell datasheet 1564577)
    type: datasheet
    url: https://www.farnell.com/datasheets/1564577.pdf
    year: 2026
gaps:
  - No space, vacuum, radiation, outgassing or flight result for steatite or talc-based ceramics was found in a source we could open; the uses listed are ground and industrial.
  - No numeric acid, alkali, humidity or long-term ageing test for steatite was found. The corrosion entry rests on Kyocera's qualitative statement; a cordierite membrane acid and alkali study (Dong et al., 2007) could not be opened.
  - Vickers hardness is not a canonical property name; it is entered as vickers_hardness.
  - Kyocera's steatite page calls the material porous, while its datasheets call the grades dense sintered; this conflict is not resolved here.
  - The dielectric loss and loss factor printed for the SO211O grade (750 and 6000 in the 10^-4 units) look implausible for a steatite and were not entered.
  - The dielectric constant at the Kyocera datasheets is printed without a frequency (JIS C 2141 standard only); the 1 MHz values come from the MIDEM paper.
  - The melting point of steatite (enstatite-type MgSiO3) was not read on a fetched page and is not entered.
  - No UNS, EN or DIN designation for steatite was printed on a source read in this run. RIKO prints IEC 672-1 class C 220, but IEC is not one of the designation systems in the schema.
  - The IPS Ceramics and Elan Technology steatite datasheets could not be opened (404 and bot-block), and the MakeItFrom pages returned a cookie wall, so their values are not used.
  - The PubChem talc hazard record could not be opened in this run (the REST lookup returned a different compound), so GHS hazard data rest on the supplier sheet and the USGS summary of the ECHA opinion.
  - Critical-mineral listing of talc (USGS 2025 list and EU critical raw materials list) was not checked.
  - Cordierite and forsterite are not profiled here; their numbers come from the Kyocera CO220O and F1023O datasheets and appear in the summary and story only as related ceramics.
sources:
  kyocera-so210o:
    title: Kyocera Fineceramics Europe SO210O steatite datasheet (white, thermal insulator)
    id: Kyocera Fineceramics Europe GmbH, datasheet dated 2023.04.03
    url: https://www.kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/steatit/Kyocera_Fineceramics_Europe_SO210O.pdf
    year: 2023
    kind: datasheet
    license: manufacturer datasheet, cited not reproduced
  kyocera-so211o:
    title: Kyocera Fineceramics Europe SO211O steatite datasheet (dark brown, good light shield)
    id: Kyocera Fineceramics Europe GmbH, datasheet dated 2023.04.03
    url: https://www.kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/steatit/Kyocera_Fineceramics_Europe_SO211O.pdf
    year: 2023
    kind: datasheet
    license: manufacturer datasheet, cited not reproduced
  kyocera-co220o:
    title: Kyocera Fineceramics Europe CO220O dense sintered cordierite datasheet
    id: Kyocera Fineceramics Europe GmbH, datasheet dated 2023.04.03
    url: https://www.kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/cordierit/Kyocera_Fineceramics_Europe_CO220O.pdf
    year: 2023
    kind: datasheet
    license: manufacturer datasheet, cited not reproduced
  kyocera-f1023o:
    title: Kyocera Fineceramics Europe F1023O dense sintered forsterite datasheet
    id: Kyocera Fineceramics Europe GmbH, datasheet dated 2023.04.03
    url: https://www.kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/forsterit/Kyocera_Fineceramics_Europe_F1023O.pdf
    year: 2023
    kind: datasheet
    license: manufacturer datasheet, cited not reproduced
  kyocera-steatite-page:
    title: 'Kyocera Fineceramics Europe: Steatite material page'
    id: kyocera-fineceramics.de/en/materials/steatite
    url: https://www.kyocera-fineceramics.de/en/materials/steatite
    year: 2026
    kind: web
    license: manufacturer web page, cited not reproduced
  du-co-steatite:
    title: 'Du-Co Ceramics: Steatite Ceramic, Magnesium Silicate (grades L-3 and L-5)'
    id: Du-Co Ceramics Company, Saxonburg PA
    url: https://www.du-co.com/materials/steatite-magnesium-silicate/
    year: 2026
    kind: web
    license: manufacturer web page, cited not reproduced
  makovsek2016:
    title: Processing of steatite ceramic with a low dielectric constant and low dielectric losses
    id: Makovšek K., Ramšak I., Malič B., Bobnar V., Kuščer D., Informacije MIDEM Vol 46 No 2 (2016)
    url: https://ojs.midem-drustvo.si/index.php/InfMIDEM/article/view/217
    year: 2016
    kind: paper
    license: journal article, cited not reproduced
  usgs-mcs2026-talc:
    title: 'Mineral Commodity Summaries 2026: Talc and Pyrophyllite'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-talc.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  stc-sds-steatite:
    title: 'Superior Technical Ceramics safety data sheet: Unfired Steatite (hydrated magnesium silicate)'
    id: STC SDS, last revision 03/22/2024
    url: https://ceramics.net/wp-content/uploads/STC-SDS-Unfired-Steatite-Rev-03-22-2024.pdf
    year: 2024
    kind: datasheet
    license: supplier document, linked not reproduced
  farnell-standoff:
    title: Farnell ceramic standoffs, grade L-5 steatite, glazed, fired at high temperature (product 2621193)
    id: Farnell datasheet 2621193
    url: https://www.farnell.com/datasheets/2621193.pdf
    year: 2026
    kind: datasheet
    license: distributor document, linked not reproduced
  riko-steatite-connector:
    title: RIKO Components steatite connector technical data, C 220 (Farnell datasheet 1564577)
    id: RIKO Components GmbH, Farnell datasheet 1564577
    url: https://www.farnell.com/datasheets/1564577.pdf
    year: 2026
    kind: datasheet
    license: distributor document, linked not reproduced
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 20
  unreachable: 3
  caveats: 2
  note: 'Written by an AI assistant on 2026-10-26 from manufacturer datasheets, one open journal paper and the USGS 2026 talc chapter read in this run. Three sources could not be opened (IPS Ceramics, Elan Technology, MakeItFrom). Caveats: the Kyocera SO211O loss values were left out as implausible, and the Kyocera sheets give no test frequency for the dielectric constant.'
story:
  recipe:
    line: Steatite is a magnesium silicate ceramic. Its raw material, talc, is a hydrated magnesium silicate; during firing the body forms mainly protoenstatite, which is an MgSiO3 phase, with a glassy phase between the grains.
    parts:
      - name: Magnesium
        symbol: Mg
        role: The main metal in the body. Talc supplies it, and it sits in the enstatite-type MgSiO3 phase that gives steatite its insulating character.
      - name: Silicon
        symbol: Si
        role: Bonded to oxygen in silicate groups. Silicon and oxygen make up the rigid crystal and the glassy phase between the grains.
      - name: Oxygen
        symbol: O
        role: Completes the silicate groups. Oxygen is the element that makes the body an oxide ceramic.
  risk_groups:
    - title: For people
      level: 0
      verdict: Not hazardous under normal use; dust is the concern
      lead: The supplier classes unfired steatite as not a hazardous substance, but grinding or machining produces dust that can irritate, and the ECHA talc opinion is a risk to note for the raw mineral.
      points:
        - label: The solid
          line: A supplier sheet for unfired steatite classifies it as not a hazardous substance or mixture under GHS, and treats it as an article with no health hazard under normal use.
        - label: Dust
          line: Dust from machining can contain crystalline silica and irritate the eyes, nose, throat and skin. Wet mopping or dry vacuuming is recommended.
        - label: Talc opinion
          line: In July 2025 an ECHA committee recommended classing talc as a Category 1B carcinogen (H350) and as STOT RE 1 (H372). This is an opinion, not a final classification of steatite.
    - title: If a part fails in service
      lead: These limits come from supplier data sheets, not from incidents in service.
      points:
        - label: Shear and torsion
          line: Steatite is strong in compression and tension but weak in shear (torsion), as are all glass-type materials. A twisted standoff can break without warning.
        - label: Temperature limits
          line: A glazed grade L-5 standoff is rated for continuous safe operation at 930 °C. A C 220 connector housing is rated to 200 °C, because the brass inserts scale above that temperature.
        - label: Fire
          line: Fired steatite is described as non-flammable (RIKO). The unfired powder's safety sheet notes a combustible organic part and a flash point of 220 °C.
  why: 'Steatite, also called magnesium silicate ceramic, is one of the most widely used technical ceramic materials (Du-Co). It is made mostly from talc, or soapstone, which the distributor puts at about 90 per cent; the powder is shaped and fired at roughly 1300 °C with additives. The result is a dense, white or brown solid that insulates well and holds its shape at high temperature. Its limits are mechanical: it is weak in shear and torsion, as glass-type materials are, and it cracks rather than bends. Its appeal is cost and insulation. The space record is empty: no vacuum, radiation or flight data for steatite were found in a source we could open.'
  uses:
    - where: Electrical connectors and terminal blocks
      line: RIKO Components sells steatite C 220 connector housings with nominal voltages printed as 250 V and 450 V, depending on the number of poles. These are ground products, not flight hardware.
    - where: Heater insulators and heater supports
      line: Du-Co lists steatite for electrical heating equipment, insulators, thermocouples and sensors, with safe operating temperatures up to 1000 °C. A distributor rates its glazed grade L-5 standoffs at 930 °C continuous safe operation.
    - where: Circuit parts
      line: Kyocera lists its white steatite SO210O for various circuit parts and as a thermal insulator.
  can_do:
    - label: Electrical insulation
      value: 18 kV/mm
      line: The white grade SO210O has a dielectric strength of 18 kV/mm and a dielectric constant of 6, both typical values from the Kyocera datasheet under JIS C 2141.
    - label: Low loss at radio frequency
      value: 0.001 to 0.003
      line: A 2016 study of talc-based steatite, fired at 1275 to 1300 °C, measured dielectric losses of 0.001 to 0.003 at 1 MHz, and a dielectric constant that fell from about 8 to about 5 as the firing temperature rose.
    - label: Heat
      value: 930 °C
      line: A glazed grade L-5 standoff has a continuous safe operating rating of 930 °C, and steatite is dimensionally stable up to about 1000 °C according to two suppliers.
    - label: Stiffness and strength
      value: 190 MPa
      line: The white grade has a flexural strength of 190 MPa and a Young's modulus of 120 GPa; the dark brown grade reaches 220 MPa.
  compare: Du-Co calls steatite cost-effective, and its density runs from 2.5 to 3.1 g/cm3 depending on grade. Cordierite (Kyocera CO220O) is about as dense at 2.5 g/cm3, has a dielectric constant of 4.9 and expands only 1.5 ppm/K from 40 to 400 °C. Forsterite (Kyocera F1023O) is denser at 3.0 g/cm3, has a dielectric constant of 6.5 and expands 10.1 ppm/K, which Kyocera markets as high thermal expansion. Steatite, at 7.7 ppm/K, lies between the two.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal expansion
      benchmark: cte
    - label: Dielectric strength
      benchmark: dielectric_strength
  handling:
    - Wet mop or dry vacuum dust from machining, and use local exhaust ventilation where dust is made.
    - Ask the supplier for specified values for critical parts, because the values quoted are typical.
    - Keep the continuous temperature below the rating for the grade, and below 200 °C where brass inserts are used.
  good_for:
    - Cheap, non-flammable electrical insulation. The white grade has a dielectric strength of 18 kV/mm.
    - Heater insulation and standoffs. A glazed grade L-5 standoff is rated to 930 °C for continuous use.
  watch_out:
    - Shear and torsion loads. Steatite is weak in shear, as glass-type materials are.
    - Metal inserts. Brass inserts scale above 200 °C in the RIKO connector housing.
    - Machining dust. The dust contains crystalline silica, and talc is under ECHA review as a carcinogen.
    - No space record. No vacuum, radiation or flight result for steatite was found in a source we could open.
  verdict: Steatite is a low-cost, non-flammable insulator for electrical parts and heater supports up to about 930 °C. It is weak in shear and torsion, and no space test data were found.