spore: profile
id: mica-muscovite
spore_version: 0.2
family: mica
name: Muscovite mica
role: dielectric
category: electronics
type: dielectrics-and-capacitors
summary: |
  Muscovite mica is a hydrated potassium aluminium silicate with the formula KAl2(AlSi3O10)(OH)2 (Wikipedia). In a 1931 National Bureau of Standards study, clear ruby muscovite averaged a dielectric constant of 7.2 and a power factor of 0.02 per cent at 25 degC over 100 to 1,000 kilocycles. A rigid mica sheet datasheet from RS PRO gives a dielectric strength of 20 kV/mm at 20 degC, and an RS muscovite insulation film is rated for 500 degC continuous service.
best_for: Electrical insulation and capacitor dielectric where low dielectric loss and heat tolerance matter. NIST measured clear ruby muscovite at 0.02 per cent power factor.
weakest_at: Stained or inclusion-bearing mica. NIST found that stains and air bubbles raise the power factor so far that the mica is unsuited for radio purposes.
identity:
  formula: KAl2(AlSi3O10)(OH)2
  crystal_system: monoclinic
  source: wiki-muscovite
  where: Opening text and infobox (formula and crystal system)
tags:
  environments: []
  stresses: []
  applications:
    - electronics-and-chips
    - thermal-control
properties:
  - benchmark: dielectric_constant
    label: Dielectric constant, clear ruby muscovite
    value: 7.2
    unit: '-'
    scope: material
    conditions:
      grade: clear ruby muscovite, 16 samples from the United States and India
      frequency: 100 to 1,000 kilocycles (as printed)
      temperature: 25 degC
      spread: +/-0.3 for individual samples (abstract)
    method: Average of measurements in NIST Table 1, row Clear muscovite
    status: ground
    source: nist-rp347
    where: Abstract; Table 1, row 'Clear muscovite' (16 samples, average 7.20)
  - benchmark: dissipation_factor
    label: Power factor (dissipation factor), clear ruby muscovite
    value: 0.02
    unit: '%'
    scope: material
    conditions:
      grade: clear ruby muscovite, 16 samples from the United States and India
      frequency: 100 to 1,000 kilocycles (as printed)
      temperature: 25 degC
      unit_in_source: per cent
      spread: +/-0.01 per cent for individual samples (abstract)
    method: NIST calls this property power factor; it is mapped to the dissipation-factor slot. Value printed as 0.02 per cent.
    status: ground
    source: nist-rp347
    where: Abstract; Table 1, row 'Clear muscovite' (average 0.02 per cent)
  - benchmark: dielectric_strength
    label: Dielectric strength, rigid mica sheet at 20 degC
    value: 20
    unit: kV/mm
    scope: material
    conditions:
      temperature: 20 degC
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (the stock item on page 1 is named phlogopite; see gaps)
    method: Value printed in RS datasheet, Electrical Specifications table
    status: ground
    source: rs-mica
    where: Page 3, Electrical Specifications, Dielectric Strength 20 C row
  - benchmark: dielectric_strength
    label: Dielectric strength, rigid mica sheet at 400 degC
    value: 13
    unit: kV/mm
    scope: material
    conditions:
      temperature: 400 degC
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
    method: Value printed in RS datasheet, Electrical Specifications table
    status: ground
    source: rs-mica
    where: Page 3, Electrical Specifications, Dielectric Strength 400 C row
  - benchmark: dielectric_strength
    label: Dielectric strength, rigid mica sheet at 600 degC
    value: 10
    unit: kV/mm
    scope: material
    conditions:
      temperature: 600 degC
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
    method: Value printed in RS datasheet, Electrical Specifications table
    status: ground
    source: rs-mica
    where: Page 3, Electrical Specifications, Dielectric Strength 600 C row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, rigid mica sheet at 20 degC
    value: 0.3
    unit: W/mK
    scope: material
    conditions:
      temperature: 20 degC
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
      unit_in_source: W/mK
    method: Value printed in RS datasheet, Electrical Specifications table
    status: ground
    source: rs-mica
    where: Page 3, Electrical Specifications, Thermal Conductivity (20 C) row
  - benchmark: max_service_temp
    label: Maximum service temperature, muscovite insulation film, continuous
    value: 500
    unit: °C
    scope: material
    conditions:
      basis: continuous
      product: RS PRO Muscovite Mica Insulation Film, 0.2 mm, stock 785-0815
    method: Value printed in the Similar Products table of the RS datasheet
    status: ground
    source: rs-mica
    where: Page 3, Similar Products table, row 785-0815 (Max Temp column)
  - benchmark: max_service_temp
    label: Maximum service temperature, muscovite insulation film, intermittent
    value: 800
    unit: °C
    scope: material
    conditions:
      basis: intermittent
      product: RS PRO Muscovite Mica Insulation Film, 0.2 mm, stock 785-0815
    method: Value printed in the Similar Products table of the RS datasheet
    status: ground
    source: rs-mica
    where: Page 3, Similar Products table, row 785-0815 (Max Temp column)
  - benchmark: density
    label: Density, rigid mica sheet
    value: 2
    value_high: 2.35
    unit: g/cm3
    scope: material
    conditions:
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
      unit_in_source: g/cm³
    method: Range printed in RS datasheet, General Specifications table
    status: ground
    source: rs-mica
    where: Page 2, General Specifications, Density row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, rigid mica sheet
    value: 110
    unit: MPa
    scope: material
    conditions:
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
      unit_in_source: N/mm2
    method: Value printed in RS datasheet as N/mm²; N/mm² equals MPa
    status: ground
    source: rs-mica
    where: Page 2, Mechanical Specifications, Tensile Strength row
  - benchmark: flexural_strength
    label: Flexural strength, rigid mica sheet
    value: 80
    unit: MPa
    scope: material
    conditions:
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
      unit_in_source: N/mm2
      test: bending
    method: Value printed in RS datasheet as N/mm²; N/mm² equals MPa
    status: ground
    source: rs-mica
    where: Page 2, Mechanical Specifications, Flexural Strength (Bending) row
  - benchmark: moisture_absorption
    label: Water absorption, rigid mica sheet
    value: 0.5
    unit: '%'
    scope: material
    conditions:
      basis: maximum, 24 h at 23 degC
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
    method: Maximum value printed as less than or equal to 0.5 per cent
    status: ground
    source: rs-mica
    where: Page 2, Mechanical Specifications, Water Absorption row
  - benchmark: heat_loss
    label: Heat loss, rigid mica sheet at 500 degC
    value: 1.5
    unit: '%'
    scope: material
    conditions:
      basis: less than
      temperature: 500 degC
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
    method: Printed as less than 1.5 per cent; heat_loss is not a canonical property name
    status: ground
    source: rs-mica
    where: Page 3, Electrical Specifications, Heat Loss 500 C row
  - benchmark: heat_loss
    label: Heat loss, rigid mica sheet at 700 degC
    value: 2
    unit: '%'
    scope: material
    conditions:
      basis: less than
      temperature: 700 degC
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
    method: Printed as less than 2 per cent; heat_loss is not a canonical property name
    status: ground
    source: rs-mica
    where: Page 3, Electrical Specifications, Heat Loss 700 C row
  - benchmark: compressive_strength_perpendicular
    label: Compressive strength perpendicular, rigid mica sheet
    value: 200
    unit: MPa
    scope: material
    conditions:
      direction: perpendicular
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
      unit_in_source: N/mm2
    method: Value printed as N/mm²; compressive_strength_perpendicular is not a canonical property name
    status: ground
    source: rs-mica
    where: Page 2, Mechanical Specifications, Compressive Strength, Perpendicular row
  - benchmark: compressive_strength_parallel
    label: Compressive strength parallel, rigid mica sheet
    value: 50
    unit: MPa
    scope: material
    conditions:
      direction: parallel
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
      unit_in_source: N/mm2
    method: Value printed as N/mm²; compressive_strength_parallel is not a canonical property name
    status: ground
    source: rs-mica
    where: Page 2, Mechanical Specifications, Compressive Strength, Parallel row
  - benchmark: refractive_index
    label: Refractive index range, muscovite (three principal indices)
    value: 1.552
    value_high: 1.618
    unit: '-'
    scope: material
    conditions:
      basis: lowest and highest of the three principal indices printed
    method: Lowest (1.552) and highest (1.618) of the printed principal refractive indices. The PDF text layer drops the Greek letter labels, so the values are not tied to a single optical axis.
    status: ground
    source: handbook-muscovite
    where: Optical Properties paragraph (refractive index values 1.552 to 1.576, 1.582 to 1.615 and 1.587 to 1.618)
corrosion:
  - environment: Furnace heating for 30 minutes at 600 degC
    headline: Most muscovite samples were practically unchanged after 30 minutes at 600 degC, but none withstood 1,200 degC well.
    effect: NIST heated 1 by 2.5 cm samples for one-half hour at temperatures from 600 degC to 1,200 degC. With one or two exceptions the micas were unaffected by 600 degC. Above 600 degC the phlogopites kept their properties better than the muscovites.
    rating: moderate
    conditions:
      exposure: one-half hour at each temperature, rapid heating, no external force
      test: furnace, samples graded for colour, surface, opacity, lamina separation and form
    source: nist-rp347
    where: Abstract; Section 4 (Effects of elevated temperatures); Conclusions
  - environment: Water exposure, 24 h at 23 degC
    headline: The RS mica sheet absorbs at most 0.5 per cent water in 24 hours.
    effect: Printed as less than or equal to 0.5 per cent. RS also lists the product as moisture resistant on page 1 of the datasheet.
    rating: low
    conditions:
      basis: 24 h at 23 degC
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
    source: rs-mica
    where: Page 2, Mechanical Specifications, Water Absorption row; page 1, Features list
  - environment: Heat loss at 500 degC and 700 degC
    headline: The RS mica sheet shows heat loss of less than 1.5 per cent at 500 degC and less than 2 per cent at 700 degC.
    effect: The datasheet prints these heat loss figures without a test duration. The same sheet has a continuous heat-resistance rating of 600 degC on page 2.
    rating: moderate
    conditions:
      product: RS PRO rigid mica sheet, printed under the heading Muscovite Mica (species uncertain; see gaps)
    source: rs-mica
    where: Page 3, Electrical Specifications, Heat Loss rows (500 C and 700 C)
uses:
  - application: electronics-and-chips
    device: Film capacitor dielectric
    example: Wikipedia states that only high-quality muscovite film mica, also called India ruby mica, is used as a dielectric in capacitors, and that the highest-grade film is used in calibration-standard capacitors.
    source: wiki-mica
    where: Section on electrical insulation and capacitors
  - application: electronics-and-chips
    device: Electrical and electronic parts
    example: USGS reports that most sheet mica was fabricated into parts for electrical and electronic equipment, and that the United States depended on imports to meet demand for sheet mica.
    source: usgs-mcs2026-mica
    where: Domestic Production and Use paragraph (2025)
  - application: thermal-control
    device: Rigid mica sheet for thermal and electrical insulation
    example: RS describes its rigid mica sheets as providing outstanding thermal and electrical insulation in a broad range of industries, with a low thermal conductivity and high dielectric strength.
    source: rs-mica
    where: Page 2, Product Description
risks:
  hazards:
    - text: NIOSH lists mica (containing less than 1% quartz), with muscovite among its synonyms, at a recommended exposure limit of TWA 3 mg/m3 (resp), an IDLH of 1500 mg/m3 and a target organ of the respiratory system. Symptoms listed include irritation of the eyes, pneumoconiosis, cough and dyspnea (breathing difficulty). Exposure routes listed are inhalation, skin and/or eye contact.
      ghs: []
      source: niosh-mica
      where: Synonyms and Trade Names; Exposure Limits; IDLH; symptom and target organ entries
    - text: OSHA lists mica (CAS 12001-26-2) with an 8-hour TWA of 20 mppcf for respirable dust, and no STEL or ceiling. The OSHA page prints no health-effects text and refers readers to PubChem for health factors.
      ghs: []
      source: osha-mica
      where: Permissible exposure limits section; health factors line
  failure_risks:
    - mode: Stains or inclusions in the mica
      trigger: Air bubbles or metallic-oxide stains in the sheet
      consequence: NIST found that the slightest trace of air bubbles or metallic oxides raises the power factor so far that the mica is unsuited for applications needing low power loss, although dielectric strength is much less affected.
      severity: moderate
      source: nist-rp347
      where: Abstract; Section IV (Discussion and conclusions)
    - mode: Exposure above 600 degC
      trigger: Heating muscovite above 600 degC for 30 minutes (the NIST test condition)
      consequence: NIST found that above 600 degC the phlogopites kept their properties better than the muscovites, and that none of the micas tested withstands 1,200 degC well.
      severity: moderate
      source: nist-rp347
      where: Abstract; Section IV (Discussion and conclusions)
  side_effects: []
  handling:
    - text: The RS mica sheet is listed as easy to cut or punch and moisture resistant (page 1 features list). The page-1 stock item is named phlogopite, so confirm the species on the supplier's sheet.
      source: rs-mica
      where: Page 1, Features list
    - text: Keep stains and air bubbles out of capacitor-grade sheet, because NIST found that stained or bubbled mica has a much higher power factor.
      source: nist-rp347
      where: Abstract; Section IV (Discussion and conclusions)
  mitigations:
    - text: Select clear, unstained sheet for radio and low-loss uses. NIST found that stained micas are unsuited for radio purposes.
      source: nist-rp347
      where: Abstract
supply:
  - subject: Mica (natural), sheet and scrap or flake
    abundance: Not found in the sources read for this profile.
    producers:
      - country: China
        tonnes: 85,000 (scrap and flake mine production, 2025 estimate)
        reserves: 1,100,000 (scrap and flake); 75,000 (sheet)
        year: 2025
      - country: Madagascar
        tonnes: 70,000 (scrap and flake mine production, 2025)
        year: 2025
      - country: Finland
        tonnes: 57,000 (scrap and flake mine production, 2025)
        year: 2025
      - country: India
        tonnes: 1,000 (sheet mine production, 2025)
        reserves: 110,000 (sheet)
        year: 2025
    critical_lists: []
    recycling: 'None (USGS Salient Statistics: Recycling: None).'
    substitutes:
      - Mica paper made from scrap mica can be substituted for sheet mica in electrical and insulation applications (USGS).
      - Ground synthetic fluorophlogopite may replace natural ground mica for uses that require the thermal and electrical properties of mica (USGS).
      - Acrylic, cellulose acetate, fiberglass, fishpaper, nylon, phenolics, polycarbonate, polyester, polyvinyl chloride and vulcanized fiber can be substituted for mica in many electrical, electronic and insulation uses (USGS).
    source: usgs-mcs2026-mica
    where: World Mine Production and Reserves table; Substitutes paragraph; Salient Statistics table (sheet imports and import reliance)
documents:
  - title: Some Electrical Properties of Foreign and Domestic Micas and the Effect of Elevated Temperatures (NBS Research Paper RP347), A. B. Lewis, E. L. Hall and F. R. Caldwell
    type: paper
    url: https://nvlpubs.nist.gov/nistpubs/jres/7/jresv7n2p403_A2b.pdf
    year: 1931
  - title: RS PRO rigid mica sheet and muscovite mica insulation film datasheet (stock 134-940 and 785-0815)
    type: datasheet
    url: https://docs.rs-online.com/0045/A700000015993317.pdf
  - title: 'USGS Mineral Commodity Summaries 2026: Mica (Natural)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-mica.pdf
    year: 2026
  - title: 'Handbook of Mineralogy: Muscovite (Mineral Data Publishing, version 1.2)'
    type: report
    url: https://www.handbookofmineralogy.org/pdfs/muscovite.pdf
    year: 2001
  - title: 'NIOSH Pocket Guide to Chemical Hazards: Mica (containing less than 1% quartz)'
    type: database
    url: https://www.cdc.gov/niosh/npg/npgd0431.html
  - title: 'OSHA Chemical Data: Mica (CAS 12001-26-2)'
    type: database
    url: https://www.osha.gov/chemicaldata/153
gaps:
  - No safety data sheet, GHS classification or PubChem record for muscovite itself was found. PubChem returned a browser-check page. The hazards entries use the NIOSH and OSHA mica entries, which cover mica containing less than 1% quartz and list muscovite as a synonym. Neither gives GHS data.
  - CAS number, UNS, EN, ASTM and other designations for muscovite were not printed in any source used, so identity.designations is left out. NIOSH and OSHA print CAS 12001-26-2 for the mica group, which lists muscovite as a synonym; it is not entered as a muscovite-specific designation.
  - Space group and atomic weights were not printed in the sources read, so they are left out.
  - Density is printed without a unit in both the Handbook of Mineralogy (D(meas.) 2.77 to 2.88; D(calc.) 2.83) and Wikipedia (specific gravity 2.76 to 3), so no density value was entered from those pages. Mohs hardness (Handbook 2.5; Wikipedia 2 to 2.25 or 2 to 2.5) is on an ordinal scale and was not entered. The Handbook refractive indices are entered, but the PDF text layer drops their Greek labels, so they are not tied to an optical axis.
  - The RS datasheet prints its specification tables under the heading Muscovite Mica, but the page-1 stock item 134-940 is named RS PRO Phlogopite Mica. The species of the rigid-sheet values (dielectric strength, density, tensile, flexural, compressive, water absorption, thermal conductivity, heat loss) is therefore uncertain and should be confirmed with the supplier.
  - Volume resistivity was printed by RS as 1016 and 109 ohm/cm (superscripts lost in text extraction), so those values were not entered.
  - Compressive strength and heat loss use names that are not in spores/property-canon.yaml (compressive_strength_perpendicular, compressive_strength_parallel, heat_loss).
  - NIST Table 2 gives clear ruby muscovite breakdown voltages of 5.7, 9.9 and 13.2 kilovolts (effective) at 1, 5 and 9 mils, which is total breakdown voltage and not kV/mm, so it is not entered as dielectric strength. The NIST values appear in the story text.
  - No vacuum, outgassing, radiation or space-flight data for muscovite mica were found in the sources read.
  - The Wikipedia values were read through a summarising fetch. The mica-group statement that mica is thermally stable to 500 degC is general to mica and is not muscovite-specific, so it is used only in the story text.
  - Abundance in the crust, critical-mineral list status and production shares by percentage were not found in the USGS page read.
  - No images were added.
sources:
  nist-rp347:
    title: Some Electrical Properties of Foreign and Domestic Micas and the Effect of Elevated Temperatures (NBS Research Paper RP347), A. B. Lewis, E. L. Hall and F. R. Caldwell
    url: https://nvlpubs.nist.gov/nistpubs/jres/7/jresv7n2p403_A2b.pdf
    year: 1931
    kind: paper
  rs-mica:
    title: RS PRO rigid mica sheet and muscovite mica insulation film datasheet (stock 134-940 and 785-0815)
    url: https://docs.rs-online.com/0045/A700000015993317.pdf
    kind: datasheet
  usgs-mcs2026-mica:
    title: 'USGS Mineral Commodity Summaries 2026: Mica (Natural)'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-mica.pdf
    year: 2026
    kind: report
  wiki-mica:
    title: 'Wikipedia: Mica'
    url: https://en.wikipedia.org/wiki/Mica
    kind: web
  wiki-muscovite:
    title: 'Wikipedia: Muscovite'
    url: https://en.wikipedia.org/wiki/Muscovite
    kind: web
  handbook-muscovite:
    title: 'Handbook of Mineralogy: Muscovite (Mineral Data Publishing, version 1.2)'
    url: https://www.handbookofmineralogy.org/pdfs/muscovite.pdf
    year: 2001
    kind: handbook
  niosh-mica:
    title: 'NIOSH Pocket Guide to Chemical Hazards: Mica (containing less than 1% quartz)'
    url: https://www.cdc.gov/niosh/npg/npgd0431.html
    kind: handbook
  osha-mica:
    title: 'OSHA Chemical Data: Mica (CAS 12001-26-2)'
    url: https://www.osha.gov/chemicaldata/153
    kind: database
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 17
  note: Written by an AI assistant on 2026-11-01 from the eight sources listed, using only numbers printed in those sources. Hazard entries use the NIOSH and OSHA mica entries, which list muscovite as a synonym.
story:
  recipe:
    line: Muscovite is a potassium aluminium silicate. Each formula unit, KAl2(AlSi3O10)(OH)2, holds one potassium atom, three aluminium atoms, three silicon atoms, twelve oxygen atoms and two hydrogen atoms, counted from the printed formula.
    parts:
      - name: Potassium
        symbol: K
        role: Sits between the silicate layers and balances the charge of the aluminium-silicate sheets.
      - name: Aluminium
        symbol: Al
        role: Two aluminium atoms sit in the octahedral sites and one in a tetrahedral site of the layered structure (formula grouping (AlSi3O10)).
      - name: Silicon
        symbol: Si
        role: Forms the silica tetrahedra of the layers with oxygen.
      - name: Oxygen
        symbol: O
        role: Ten oxygens in the silicate framework and two in the hydroxyl groups.
      - name: Hydrogen
        symbol: H
        role: Forms the two hydroxyl groups, (OH)2, in the printed formula.
  risk_groups:
    - title: For people
      level: 0
      verdict: Dust limits set by NIOSH and OSHA; no GHS data found
      lead: NIOSH and OSHA list mica (containing less than 1% quartz) with muscovite as a synonym. Neither page prints a GHS classification, and no safety data sheet for muscovite itself was found, so this profile cannot rate the powder beyond its dust limits.
      points:
        - label: The powder
          line: Keep dust below the respirable limit that NIOSH and OSHA set for mica, and check the supplier's safety data sheet for the grade you handle before cutting or grinding.
  why: Muscovite mica is a layered potassium aluminium silicate with the formula KAl2(AlSi3O10)(OH)2 (Wikipedia). It is the mica that electrical makers use most, and Wikipedia calls it the principal mica used by the electrical industry. NIST measured clear ruby muscovite at a dielectric constant of 7.2 and a power factor of 0.02 per cent at 25 degC, and those figures are the reference values in the 1931 study.
  uses:
    - where: Capacitor dielectric
      line: Wikipedia says only high-quality muscovite film mica, also called India ruby mica, is used as a dielectric in capacitors, and the highest grade is used in calibration-standard capacitors.
    - where: Electrical and electronic parts
      line: USGS says that most sheet mica was made into parts for electrical and electronic equipment, and that the United States relied on imports for sheet mica.
    - where: High-temperature insulation
      line: RS sells rigid mica sheet for thermal and electrical insulation, and lists a muscovite insulation film rated for 500 degC continuous and 800 degC intermittent.
  can_do:
    - label: Dielectric constant
      benchmark: dielectric_constant
      value: '7.2'
      line: NIST averaged 7.20 for 16 clear muscovite samples at 25 degC over 100 to 1,000 kilocycles, with individual samples varying by plus or minus 0.3.
    - label: Power factor
      benchmark: dissipation_factor
      value: 0.02 per cent
      line: NIST gives an average power factor of 0.02 per cent for the same clear muscovite, with individual samples varying by plus or minus 0.01 per cent.
    - label: Heat tolerance
      benchmark: max_service_temp
      value: 500 degC continuous
      line: RS rates its muscovite insulation film at 500 degC continuous and 800 degC intermittent. NIST found that most muscovite was unchanged after 30 minutes at 600 degC.
  compare: Muscovite mica is a low-loss, high-temperature dielectric. NIST measured its power factor at 0.02 per cent, and the RS datasheet rates the muscovite insulation film at 500 degC continuous. This profile holds mica values only, so it does not yet compare mica against other dielectrics. The compare table will fill in as the other dielectric profiles are written.
  compare_rows:
    - label: Dielectric constant
      benchmark: dielectric_constant
    - label: Power factor (dissipation factor)
      benchmark: dissipation_factor
    - label: Maximum service temperature
      benchmark: max_service_temp
  handling:
    - Keep the sheet free of stains and air bubbles if it is used for low-loss or radio work, because NIST found these raise the power factor.
    - Cut or punch the sheet as needed, since RS lists the rigid sheet as easy to cut or punch.
    - Keep dust below the respirable limit that NIOSH and OSHA set for mica, and check the supplier's safety data sheet for the grade you handle.
  good_for:
    - Low power loss at radio frequencies. NIST measured 0.02 per cent power factor for clear ruby muscovite.
    - High-temperature insulation. RS rates its muscovite insulation film at 500 degC continuous and 800 degC intermittent.
  watch_out:
    - Stained or bubbly mica. NIST found these raise the power factor too high for radio purposes.
    - Temperatures above 600 degC. NIST found that muscovites kept their properties less well than phlogopites above that temperature, and none withstood 1,200 degC well.
    - Species uncertainty in the RS sheet values. The RS sheet specifications are printed under the heading Muscovite Mica, but the stock item is named phlogopite, so confirm the species before design use.
  verdict: Muscovite mica is a well-measured, low-loss insulator for electrical and capacitor use up to about 500 degC. Its loss is strongly affected by stains and bubbles, and the RS sheet values need their species confirmed.