{
  "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.\n",
  "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",
    "designations": [],
    "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,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "dissipation_factor",
      "label": "Power factor (dissipation factor), clear ruby muscovite",
      "value": 0.02,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "dielectric_strength",
      "label": "Dielectric strength, rigid mica sheet at 20 degC",
      "value": 20,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "dielectric_strength",
      "label": "Dielectric strength, rigid mica sheet at 400 degC",
      "value": 13,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "dielectric_strength",
      "label": "Dielectric strength, rigid mica sheet at 600 degC",
      "value": 10,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, rigid mica sheet at 20 degC",
      "value": 0.3,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Maximum service temperature, muscovite insulation film, continuous",
      "value": 500,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Maximum service temperature, muscovite insulation film, intermittent",
      "value": 800,
      "bound": "exact",
      "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)",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, rigid mica sheet",
      "value": 2,
      "value_high": 2.35,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, rigid mica sheet",
      "value": 110,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Flexural strength, rigid mica sheet",
      "value": 80,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "moisture_absorption",
      "label": "Water absorption, rigid mica sheet",
      "value": 0.5,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "heat_loss",
      "label": "Heat loss, rigid mica sheet at 500 degC",
      "value": 1.5,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "heat_loss",
      "label": "Heat loss, rigid mica sheet at 700 degC",
      "value": 2,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "compressive_strength_perpendicular",
      "label": "Compressive strength perpendicular, rigid mica sheet",
      "value": 200,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "compressive_strength_parallel",
      "label": "Compressive strength parallel, rigid mica sheet",
      "value": 50,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index range, muscovite (three principal indices)",
      "value": 1.552,
      "value_high": 1.618,
      "bound": "exact",
      "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)",
      "source_detail": {
        "title": "Handbook of Mineralogy: Muscovite (Mineral Data Publishing, version 1.2)",
        "url": "https://www.handbookofmineralogy.org/pdfs/muscovite.pdf",
        "year": 2001,
        "kind": "handbook"
      }
    }
  ],
  "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)"
    }
  ],
  "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"
      }
    ]
  },
  "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"
    }
  ],
  "supply": [
    {
      "subject": "Mica (natural), sheet and scrap or flake",
      "abundance": "Not found in the sources read for this profile.",
      "producers": [
        {
          "country": "China",
          "year": 2025
        },
        {
          "country": "Madagascar",
          "year": 2025
        },
        {
          "country": "Finland",
          "year": 2025
        },
        {
          "country": "India",
          "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)"
    }
  ],
  "media": [],
  "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."
  ],
  "story": {
    "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",
        "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.",
        "benchmark": "dielectric_constant",
        "scope": "material",
        "value": "7.2"
      },
      {
        "label": "Power factor",
        "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.",
        "benchmark": "dissipation_factor",
        "scope": "material",
        "value": "0.02 per cent"
      },
      {
        "label": "Heat tolerance",
        "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.",
        "benchmark": "max_service_temp",
        "scope": "material",
        "value": "500 degC continuous"
      }
    ],
    "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",
        "scope": "material"
      },
      {
        "label": "Power factor (dissipation factor)",
        "benchmark": "dissipation_factor",
        "scope": "material"
      },
      {
        "label": "Maximum service temperature",
        "benchmark": "max_service_temp",
        "scope": "material"
      }
    ],
    "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.",
    "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",
        "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."
          }
        ],
        "level": 0,
        "verdict": "Dust limits set by NIOSH and OSHA; no GHS data found"
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 17,
    "unreachable": 0,
    "caveats": 0,
    "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."
  },
  "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",
  "url": "https://spacemushroom.com/profiles/mica-muscovite/"
}