{
  "spore": "profile",
  "id": "magnesium-fluoride",
  "spore_version": "0.2",
  "family": "optical-crystals",
  "name": "Magnesium fluoride (single-crystal MgF2)",
  "abbreviation": "MgF2",
  "role": "VUV and UV optical crystal, and protective overcoat for aluminium mirrors",
  "category": "glasses-optics",
  "type": "optical-crystals",
  "summary": "Magnesium fluoride (MgF2) is a tetragonal optical crystal with a rutile structure. Crystran transmits it from 0.12 to 7 µm and says it passes the hydrogen Lyman-alpha line at 121 nm. Its density is 3.1766 g/cc at 25°C and its melting point is 1255°C on the Crystran data sheet, while the Crystran safety sheet prints 1248°C and PubChem prints 1263°C. NASA Goddard describes aluminium mirrors protected by an MgF2 layer, and the Hubble coating it cites uses a 25 nm MgF2 overcoat. The sources read give no space radiation or outgassing test for bulk MgF2.\n",
  "best_for": "Vacuum-ultraviolet and excimer-laser optics, and mirror overcoats that must pass the hydrogen Lyman-alpha line at 121 nm (Crystran; NASA Goddard)",
  "weakest_at": "Mechanical strength and cleavage: Crystran gives an apparent elastic limit of 49.6 MPa and says the crystal can cleave on the c-axis",
  "identity": {
    "formula": "MgF2",
    "cas": "7783-40-6",
    "crystal_system": "tetragonal",
    "space_group": "P42/mnm (#136), rutile structure",
    "designations": [],
    "source": "crystran-mgf2-datasheet",
    "where": "Class/Structure row (Tetragonal P42/mnm (#136) Rutile Structure); CAS 7783-40-6 from crystran-mgf2-msds section 3.1 and PubChem CID 24546"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "optics-and-cameras"
    ]
  },
  "properties": [
    {
      "benchmark": "transmission_range",
      "label": "Transmission range",
      "value": 0.12,
      "value_high": 7,
      "bound": "range",
      "unit": "µm",
      "scope": "material",
      "conditions": {
        "thickness": "not stated on the page"
      },
      "method": "Range printed in the Crystran data table; not a canonical property name",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Transmission Range row (0.12 to 7µm(1))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index, ordinary ray at 0.22 µm",
      "value": 1.413,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "wavelength": "0.22 µm",
        "ray": "ordinary (No)"
      },
      "method": "Value printed in the Crystran data table, which cites Laporte et al. (reference 4)",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Refractive Index row (No 1.413 at 0.22µm)",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index, extraordinary ray at 0.220 µm",
      "value": 1.426,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "wavelength": "0.220 µm",
        "ray": "extraordinary (Ne)"
      },
      "method": "Value printed in the Crystran refractive index table",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Refractive index table, row 0.220, Ne column",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index, ordinary ray at 5.000 µm",
      "value": 1.334,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "wavelength": "5.000 µm",
        "ray": "ordinary (No)"
      },
      "method": "Value printed in the Crystran refractive index table",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Refractive index table, row 5.000, No column",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "reststrahlen_peak",
      "label": "Reststrahlen peak",
      "value": 20,
      "bound": "exact",
      "unit": "µm",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed in the Crystran data table; not a canonical property name",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Reststrahlen Peak row (20µm (1))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density",
      "value": 3.1766,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "25 °C",
        "unit_in_source": "g/cc"
      },
      "method": "Value printed on the Crystran data sheet",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Density row (3.1766g/cc at 25°C)",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, safety sheet (specific gravity)",
      "value": 3.18,
      "bound": "exact",
      "unit": "g/mL",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Printed as SPECIFIC GRAVITY in the Crystran safety sheet; a rounded value, and it differs from the data sheet",
      "status": "ground",
      "source": "crystran-mgf2-msds",
      "where": "Section 9.1, SPECIFIC GRAVITY row",
      "source_detail": {
        "title": "Crystran: Safety Data Sheet, Magnesium Fluoride Optical Crystal (REACH format, revision 2026)",
        "id": "Revision 2026, issued 6 July 2026; CAS 7783-40-6; EC 231-995-1",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-msds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, data sheet",
      "value": 1255,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "single crystal"
      },
      "method": "Value printed on the Crystran data sheet; the safety sheet prints a different value (see the next melting point row)",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Melting Point row (1255°C)",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, safety sheet",
      "value": 1248,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "magnesium fluoride optical crystal, no temperature stated"
      },
      "method": "Value printed in the Crystran safety sheet, section 9.1",
      "status": "ground",
      "source": "crystran-mgf2-msds",
      "where": "Section 9.1, MELTING POINT row (1248C)",
      "source_detail": {
        "title": "Crystran: Safety Data Sheet, Magnesium Fluoride Optical Crystal (REACH format, revision 2026)",
        "id": "Revision 2026, issued 6 July 2026; CAS 7783-40-6; EC 231-995-1",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-msds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, experimental entry",
      "value": 1263,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "magnesium fluoride, no grade given"
      },
      "method": "Experimental property entry in the PubChem record for CID 24546",
      "status": "ground",
      "source": "pubchem-24546",
      "where": "Chemical and Physical Properties > Experimental Properties > Melting Point (1263 °C)",
      "source_detail": {
        "title": "PubChem compound record, Magnesium fluoride, CID 24546",
        "id": "CID 24546; F2Mg; CAS 7783-40-6; EC 231-995-1; molecular weight 62.302 (computed)",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24546/JSON",
        "year": 2026,
        "kind": "database",
        "license": "public domain (NCBI)"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, safety sheet",
      "value": 2260,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "760 mmHg"
      },
      "method": "Value printed in the Crystran safety sheet, section 9.1",
      "status": "ground",
      "source": "crystran-mgf2-msds",
      "where": "Section 9.1, BOILING POINT (760mm Hg) row (2260C)",
      "source_detail": {
        "title": "Crystran: Safety Data Sheet, Magnesium Fluoride Optical Crystal (REACH format, revision 2026)",
        "id": "Revision 2026, issued 6 July 2026; CAS 7783-40-6; EC 231-995-1",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-msds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, experimental entry",
      "value": 2227,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "760 mmHg"
      },
      "method": "Experimental property entry in the PubChem record for CID 24546",
      "status": "ground",
      "source": "pubchem-24546",
      "where": "Chemical and Physical Properties > Experimental Properties > Boiling Point (2227 °C @760 [mm Hg])",
      "source_detail": {
        "title": "PubChem compound record, Magnesium fluoride, CID 24546",
        "id": "CID 24546; F2Mg; CAS 7783-40-6; EC 231-995-1; molecular weight 62.302 (computed)",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24546/JSON",
        "year": 2026,
        "kind": "database",
        "license": "public domain (NCBI)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, parallel to the optic axis",
      "value": 21,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "orientation": "parallel (para)",
        "temperature": "300 K",
        "unit_in_source": "W m-1 K-1 at 300K"
      },
      "method": "Value printed on the Crystran data sheet, which cites Kashnow and McCarthy (reference 3)",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Thermal Conductivity row (21 (para))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, perpendicular to the optic axis",
      "value": 33.6,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "orientation": "perpendicular (perp)",
        "temperature": "300 K",
        "unit_in_source": "W m-1 K-1 at 300K"
      },
      "method": "Value printed on the Crystran data sheet, which cites Kashnow and McCarthy (reference 3)",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Thermal Conductivity row (33.6 (perp))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity",
      "value": 1003,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page",
        "unit_in_source": "J Kg m-1 K-1 as printed"
      },
      "method": "Value printed on the Crystran data sheet; the printed unit has an extra m and is read here as the usual J/(kg·K)",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Specific Heat Capacity row",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Dielectric constant, parallel to the optic axis",
      "value": 4.87,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "orientation": "parallel (para)",
        "frequency": "1 MHz"
      },
      "method": "Value printed on the Crystran data sheet, which cites reference 1 (Duncanson et al. 1958)",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Dielectric Constant row (4.87 (para) 5.45 (perp) at 1MHz)",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Dielectric constant, perpendicular to the optic axis",
      "value": 5.45,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "orientation": "perpendicular (perp)",
        "frequency": "1 MHz"
      },
      "method": "Value printed on the Crystran data sheet, which cites reference 1 (Duncanson et al. 1958)",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Dielectric Constant row (5.45 (perp))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus",
      "value": 138,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on the Crystran data sheet, which cites Kandil et al. 1981 (reference 2)",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Youngs Modulus (E) row (138 GPa (2))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "shear_modulus",
      "label": "Shear modulus",
      "value": 54.66,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on the Crystran data sheet, which cites reference 2",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Shear Modulus (G) row (54.66GPa (2))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus",
      "value": 101.32,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on the Crystran data sheet, which cites reference 2",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Bulk Modulus (K) row (101.32 GPa (2))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "label": "Poisson ratio",
      "value": 0.276,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on the Crystran data sheet, which cites reference 2",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Poisson Ratio row (0.276 (2))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "apparent_elastic_limit",
      "label": "Apparent elastic limit",
      "value": 49.6,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on the Crystran data sheet (7200 psi also printed); not a canonical property name",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Apparent Elastic Limit row (49.6 MPa (7200 psi))",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "water_solubility",
      "label": "Solubility in water",
      "value": 0.0002,
      "bound": "exact",
      "unit": "g/100 g water",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on the Crystran data sheet; not a canonical property name",
      "status": "ground",
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Solubility row (0.0002g/100g water)",
      "source_detail": {
        "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
        "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "uv_cutoff_wavelength",
      "label": "Short-wavelength cutoff, typical deposited MgF2 thin film (not the Crystran crystal)",
      "value": 115,
      "bound": "exact",
      "unit": "nm",
      "scope": "material",
      "conditions": {
        "form": "deposited thin film, as a typical value in the JPL table",
        "band_energy_in_source": "10 – 11 eV"
      },
      "method": "Value printed in a JPL table of typical deposited thin films for UV optical applications; it is not a measurement of the Crystran crystal and is recorded only as a thin-film reference",
      "status": "ground",
      "source": "jpl-balasubramanian-2016",
      "where": "Protective layers slide, table Properties of Typical Deposited Thin Films for UV Optical Applications, magnesium fluoride row (~λ Cut Off (nm) 115)",
      "source_detail": {
        "title": "Balasubramanian (JPL / Caltech): Mirror Coatings for large aperture UV to IR Telescopes, HabEx Technology Meeting slides",
        "id": "JPL HabEx Technology Meeting, 3 August 2016",
        "url": "https://www.jpl.nasa.gov/habex/documents/Aug2016/Balasubramanian-Mirror-Coatings-Technology.pdf",
        "year": 2016,
        "kind": "report",
        "license": "JPL slides, linked not reproduced"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Strong mineral acids",
      "headline": "Magnesium fluoride reacts with strong mineral acids, and the decomposition product is hydrogen fluoride gas.",
      "effect": "The Crystran safety sheet lists strong mineral acids as reacting with the material and as incompatible, and it names hydrogen fluoride gas as the decomposition product. No rate or concentration is printed, so the rating is qualitative.",
      "rating": "moderate",
      "conditions": {
        "basis": "qualitative reactivity statement; no rate or concentration printed",
        "agent": "strong mineral acids"
      },
      "source": "crystran-mgf2-msds",
      "where": "Sections 10.1, 10.5 and 10.6"
    },
    {
      "environment": "Water, room temperature",
      "headline": "Magnesium fluoride is practically insoluble in water.",
      "effect": "The data sheet gives a solubility of 0.0002 g per 100 g of water, and the safety sheet calls the material practically insoluble (section 9.1). No dissolution or corrosion test is printed.",
      "rating": "low",
      "conditions": {
        "note": "solubility figure, not a corrosion rate; temperature not stated"
      },
      "source": "crystran-mgf2-datasheet",
      "where": "Data table, Solubility row; crystran-mgf2-msds section 9.1"
    },
    {
      "environment": "Storage and handling of aluminium mirrors overcoated with MgF2",
      "headline": "An aluminium mirror with an MgF2 overcoat, made in 2011, fell to about 65% average reflectance in the 110 to 170 nm range after poor handling.",
      "effect": "NASA Goddard says plasma treatment restored that sample to a pristine value of 85% in the 110 to 170 nm range, and its summary gives 84% in the 115 to 170 nm range for a six-year-old sample. The paper does not separate MgF2 ageing from handling damage.",
      "rating": "moderate",
      "conditions": {
        "basis": "reflectance of an aluminium mirror with an MgF2 overcoat, not of bulk MgF2",
        "period": "six years"
      },
      "source": "nasa-quijada-2018",
      "where": "Section 4.1 (Al+MgF2 paragraph) and the closing summary paragraph"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "The Crystran safety sheet (revision 2026, issued 6 July 2026) gives H315 (causes skin irritation), H319 (causes serious eye irritation) and H332 (harmful if inhaled), with the signal word Warning.",
        "ghs": [
          "H315",
          "H319",
          "H332"
        ],
        "source": "crystran-mgf2-msds",
        "where": "Sections 2.1 and 2.2"
      },
      {
        "text": "PubChem's aggregated GHS summary for magnesium fluoride lists H315, H319 and H335 (May cause respiratory irritation) from ECHA notifications, and notes that the chemical does not meet GHS hazard criteria in 168 of 498 company reports.",
        "ghs": [
          "H315",
          "H319",
          "H335"
        ],
        "source": "pubchem-24546",
        "where": "Safety and Hazards > Hazards Identification > GHS Classification"
      },
      {
        "text": "The same safety sheet says the material is toxic by ingestion and by inhalation of dust, with a cumulative effect, that it affects the nervous system, and that its oral LD50 in rats is above 2330 mg/kg.",
        "ghs": [],
        "source": "crystran-mgf2-msds",
        "where": "Section 11.1"
      },
      {
        "text": "The occupational exposure limit is 2.5 mg/m3 long term, expressed as fluoride, in both the Crystran safety sheet and PubChem.",
        "ghs": [],
        "source": "crystran-mgf2-msds",
        "where": "Section 8.1, OEL row; PubChem gives the same 2.5 mg/m3 as F in its Permissible Exposure Limit row"
      },
      {
        "text": "Strong mineral acids release hydrogen fluoride gas from this material, according to the safety sheet decomposition statement.",
        "ghs": [],
        "source": "crystran-mgf2-msds",
        "where": "Section 10.6"
      }
    ],
    "failure_risks": [
      {
        "mode": "Optic-axis orientation (slight birefringence)",
        "trigger": "Window cut with the optic axis at an angle to the faces",
        "consequence": "The data sheet says the material is slightly birefringent and is usually supplied with the optic axis perpendicular to the window faces, so a window cut another way changes the polarisation of light.",
        "severity": "low",
        "source": "crystran-mgf2-datasheet",
        "where": "Introduction text, first paragraph"
      },
      {
        "mode": "Cleavage on the c-axis",
        "trigger": "Mechanical stress or impact on a crystal or polished piece",
        "consequence": "The data sheet says the crystal can cleave on the c-axis, but not easily, and gives an apparent elastic limit of 49.6 MPa.",
        "severity": "low",
        "source": "crystran-mgf2-datasheet",
        "where": "Class/Structure row; Apparent Elastic Limit row"
      },
      {
        "mode": "Reflectance loss of an overcoated aluminium mirror",
        "trigger": "Long storage or poor handling of an Al+MgF2 mirror",
        "consequence": "NASA Goddard reports an aluminium mirror with an MgF2 overcoat that fell to about 65% average reflectance over time, and plasma treatment restored it.",
        "severity": "moderate",
        "source": "nasa-quijada-2018",
        "where": "Section 4.1"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Wear PVA gloves, a laboratory coat and safety goggles or glasses where chipping or dust may occur; provide general mechanical and local exhaust ventilation; wash hands after handling.",
        "source": "crystran-mgf2-msds",
        "where": "Section 8.1, Exposure controls"
      },
      {
        "text": "Avoid generating dust, and take up broken pieces into containers for disposal.",
        "source": "crystran-mgf2-msds",
        "where": "Sections 6.1, 6.3 and 7.1"
      },
      {
        "text": "Keep away from foodstuffs and strong acids.",
        "source": "crystran-mgf2-msds",
        "where": "Section 7.2"
      }
    ],
    "mitigations": [
      {
        "text": "Specify the optic-axis orientation when ordering windows; the usual cut has the optic axis perpendicular to the faces.",
        "source": "crystran-mgf2-datasheet",
        "where": "Introduction text, first paragraph"
      },
      {
        "text": "Crystran normally cuts and orients windows with the c-axis normal to the surface, which is said to give minimum birefringence.",
        "source": "crystran-mgf2-web",
        "where": "Product page, text under the Applications paragraph"
      }
    ]
  },
  "uses": [
    {
      "application": "optics-and-cameras",
      "device": "UV optics and excimer-laser windows",
      "example": "Crystran says magnesium fluoride is used mostly for UV optics and is excellent for excimer laser applications.",
      "source": "crystran-mgf2-datasheet",
      "where": "Applications text, first paragraph"
    },
    {
      "application": "optics-and-cameras",
      "device": "Aluminium mirror overcoat for space ultraviolet instruments",
      "example": "NASA Goddard describes aluminium mirrors protected by an MgF2 overcoat, and gives the pre-launch Hubble (HST) coating as an aluminium layer with an MgF2 overcoat of 25 nm.",
      "source": "nasa-quijada-2018",
      "where": "Section 2.1, paragraph after the Figure 1 reference"
    },
    {
      "application": "optics-and-cameras",
      "device": "Typical deposited metal-fluoride UV coating",
      "example": "A JPL table of typical deposited thin films for UV optical applications lists magnesium fluoride with a cutoff near 115 nm.",
      "source": "jpl-balasubramanian-2016",
      "where": "Protective layers slide, Properties of Typical Deposited Thin Films table"
    }
  ],
  "supply": [
    {
      "subject": "Fluorine feedstock, fluorspar (the mineral form of calcium fluoride)",
      "abundance": "USGS: world mine production of fluorspar was 10,000 thousand tons in 2025, and world reserves are 330,000 thousand tons, of which China holds 110,000 thousand tons. The USGS chapter says aqueous HF is the primary feedstock for virtually all fluorine-bearing chemicals, but it does not name magnesium fluoride.",
      "producers": [
        {
          "country": "China",
          "share_percent": 60,
          "year": 2025
        },
        {
          "country": "Mongolia",
          "share_percent": 15,
          "year": 2025
        },
        {
          "country": "Mexico",
          "share_percent": 15,
          "year": 2025
        },
        {
          "country": "South Africa",
          "share_percent": 4.1,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 final critical minerals list, as summarised by CRS report IF13145 (fluorspar listed)",
          "listed": true
        }
      ],
      "recycling": "USGS: synthetic fluorspar may be produced from waste neutralisation in uranium enrichment, petroleum alkylation and stainless-steel pickling, but undesirable impurities constrain its use.",
      "substitutes": [
        "USGS: fluosilicic acid has been used as an alternative to fluorspar in the production of AlF3 and HF."
      ],
      "source": "usgs-mcs2026-fluorspar",
      "where": "World Mine Production and Reserves table, 2025 column (China 6,000; Mongolia 1,500; Mexico 1,500; South Africa 410; world total 10,000 thousand tons). Shares are calculated as country value divided by the printed world total. Recycling and Substitutes text."
    },
    {
      "subject": "Magnesium feedstock (magnesium compounds)",
      "abundance": "USGS: most U.S. magnesium compounds were produced from seawater and natural brines in 2025. World magnesite mine production was 21,000 thousand tons in 2025, with China at 12,700 thousand tons. USGS prints no production figure for magnesium fluoride.",
      "producers": [],
      "critical_lists": [],
      "substitutes": [],
      "source": "usgs-mcs2026-magnesium-compounds",
      "where": "Domestic Production and Use paragraph; World Magnesite Mine Production table, 2025 column"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (undated PDF, data table and refractive index table)",
      "type": "datasheet",
      "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
      "year": 2026
    },
    {
      "title": "Crystran: Safety Data Sheet, Magnesium Fluoride Optical Crystal (revision 2026, issued 6 July 2026)",
      "type": "sds",
      "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-msds.pdf",
      "year": 2026
    },
    {
      "title": "PubChem: Magnesium fluoride, CID 24546, compound record (pug_view JSON)",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24546/JSON",
      "year": 2026
    },
    {
      "title": "Quijada et al.: E-beam generated plasma etching for developing high-reflectance mirrors for far-ultraviolet astronomical instrument applications (NASA NTRS 20180005725)",
      "type": "paper",
      "url": "https://ntrs.nasa.gov/api/citations/20180005725/downloads/20180005725.pdf",
      "year": 2018
    },
    {
      "title": "Balasubramanian (JPL): Mirror Coatings for large aperture UV to IR Telescopes, HabEx Technology Meeting, 3 August 2016",
      "type": "report",
      "url": "https://www.jpl.nasa.gov/habex/documents/Aug2016/Balasubramanian-Mirror-Coatings-Technology.pdf",
      "year": 2016
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Fluorspar",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Magnesium Compounds",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-magnesium-compounds.pdf",
      "year": 2026
    },
    {
      "title": "Congressional Research Service: U.S. Geological Survey's Critical Minerals List (IF13145)",
      "type": "report",
      "url": "https://www.everycrsreport.com/reports/IF13145.html",
      "year": 2026
    }
  ],
  "gaps": [
    "Thermal expansion is printed as 13.7 (para) and 8.9 (perp) times 10 to the minus 6 per K. Because the printed form uses an exponent, these values are left out of the record.",
    "The absorption coefficient is printed with a 10 to the minus 3 exponent, so it is left out.",
    "Refractive index change with temperature (dn/dT) is printed as 2.3 (para) and 1.7 (perp) at 0.4 µm without a unit, so it is not entered.",
    "Knoop hardness is printed as 415 without a unit, so it is not entered.",
    "The molecular weight is printed as 62.32 without a unit on the data sheet, and PubChem gives 62.302 without a unit, so neither is entered.",
    "PubChem's experimental density of 3.148 at 25 °C has no unit printed, so it is not entered.",
    "The three melting points differ: 1255 °C on the data sheet, 1248 °C on the safety sheet and 1263 °C in PubChem. All three are recorded, and the data sheet value is used for the headline.",
    "No outgassing (TML or CVCM), ground radiation, UV ageing or atomic-oxygen result for bulk MgF2 was found in a source we could open.",
    "A 2011 mirror result is the only ageing data read from a fetched source. A search summary mentions a 30-month humidity study of Al+MgF2 mirrors, but its full text was not opened, so its figures are not used.",
    "The 115 nm cutoff is a typical value for a deposited thin film in the JPL table. No cutoff for the Crystran crystal itself is printed beyond the 0.12 µm transmission limit.",
    "The data sheet prints the specific heat unit as J Kg m-1 K-1 and gives no temperature. The value is recorded with the unit read as J/(kg·K), and this is noted in the method.",
    "The fluorspar and magnesium compound USGS chapters do not name magnesium fluoride, so no MgF2 production statistic was found. The supply shares are for fluorspar, the fluorine feedstock, and are calculated from printed totals.",
    "Only Crystran's sheets were read for the grade. No other supplier's data sheet or safety sheet was opened.",
    "PubChem's H335 comes from aggregated ECHA notifications. The Crystran safety sheet does not list H335, so the two hazard lists are shown side by side and not merged.",
    "PubChem lists Irtran 1 as a depositor-supplied synonym. Neither the Crystran sheets nor the Crystran page print it, and the verify script cannot read it from the PubChem JSON page, so no designation is entered.",
    "No media (photograph or drawing with a licence) was checked for this profile."
  ],
  "story": {
    "why": "Magnesium fluoride is a tetragonal optical crystal that transmits from 0.12 to 7 µm, with a refractive index of 1.413 at 0.22 µm (Crystran). It passes the hydrogen Lyman-alpha line at 121 nm, and NASA Goddard uses an MgF2 overcoat to keep aluminium far-ultraviolet mirrors reflective. The Hubble coating it cites has a 25 nm MgF2 overcoat.",
    "uses": [
      {
        "where": "UV optics and excimer lasers",
        "line": "Crystran says magnesium fluoride is used mostly for UV optics and is excellent for excimer laser applications."
      },
      {
        "where": "Space telescope mirror overcoats",
        "line": "NASA Goddard's 2018 paper gives the pre-launch Hubble (HST) coating as an aluminium layer with a 25 nm MgF2 overcoat, and lists GSFC coating work on COSTAR, GHRS, STIS and COS and optics for FUSE."
      },
      {
        "where": "Lyman-alpha optics",
        "line": "Crystran says the crystal transmits well into the VUV to the hydrogen Lyman-alpha line at 121 nm and beyond."
      }
    ],
    "can_do": [
      {
        "label": "Range",
        "line": "Crystran's data table gives a transmission range of 0.12 to 7 µm.",
        "benchmark": "transmission_range",
        "scope": "material"
      },
      {
        "label": "Refraction",
        "line": "Refractive index 1.413 for the ordinary ray at 0.22 µm, and 1.334 for the ordinary ray at 5.000 µm, per the Crystran refractive index table.",
        "benchmark": "refractive_index",
        "scope": "material"
      },
      {
        "label": "Heat",
        "line": "Thermal conductivity is 21 W/(m·K) parallel and 33.6 W/(m·K) perpendicular to the optic axis at 300 K, per the Crystran data table.",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Stiffness",
        "line": "Young's modulus 138 GPa and bulk modulus 101.32 GPa, per the Crystran data table.",
        "benchmark": "elastic_modulus",
        "scope": "material"
      },
      {
        "label": "Mirror reflectance",
        "line": "NASA Goddard reports that plasma treatment restored an aged Al+MgF2 mirror to 85% average reflectance in the 110 to 170 nm range.",
        "scope": "material"
      }
    ],
    "compare": "The JPL 2016 HabEx slides list magnesium fluoride among typical deposited thin films for UV optical applications, with a cutoff near 115 nm, and place it between aluminium fluoride and calcium fluoride in their table. That table gives thin-film values, not bulk crystal values. For far-ultraviolet mirrors, NASA Goddard works with MgF2 and LiF overcoats and with AlF3 passivation, and its 2018 paper extends the work to AlF3. The sources read give no side-by-side ground or space test of the three fluorides, and the melting points of magnesium fluoride differ between its own sheets and PubChem.",
    "compare_rows": [
      {
        "label": "Heat conduction",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Stiffness",
        "benchmark": "elastic_modulus",
        "scope": "material"
      }
    ],
    "handling": [
      "Wear PVA gloves, a laboratory coat and safety goggles or glasses where chipping or dust may occur, and use general and local exhaust ventilation (safety sheet section 8.1).",
      "Avoid generating dust, and take up broken pieces into containers for disposal (safety sheet sections 6.1 and 6.3).",
      "Keep away from foodstuffs and strong acids (safety sheet section 7.2)."
    ],
    "good_for": [
      "Vacuum-ultraviolet and excimer-laser optics, using the highest-purity grades (Crystran).",
      "Protective overcoats on aluminium far-ultraviolet mirrors, where the MgF2 layer stops the aluminium oxidising (NASA Goddard).",
      "Optics in water-exposed settings where low solubility matters, with a solubility of 0.0002 g per 100 g of water (Crystran)."
    ],
    "watch_out": [
      "Optic axis. The crystal is slightly birefringent, so windows are usually cut with the optic axis perpendicular to the faces.",
      "Acids. Strong mineral acids react with magnesium fluoride and release hydrogen fluoride gas.",
      "Mirror ageing. An aluminium mirror with an MgF2 overcoat fell to about 65% reflectance after poor handling and was restored by plasma treatment (NASA Goddard).",
      "No space test. No radiation, outgassing or atomic-oxygen result for bulk magnesium fluoride was found in the sources read."
    ],
    "verdict": "Magnesium fluoride is a tetragonal crystal that transmits into the vacuum ultraviolet, and Crystran supplies it for UV and excimer-laser optics. NASA Goddard's coating work shows that MgF2 overcoats protect aluminium far-ultraviolet mirrors, but the sources read give no space test of bulk MgF2 itself.",
    "recipe": {
      "line": "Magnesium fluoride is the compound MgF2, with one magnesium atom and two fluorine atoms per formula unit. Crystran grows it as a single crystal by the vacuum Stockbarger technique in ingots of various diameters, and the crystal has a tetragonal rutile structure.",
      "parts": [
        {
          "name": "Magnesium",
          "symbol": "Mg",
          "role": "The metal. One atom per formula unit, from the formula MgF2 (PubChem lists the molecular formula as F2Mg).",
          "source": "pubchem-24546",
          "where": "Names and Identifiers > Molecular Formula (F2Mg)"
        },
        {
          "name": "Fluorine",
          "symbol": "F",
          "role": "The halogen. Two atoms per formula unit, from the same formula.",
          "source": "pubchem-24546",
          "where": "Names and Identifiers > Molecular Formula (F2Mg)"
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The Crystran safety sheet (revision 2026) gives H315, H319 and H332 with the signal word Warning. PubChem's aggregated summary also lists H335.",
        "points": [
          {
            "label": "Dust",
            "line": "The sheet gives an occupational limit of 2.5 mg/m3 long term, expressed as fluoride, and says to avoid generating dust."
          },
          {
            "label": "Toxicity",
            "line": "The sheet says the material is toxic by ingestion and by inhalation of dust, with a cumulative effect, and gives an oral LD50 above 2330 mg/kg in rats."
          }
        ],
        "level": 1,
        "verdict": "Harmful if inhaled; irritating to skin and eyes"
      },
      {
        "title": "If it fails",
        "lead": "The failure results come from the Crystran data sheet and the NASA mirror paper. No flight failure record was read.",
        "points": [
          {
            "label": "Cleavage",
            "line": "The data sheet says the crystal can cleave on the c-axis, but not easily."
          },
          {
            "label": "Mirror ageing",
            "line": "An aluminium mirror with an MgF2 overcoat, made in 2011, fell to about 65% average reflectance in the 110 to 170 nm range after poor handling. Plasma treatment restored it to 85% (NASA Goddard)."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Protective equipment",
            "line": "PVA gloves, a laboratory coat, safety goggles or glasses where chipping or dust may occur, and mechanical and local exhaust ventilation."
          },
          {
            "label": "Incompatible materials",
            "line": "Strong mineral acids react with the material and release hydrogen fluoride gas, according to the safety sheet."
          }
        ],
        "gap": "The sheets give no storage temperature or humidity limit."
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 24,
    "unreachable": 0,
    "caveats": 4,
    "note": "Written by an AI assistant on 2026-11-01 from the Crystran data sheet and safety sheet (revision 2026), PubChem CID 24546, the NASA Goddard 2018 paper on FUV mirror coatings, the JPL 2016 HabEx coating slides, and the USGS 2026 fluorspar and magnesium compounds chapters, with the CRS IF13145 summary for the critical list. Caveats: the MgF2 record is for one supplier's crystal; the melting and boiling points disagree across sources; the 115 nm cutoff is a thin-film value; thermal expansion and the absorption coefficient are left out because they are printed with exponents."
  },
  "sources": {
    "crystran-mgf2-datasheet": {
      "title": "Crystran: Magnesium Fluoride (MgF2) materials data sheet (data table, refractive index table, transmission curves)",
      "id": "magnesium-fluoride-mgf2-data-sheet.pdf (undated; pages 68 and 69)",
      "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-data-sheet.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "crystran-mgf2-msds": {
      "title": "Crystran: Safety Data Sheet, Magnesium Fluoride Optical Crystal (REACH format, revision 2026)",
      "id": "Revision 2026, issued 6 July 2026; CAS 7783-40-6; EC 231-995-1",
      "url": "https://www.crystran.com/wp-content/uploads/2025/09/magnesium-fluoride-mgf2-msds.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "crystran-mgf2-web": {
      "title": "Crystran: Magnesium Fluoride (MgF2) product page",
      "id": "product page; the Lyman-alpha, excimer and Stockbarger text is read here",
      "url": "https://www.crystran.com/optical-materials/magnesium-fluoride-mgf2",
      "year": 2026,
      "kind": "web",
      "license": "supplier web page, linked not reproduced"
    },
    "pubchem-24546": {
      "title": "PubChem compound record, Magnesium fluoride, CID 24546",
      "id": "CID 24546; F2Mg; CAS 7783-40-6; EC 231-995-1; molecular weight 62.302 (computed)",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/24546/JSON",
      "year": 2026,
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "nasa-quijada-2018": {
      "title": "Quijada, Boris, del Hoyo, Wollack, Kozen, Walton and Dwivedi: E-beam generated plasma etching for developing high-reflectance mirrors for far-ultraviolet astronomical instrument applications (NASA GSFC and NRL)",
      "id": "NASA NTRS citation 20180005725",
      "url": "https://ntrs.nasa.gov/api/citations/20180005725/downloads/20180005725.pdf",
      "year": 2018,
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    },
    "jpl-balasubramanian-2016": {
      "title": "Balasubramanian (JPL / Caltech): Mirror Coatings for large aperture UV to IR Telescopes, HabEx Technology Meeting slides",
      "id": "JPL HabEx Technology Meeting, 3 August 2016",
      "url": "https://www.jpl.nasa.gov/habex/documents/Aug2016/Balasubramanian-Mirror-Coatings-Technology.pdf",
      "year": 2016,
      "kind": "report",
      "license": "JPL slides, linked not reproduced"
    },
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      "title": "Mineral Commodity Summaries 2026, Fluorspar (USGS, Vanessa Londono)",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf",
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      "kind": "report",
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    },
    "usgs-mcs2026-magnesium-compounds": {
      "title": "Mineral Commodity Summaries 2026, Magnesium Compounds (USGS, Vanessa Londono)",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-magnesium-compounds.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "crs-if13145": {
      "title": "Congressional Research Service: U.S. Geological Survey's Critical Minerals List (IF13145)",
      "id": "IF13145; 2025 final list published 7 November 2025",
      "url": "https://www.everycrsreport.com/reports/IF13145.html",
      "year": 2026,
      "kind": "report",
      "license": "CRS report, linked not reproduced"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/magnesium-fluoride/"
}