{
  "spore": "profile",
  "id": "rubidium",
  "spore_version": "0.2",
  "family": "alkali-metals",
  "name": "Rubidium",
  "abbreviation": "Rb",
  "role": "atomic clock reference metal",
  "category": "metals",
  "type": "heavy-metals",
  "summary": "Rubidium (Rb, CAS 7440-17-7) is a soft, silvery alkali metal with atomic number 37. An Alfa Aesar safety data sheet gives its density as 1.532 g/cm3 at 20 °C, and sources in this profile give its melting point as 38.9 °C, 39.31 °C and 39.5 °C. It reacts violently with water and tarnishes in air, so it is stored under dry inert gas. The USGS found no reported rubidium mine production worldwide in 2025, and its main use named in the source is as an atomic resonance-frequency reference, which is the basis of rubidium clocks flown on navigation satellites.",
  "best_for": "Atomic frequency references: rubidium clocks were flown on GPS Block IIR satellites and on the Galileo test satellite GIOVE-A (NASA-hosted paper; Airbus catalogue)",
  "weakest_at": "Handling: it reacts violently with water and tarnishes in air, and CAMEO Chemicals says it burns spontaneously in dry oxygen",
  "identity": {
    "formula": "Rb",
    "cas": "7440-17-7",
    "designations": [],
    "source": "pubchem-rb",
    "where": "PubChem compound record CID 5357696, section 2.3.1 (CAS)"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "electronics-and-chips",
      "optics-and-cameras"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density at 20 °C, Alfa Aesar safety data sheet",
      "value": 1.532,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "form": "solid metal, product 10315 (rubidium metal, 7440-17-7)",
        "temperature": "20 °C",
        "unit_in_source": "g/cm³"
      },
      "method": "Value printed in a supplier safety data sheet",
      "status": "ground",
      "source": "purdue-rb-sds",
      "where": "Section 9, Density at 20 °C (68 °F)",
      "source_detail": {
        "title": "Safety data sheet: Rubidium metal, Alfa Aesar product 10315 (copy hosted by Purdue University)",
        "id": "Alfa Aesar product 10315, CAS 7440-17-7",
        "url": "https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/rubidium%20metal%20%20-%20Alfa%2010315.pdf",
        "year": 2015,
        "kind": "datasheet",
        "license": "Supplier safety data sheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, element (Wolfram ElementData)",
      "value": 1.532,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "form": "solid metal",
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference data page that cites Mathematica ElementData",
      "status": "ground",
      "note": "Agrees with the safety data sheet value above.",
      "source": "periodictable-rb",
      "where": "Overview and Bulk physical properties, Density",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of solid (WebElements)",
      "value": 1532,
      "bound": "exact",
      "unit": "kg/m3",
      "scope": "material",
      "conditions": {
        "form": "solid metal",
        "temperature": "not stated on the page",
        "unit_in_source": "kg m‑3"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "note": "The same figure as 1.532 g/cm3 in other sources, in SI units.",
      "source": "webelements-rb",
      "where": "Density properties, Density of solid",
      "source_detail": {
        "title": "WebElements: Rubidium, physical properties",
        "id": "WebElements periodic table, element 37",
        "url": "https://www.webelements.com/rubidium/physics.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of liquid rubidium (Wolfram ElementData)",
      "value": 1.46,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "form": "liquid metal",
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "source": "periodictable-rb",
      "where": "Bulk physical properties, Density (Liquid)",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, Alfa Aesar safety data sheet",
      "value": 38.9,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "rubidium metal",
        "unit_in_source": "38.9 °C (102 °F)",
        "pressure": "not stated"
      },
      "method": "Value printed in a supplier safety data sheet",
      "status": "ground",
      "note": "Three sources give 38.9 °C, 39.31 °C and 39.5 °C. This profile keeps all three rather than choosing one.",
      "source": "purdue-rb-sds",
      "where": "Section 9, Melting point/Melting range",
      "source_detail": {
        "title": "Safety data sheet: Rubidium metal, Alfa Aesar product 10315 (copy hosted by Purdue University)",
        "id": "Alfa Aesar product 10315, CAS 7440-17-7",
        "url": "https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/rubidium%20metal%20%20-%20Alfa%2010315.pdf",
        "year": 2015,
        "kind": "datasheet",
        "license": "Supplier safety data sheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, Wolfram ElementData",
      "value": 39.31,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "rubidium metal",
        "pressure": "not stated"
      },
      "method": "Value printed on a reference data page that cites Mathematica ElementData",
      "status": "ground",
      "note": "See the safety data sheet value of 38.9 °C; the sources disagree by about one kelvin.",
      "source": "periodictable-rb",
      "where": "Overview and Thermal properties, Melting Point",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, PAC Chemical Database (via PubChem)",
      "value": 39.5,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "rubidium",
        "pressure": "not stated"
      },
      "method": "Value listed in the PubChem record, attributed to the U.S. DOE PAC Chemical Database",
      "status": "ground",
      "source": "pubchem-rb",
      "where": "Section 3.2.3 Melting Point",
      "source_detail": {
        "title": "PubChem compound record: Rubidium (CID 5357696)",
        "id": "PubChem CID 5357696; CAS 7440-17-7",
        "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Rubidium",
        "year": 2026,
        "kind": "database",
        "license": "Public database record (cited)"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, Wolfram ElementData",
      "value": 688,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "not stated on the page"
      },
      "method": "Value printed on a reference data page that cites Mathematica ElementData",
      "status": "ground",
      "source": "periodictable-rb",
      "where": "Overview and Thermal properties, Boiling Point",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, solid phase",
      "value": 364,
      "bound": "exact",
      "unit": "J/(kg K)",
      "scope": "material",
      "conditions": {
        "phase": "solid",
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference data page; the page notes it is given for the solid phase",
      "status": "ground",
      "source": "periodictable-rb",
      "where": "Thermal properties, Specific Heat",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity",
      "value": 58,
      "bound": "exact",
      "unit": "W/(m K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "note": "WebElements prints the same 58 W m-1 K-1.",
      "source": "periodictable-rb",
      "where": "Thermal properties, Thermal Conductivity",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus",
      "value": 2.4,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "note": "Wolfram ElementData prints the same 2.4 GPa.",
      "source": "webelements-rb",
      "where": "Elastic properties, Young's modulus",
      "source_detail": {
        "title": "WebElements: Rubidium, physical properties",
        "id": "WebElements periodic table, element 37",
        "url": "https://www.webelements.com/rubidium/physics.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus",
      "value": 2.5,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "source": "periodictable-rb",
      "where": "Bulk physical properties, Bulk Modulus",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "molar_mass",
      "label": "Molecular weight of the element (PubChem computed)",
      "value": 85.468,
      "bound": "exact",
      "unit": "g/mol",
      "scope": "material",
      "conditions": {
        "form": "Rb, element, computed from the isotope mix"
      },
      "method": "Computed value printed by PubChem 2.2 (release 2025.05.06)",
      "status": "calculated",
      "source": "pubchem-rb",
      "where": "Section 3.1 Computed Properties, Molecular Weight",
      "source_detail": {
        "title": "PubChem compound record: Rubidium (CID 5357696)",
        "id": "PubChem CID 5357696; CAS 7440-17-7",
        "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Rubidium",
        "year": 2026,
        "kind": "database",
        "license": "Public database record (cited)"
      }
    },
    {
      "benchmark": "isotopic_abundance",
      "label": "Mole fraction of rubidium-85 in natural rubidium",
      "value": 0.7217,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "isotope": "85Rb",
        "basis": "standard isotopic composition, mole fraction; uncertainty printed as (2)"
      },
      "method": "Value printed on the NIST atomic weights and isotopic compositions page",
      "status": "ground",
      "source": "nist-rb",
      "where": "Table of isotopes, row 85, Isotopic composition (mole fraction)",
      "source_detail": {
        "title": "NIST: Atomic weights and isotopic compositions, rubidium (Rb, atomic number 37)",
        "id": "NIST Physical Measurement Laboratory",
        "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Rb&all=all&ascii=html",
        "year": 2026,
        "kind": "database",
        "license": "U.S. government work (cited)"
      }
    },
    {
      "benchmark": "isotopic_abundance",
      "label": "Mole fraction of rubidium-87 in natural rubidium",
      "value": 0.2783,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "isotope": "87Rb",
        "basis": "standard isotopic composition, mole fraction; uncertainty printed as (2)"
      },
      "method": "Value printed on the NIST atomic weights and isotopic compositions page",
      "status": "ground",
      "source": "nist-rb",
      "where": "Table of isotopes, row 87, Isotopic composition (mole fraction)",
      "source_detail": {
        "title": "NIST: Atomic weights and isotopic compositions, rubidium (Rb, atomic number 37)",
        "id": "NIST Physical Measurement Laboratory",
        "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Rb&all=all&ascii=html",
        "year": 2026,
        "kind": "database",
        "license": "U.S. government work (cited)"
      }
    },
    {
      "benchmark": "atomic_number",
      "label": "Atomic number",
      "value": 37,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "element": "rubidium, Rb"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "source": "periodictable-rb",
      "where": "Overview, Atomic Number",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "first_ionization_energy",
      "label": "First ionization energy",
      "value": 403,
      "bound": "exact",
      "unit": "kJ/mol",
      "scope": "material",
      "conditions": {
        "basis": "first value of the ionization energy list printed on the page"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "source": "periodictable-rb",
      "where": "Reactivity, Ionization Energies (first entry of the list)",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "electronegativity",
      "label": "Electronegativity",
      "value": 0.82,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "scale": "scale not named on the page"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "source": "periodictable-rb",
      "where": "Reactivity, Electronegativity",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "atomic_radius",
      "label": "Atomic radius",
      "value": 265,
      "bound": "exact",
      "unit": "pm",
      "scope": "material",
      "conditions": {
        "basis": "as printed on the page; definition not stated"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "source": "periodictable-rb",
      "where": "Atomic dimensions and structure, Atomic Radius",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "lattice_constant",
      "label": "Lattice constant of the rubidium cell as printed",
      "value": 558.5,
      "bound": "exact",
      "unit": "pm",
      "scope": "material",
      "conditions": {
        "structure": "three equal constants with right angles printed; space group number 229 printed on the same page",
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "note": "PubChem lists a different cell for rubidium (from an older paper); the two are not reconciled here.",
      "source": "periodictable-rb",
      "where": "Atomic dimensions and structure, Lattice Constants",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "crustal_abundance",
      "label": "Abundance in Earth's crust as printed",
      "value": 0.006,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "percent in Earth's crust, as printed on the page"
      },
      "method": "Value printed on a reference data page",
      "status": "ground",
      "source": "periodictable-rb",
      "where": "Abundances, % in Earth's Crust",
      "source_detail": {
        "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
        "id": "Mathematica ElementData, Wolfram Research",
        "url": "https://periodictable.com/Elements/037/data.html",
        "year": 2026,
        "kind": "database",
        "license": "Cited, not reproduced"
      }
    },
    {
      "benchmark": "recoverable_reserves",
      "label": "World recoverable reserves of rubidium materials (USGS estimate)",
      "value": 200000,
      "bound": "upper",
      "unit": "tons",
      "scope": "material",
      "conditions": {
        "basis": "recoverable rubidium materials; USGS names Australia, Canada, China and Namibia as the countries estimated to hold them",
        "note": "printed as less than the figure"
      },
      "method": "Estimate printed in the USGS Mineral Commodity Summaries chapter",
      "status": "ground",
      "source": "usgs-mcs2026-rubidium",
      "where": "World Mine Production and Reserves",
      "source_detail": {
        "title": "Mineral Commodity Summaries 2026: Rubidium (U.S. Geological Survey, February 2026)",
        "id": "USGS Mineral Commodity Summaries, February 2026",
        "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rubidium.pdf",
        "year": 2026,
        "kind": "report",
        "license": "U.S. government work (cited)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Air at room temperature",
      "headline": "Rubidium tarnishes rapidly in air; no corrosion rate was found in any source opened.",
      "effect": "CAMEO Chemicals says rubidium tarnishes rapidly upon exposure to air, and PubChem's summary of the same source says it tarnishes in air. Neither gives a rate, a film thickness or a time scale, so none is recorded. The supplier safety data sheet asks for storage under dry inert gas and away from air.",
      "rating": "unknown",
      "conditions": {
        "exposure": "room-temperature air; humidity, time and temperature not stated"
      },
      "source": "cameo-rb",
      "where": "Air and Water Reactions (section 9.7.1)"
    },
    {
      "environment": "Liquid water and moist air",
      "headline": "Water is the severe case: the reaction gives corrosive rubidium hydroxide and flammable hydrogen.",
      "effect": "CAMEO Chemicals says rubidium reacts violently with water to form corrosive rubidium hydroxide and hydrogen, a flammable gas, and that the heat of the reaction usually ignites the hydrogen. The safety data sheet also lists a severe skin burn and eye damage hazard (H314).",
      "rating": "severe",
      "conditions": {
        "exposure": "contact with liquid water or moisture"
      },
      "source": "cameo-rb",
      "where": "Air and Water Reactions (section 9.7.1); Reactivity Alerts (section 9.7.3)"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem's GHS summary for rubidium lists H260 (in contact with water releases flammable gases which may ignite spontaneously) and H314 (causes severe skin burns and eye damage), with signal word Danger.",
        "ghs": [
          "H260",
          "H314"
        ],
        "source": "pubchem-rb",
        "where": "Section 9.1.1 GHS Classification"
      },
      {
        "text": "The Alfa Aesar safety data sheet (copy hosted by Purdue) gives the same two hazard statements, Danger, and the precautionary statement P231+P232, which reads 'Handle under inert gas. Protect from moisture.'",
        "ghs": [
          "H260",
          "H314"
        ],
        "source": "purdue-rb-sds",
        "where": "Section 2, GHS label elements"
      },
      {
        "text": "For fires involving rubidium, the Emergency Response Guidebook guide quoted by CAMEO Chemicals says do not use water or foam, and suggests dry chemical, dry sand or class D extinguishers for metal fires.",
        "ghs": [],
        "source": "cameo-rb",
        "where": "Fire Fighting and Emergency Response Planning (ERG Guide 138)"
      },
      {
        "text": "The Emergency Response Guidebook first-aid text says to wipe the metal off the skin at once and flush skin or eyes with running water.",
        "ghs": [],
        "source": "cameo-rb",
        "where": "First Aid, Specific First Aid (ERG Guide 138)"
      }
    ],
    "failure_risks": [
      {
        "mode": "Reaction with water or moist air",
        "trigger": "Water or humid air reaching the metal",
        "consequence": "Flammable hydrogen gas, usually ignited by the heat of the reaction, plus corrosive rubidium hydroxide (CAMEO Chemicals).",
        "severity": "high",
        "source": "cameo-rb",
        "where": "Air and Water Reactions (section 9.7.1)"
      },
      {
        "mode": "Spontaneous burning in dry oxygen",
        "trigger": "Exposure to dry oxygen; readily catches fire in air when molten",
        "consequence": "The metal burns spontaneously in dry oxygen, according to the CAMEO Chemicals reactivity profile reproduced in PubChem.",
        "severity": "high",
        "source": "pubchem-rb",
        "where": "Section 9.7.4, Reactivity Profile"
      },
      {
        "mode": "Tarnish in air",
        "trigger": "Exposure to air",
        "consequence": "A tarnish film forms on the metal; no thickness or rate is recorded in the sources opened.",
        "severity": "low",
        "source": "cameo-rb",
        "where": "Air and Water Reactions (section 9.7.1)"
      }
    ],
    "side_effects": [
      {
        "text": "Hydrogen and corrosive rubidium hydroxide are released when the metal reacts with water, and the hydrogen is flammable.",
        "affects": "Storage area and the people handling the metal",
        "source": "cameo-rb",
        "where": "Air and Water Reactions (section 9.7.1)"
      }
    ],
    "handling": [
      {
        "text": "Handle under dry protective gas, keep the container tightly sealed, and store under dry inert gas, away from water, moisture, air and oxidizing agents, according to the Alfa Aesar safety data sheet.",
        "source": "purdue-rb-sds",
        "where": "Section 7, Handling and storage"
      },
      {
        "text": "For a spill, cover with dry earth, dry sand or another non-combustible material and do not apply water, per the Emergency Response Guidebook guide quoted by CAMEO Chemicals.",
        "source": "cameo-rb",
        "where": "Nonfire Spill Response (section 9.5.1)"
      }
    ],
    "mitigations": [
      {
        "text": "Use dry chemical, dry sand, sodium chloride powder, graphite powder or class D extinguishers on metal fires (Emergency Response Guidebook guide quoted by CAMEO Chemicals).",
        "source": "cameo-rb",
        "where": "Emergency Response Planning, Fire Involving Metals or Powders"
      }
    ]
  },
  "uses": [
    {
      "application": "electronics-and-chips",
      "device": "Rubidium atomic frequency standard on navigation satellites",
      "example": "Airbus's catalogue entry says the Rubidium Atomic Frequency Standard was first flown on GIOVE-A, the Galileo test satellite, and has operated successfully since.",
      "source": "satcatalog-rafs",
      "where": "Overview of the component page"
    },
    {
      "application": "electronics-and-chips",
      "device": "GPS Block IIR navigation satellites",
      "example": "A NASA-hosted paper by Riley describes rubidium atomic frequency standards provided for the GPS Block IIR NAVSTAR satellites, which were to replenish and upgrade the space segment of the Global Positioning System.",
      "source": "ntrs-riley-1990",
      "where": "Abstract"
    },
    {
      "application": "optics-and-cameras",
      "device": "Photomultiplier tubes, night-vision devices and photoelectric cells",
      "example": "The USGS says rubidium's photoemissive properties make it useful for photomultiplier tubes, night-vision devices, photoelectric cells and spectrometers.",
      "source": "usgs-mcs2026-rubidium",
      "where": "Domestic Production and Use"
    }
  ],
  "supply": [
    {
      "subject": "Rubidium",
      "abundance": "Rubidium is not a major constituent of any mineral; the crustal abundance printed on the reference data page is in the properties list.",
      "producers": [],
      "critical_lists": [],
      "recycling": "USGS: Recycling: None.",
      "substitutes": [
        "USGS: rubidium and cesium can be used interchangeably in many applications because they have similar physical properties and atomic radii; cesium is more electropositive and is preferred for some applications."
      ],
      "source": "usgs-mcs2026-rubidium",
      "where": "Domestic Production and Use; World Mine Production and Reserves (the USGS prints that there were no official sources for rubidium production data in 2025, so no country shares are recorded); Recycling; Substitutes (Mineral Commodity Summaries, February 2026). Rubidium is a byproduct of pollucite (cesium) and lepidolite (lithium) mining, per the same chapter."
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Alfa Aesar safety data sheet, rubidium metal, product 10315 (copy hosted by Purdue University; last revision 2015)",
      "type": "sds",
      "url": "https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/rubidium%20metal%20%20-%20Alfa%2010315.pdf",
      "year": 2015
    },
    {
      "title": "PubChem: Rubidium, CID 5357696, GHS and computed properties",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Rubidium",
      "year": 2026
    },
    {
      "title": "CAMEO Chemicals: Rubidium (NOAA chemical 1439)",
      "type": "database",
      "url": "https://cameochemicals.noaa.gov/chemical/1439",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Rubidium",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rubidium.pdf",
      "year": 2026
    },
    {
      "title": "NIST: Atomic weights and isotopic compositions for rubidium",
      "type": "database",
      "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Rb&all=all&ascii=html",
      "year": 2026
    },
    {
      "title": "WebElements: Rubidium physical properties",
      "type": "database",
      "url": "https://www.webelements.com/rubidium/physics.html",
      "year": 2026
    },
    {
      "title": "Wolfram ElementData: Rubidium (periodictable.com)",
      "type": "database",
      "url": "https://periodictable.com/Elements/037/data.html",
      "year": 2026
    },
    {
      "title": "Airbus Rubidium Atomic Frequency Standard component entry (satcatalog.com)",
      "type": "database",
      "url": "https://www.satcatalog.com/component/rubidium-atomic-frequency-standard/",
      "year": 2026
    },
    {
      "title": "Rubidium atomic frequency standards for GPS Block IIR (NASA NTRS 19910016457)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/citations/19910016457",
      "year": 1990
    }
  ],
  "gaps": [
    "No flight, radiation, vacuum, outgassing or thermal-cycling result for rubidium metal was found in any source opened. The satellite-clock sources describe units, not the metal.",
    "Melting point is recorded from three sources that disagree (38.9, 39.31 and 39.5 °C); none is chosen as the reference value.",
    "Electrical resistivity and conductivity are printed with exponents on both data pages and were not recorded (exponent-form values).",
    "Mechanical strength of pure rubidium (yield, tensile, hardness in engineering units) was not found; the Mohs and Brinell figures on the reference page are not recorded because no canonical property name fits.",
    "PubChem lists a different crystal cell for rubidium from an older paper; the cubic cell in the properties is from Wolfram ElementData only, and the conflict is not resolved.",
    "The manufacturing process for rubidium metal was not described in any source opened, so the recipe gives composition only.",
    "No corrosion rate, film thickness or ageing time for rubidium in air or under inert gas was found; the corrosion rating for air is unknown.",
    "No country shares of production are recorded: the USGS states that there were no official sources for rubidium production data in 2025.",
    "The USGS chapter text read does not state whether rubidium is on a critical-minerals list, so critical_lists is empty.",
    "DTIC clock papers on the space rubidium clock for Galileo and on GPS rubidium clock life tests could not be opened (the pages returned a maintenance notice), so their design figures are not recorded.",
    "Several property names are not in spores/property-canon.yaml and were used as snake_case names: molar_mass, isotopic_abundance, atomic_number, first_ionization_energy, electronegativity, atomic_radius, lattice_constant, crustal_abundance and recoverable_reserves.",
    "No designations (UNS, EN, DIN, JIS) apply to the element; the CAS number is the identifier used."
  ],
  "story": {
    "why": "Rubidium is a soft, silvery alkali metal, and it is one of the reactive metals in its group. The USGS names its main use as an atomic resonance-frequency reference, the principle behind the rubidium clocks flown on navigation satellites. Specialty glass is the leading market for rubidium compounds according to the same USGS chapter, and the metal also appears in photomultiplier tubes, night-vision devices and catalysts. Rubidium is a byproduct of pollucite and lepidolite mining, not a primary product, so supply depends on those mines and on stockpiles.",
    "uses": [
      {
        "where": "Navigation satellite clocks",
        "line": "Airbus lists a Rubidium Atomic Frequency Standard that was first flown on GIOVE-A, the Galileo test satellite, with successful operation since then. A NASA-hosted paper by Riley describes rubidium atomic frequency standards provided for the GPS Block IIR satellites."
      },
      {
        "where": "Optical sensors",
        "line": "The USGS says rubidium's photoemissive properties make it useful for photomultiplier tubes, night-vision devices, photoelectric cells and spectrometers."
      }
    ],
    "can_do": [
      {
        "label": "Set a time reference",
        "line": "The USGS describes rubidium as an atomic resonance-frequency reference, the basis of the clocks flown for global positioning.",
        "scope": "material"
      },
      {
        "label": "Respond to light",
        "line": "Rubidium's photoemissive properties are used in photomultiplier tubes and night-vision devices, per the USGS.",
        "scope": "material"
      },
      {
        "label": "Stand in for cesium",
        "line": "The USGS says the two can be used interchangeably in many applications because of their similar physical properties and atomic radii.",
        "scope": "material"
      }
    ],
    "compare": "The USGS says rubidium and cesium can be used interchangeably in many applications, because they have similar physical properties and atomic radii, and that cesium is the more electropositive of the two and is preferred for some uses. Within this profile, the density of 1.532 g/cm3 and the melting point of 38.9 °C in the safety data sheet are the figures to set against other metals in the same table, and the table rows below use this profile's own values.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "handling": [
      "Store under dry inert gas in a tightly sealed container, away from water and oxidizing agents.",
      "Never use water on a rubidium fire or spill; cover spills with dry earth or dry sand.",
      "Wear protection against severe skin burns: the GHS statement H314 applies."
    ],
    "good_for": [
      "Timing: rubidium frequency standards were flown on navigation satellites, as the Airbus catalogue and the NASA-hosted paper describe.",
      "Specialty glass and optical devices: the USGS names specialty glass as the leading market, with photomultiplier tubes and night-vision devices."
    ],
    "watch_out": [
      "Reacts violently with water, forming flammable hydrogen and corrosive rubidium hydroxide.",
      "Tarnishes in air. No corrosion rate was found, so storage under inert gas is the only guidance in the sources.",
      "Supply: the USGS reports no official rubidium production data for 2025, and rubidium comes mainly from byproducts."
    ],
    "verdict": "Rubidium is a reactive alkali metal whose main documented use is as a frequency reference in navigation satellites. Its handling risk is high, and the sources in this profile give no space-environment data for the metal itself.",
    "recipe": {
      "line": "Rubidium is a single element, Rb, with atomic number 37, and it is an alkali metal. Natural rubidium is a mix of two isotopes: rubidium-85 with a mole fraction of 0.7217 and rubidium-87 with 0.2783, per the NIST table. No source opened for this profile describes how the metal is made.",
      "parts": [
        {
          "name": "Rubidium",
          "symbol": "Rb",
          "role": "The whole material. The element's mass is taken from PubChem's computed molecular weight, 85.468 g/mol.",
          "atoms": 1,
          "atomic_weight": 85.468
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "Rubidium is classed as a skin corrosive and as a water-reactive substance, so it is handled as a hazardous material.",
        "points": [
          {
            "label": "Skin and eyes",
            "line": "The safety data sheet and PubChem's GHS summary both give H314, causes severe skin burns and eye damage."
          },
          {
            "label": "Water",
            "line": "H260 means contact with water releases flammable gases which may ignite spontaneously. CAMEO Chemicals says the heat of the reaction usually ignites the hydrogen."
          },
          {
            "label": "First aid",
            "line": "The first-aid text quoted from the Emergency Response Guidebook says to wipe the metal off the skin at once and flush with running water."
          }
        ],
        "level": 2,
        "verdict": "Severe burns; reacts violently with water"
      },
      {
        "title": "If it reacts",
        "lead": "These are reactions the sources describe; no incident record was opened.",
        "points": [
          {
            "label": "Fire",
            "line": "Do not use water or foam on a rubidium fire. Use dry chemical, dry sand or class D extinguishers, as the Emergency Response Guidebook guide quoted by CAMEO Chemicals says."
          },
          {
            "label": "Burning",
            "line": "PubChem's reactivity profile, reproduced from CAMEO Chemicals, says the metal burns spontaneously in dry oxygen and catches fire in air when molten."
          }
        ],
        "level": 1,
        "verdict": "Fire needs a dry agent, not water"
      },
      {
        "title": "Handling and storage",
        "lead": "The supplier safety data sheet sets the storage rules.",
        "points": [
          {
            "label": "Storage",
            "line": "Handle under dry protective gas and keep the container tightly sealed. Store under dry inert gas, away from water, moisture, air and oxidizing agents."
          },
          {
            "label": "Spills",
            "line": "Cover a spill with dry earth, dry sand or another non-combustible material, and do not apply water."
          }
        ],
        "level": 0,
        "verdict": "Dry inert gas, sealed container"
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 22,
    "unreachable": 2,
    "caveats": 3,
    "note": "Read by an AI assistant on 2026-11-01 from the pages and PDFs named in each entry. verify-values found all 20 other values printed in their sources. Two PubChem values (melting point 39.5 °C and molar mass 85.468 g/mol) could not be re-checked by script because the PubChem page returns a browser-check shell to curl; they were read in a browser in this run. Caveats: the melting point disagrees across three sources and all three are kept; the PubChem page is JavaScript-rendered; the corrosion rating for air is unknown because no rate was found."
  },
  "sources": {
    "purdue-rb-sds": {
      "title": "Safety data sheet: Rubidium metal, Alfa Aesar product 10315 (copy hosted by Purdue University)",
      "id": "Alfa Aesar product 10315, CAS 7440-17-7",
      "url": "https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/rubidium%20metal%20%20-%20Alfa%2010315.pdf",
      "year": 2015,
      "kind": "datasheet",
      "license": "Supplier safety data sheet (cited, not reproduced)"
    },
    "pubchem-rb": {
      "title": "PubChem compound record: Rubidium (CID 5357696)",
      "id": "PubChem CID 5357696; CAS 7440-17-7",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Rubidium",
      "year": 2026,
      "kind": "database",
      "license": "Public database record (cited)"
    },
    "cameo-rb": {
      "title": "CAMEO Chemicals: Rubidium (NOAA chemical 1439), with Emergency Response Guidebook guide 138",
      "id": "UN 1423 (as printed on the record)",
      "url": "https://cameochemicals.noaa.gov/chemical/1439",
      "year": 2026,
      "kind": "database",
      "license": "NOAA public record (cited)"
    },
    "usgs-mcs2026-rubidium": {
      "title": "Mineral Commodity Summaries 2026: Rubidium (U.S. Geological Survey, February 2026)",
      "id": "USGS Mineral Commodity Summaries, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rubidium.pdf",
      "year": 2026,
      "kind": "report",
      "license": "U.S. government work (cited)"
    },
    "nist-rb": {
      "title": "NIST: Atomic weights and isotopic compositions, rubidium (Rb, atomic number 37)",
      "id": "NIST Physical Measurement Laboratory",
      "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Rb&all=all&ascii=html",
      "year": 2026,
      "kind": "database",
      "license": "U.S. government work (cited)"
    },
    "webelements-rb": {
      "title": "WebElements: Rubidium, physical properties",
      "id": "WebElements periodic table, element 37",
      "url": "https://www.webelements.com/rubidium/physics.html",
      "year": 2026,
      "kind": "database",
      "license": "Cited, not reproduced"
    },
    "periodictable-rb": {
      "title": "Wolfram ElementData: Technical data for Rubidium (periodictable.com)",
      "id": "Mathematica ElementData, Wolfram Research",
      "url": "https://periodictable.com/Elements/037/data.html",
      "year": 2026,
      "kind": "database",
      "license": "Cited, not reproduced"
    },
    "satcatalog-rafs": {
      "title": "Rubidium Atomic Frequency Standard (Airbus), component entry, satcatalog.com",
      "id": "Airbus Rubidium Atomic Frequency Standard",
      "url": "https://www.satcatalog.com/component/rubidium-atomic-frequency-standard/",
      "year": 2026,
      "kind": "database",
      "license": "Cited, not reproduced"
    },
    "ntrs-riley-1990": {
      "title": "Rubidium atomic frequency standards for GPS Block IIR (Riley, Edgerton, Germeshausen and Grier)",
      "id": "NASA NTRS citation 19910016457",
      "url": "https://ntrs.nasa.gov/citations/19910016457",
      "year": 1990,
      "kind": "paper",
      "license": "NASA public record (cited)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/rubidium/"
}