Ruthenium Ru

spore: profile
id: ruthenium
spore_version: 0.2
family: precious-metals
name: Ruthenium
abbreviation: Ru
role: hard platinum-group metal for chip interconnects and contacts
category: metals
type: precious-metals
summary: |
  Ruthenium is the pure metal Ru, atomic number 44, a hard and dense platinum-group metal. Wikipedia gives a density of 12.364 g/cm3 at 20 °C and a melting point of 2334 °C, and it is not attacked by acids, even aqua regia. It is recovered as a by-product of nickel, copper and platinum processing, and the USGS lists it as a critical mineral. Most use is in electronics, where a 2020 first-principles study finds that fcc ruthenium lines have lower resistance than copper below 21 nm line width. No flight or space test data were found for the metal.
best_for: Hard, dense electrical contacts and thin conducting layers where a very high melting point and acid resistance matter (Wikipedia, USGS)
weakest_at: 'Oxidation at high temperature: the source shows volatile RuO4 escaping from a thin film annealed at 600 °C in dry oxygen, and the metal is attacked by hypochlorite and halogens (Wikipedia)'
identity:
  formula: Ru (element, atomic number 44); refined sponge and powder under ASTM B717, grades 99.80 and 99.90
  cas: 7440-18-8
  source: wikipedia-ru
  where: Infobox, CAS number row
  designations:
    - system: ASTM
      code: B717
      note: Standard Specification for Refined Ruthenium, sponge and powder, grades 99.80 and 99.90
      source: astm-b717
      where: Title and scope sentence on the ASTM B717-23 listing page
tags:
  applications:
    - electronics-and-chips
properties:
  - benchmark: density
    label: Density, ruthenium at 20 °C (Wikipedia infobox)
    value: 12.364
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    source: wikipedia-ru
    where: Infobox, Density (at 20 °C) row
  - benchmark: density
    label: Density, solid ruthenium (WebElements)
    value: 12370
    unit: kg/m3
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-ru
    where: Physical properties page, row Density of solid
  - benchmark: density
    label: Density, ruthenium at 20 °C (Goodfellow)
    value: 12.2
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
      purity: 99.9% (3N)
    method: Value printed in a supplier product table for ruthenium rod
    status: ground
    note: Goodfellow is a supplier catalogue, not a manufacturer datasheet. The three density values differ by about 1 percent and are all recorded.
    source: goodfellow-ru
    where: Physical Properties table, Density row
  - benchmark: melting_point
    label: Melting point, ruthenium (Wikipedia infobox)
    value: 2334
    unit: °C
    scope: material
    conditions:
      unit_in_source: 2607 K (2334 °C, 4233 °F)
      pressure: not stated
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    source: wikipedia-ru
    where: Infobox, Melting point row
  - benchmark: melting_point
    label: Melting point, ruthenium (PubChem experimental property)
    value: 2334
    unit: °C
    scope: material
    conditions:
      form: element, CAS 7440-18-8
      pressure: not stated
    method: Experimental value listed in the PubChem record for the element
    status: ground
    note: PubChem also lists 2333 °C under a second experimental entry; that value is not entered.
    source: pubchem-ru
    where: Chemical and Physical Properties, Experimental Properties, Melting Point (2,334 °C)
  - benchmark: melting_point
    label: Melting point, ruthenium (Goodfellow)
    value: 2310
    unit: °C
    scope: material
    conditions:
      purity: 99.9% (3N)
    method: Value printed in a supplier product table for ruthenium rod
    status: ground
    note: The Goodfellow value is 24 °C below the Wikipedia and PubChem values; both are recorded.
    source: goodfellow-ru
    where: Thermal Properties table, Melting point row
  - benchmark: boiling_point
    label: Boiling point, ruthenium (Wikipedia infobox)
    value: 4150
    unit: °C
    scope: material
    conditions:
      unit_in_source: 4423 K (4150 °C, 7502 °F)
      pressure: not stated
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    source: wikipedia-ru
    where: Infobox, Boiling point row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, ruthenium (Wikipedia infobox)
    value: 117
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    source: wikipedia-ru
    where: Infobox, Thermal conductivity row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, ruthenium (WebElements)
    value: 120
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    note: WebElements gives 120 and Wikipedia and Goodfellow give 117; the difference is recorded, not resolved.
    source: webelements-ru
    where: Physical properties page, row Thermal conductivity
  - benchmark: electrical_resistivity
    label: Electrical resistivity, ruthenium at 0 °C (Wikipedia infobox)
    value: 71
    unit: nΩ·m
    scope: material
    conditions:
      temperature: 0 °C
      unit_in_source: 71 nΩ⋅m (at 0 °C)
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    source: wikipedia-ru
    where: Infobox, Electrical resistivity row
  - benchmark: electrical_resistivity
    label: Electrical resistivity, ruthenium at 20 °C (Goodfellow)
    value: 7.7
    unit: µΩ·cm
    scope: material
    conditions:
      temperature: 20 °C
      purity: 99.9% (3N)
    method: Value printed in a supplier product table for ruthenium rod
    status: ground
    note: The same 7.7 µΩ·cm is 7.7e-8 Ω·m; WebElements gives 7.1e-8 Ω·m without a temperature, and both are recorded.
    source: goodfellow-ru
    where: Electrical Properties table, Electrical resistivity row
  - benchmark: electrical_resistivity
    label: Electrical resistivity, fcc ruthenium bulk (ab initio, phonon-limited)
    value: 3.8
    unit: µΩ·cm
    scope: material
    conditions:
      phase: fcc
      basis: phonon-limited bulk resistivity from first-principles calculation
    method: Calculated in the cited arXiv paper, not measured
    status: calculated
    note: The same paper gives 11.1 µΩ·cm for hcp ruthenium in the same table and an experimental reference of 7.8 µΩ·cm for hcp ruthenium; the calculated fcc value is entered only.
    source: arxiv-ru-interconnect
    where: Table I, row Ru (fcc), column rho
  - benchmark: cte
    label: Coefficient of thermal expansion at 20 °C
    value: 6.78
    unit: ppm/K
    scope: material
    conditions:
      temperature: 20 °C
      unit_in_source: 6.78×10−6/K (at 20 °C)
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    source: wikipedia-ru
    where: Infobox, Thermal expansion row
  - benchmark: elastic_modulus
    label: Young's modulus, ruthenium (Wikipedia infobox)
    value: 447
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    source: wikipedia-ru
    where: Infobox, Young's modulus row
  - benchmark: shear_modulus
    label: Shear modulus, ruthenium (Wikipedia infobox)
    value: 173
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    source: wikipedia-ru
    where: Infobox, Shear modulus row
  - benchmark: bulk_modulus
    label: Bulk modulus, ruthenium (Wikipedia infobox)
    value: 220
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    note: Goodfellow gives 286 GPa for the same property; the two values differ and both are recorded.
    source: wikipedia-ru
    where: Infobox, Bulk modulus row
  - benchmark: bulk_modulus
    label: Bulk modulus, ruthenium (Goodfellow)
    value: 286
    unit: GPa
    scope: material
    conditions:
      purity: 99.9% (3N)
    method: Value printed in a supplier product table for ruthenium rod
    status: ground
    source: goodfellow-ru
    where: Mechanical Properties table, Bulk modulus row
  - benchmark: poissons_ratio
    label: Poisson's ratio, ruthenium
    value: 0.3
    unit: '-'
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the infobox of the Wikipedia article on ruthenium, with no unit or condition
    status: ground
    source: wikipedia-ru
    where: Infobox, Poisson ratio row
  - benchmark: mohs_hardness
    label: Mohs hardness, ruthenium
    value: 6.5
    unit: '-'
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the infobox of the Wikipedia article on ruthenium, with no unit
    status: ground
    note: mohs_hardness is not in the canonical property list.
    source: wikipedia-ru
    where: Infobox, Mohs hardness row
  - benchmark: brinell_hardness
    label: Brinell hardness, ruthenium (Wikipedia infobox)
    value: 2160
    unit: MPa
    scope: material
    conditions:
      temper: not stated
    method: Value printed in the infobox of the Wikipedia article on ruthenium
    status: ground
    note: brinell_hardness is not in the canonical property list.
    source: wikipedia-ru
    where: Infobox, Brinell hardness row
  - benchmark: vickers_hardness
    label: Vickers hardness, ruthenium hard temper (Goodfellow)
    value: 750
    unit: kgf/mm2
    scope: material
    conditions:
      temper: hard
      purity: 99.9% (3N)
    method: Value printed in a supplier product table for ruthenium rod
    status: ground
    note: vickers_hardness is not in the canonical property list.
    source: goodfellow-ru
    where: Mechanical Properties table, Vickers hardness row, column Hard
  - benchmark: vickers_hardness
    label: Vickers hardness, ruthenium soft temper (Goodfellow)
    value: 350
    unit: kgf/mm2
    scope: material
    conditions:
      temper: soft
      purity: 99.9% (3N)
    method: Value printed in a supplier product table for ruthenium rod
    status: ground
    note: vickers_hardness is not in the canonical property list.
    source: goodfellow-ru
    where: Mechanical Properties table, Vickers hardness row, column Soft
corrosion:
  - environment: Acids, including aqua regia
    headline: Ruthenium is not attacked by acids, even aqua regia, according to the Wikipedia summary.
    effect: The Wikipedia chemical-properties section gives this as the metal's acid resistance. No rate or concentration is stated.
    rating: low
    conditions:
      basis: encyclopaedia summary; concentrations not stated
    source: wikipedia-ru
    where: Chemical properties section
  - environment: Sodium hypochlorite and halogens at high temperature
    headline: Ruthenium is attacked by sodium hypochlorite and by halogens at high temperatures.
    effect: The Wikipedia summary names these attacks. It gives no temperature, rate or product for either.
    rating: moderate
    conditions:
      temperature: high, not stated
      basis: encyclopaedia summary; no measured rate
    source: wikipedia-ru
    where: Chemical properties section
  - environment: Dry oxygen at 600 °C (amorphous Ru-Si-O thin film)
    headline: In a thin Ru-Si-O film annealed in dry oxygen at 600 °C, RuO2 grains grew out of the film and volatile RuO4 escaped.
    effect: The paper studies a silicate thin film, not bulk ruthenium metal, so it shows oxide growth and RuO4 loss in that film only.
    rating: moderate
    conditions:
      temperature: 600 °C
      atmosphere: dry oxygen, 30 min anneal
      specimen: amorphous Ru-Si-O thin film
    source: caltech-ru-sio
    where: Abstract
risks:
  hazards:
    - text: 'PubChem reports ECHA C&L notifications for ruthenium: H228 flammable solid (49.9 %) and H413 may cause long lasting harmful effects to aquatic life (22.9 %). The signal word is Danger.'
      ghs:
        - H228
        - H413
      source: pubchem-ru
      where: Safety and Hazards, GHS Classification
    - text: The Chemicalbook safety data sheet for ruthenium (revision 2026-06-27) gives the signal word Danger and the codes H228 flammable solid, H252 self-heating in large quantities, H315 causes skin irritation, H319 causes serious eye irritation and H335 may cause respiratory irritation.
      ghs:
        - H228
        - H252
        - H315
        - H319
        - H335
      source: chemicalbook-ru-sds
      where: Section 2, Hazard statements
  failure_risks:
    - mode: Flammable solid
      trigger: Ruthenium metal handled as sponge or powder in air
      consequence: The SDS classifies the material as a flammable solid (H228), and PubChem's notifications carry the same code.
      severity: moderate
      source: chemicalbook-ru-sds
      where: Section 2, Hazard statements H228
    - mode: Self-heating
      trigger: Large quantities of the material
      consequence: The SDS lists H252 self-heating in large quantities; may catch fire.
      severity: moderate
      source: chemicalbook-ru-sds
      where: Section 2, Hazard statements H252
  side_effects:
    - text: Ruthenium price averaged 451.02 dollars per troy ounce in 2024 and an estimated 690 dollars in 2025, according to the USGS price table.
      affects: Cost of electronic contacts, resistors and research samples
      source: usgs-pgm-2026
      where: Salient Statistics, Price, dollars per troy ounce, Ruthenium row
  handling:
    - text: The SDS lists the material as combustible in Section 5 and as a flammable solid in Section 2.
      source: chemicalbook-ru-sds
      where: Sections 2 and 5
    - text: The SDS gives no fire-protection or storage instructions beyond its GHS classification.
      source: chemicalbook-ru-sds
      where: Sections 2 to 9
  mitigations: []
uses:
  - application: electronics-and-chips
    device: Ruthenium liner or conductor in advanced chip interconnects (calculation only)
    example: A first-principles study finds that the line resistance of fcc ruthenium is lower than that of copper below 21 nm line width, because copper loses conductor volume to adhesion and wetting liners.
    source: arxiv-ru-interconnect
    where: Abstract, last sentences
  - application: electronics-and-chips
    device: Electrical contacts and chip resistors in computers
    example: The USGS 2025 critical-minerals entry for ruthenium says it is used as catalysts, as well as electrical contacts and chip resistors in computers.
    source: usgs-crit-2025
    where: List entry for Ruthenium
supply:
  - subject: Abundance in the Earth's crust
    abundance: about 100 parts per trillion (Wikipedia, Occurrence section)
    producers: []
    total: Ruthenium is found mainly in ores alongside other platinum-group metals, including deposits in the Ural Mountains and in North and South America (Wikipedia, Occurrence).
    source: wikipedia-ru
    where: Occurrence section
  - subject: Ruthenium mine output
    producers: []
    total: The USGS 2026 platinum-group summary gives mine production only for palladium and platinum, so no ruthenium output figure is entered.
    source: usgs-pgm-2026
    where: Salient Statistics and World Mine Production and Reserves table
  - subject: United States ruthenium imports for consumption
    producers: []
    total: 'Imports in kilograms: 18,000 (2021), 13,300 (2022), 10,800 (2023), 9,780 (2024), and 14,000 (2025 estimated).'
    source: usgs-pgm-2026
    where: Salient Statistics, Imports for consumption, Ruthenium row
  - subject: Ruthenium recovery
    recycling: Ruthenium is recovered as a by-product of processing nickel, copper and platinum ores, collecting in the anode mud from electrorefining. No ruthenium recovery figure is given in the USGS summary.
    source: wikipedia-ru
    where: Production section
  - subject: Critical-mineral status
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: true
    source: usgs-crit-2025
    where: List entry for Ruthenium
  - subject: Substitution
    substitutes:
      - 'USGS: for some industrial end uses one platinum-group metal can substitute for another, but with losses in efficiency.'
    source: usgs-pgm-2026
    where: Substitutes paragraph
documents:
  - title: 'Wikipedia: Ruthenium'
    type: database
    url: https://en.wikipedia.org/wiki/Ruthenium
    year: 2026
  - title: 'Goodfellow: Ruthenium rod, 99.9% (3N), product group page'
    type: datasheet
    url: https://www.goodfellow.com/usa/ruthenium-rod-group
  - title: 'WebElements: Ruthenium physical properties'
    type: database
    url: https://webelements.co.uk/ruthenium/physics.html
  - title: PubChem compound record for the ruthenium element
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23950
  - title: 'Chemicalbook safety data sheet: ruthenium, revision 2026-06-27'
    type: sds
    url: https://www.chemicalbook.com/msds/ruthenium.htm
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Platinum-Group Metals'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-platinum-group.pdf
    year: 2026
  - title: USGS 2025 List of Critical Minerals (final list, 60 minerals)
    type: report
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
  - title: ASTM B717-23 Standard Specification for Refined Ruthenium (listing page)
    type: standard
    url: https://eshop.normservis.sk/norma/astm-b717-23-1.4.2023.html
    year: 2023
  - title: Philip et al., First principles evaluation of fcc ruthenium for use in advanced interconnects (arXiv 2001.02216)
    type: paper
    url: https://arxiv.org/pdf/2001.02216
    year: 2020
  - title: Instability of Amorphous Ru-Si-O Thin Films under Thermal Oxidation, J. Electrochem. Soc. 146(4), 1546-1548
    type: paper
    url: https://authors.library.caltech.edu/records/xm8cb-psc97
    year: 1999
gaps:
  - No ruthenium mine output or country shares were found. The USGS 2026 platinum-group summary gives mine production only for palladium and platinum, so the producers list is empty.
  - No UNS, EN, DIN, JIS or trade-name designation was found for ruthenium. A UNS search returned none, and the ASTM B717 page prints none. ASTM B717 is the only designation entered.
  - 'Melting point differs across sources: Wikipedia and PubChem give 2334 °C, Goodfellow gives 2310 °C. Both are recorded.'
  - 'Thermal conductivity differs: Wikipedia and Goodfellow give 117 W/(m·K), WebElements gives 120 W/(m·K) without a temperature. Both are recorded.'
  - 'Bulk modulus differs: Wikipedia gives 220 GPa and Goodfellow gives 286 GPa. Both are recorded.'
  - The ChemicalBook SDS gives a relative density of 12,45 g/mL with no temperature. It is a secondary listing and was not entered.
  - The PubChem density (12.1 at 25 °C) is printed without a unit, so it was not entered.
  - The ChemicalBook SDS and PubChem give different GHS codes (H252, H315, H319 and H335 in the SDS; H413 in PubChem). Both are recorded and the difference is not resolved.
  - No manufacturer datasheet for ruthenium (Heraeus, Johnson Matthey) was found in search. Goodfellow is a supplier catalogue, and the hardness values come only from it.
  - No space flight, vacuum, radiation or atomic-oxygen test data were found. A NASA search returned only iridium-coated rhenium thruster chambers, not ruthenium, so no environment tag is set.
  - Ruthenium-based dye sensitizers were found in open reviews, but they are compounds, not the metal, so they are not listed as a use.
  - The EU critical raw materials list was not checked for ruthenium.
  - Brinell and Mohs hardness and the Vickers rows are not in the canonical property list; short snake_case names are used as noted on each row.
sources:
  wikipedia-ru:
    title: Ruthenium (Wikipedia, English)
    url: https://en.wikipedia.org/wiki/Ruthenium
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  usgs-pgm-2026:
    title: Mineral Commodity Summaries 2026, Platinum-Group Metals
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-platinum-group.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit-2025:
    title: About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)
    id: Final 2025 List of Critical Minerals, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  webelements-ru:
    title: WebElements, Ruthenium physical properties
    url: https://webelements.co.uk/ruthenium/physics.html
    kind: database
    license: WebElements, University of Sheffield (cited, not reproduced)
  goodfellow-ru:
    title: Goodfellow, Ruthenium rod (99.9% 3N), product group
    url: https://www.goodfellow.com/usa/ruthenium-rod-group
    kind: datasheet
    license: supplier catalogue (cited, not reproduced)
  pubchem-ru:
    title: PubChem compound record, ruthenium element (CID 23950)
    id: CID 23950; CAS 7440-18-8
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23950/JSON
    kind: database
    license: public domain (NCBI)
  chemicalbook-ru-sds:
    title: Chemicalbook safety data sheet, ruthenium (revision 2026-06-27)
    url: https://www.chemicalbook.com/msds/ruthenium.htm
    year: 2026
    kind: datasheet
    license: supplier listing (cited, not reproduced)
  arxiv-ru-interconnect:
    title: First principles evaluation of fcc ruthenium for use in advanced interconnects (Philip et al., IBM Research and Synopsys)
    id: arXiv 2001.02216
    url: https://arxiv.org/pdf/2001.02216
    year: 2020
    kind: paper
    license: arXiv preprint (cited, not reproduced)
  caltech-ru-sio:
    title: Instability of Amorphous Ru-Si-O Thin Films under Thermal Oxidation (J. Electrochem. Soc. 146(4), 1546-1548)
    url: https://authors.library.caltech.edu/records/xm8cb-psc97
    year: 1999
    kind: paper
    license: Caltech authors record (cited, not reproduced)
  astm-b717:
    title: ASTM B717-23 Standard Specification for Refined Ruthenium (listing page)
    url: https://eshop.normservis.sk/norma/astm-b717-23-1.4.2023.html
    year: 2023
    kind: standard
    license: standard listing (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 22
  unreachable: 0
  caveats: 4
  note: 'Values were read by an AI assistant on 2026-10-26 from the pages named in each entry. The arXiv paper was read from a PDF download. Caveats: the melting point, thermal conductivity and bulk modulus sources disagree; the fcc resistivity is a calculation; the SDS and PubChem hazard codes differ.'
story:
  recipe:
    line: 'Ruthenium is a single-element metal (Ru, atomic number 44) with a hexagonal close-packed crystal structure (Wikipedia infobox). It is refined from platinum-group ore: the metals are dissolved, ruthenium is separated from osmium as volatile oxides, and ammonium ruthenium chloride is reduced with hydrogen to a powder (Wikipedia, Production).'
    parts:
      - name: Ruthenium
        symbol: Ru
        atoms: 1
        atomic_weight: 101.07
        role: The whole material. Wikipedia gives a standard atomic weight of 101.07 and lists it as a rare transition metal, usually a minor component of platinum ores.
  risk_groups:
    - title: For people
      level: 1
      verdict: Flammable solid in the SDS
      lead: The SDS and PubChem both list ruthenium as a flammable solid, and the SDS adds irritation codes. Little health data are given in the sources.
      points:
        - label: The metal
          line: The SDS lists H228 flammable solid, H252 self-heating in large quantities, H315 skin irritation, H319 serious eye irritation and H335 respiratory irritation, with the signal word Danger. PubChem notifications list H228 and H413.
        - label: Environment
          line: PubChem notifications give H413, which may cause long lasting harmful effects to aquatic life.
    - title: If it fails
      lead: These routes come from the SDS and from the high-temperature sources. None are from field incidents.
      points:
        - label: Oxidation
          line: In a thin Ru-Si-O film annealed in dry oxygen at 600 °C, RuO2 grew and volatile RuO4 escaped. This is a film result, not bulk metal.
        - label: Self-heating
          line: The SDS lists self-heating in large quantities, which may catch fire.
    - title: Handling and storage
      points:
        - label: Fire
          line: The SDS classes the metal as combustible in Section 5 and as a flammable solid in Section 2.
        - label: Storage
          line: The SDS gives no storage instructions beyond its GHS classification.
  why: Ruthenium is a hard, dense platinum-group metal. Wikipedia gives a density of 12.364 g/cm3 at 20 °C and a melting point of 2334 °C, and it is not attacked by acids, even aqua regia. Its electrical resistivity is 71 nΩ·m at 0 °C according to Wikipedia, and it is a minor by-product of platinum ores. Its main use is in electronics, where it is studied as a conductor and liner for advanced chip interconnects.
  uses:
    - where: Electronics and chips
      line: A first-principles study finds that fcc ruthenium lines have lower resistance than copper below 21 nm line width, because copper loses conductor volume to liners. This is a calculation, not a production result.
    - where: Electrical contacts and chip resistors
      line: The USGS 2025 critical-minerals list says ruthenium is used as catalysts, as well as electrical contacts and chip resistors in computers.
  can_do:
    - label: Stay solid at high heat
      value: 2334 °C melting point
      benchmark: melting_point
      line: Wikipedia and PubChem give 2334 °C. Goodfellow gives 2310 °C.
    - label: Dense and hard
      value: 12.364 g/cm3 density
      benchmark: density
      line: Wikipedia gives 12.364 g/cm3 at 20 °C. Goodfellow gives a Vickers hardness of 750 kgf/mm2 in the hard temper and 350 kgf/mm2 in the soft temper.
    - label: Conduct current
      value: 71 nΩ·m resistivity
      benchmark: electrical_resistivity
      line: Wikipedia gives 71 nΩ·m at 0 °C. Goodfellow gives 7.7 µΩ·cm at 20 °C.
    - label: Resist acid
      value: Not attacked by acids
      line: Wikipedia says the metal is not attacked by acids, even aqua regia, but is attacked by hypochlorite and halogens at high temperature.
  compare: Within this profile, the cited calculation puts fcc ruthenium at 3.8 µΩ·cm and hcp ruthenium at 11.1 µΩ·cm, in the same table. The measured resistivity values (71 nΩ·m at 0 °C in Wikipedia, 7.7 µΩ·cm at 20 °C in Goodfellow) are not directly comparable with the calculated ones. The thermal conductivity values disagree between sources, and the sources do not compare ruthenium with other platinum-group metals.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Treat the sponge and powder as a flammable solid (H228) and keep it away from ignition sources.
    - Expect self-heating in large quantities (H252), as the SDS warns.
    - The SDS lists serious eye irritation (H319) and skin irritation (H315).
  good_for:
    - Electrical contacts and thin conducting layers in electronics, as the USGS and the arXiv study describe.
    - Acid-resistant parts, since the metal is not attacked by acids, even aqua regia, according to Wikipedia.
  watch_out:
    - 'Oxidation at high temperature: volatile RuO4 escaped from a thin film annealed at 600 °C in dry oxygen.'
    - Flammable solid and self-heating in large quantities, according to the SDS.
    - Thermal conductivity and bulk modulus differ between sources, and these differences are not resolved.
    - No ruthenium mine output or country shares were found, so supply concentration is not known from these sources.
  verdict: Ruthenium is a hard, dense platinum-group metal that resists acids and has a very high melting point. Its main use is in electronics, where it is studied for chip interconnects and used in contacts and resistors. The SDS classes it as a flammable solid, and the sources do not give supply shares or any space test data.