Scandium Sc

spore: profile
id: scandium
spore_version: 0.2
family: rare-earth-metals
name: Scandium
abbreviation: Sc
role: aluminium alloying element for aerospace parts, with smaller uses in solid oxide fuel cells and metal-halide lamps
category: metals
type: heavy-metals
summary: |
  Scandium is the element Sc (atomic number 21), a silvery-white metal that is usually classed as a rare-earth element. The metal has a density of 2.99 g/cm3 at 25 °C in a 2023 supplier safety data sheet and a melting point of 1541 °C in the Wikipedia infobox. It is not rare in the Earth's crust, with an estimate of 18 to 25 ppm, but it is spread thinly and produced only as a byproduct, at about 80 tonnes of scandium oxide in 2025 according to USGS. Its main use is a small addition of 0.1 to 0.5 % scandium to aluminium alloys for aerospace parts. The metal is a flammable solid: fine powder, thin foil and turnings ignite, and it releases flammable hydrogen on contact with water and dilute acids.
best_for: Aluminium-scandium alloys for aerospace parts, where a small scandium addition refines grain and strengthens welds (Wikipedia; Zaki Ahmad, JOM 2003)
weakest_at: 'Availability and price: about 80 tonnes of oxide a year worldwide in 2025, and a scandium metal ingot price of 5,200 dollars per kg (USGS)'
identity:
  formula: Sc (element, atomic number 21); sold as lump, foil, pieces, powder and as 99.9 % to 99.999 % metal
  cas: 7440-20-2
  crystal_system: hexagonal close-packed (hP2)
  source: pubchem-sc
  where: Other Identifiers, CAS entry (PubChem CID 23952); the Wikipedia infobox gives the crystal structure as hexagonal close-packed (hP2) with a = 330.89 pm and c = 526.80 pm at 20 °C
tags:
  environments: []
  applications:
    - structures
properties:
  - benchmark: density
    label: Density, scandium (Wikipedia, at 20 °C)
    value: 2.989
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
      purity: not stated
    method: Value printed in the Wikipedia infobox, which cites a reference for it
    status: ground
    source: wiki-sc
    where: Infobox, row Density (at 20° C) 2.989 g/cm3
  - benchmark: density
    label: Density, scandium metal (supplier SDS)
    value: 2.99
    unit: g/cm3
    scope: material
    conditions:
      temperature: 25 °C
      purity: not stated
    method: Value printed in a supplier safety data sheet, Section 9 (physical and chemical properties)
    status: ground
    source: chemos-sc-sds
    where: Section 9, row Density, 2.99 g/cm³ at 25 °C
  - benchmark: density
    label: Density of solid, scandium (WebElements)
    value: 2985
    unit: kg/m3
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page, row Density of solid, in the unit printed there
    status: ground
    source: webelements-sc
    where: Density properties, row Density of solid 2985 kg m-3
  - benchmark: melting_point
    label: Melting point, scandium (Wikipedia)
    value: 1541
    unit: °C
    scope: material
    conditions:
      pressure: not stated
      unit_in_source: 1814 K (1541 °C, 2806 °F)
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wiki-sc
    where: Infobox, row Melting point 1814 K (1541 °C, 2806 °F)
  - benchmark: melting_point
    label: Melting point/freezing point, scandium (supplier SDS)
    value: 1540
    unit: °C
    scope: material
    conditions:
      pressure: not stated
      purity: not stated
    method: Value printed in a supplier safety data sheet, Section 9
    status: ground
    source: chemos-sc-sds
    where: Section 9, row Melting point/freezing point 1,540 °C
  - benchmark: melting_point
    label: Melting point, scandium foil (Lesker SDS)
    value: 1541
    unit: °C
    scope: material
    conditions:
      form: metal foil
      pressure: not stated
    method: Value printed in a 1995 supplier safety data sheet, Section III
    status: ground
    source: lesker-sc-sds
    where: Section III, Physical Data, row Melting Point (oC) 1541
  - benchmark: boiling_point
    label: Boiling point, scandium (Wikipedia)
    value: 2836
    unit: °C
    scope: material
    conditions:
      pressure: not stated
      unit_in_source: 3109 K (2836 °C, 5136 °F)
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wiki-sc
    where: Infobox, row Boiling point 3109 K (2836 °C, 5136 °F)
  - benchmark: boiling_point
    label: Boiling point, scandium foil (Lesker SDS)
    value: 2831
    unit: °C
    scope: material
    conditions:
      pressure: 760 mmHg
      unit_in_source: 2831 @ 760mmHg
    method: Value printed in a 1995 supplier safety data sheet, Section III, with the label Boiling Point (0oC) as printed
    status: ground
    note: The Lesker sheet prints 2831 and the Wikipedia infobox and Chemos sheet print 2836 °C. The sources differ by 5 °C, so both are kept.
    source: lesker-sc-sds
    where: Section III, Physical Data, row Boiling Point (0oC) 2831 @ 760mmHg
  - benchmark: thermal_conductivity
    label: Thermal conductivity, scandium (Wikipedia)
    value: 15.8
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated in the infobox
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wiki-sc
    where: Infobox, row Thermal conductivity 15.8 W/(m⋅K)
  - benchmark: thermal_conductivity
    label: Thermal conductivity, scandium (WebElements)
    value: 16
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-sc
    where: Heat and conduction, row Thermal conductivity 16 W m-1 K-1
  - benchmark: cte
    label: Coefficient of thermal expansion, scandium (Wikipedia, average)
    value: 9.97
    unit: ppm/K
    scope: material
    conditions:
      temperature: 20 °C
      crystal_form: hexagonal close-packed; average of the a and c axis values (alpha_V/3, footnote a)
      unit_in_source: 9.97×10−6/K
    method: Value printed in the Wikipedia infobox row Thermal expansion; the footnote gives the anisotropic axis values 7.98 (a) and 13.94 (c) at 20 °C, so the average is axis-dependent
    status: ground
    source: wiki-sc
    where: Infobox, row Thermal expansion 9.97×10−6/K (at 20 °C); footnote a
  - benchmark: cte
    label: Coefficient of linear thermal expansion, scandium (WebElements)
    value: 10.2
    unit: ppm/K
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-sc
    where: Heat and conduction, row Coefficient of linear thermal expansion 10.2 × 10-6 K-1
  - benchmark: elastic_modulus
    label: Young's modulus, scandium (Wikipedia)
    value: 74.4
    unit: GPa
    scope: material
    conditions:
      temperature: not stated in the infobox
      material_condition: polycrystalline, as printed
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wiki-sc
    where: Infobox, row Young's modulus 74.4 GPa
  - benchmark: elastic_modulus
    label: Young's modulus, scandium (WebElements)
    value: 74
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-sc
    where: Elastic properties, row Young's modulus 74 GPa
  - benchmark: shear_modulus
    label: Shear modulus, scandium (Wikipedia)
    value: 29.1
    unit: GPa
    scope: material
    conditions:
      temperature: not stated in the infobox
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wiki-sc
    where: Infobox, row Shear modulus 29.1 GPa
  - benchmark: shear_modulus
    label: Rigidity modulus, scandium (WebElements)
    value: 29
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-sc
    where: Elastic properties, row Rigidity modulus 29 GPa
  - benchmark: bulk_modulus
    label: Bulk modulus, scandium (Wikipedia)
    value: 56.6
    unit: GPa
    scope: material
    conditions:
      temperature: not stated in the infobox
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wiki-sc
    where: Infobox, row Bulk modulus 56.6 GPa
  - benchmark: bulk_modulus
    label: Bulk modulus, scandium (WebElements)
    value: 57
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-sc
    where: Elastic properties, row Bulk modulus 57 GPa
  - benchmark: poissons_ratio
    label: Poisson's ratio, scandium (Wikipedia)
    value: 0.279
    unit: '-'
    scope: material
    conditions:
      temperature: not stated in the infobox
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wiki-sc
    where: Infobox, row Poisson ratio 0.279
  - benchmark: poissons_ratio
    label: Poisson's ratio, scandium (WebElements)
    value: 0.28
    unit: '-'
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page, printed with no units
    status: ground
    source: webelements-sc
    where: Elastic properties, row Poisson's ratio 0.28 (no units)
  - benchmark: brinell_hardness
    label: Brinell hardness range, scandium (Wikipedia)
    value: 736
    value_high: 1200
    unit: MPa
    scope: material
    conditions:
      temperature: not stated
      note_on_range: the infobox gives a range, not a single test value
    method: Range printed in the Wikipedia infobox
    status: ground
    note: No canonical name exists for hardness in the property file, so brinell_hardness is a new name and is listed in gaps.
    source: wiki-sc
    where: Infobox, row Brinell hardness 736–1200 MPa
  - benchmark: brinell_hardness
    label: Brinell hardness, scandium (WebElements)
    value: 750
    unit: MPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page as MN m-2, which equals MPa
    status: ground
    note: No canonical name exists for hardness, so brinell_hardness is a new name and is listed in gaps.
    source: webelements-sc
    where: Hardnesses, row Brinell hardness 750 MN m-2
  - benchmark: electrical_resistivity
    label: Electrical resistivity, scandium alpha polycrystal (calculated)
    value: 562
    unit: nΩ·m
    scope: material
    conditions:
      form: alpha, polycrystalline
      temperature: room temperature
      basis: calculated, as printed
    method: Value printed in the Wikipedia infobox, row Electrical resistivity, which says calculated
    status: ground
    source: wiki-sc
    where: Infobox, row Electrical resistivity, alpha poly 562 nΩ⋅m (at r.t., calculated)
  - benchmark: specific_heat
    label: Specific heat capacity, scandium (Wikipedia)
    value: 567.666
    unit: J/(kg·K)
    scope: material
    conditions:
      temperature: not stated in the infobox
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wiki-sc
    where: Infobox, row Specific heat capacity 567.666 J/(kg·K)
corrosion:
  - environment: Air at room temperature, bulk metal
    headline: Bulk scandium only tarnishes slowly in air, with a yellowish or pinkish cast.
    effect: Wikipedia says scandium is a soft metal that is susceptible to weathering and develops a slightly yellowish or pinkish cast when oxidized by air. No rate of oxide growth was given in the sources read.
    rating: low
    conditions:
      atmosphere: air
      form: bulk metal
      temperature: room temperature
    source: wiki-sc
    where: Properties, Chemical characteristics, first paragraph
  - environment: Air as turnings, fines, powder or thin foil
    headline: Fine forms ignite in air.
    effect: Wikipedia says scandium turnings ignite in the air with a brilliant yellow flame to form scandium oxide. The Lesker sheet calls the powder or thin foil a flammable solid. Apollo says metal dust fires are slow moving but intense and can reignite.
    rating: severe
    conditions:
      form: turnings, fines, powder, dust or thin foil
      temperature: not stated
    source: wiki-sc
    where: Properties, Chemical characteristics, last sentence; Lesker Section III Other Comments; Apollo Section 5.1 and fire section
  - environment: Water and dilute acids
    headline: Scandium reacts with water and dilute acids to release hydrogen.
    effect: The Lesker sheet says scandium reacts with water and dilute acids to produce flammable explosive hydrogen gas. Wikipedia says it dissolves slowly in most dilute acids. The Lesker sheet prints the reaction with water as NA, so no rate was given.
    rating: moderate
    conditions:
      acid: dilute, not named
      temperature: not stated
    source: lesker-sc-sds
    where: Section III, Other Comments; Wikipedia Chemical characteristics, first paragraph
  - environment: Mixture of 1:1 nitric acid and 48.0 % hydrofluoric acid
    headline: Scandium is passive in a nitric and hydrofluoric acid mixture.
    effect: Wikipedia says scandium does not dissolve in a 1:1 mixture of nitric acid and 48.0 % hydrofluoric acid, possibly because an impermeable passive layer forms.
    rating: low
    conditions:
      acid: 1:1 HNO3 with 48.0 % HF
      temperature: not stated
    source: wiki-sc
    where: Properties, Chemical characteristics, first paragraph
  - environment: Halogens, strong oxidizers, acid chlorides and chlorates
    headline: Scandium is incompatible with halogens and strong oxidizers.
    effect: The Lesker sheet lists air, strong acids, strong oxidizing agents, acid chlorides, halogens, chlorates, bromates and iodates as materials to avoid, and gives hydrogen as the hazardous decomposition product. The Chemos sheet gives no incompatible materials in Section 10.5.
    rating: severe
    conditions:
      atmosphere: halogen vapour or strong oxidizer
      temperature: not stated
    source: lesker-sc-sds
    where: Section VII Reactivity Data, Incompatibility (materials to avoid)
  - environment: 3.5 wt.% NaCl solution, Al-Sc alloy (not scandium metal)
    headline: Al-Sc and Al-Mg-Sc alloys corrode at 0.02 to 0.05 mm/year in salt solution.
    effect: Table IV of the 2003 review gives corrosion rates in 3.5 wt.% NaCl of 0.023 mm/year for Al-2.5Sc, 0.031 mm/year for Al-2.5Mg-0.10Sc, 0.046 mm/year for Al-2.5Mg-0.15Sc and 0.038 mm/year for Al-2.5Mg-0.30Sc. The review says the alloys show good corrosion resistance typical of Al-Mg alloys such as 5456 and 6061.
    rating: low
    conditions:
      electrolyte: 3.5 wt.% NaCl
      alloy: Al-Sc and Al-Mg-Sc, not scandium metal
      test: test duration not given in Table IV as read
    source: jom-al-sc
    where: Table IV, Corrosion Rates of Al-Mg-Sc Alloys in 3.5 wt.% NaCl; Corrosion Behavior section
  - environment: Scalmalloy powder alloy, supplier description
    headline: The supplier says Scalmalloy is corrosion-resistant.
    effect: ASM International's product page says Scalmalloy is corrosion-resistant and offers exceptionally high corrosion resistance. The page gives no test conditions or corrosion rates, so this is a qualitative supplier claim.
    rating: low
    conditions:
      basis: supplier description, no test conditions
    source: asm-scalmalloy
    where: Product description, paragraphs 2 and 3
risks:
  hazards:
    - text: 'PubChem GHS summary (ECHA C&L notifications, 105 company reports): H228 flammable solid in 93.3 % of the notified classifications, with signal word Danger. 5 of 105 reports say the substance does not meet GHS criteria.'
      ghs:
        - H228
      source: pubchem-sc
      where: Safety and Hazards, Hazards Identification, GHS Classification; Hazard Classes and Categories, Flam. Sol. 2 (93.3%)
    - text: 'Chemos GmbH SDS, revision 2023-11-09: flammable solid, Category 1, H228, signal word Danger, with P210, P240, P241, P280 and P370+P378. Transport as UN 3089, metal powder, flammable, n.o.s.'
      ghs:
        - H228
      source: chemos-sc-sds
      where: Section 2.1 Classification, row 2.7 flammable solid; Section 2.2 hazard and precautionary statements; Section 14.1 and 14.2
    - text: 'Apollo Scientific SDS for scandium lump, vacuum remelted (IN3112, issue 16/09/2022, print 31/07/2023): classified H228 (flammable solid, Category 1) and H240 (heating may cause an explosion, self-reactive type A), with H315, H319 and H335, signal word Danger. Shipping name metal powder, flammable, n.o.s.'
      ghs:
        - H228
        - H240
        - H315
        - H319
        - H335
      source: apollo-sc-sds
      where: Section 2.1 Classification, CLP and Chemwatch legend; Section 2.2 label elements; Section 14
    - text: 'Kurt J. Lesker Company SDS for scandium metal foil (last revision 9/16/95): flammable solid when a powder or thin foil, reacts with water and dilute acids to give flammable explosive hydrogen, and high-concentration dust may irritate the skin, eyes and respiratory tract. No GHS statements are printed.'
      ghs: []
      source: lesker-sc-sds
      where: Section III, Other Comments; Section IV Fire and Explosion Hazard Data
    - text: 'Wikipedia health paragraph: elemental scandium is considered non-toxic, though animal testing of scandium compounds has not been extensive. The LD50 of scandium chloride in rats is 755 mg/kg intraperitoneal and 4 g/kg oral, so compounds are to be handled as moderately toxic.'
      ghs: []
      source: wiki-sc
      where: Health and safety section
  failure_risks:
    - mode: Ignition of fines, turnings, powder and dust
      trigger: Fine powder, thin foil, turnings or deposited dust exposed to heat, sparks, friction or flame
      consequence: Chemos says deposited combustible dust has considerable explosion potential and that the material carries a risk of ignition when heated. Apollo says metal dust fires are intense and difficult to extinguish, and that a burning dust cloud can explode.
      severity: critical
      source: chemos-sc-sds
      where: Section 5.2 Special hazards; Section 7.2 Flammability hazards; Section 10.1 Reactivity
    - mode: Hydrogen release on contact with water or acid
      trigger: Metal or fines in water, moisture or dilute acid, including water applied to a fire
      consequence: The Lesker sheet says the reaction gives flammable explosive hydrogen. Apollo says water or foam may generate explosive hydrogen, so smothering is preferred to water on a metal fire.
      severity: high
      source: lesker-sc-sds
      where: Section III, Other Comments; Section IV Unusual Fire and Explosion Hazards
    - mode: Surface tarnish in air
      trigger: Long exposure to air at room temperature
      consequence: Scandium develops a slightly yellowish or pinkish cast and is susceptible to weathering. The sources read give no rate of loss, and the effect is not described as structural.
      severity: low
      source: wiki-sc
      where: Properties, Chemical characteristics, first paragraph
    - mode: Reaction with halogens and strong oxidizers
      trigger: Contact with halogens, strong oxidizing agents, chlorates, bromates or iodates
      consequence: The Lesker sheet lists these as materials to avoid, with hydrogen as the decomposition product. No reaction rate or temperature was given in the sources read.
      severity: moderate
      source: lesker-sc-sds
      where: Section VII Reactivity Data
  side_effects:
    - text: Dusts in high concentrations may cause skin, eye and respiratory tract irritation, and inhalation may aggravate existing asthma, emphysema or bronchitis (Lesker sheet).
      affects: Workers who handle fines or dust
      source: lesker-sc-sds
      where: Section III, Other Comments; Section VI Health Hazard Data
  handling:
    - text: Store under inert gas, in tightly closed containers, in a dry area, and use non-sparking tools and grounded, bonded equipment when transferring (Lesker sheet).
      source: lesker-sc-sds
      where: Section IX Precautions to be Taken in Handling and Storing
    - text: Keep away from heat, hot surfaces, sparks and open flames, and remove dust deposits to avoid explosive atmospheres (Chemos SDS).
      source: chemos-sc-sds
      where: Section 7.2 Conditions for safe storage, Explosive atmospheres and Flammability hazards
    - text: For a fire, use dry chemical or a Class D extinguisher (Lesker), or sand, carbon dioxide or powder (Chemos, P370+P378). Do not use water (Lesker) or a water jet (Chemos Section 5.1). Apollo says smother metal dust fires with dry sand, graphite powder or a dry sodium chloride based extinguisher, and says not to use water, CO2 or foam.
      source: lesker-sc-sds
      where: Section IV Extinguishing Media; Chemos Section 5.1; Apollo Section 5.1
    - text: Avoid breathing dust, and wear NIOSH-approved respiratory protection, gloves and eye protection. Sweep up spills into a closed container with non-sparking tools, and prohibit vacuuming (Lesker sheet).
      source: lesker-sc-sds
      where: Section V Spill or Leak Process; Section VIII Special Protective Information
  mitigations: []
uses:
  - application: structures
    device: Aluminium-scandium alloy minor aerospace parts in the MiG-21 and MiG-29 military aircraft
    example: Wikipedia says the main application of scandium by weight is aluminium-scandium alloys with 0.1 to 0.5 % scandium for minor aerospace components, used in Russian MiG-21 and MiG-29 aircraft, and that parts of the MiG-29 are made from Al-Sc alloy.
    source: wiki-sc
    where: Applications, Aluminium alloys section
  - application: structures
    device: Scalmalloy, a scandium-aluminium-magnesium powder for laser powder bed additive manufacturing of aerospace structures
    example: ASM International says Scalmalloy was developed by Airbus Group APWorks with Airbus R&D as a powder alloy for additive manufacturing of high-strength aerospace structures, with specific strength approaching that of titanium, while the AlSi10Mg powder is only half as strong.
    source: asm-scalmalloy
    where: Product description, paragraphs 1 and 2
supply:
  - subject: Scandium (USGS says it is produced only as a byproduct; no country shares are printed)
    abundance: 18 to 25 ppm in the Earth's crust (Wikipedia, citing estimates); USGS does not give a crustal abundance in its chapter
    producers: []
    critical_lists:
      - list: EU critical raw materials list, as printed on the European Commission page (scandium is listed)
        listed: true
    recycling: 'USGS: Recycling: None.'
    substitutes:
      - 'USGS: titanium and aluminium high-strength alloys and carbon-fibre materials may substitute in high-performance scandium-alloy applications. In some applications that rely on scandium''s unique properties, substitution is not possible.'
    source: usgs-sc-2026
    where: World Mine Production and Reserves (China the leading producer; global production about 80 t of scandium oxide in 2025 from a capacity above 90 t/yr; byproduct of nickel and titanium streams; Australia reserves about 34,000 t as of December 2023); Recycling; Substitutes; abundance from Wikipedia Occurrence section
  - subject: Scandium oxide imported into the United States
    producers:
      - country: Japan
        share_percent: 89
        year: 2024
      - country: China
        share_percent: 11
        year: 2024
    critical_lists: []
    recycling: ''
    substitutes: []
    source: usgs-sc-2026
    where: 'Import Sources (2021–24) paragraph: Japan 89 % and China 11 % of scandium oxide shipping records; the year column is the end of the 2021 to 2024 range. Imports of scandium oxide were 4 t in 2025e (Salient Statistics).'
  - subject: Scandium metal price and export controls
    producers: []
    critical_lists: []
    recycling: ''
    substitutes: []
    source: usgs-sc-2026
    where: 'Salient Statistics, price rows: scandium metal ingot 99.999 %, 1 to 10 kg lots, 5,200 dollars per kg in 2025e; scandium oxide 99.99 % powder, 640 dollars per kg in 2025e; scandium-aluminium alloy 2 % ingot, 30 dollars per kg in 2025e. Events, Trends and Issues: in April 2025 China tightened export controls on scandium metal, alloys, oxides and compounds.'
documents:
  - title: 'USGS Mineral Commodity Summaries 2026: Scandium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-scandium.pdf
    year: 2026
  - title: 'Wikipedia: Scandium'
    type: database
    url: https://en.wikipedia.org/wiki/Scandium
    year: 2026
  - title: PubChem compound record for scandium (CID 23952), including ECHA C&L Inventory classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23952
    year: 2026
  - title: 'WebElements: Scandium, physical properties (University of Sheffield)'
    type: datasheet
    url: https://winter.group.shef.ac.uk/webelements/scandium/physics.html
  - title: 'Safety data sheet: Scandium, Chemos GmbH article A0055277 (revision 2023-11-09)'
    type: sds
    url: https://www.chemos.de/import/data/msds/GB_en/7440-20-2-A0055277-GB-en.pdf
    year: 2023
  - title: 'Safety data sheet: Scandium, lump, vacuum remelted, Apollo Scientific IN3112 (issue 16/09/2022)'
    type: sds
    url: https://store.apolloscientific.co.uk/storage/msds/IN3112_msds.pdf
    year: 2022
  - title: 'Kurt J. Lesker Company material safety data sheet: Scandium metal foil (last revision 9/16/95)'
    type: sds
    url: https://www.lesker.com/newweb/deposition_materials/pdf/msds_sc.pdf
    year: 1995
  - title: Zaki Ahmad, The Properties and Application of Scandium-Reinforced Aluminum, JOM (February 2003)
    type: paper
    url: https://dunand.northwestern.edu/refs/files/JOM-0302-35.pdf
    year: 2003
  - title: 'ASM International: Scalmalloy, strong scandium-aluminum-magnesium powder-metal alloy designed for 3D printing'
    type: datasheet
    url: https://www.asminternational.org/?p=66634
  - title: 'European Commission: critical raw materials'
    type: report
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
gaps:
  - 'Scandium-specific producer shares: USGS says China was the leading producer but prints no country share, so producers is empty. The 2025 global output (about 80 t of oxide) is given in the supply text.'
  - 'USGS 2025 critical minerals list: the USGS page returned HTTP 403, so only the EU critical raw materials list is recorded in critical_lists.'
  - 'Space flight: no flown scandium metal was found in the sources read, and no vacuum, radiation or thermal-cycling test on scandium was opened. tags.environments is empty for that reason.'
  - Hardness is entered under a new name, brinell_hardness, because the property file has no canonical hardness name. WebElements prints MN m-2 and that value is entered as MPa, which is the same unit.
  - Aluminium-scandium alloy strengths in Tables I and II of the 2003 review (for example Al-0.5Sc at 286 MPa yield, in the WR/A condition) describe alloys, not scandium metal, so they appear in the story text only and are not entered as properties.
  - 'Scalmalloy mechanical values: the ASM page prints no numbers. Values seen in search snippets were not used.'
  - 'Purity: the physical values come from unspecified or lump and foil forms. No 99.9 % or 99.99 % datasheet with its own property values was opened; the Goodfellow scandium page returned HTTP 404.'
  - Corrosion data are qualitative apart from the Table IV alloy rates in NaCl. No corrosion rate for scandium metal itself was found in an opened source.
  - 'Hazard classes differ by supplier and form: Chemos gives Flam. Sol. 1 (H228), PubChem reports Flam. Sol. 2 (H228) in 93.3 % of reports, Apollo gives H228 and H240 for the lump, and the 1995 Lesker sheet has no GHS statements. The form and the date matter.'
  - The crustal abundance of 18 to 25 ppm is a Wikipedia estimate. No USGS crustal table for scandium was opened.
  - Melting and boiling points differ by 1 to 5 °C between sources, and all are entered with their sources.
  - The 2003 review describes primary production at Zhovti Vody, Ukraine. That is out of date against the USGS 2026 chapter, which describes byproduct recovery from nickel and titanium streams, so the USGS statement is used.
  - Electronegativity, ionization energy, heat of fusion and molar heat capacity are printed by Wikipedia but have no canonical name in the property file, so they are not entered.
  - The metal-halide lamp and solid oxide fuel cell uses are described in the story only. Their application tags are not in the uses list because no matching application tag was found.
  - A Wikipedia 2026 note on a planned Syerston scandium loan was not used because it is a financing news item and not a property.
  - 'No media (figures) added: no scandium image was checked for caption, source and licence, so the media key is left out.'
sources:
  usgs-sc-2026:
    title: 'Mineral Commodity Summaries 2026: Scandium (USGS)'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-scandium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  wiki-sc:
    title: Scandium (Wikipedia)
    url: https://en.wikipedia.org/wiki/Scandium
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  pubchem-sc:
    title: 'PubChem compound record: Scandium (CID 23952), including ECHA C&L Inventory classification'
    id: CAS 7440-20-2
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23952
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to ECHA and others
  webelements-sc:
    title: 'WebElements: Scandium, physical properties (University of Sheffield)'
    url: https://winter.group.shef.ac.uk/webelements/scandium/physics.html
    kind: database
    license: WebElements, cited not reproduced
  chemos-sc-sds:
    title: 'Safety data sheet: Scandium, Chemos GmbH article A0055277 (revision 2023-11-09)'
    id: CAS 7440-20-2
    url: https://www.chemos.de/import/data/msds/GB_en/7440-20-2-A0055277-GB-en.pdf
    year: 2023
    kind: datasheet
    license: supplier safety data sheet, cited not reproduced
  apollo-sc-sds:
    title: 'Safety data sheet: Scandium, lump, vacuum remelted, Apollo Scientific IN3112 (issue 16/09/2022)'
    id: IN3112
    url: https://store.apolloscientific.co.uk/storage/msds/IN3112_msds.pdf
    year: 2022
    kind: datasheet
    license: supplier safety data sheet, cited not reproduced
  lesker-sc-sds:
    title: 'Kurt J. Lesker Company material safety data sheet: Scandium metal foil (9/16/95)'
    url: https://www.lesker.com/newweb/deposition_materials/pdf/msds_sc.pdf
    year: 1995
    kind: datasheet
    license: supplier safety data sheet, cited not reproduced
  jom-al-sc:
    title: Zaki Ahmad, The Properties and Application of Scandium-Reinforced Aluminum (JOM, February 2003)
    url: https://dunand.northwestern.edu/refs/files/JOM-0302-35.pdf
    year: 2003
    kind: paper
    license: cited not reproduced
  asm-scalmalloy:
    title: Scalmalloy, strong scandium-aluminum-magnesium powder-metal alloy designed for 3D printing (ASM International)
    url: https://www.asminternational.org/?p=66634
    kind: datasheet
    license: cited not reproduced
  eu-crm:
    title: 'European Commission: critical raw materials'
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    kind: web
    license: cited not reproduced
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 24
  unreachable: 2
  caveats: 5
  note: 'Read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Unreachable: Goodfellow scandium page (HTTP 404) and USGS 2025 critical minerals page (HTTP 403). Caveats: most physical values come from one encyclopedia (Wikipedia) and one database (WebElements); the supply shares are for US imports only; the hazard classes differ by supplier and form; the corrosion rates are for Al-Sc alloys, not the metal.'
story:
  recipe:
    line: Scandium metal is the single element Sc. Wikipedia says the metal is made by converting the oxide to scandium fluoride with hydrofluoric acid (Sc2O3 + 6 HF gives 2 ScF3 + 3 H2O) and then reducing the fluoride with metallic calcium (2 ScF3 + 3 Ca gives 3 CaF2 + 2 Sc). Scandium is recovered mainly as a byproduct of nickel, titanium and rare-earth processing, and is sold as oxide. In its main alloy use, aluminium-scandium alloys contain 0.1 to 0.5 % scandium.
    parts:
      - name: Scandium
        symbol: Sc
        atoms: 1
        atomic_weight: 44.956
        role: The whole material. Wikipedia gives a standard atomic weight of 44.956 for scandium.
  risk_groups:
    - title: For people
      lead: The hazard depends on the form. Solid scandium is not classed as toxic in the sources read, but fine powder, dust and turnings are flammable, and the metal releases hydrogen with water.
      level: 1
      verdict: Form-dependent
      points:
        - label: Fines and dust
          line: Chemos classes the metal as a flammable solid (H228) and warns that deposited dust has considerable explosion potential. Apollo classes its lump as H240 (heating may cause an explosion) as well.
        - label: Water and acid
          line: The Lesker sheet says scandium reacts with water and dilute acids to give flammable, explosive hydrogen.
        - label: Toxicity
          line: Wikipedia calls elemental scandium non-toxic, with a rat LD50 for scandium chloride of 755 mg/kg intraperitoneal and 4 g/kg oral. Compounds are to be handled as moderately toxic.
    - title: If it fails
      lead: 'The sources give four failure routes: a fire in fines or dust, hydrogen release on contact with water or acid, surface tarnish in air, and reaction with halogens.'
      points:
        - label: Fire
          line: Use sand, carbon dioxide or a dry powder or Class D extinguisher. Water is not recommended (Lesker), and Apollo says not to use water, CO2 or foam on metal dust fires.
        - label: Tarnish
          line: Scandium develops a slightly yellowish or pinkish cast in air and is susceptible to weathering (Wikipedia).
        - label: Halogens
          line: The Lesker sheet lists halogens, strong oxidizers, acid chlorides and chlorates as materials to avoid.
    - title: Handling and storage
      points:
        - label: Keep it dry
          line: Store under inert gas, in tightly closed containers and in a dry area (Lesker).
        - label: Avoid ignition
          line: Keep away from heat, sparks and open flames, and remove dust deposits (Chemos).
        - label: Dust
          line: Avoid breathing dust, and use NIOSH-approved respiratory protection with gloves and eye protection (Lesker).
  why: 'Scandium is a light rare-earth-type metal whose main value is its effect on aluminium. A scandium addition of 0.1 to 0.5 % forms fine Al3Sc precipitates that refine grain, strengthen welds and reduce hot cracking, and this is why it is used in aerospace aluminium parts (Wikipedia; Zaki Ahmad, JOM 2003). The metal itself is expensive and scarce: USGS reports about 80 tonnes of oxide produced in 2025, with no domestic commercial mining or recovery in the United States. Its main use is in aluminium alloys. No scandium metal flight record was found in the sources read.'
  uses:
    - where: Aerospace aluminium parts
      line: Wikipedia says the main application of scandium by weight is aluminium-scandium alloys for minor aerospace components, used in the Russian MiG-21 and MiG-29 aircraft.
    - where: Additive manufacturing of aerospace structures
      line: ASM International says Scalmalloy, a scandium-aluminium-magnesium powder developed by Airbus Group APWorks with Airbus R&D, is used for additive manufacturing of high-strength aerospace structures.
    - where: Metal-halide lamps
      line: Wikipedia says about 80 kg of scandium is used a year worldwide in metal-halide lamps, mostly as scandium triiodide with sodium iodide, which gives a white light that suits colour-accurate TV cameras.
    - where: Solid oxide fuel cells
      line: USGS lists solid oxide fuel cells among the principal 2025 uses of scandium, where scandia-stabilized zirconia is the electrolyte. Wikipedia says the use is proposed and the scandium oxide improves the ionic conductivity of zirconia.
  can_do:
    - label: Weight
      value: 2.99 g/cm3
      benchmark: density
      line: Density is 2.99 g/cm3 at 25 °C in the Chemos SDS, and 2.989 g/cm3 at 20 °C in the Wikipedia infobox.
    - label: Melting
      value: 1541 °C
      benchmark: melting_point
      line: Melting point is 1541 °C in the Wikipedia infobox and the Lesker sheet, and 1540 °C in the Chemos SDS.
    - label: Stiffness
      value: 74.4 GPa
      benchmark: elastic_modulus
      line: Young's modulus is 74.4 GPa (Wikipedia) and 74 GPa (WebElements).
    - label: Heat conduction
      value: 16 W/(m·K)
      benchmark: thermal_conductivity
      line: Thermal conductivity is 16 W/(m·K) (WebElements) and 15.8 W/(m·K) (Wikipedia), a modest value for a metal.
    - label: Hardness
      value: 736 to 1200 MPa
      benchmark: brinell_hardness
      line: Wikipedia gives a Brinell hardness range of 736 to 1200 MPa, and WebElements gives 750 MPa, both with no test conditions.
  compare: Scandium is a light metal with a density of 2.99 g/cm3 in the Chemos SDS. It is not used as a structural metal on its own. Its value is the effect it has on aluminium, where the Al-Sc alloys of the 2003 review are the form in which the metal is mainly used. The comparison rows below give scandium metal values only.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Store dry, under inert gas, in closed containers (Lesker).
    - Keep away from heat, sparks and open flames, and remove dust deposits (Chemos).
    - Do not use water on a fire. Use sand, dry powder or a Class D extinguisher (Lesker, Chemos, Apollo).
    - Use non-sparking tools and avoid breathing dust (Lesker).
  good_for:
    - Aluminium-scandium alloys for aerospace parts, where 0.1 to 0.5 % scandium refines grain and strengthens welds (Wikipedia; JOM 2003).
    - Additive manufacturing of high-strength aerospace structures with the Scalmalloy powder (ASM International).
  watch_out:
    - Fine powder, turnings and dust are flammable, and dust can explode (Chemos, Apollo).
    - The metal releases flammable hydrogen with water and dilute acids (Lesker).
    - 'Supply is thin and concentrated: USGS reports about 80 t of oxide in 2025, China as the leading producer, and China''s April 2025 export controls cover scandium metal and alloys.'
    - The hazard classes differ by supplier and form, and the aluminium corrosion rates in the 2003 review are for alloys, not the metal.
  verdict: Scandium is a light, stiff metal whose real value is as a small addition to aluminium alloys for aerospace parts. The pure metal is scarce, flammable in fine form and reacts with water, so it needs dry, inert handling.