spore: profile
id: ilmenite
spore_version: 0.2
family: iron-titanium-oxide
name: Ilmenite
role: oxygen-extraction feedstock
category: regolith
type: extracted-metals-and-oxygen
summary: |
  Ilmenite (FeTiO3) is an iron-titanium oxide mineral with a trigonal crystal structure. Webmineral gives its calculated density as 4.79 gm/cc and its molecular weight as 151.73 gm. Wikipedia gives a liquidus melting point of 1710 °C at a peritectic point, and a Mohs hardness of 5 to 6. Ilmenite is the main titanium mineral concentrate: USGS reports 9,400 thousand metric tons (TiO2 content) of world ilmenite mine production in 2025, with China at about one-third of the total. Lunar ilmenite is named as a target for oxygen extraction; one arXiv paper (2601.14719) gives an apparent yield of 1.10 wt% oxygen under hydrogen reduction. The Handbook of Mineralogy gives a Vickers hardness of 566 to 698 VHN, and its ideal FeTiO3 composition carries 52.65 wt% TiO2.
best_for: Titanium and TiO2 feedstock (more than 80 percent of titanium concentrate comes from ilmenite, per Wikipedia), and the lunar oxygen research case
weakest_at: The 1.10 wt% oxygen yield is an apparent figure from one arXiv paper, and that paper does not state the temperature for it in the text read; no lunar sample or flight data are in this profile
identity:
  formula: FeTiO3 (idealized); Fe2+TiO3 (empirical, webmineral)
  crystal_system: trigonal
  space_group: R3 (no. 148)
  source: wikipedia-ilmenite
  where: 'Wikipedia infobox: formula FeIITiO3, trigonal, rhombohedral class (3), space group R3 (no. 148), Z = 6, cell a = 5.08854(7) Å and c = 14.0924(3) Å. Webmineral prints a = 5.093 and c = 14.06 with no unit, and the same space group R 3.'
tags:
  applications:
    - in-space-manufacturing
    - structures
properties:
  - benchmark: density
    label: Calculated density
    value: 4.79
    unit: gm/cc
    scope: material
    conditions:
      basis: calculated density printed by webmineral (Den(Calc)); the page's specific gravity note also gives 4.79 gm/cc
      form: ideal mineral, Fe2+TiO3
    method: Calculated density printed on the webmineral data page
    status: calculated
    source: webmineral-ilmenite
    where: Physical Properties, Den(Calc) and specific gravity note
  - benchmark: density
    label: Specific gravity range
    value: 4.7
    value_high: 4.79
    bound: range
    unit: '-'
    scope: material
    conditions:
      basis: specific gravity range printed in the Wikipedia infobox; the article text gives specific gravity 4.7
      form: ilmenite mineral
    method: Range printed in the Wikipedia infobox (specific gravity is a dimensionless ratio)
    status: ground
    source: wikipedia-ilmenite
    where: Infobox, Specific gravity row
  - benchmark: melting_point
    label: Liquidus temperature (peritectic)
    value: 1710
    unit: °C
    scope: material
    conditions:
      basis: liquidus temperature at a peritectic point, as printed
    method: Value printed in the Wikipedia infobox, melting point row
    status: ground
    source: wikipedia-ilmenite
    where: Infobox, Melting point row
  - benchmark: mohs_hardness
    label: Mohs hardness (infobox range)
    value: 5
    value_high: 6
    bound: range
    unit: '-'
    scope: material
    conditions:
      basis: range printed in the Wikipedia infobox
    method: Range printed in the Wikipedia infobox
    status: ground
    note: The Wikipedia text says Mohs hardness 5.6 to 6, which differs from the infobox range 5 to 6 at the low end. Both are shown and neither is reconciled.
    source: wikipedia-ilmenite
    where: Infobox, Mohs hardness row; Structure and properties section
  - benchmark: hardness_apatite_knife
    label: Hardness on an apatite-knife scale (not labelled Mohs by the source)
    value: 5
    value_high: 5.5
    bound: range
    unit: '-'
    scope: material
    conditions:
      basis: printed as 5-5.5 with the note Apatite-Knife Blade; the page does not label this scale as Mohs
    method: Range printed on the webmineral data page
    status: ground
    source: webmineral-ilmenite
    where: Physical Properties, Hardness row
  - benchmark: molar_mass
    label: Molecular weight of Fe2+TiO3
    value: 151.73
    unit: gm
    scope: material
    conditions:
      formula: Fe2+TiO3 (empirical formula printed by webmineral)
    method: Value printed on the webmineral data page as Molecular Weight; the method is not stated
    status: calculated
    source: webmineral-ilmenite
    where: Chemical data, Molecular Weight row
  - benchmark: refractive_index
    label: Calculated refractive index (uniaxial, negative)
    value: 2.42
    unit: '-'
    scope: material
    conditions:
      basis: NCalc from the calculated density using the Gladstone-Dale constant KC 0.2959, as printed by webmineral; the page also gives 2.4 from the measured density
      optics: uniaxial (-)
    method: Calculated by the Gladstone-Dale relation as printed on webmineral
    status: calculated
    source: webmineral-ilmenite
    where: Optical Data, NCalc row
  - benchmark: hematite_content
    label: Hematite (Fe2O3) in natural ilmenite, upper value
    value: 6
    bound: upper
    unit: wt%
    scope: material
    conditions:
      basis: upper value printed in the mineral chemistry section; ilmenite with more Fe2O3 is called ferrian ilmenite
    method: Value printed in the Wikipedia article text
    status: ground
    source: wikipedia-ilmenite
    where: Mineral chemistry section
  - benchmark: ferrian_ilmenite_fe2o3
    label: Fe2O3 content of ferrian ilmenite
    value: 6
    value_high: 13
    bound: range
    unit: percent
    scope: material
    conditions:
      basis: ilmenite containing 6 to 13 percent Fe2O3 is called ferrian ilmenite
    method: Range printed in the Wikipedia article text
    status: ground
    source: wikipedia-ilmenite
    where: Mineral chemistry section
  - benchmark: solid_solution_onset_temperature
    label: Complete ilmenite-hematite solid solution above this temperature
    value: 950
    unit: °C
    scope: material
    conditions:
      basis: text says that at temperatures above 950 °C (1,740 °F) there is complete solid solution between ilmenite and hematite
    method: Value printed in the Wikipedia article text
    status: ground
    source: wikipedia-ilmenite
    where: Mineral chemistry section
  - benchmark: vickers_hardness
    label: Vickers hardness (printed as VHN, 100 g load)
    value: 566
    value_high: 698
    bound: range
    unit: VHN
    scope: material
    conditions:
      basis: range printed as VHN = 566-698 at a 100 g load in the physical properties paragraph
      load: 100 g
    method: Range printed in the Handbook of Mineralogy physical properties paragraph; unit as printed
    status: ground
    source: handbook-mineralogy-ilmenite
    where: Physical Properties paragraph, Hardness = 5-6 VHN = 566-698 (100 g load)
  - benchmark: tio2_content
    label: TiO2 content of ideal FeTiO3 (analysis column 2)
    value: 52.65
    unit: wt%
    scope: material
    conditions:
      basis: column (2) of the handbook chemistry table, printed as the ideal formula FeTiO3
      form: ideal FeTiO3, not a measured analysis
    method: Column (2) of the Handbook of Mineralogy chemistry table, labelled FeTiO3
    status: calculated
    source: handbook-mineralogy-ilmenite
    where: Chemistry table, TiO2 row, column (2)
  - benchmark: hydrogen_reduction_oxygen_yield
    label: Apparent oxygen yield under hydrogen reduction
    value: 1.1
    unit: wt%
    scope: material
    conditions:
      basis: apparent yield printed in the text for ilmenite under hydrogen reduction conditions; the paper calls it apparent
      temperature: not stated in the text read
    method: Value stated in the results text of the arXiv paper (its own experiment); not a flight result
    status: ground
    source: arxiv-2601-14719
    where: Section 3.2.1 Hydrogen TPR Reduction Behavior, paragraph naming ilmenite the most efficient oxygen source
  - benchmark: hydrogen_reduction_temperature
    label: Hydrogen reduction temperature for ilmenite-rich regolith (cited prior work)
    value: 900
    unit: °C
    scope: material
    conditions:
      basis: temperature at which the paper cites prior hydrogen reduction of ilmenite-rich regolith, given there as up to 1-2 wt% oxygen
      feedstock: ilmenite-rich regolith
    method: Temperature stated in the arXiv paper, citing earlier work (Sargeant et al. 2020a; Reiss et al. 2019); the profile does not reproduce those experiments
    status: ground
    source: arxiv-2601-14719
    where: Section 3.2.1 Hydrogen TPR Reduction Behavior, paragraph citing prior work at 900 °C
corrosion:
  - environment: Natural weathering in placer deposits
    headline: Ilmenite weathers to leucoxene, which is enriched to 70 percent or more TiO2, and weathering lowers its iron content.
    effect: Ilmenite alters or weathers to form the pseudo-mineral leucoxene, enriched to 70% or more of TiO2 (Wikipedia). In placer deposits, weathering reduces the iron content and increases the titanium percentage (Wikipedia).
    rating: unknown
    conditions:
      basis: natural weathering; the source gives no rate, duration or test condition
      product: leucoxene
    source: wikipedia-ilmenite
    where: Mineral chemistry paragraph on leucoxene; placer deposit sentence in the same article
risks:
  hazards:
    - text: 'Teichert SDS (effective 06/01/24) GHS label elements list two hazard statements: May cause irritation of eyes and skin; May cause respiratory irritation. No H-codes are printed.'
      ghs: []
      source: teichert-sds-ilmenite
      where: Section 2, GHS label elements, Hazard Statements list
    - text: 'Valentine Clays SDS (EU format, Regulation (EC) 2020/878) classifies ilmenite as Not Classified under CLP, but adds an other hazard: repeated inhalation of crystalline silica dust over time can cause lung disease and cancer.'
      ghs: []
      source: valentine-sds-ilmenite
      where: Section 2.1 Classification and Section 2.3 Other Hazards
    - text: Pottery Crafts P3324 SDS gives Not Classified for physical, health and environmental hazards, with hazard statements printed as NC. The three SDS sheets disagree and all are shown.
      ghs: []
      source: potterycrafts-msds-ilmenite
      where: Section 2.1 Classification, Hazard statements row
    - text: 'Respirable crystalline silica (quartz, CAS 14808-60-7, listed as a component of the Teichert product): prolonged and repeated exposure to high concentrations of respirable silica dust could lead to lung disease including chronic pulmonary obstructive disease and silicosis.'
      ghs: []
      source: teichert-sds-ilmenite
      where: Section 2, Inhalation and Chronic Effects; Section 3 Composition
    - text: 'Dust fire and explosion: the Teichert SDS says concentrated suspensions of fine particles in air may be ignitable/explosive.'
      ghs: []
      source: teichert-sds-ilmenite
      where: Section 5 Fire Fighting Measures, Flammable Properties
    - text: Naturally occurring radioactive elements of the uranium and thorium series are present at low levels in common ilmenite, per the Valentine Clays SDS.
      ghs: []
      source: valentine-sds-ilmenite
      where: Section 2.3 Other Hazards
  failure_risks:
    - mode: Low oxygen yield from highland and polar regolith with little ilmenite
      trigger: Hydrogen reduction of Lunar Highlands Soil or Lunar South Pole simulant, where ilmenite is scarce
      consequence: Apparent oxygen yield of about 0.02 wt% for the highland simulant and 0.01 wt% for the south-pole simulant, from temperature-programmed reduction. These are simulant results, not ilmenite.
      severity: high
      source: arxiv-2601-14719
      where: Section 3.2.1 Hydrogen TPR Reduction Behavior, text on Lunar Highlands Soil and LSP oxygen extraction
    - mode: Water, not free oxygen, leaves the reduction step first
      trigger: Hydrogen reduction by reaction FeTiO3 + H2 gives Fe + TiO2 + H2O
      consequence: The paper says water is an intermediate rather than gaseous oxygen directly, and that water electrolysis then liberates breathable O2, so a further step is needed.
      severity: moderate
      source: arxiv-2601-14719
      where: Reaction (1) in Section 3.2.1; the Results and Discussion paragraph on water as an intermediate after Figure 5
  side_effects: []
  handling: []
  mitigations: []
uses:
  - application: in-space-manufacturing
    device: Lunar in-situ oxygen extraction (research concept, not a flight result)
    example: Wikipedia says ilmenite is targeted for water and oxygen extraction by a reduction reaction with CO and H2 buffers, and gives no yield figure.
    source: wikipedia-ilmenite
    where: Lunar ilmenite section
  - application: structures
    device: Titanium feedstock for titanium metal and TiO2 pigment
    example: Wikipedia says more than 80 percent of titanium concentrate comes from ilmenite, with the rest from titaniferous slags and rutile.
    source: wikipedia-ilmenite
    where: Processing and consumption section
  - application: structures
    device: Titanium metal in aerospace
    example: USGS reports that the majority of titanium metal was used in aerospace applications, and withholds the detailed 2025 consumption data.
    source: usgs-mcs2026-titanium
    where: Domestic Production and Use paragraph
supply:
  - subject: Ilmenite (titanium mineral concentrate, FeTiO3)
    abundance: Not found for ilmenite in a USGS source read here. Wikipedia gives titanium at about 0.6 percent of the Earth's crust and as the ninth most abundant element (titanium, not ilmenite alone).
    producers:
      - country: China
        share_percent: 34
        year: 2025
      - country: Mozambique
        share_percent: 20.2
        year: 2025
      - country: South Africa
        share_percent: 13.8
        year: 2025
      - country: Australia
        share_percent: 8.3
        year: 2025
      - country: Canada
        share_percent: 3.8
        year: 2025
    critical_lists:
      - list: USGS Final 2025 List of Critical Minerals (titanium listed; ilmenite not listed on its own)
        listed: true
    recycling: 'USGS: Recycling: None.'
    substitutes:
      - 'USGS: ilmenite, leucoxene, rutile, slag and synthetic rutile compete as feedstock sources for TiO2 pigment, titanium metal and welding-rod coatings.'
    source: usgs-mcs2026-titanium-concentrates
    where: World Mine Production and Reserves table, ilmenite rows, 2025 column (data in thousand metric tons, TiO2 content; the world total is 9,400, and the shares are calculated by Space Mushroom against it). World ilmenite reserves printed as more than 490,000 thousand tons (TiO2 content). China share from the Events, Trends and Issues paragraph (about one-third). Recycling and Substitutes sections, pages 199 and 200.
documents:
  - title: 'Wikipedia: Ilmenite (article used for composition, mineral chemistry and lunar concept)'
    type: database
    url: https://en.wikipedia.org/wiki/Ilmenite
    year: 2026
  - title: 'Webmineral: Ilmenite mineral data'
    type: database
    url: https://www.webmineral.com/data/Ilmenite.shtml
    year: 2026
  - title: USGS Mineral Commodity Summaries 2026, Titanium Mineral Concentrates (pages 199 and 200)
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026.pdf
    year: 2026
  - title: USGS Mineral Commodity Summaries 2026, Titanium and Titanium Dioxide
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
    year: 2026
  - title: Teichert Aggregates Ilmenite SDS (revision 6/1/2024)
    type: sds
    url: https://teichert.com/wp-content/uploads/Ilmenite-Teichert-SDS-6.2024.pdf
    year: 2024
  - title: Valentine Clays Ilmenite SDS (EU format, Regulation (EC) No 2020/878)
    type: sds
    url: https://valentineclays.co.uk/cdn/shop/files/Ilmenite_Safety_Data_Sheet.pdf
  - title: Pottery Crafts Ilmenite MSDS (P3324)
    type: sds
    url: https://potterycrafts.co.uk/cdn/shop/files/P3324_ILMENITE_MSDS_25.pdf
    year: 2025
  - title: arXiv 2601.14719, Physicochemical properties of lunar regolith simulant for in situ oxygen production
    type: paper
    url: https://arxiv.org/pdf/2601.14719
    year: 2026
  - title: Handbook of Mineralogy, Ilmenite
    type: report
    url: https://www.handbookofmineralogy.org/pdfs/ilmenite.pdf
    year: 2005
gaps:
  - 'Oxygen yield: the arXiv paper 2601.14719 gives an apparent 1.10 wt% oxygen for ilmenite under hydrogen reduction, but its temperature and sample are not stated in the text read. The reduction rate and the Sargeant et al. (2020) papers in Planetary and Space Science were not opened; their figures seen in search snippets are not used.'
  - 'No CAS number is set in identity: PubChem could not be opened. The Teichert SDS prints 12168-52-4 for ilmenite and the Valentine Clays SDS prints 103170-28-1; the two differ, so neither is used as the profile CAS.'
  - No corrosion test data for ilmenite were found. Weathering to leucoxene is cited from Wikipedia with no rate, duration or test condition.
  - No Curie temperature or magnetic numbers. Webmineral says naturally weak magnetism and Wikipedia says weakly magnetic, with no values.
  - No thermal conductivity, specific heat, thermal expansion or elastic modulus were found.
  - Measured density printed by webmineral (4.72) has no unit on the page, so it is not used.
  - 'Mohs hardness conflicts across sources: Wikipedia infobox 5 to 6, Wikipedia text 5.6 to 6, webmineral 5 to 5.5 on an apatite-knife scale. All are shown and none is reconciled.'
  - 'Cell parameters are in identity.where only: Wikipedia prints them in angstroms and webmineral prints them without units.'
  - The EU critical raw materials list was not opened in this run, so no EU list entry is given for titanium or ilmenite.
  - Atomic weights for iron, titanium and oxygen were not read from a fetched page, so story.recipe gives atom counts only.
  - No media (photos or drawings) added for this profile.
  - Only 14 sourced properties and 9 sources were reached in this run. The site bar is met, but the lithium standard asks for 15 properties.
  - 'Benchmark names not in spores/property-canon.yaml: vickers_hardness, tio2_content, hydrogen_reduction_oxygen_yield, hydrogen_reduction_temperature and hardness_apatite_knife. No canonical name was found for these.'
sources:
  wikipedia-ilmenite:
    title: Ilmenite
    id: Wikipedia article, Ilmenite (en)
    url: https://en.wikipedia.org/wiki/Ilmenite
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (Wikipedia)
  webmineral-ilmenite:
    title: Ilmenite mineral data
    id: Webmineral data page
    url: https://www.webmineral.com/data/Ilmenite.shtml
    year: 2026
    kind: database
    license: web page, cited not reproduced
  usgs-mcs2026-titanium-concentrates:
    title: Mineral Commodity Summaries 2026, Titanium Mineral Concentrates (pages 199 and 200 of the compilation)
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-titanium:
    title: Mineral Commodity Summaries 2026, Titanium and Titanium Dioxide
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit-2025:
    title: Mineral Commodity Summaries 2026, Final 2025 List of Critical Minerals (table in the introduction)
    id: USGS Final 2025 List of Critical Minerals, published November 7, 2025
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026.pdf
    year: 2025
    kind: report
    license: public domain (USGS)
  teichert-sds-ilmenite:
    title: Teichert Aggregates, Ilmenite Safety Data Sheet (effective 06/01/24, replaces June 2018)
    id: Teichert Aggregates SDS, revision date 6/1/2024
    url: https://teichert.com/wp-content/uploads/Ilmenite-Teichert-SDS-6.2024.pdf
    year: 2024
    kind: datasheet
    license: Supplier SDS, cited
  valentine-sds-ilmenite:
    title: 'Valentine Clays, Safety Data Sheet: Ilmenite (EU format, Regulation (EC) No 2020/878)'
    id: Valentine Clays SDS, Ilmenite
    url: https://valentineclays.co.uk/cdn/shop/files/Ilmenite_Safety_Data_Sheet.pdf
    kind: datasheet
    license: Supplier SDS, cited
  potterycrafts-msds-ilmenite:
    title: Pottery Crafts, Ilmenite MSDS (product P3324)
    id: Potterycrafts P3324 ILMENITE MSDS
    url: https://potterycrafts.co.uk/cdn/shop/files/P3324_ILMENITE_MSDS_25.pdf
    year: 2025
    kind: datasheet
    license: Supplier SDS, cited
  arxiv-2601-14719:
    title: Physicochemical properties of lunar regolith simulant for in situ oxygen production
    id: arXiv:2601.14719v1
    url: https://arxiv.org/pdf/2601.14719
    year: 2026
    kind: paper
    license: arXiv, cited
  handbook-mineralogy-ilmenite:
    title: Handbook of Mineralogy, Ilmenite (Mineral Data Publishing)
    id: Handbook of Mineralogy, version 1, c 2001-2005
    url: https://www.handbookofmineralogy.org/pdfs/ilmenite.pdf
    year: 2005
    kind: handbook
    license: Mineral Data Publishing, cited
license: CC-BY-4.0
updated: '2026-11-02'
review:
  status: draft
  method: assistant
  checked_values: 14
  unreachable: 2
  caveats: 4
  note: Written by an assistant on 2026-11-01 from five fetched sources; deepened on 2026-11-02 with the Teichert, Valentine Clays and Pottery Crafts SDS sheets, the arXiv 2601.14719 paper and the Handbook of Mineralogy entry, all read in this run. Fourteen values are checked. PubChem could not be opened, and the Sargeant 2020 papers were not reached.
story:
  recipe:
    line: 'Ilmenite has the idealized formula FeTiO3: one iron atom, one titanium atom and three oxygen atoms per formula unit. Wikipedia writes the iron as Fe(II). Webmineral gives the empirical form Fe2+TiO3.'
    parts:
      - name: Iron
        symbol: Fe
        role: The redox-active metal. In the lunar concept, reducing the iron oxide is the step that releases oxygen.
      - name: Titanium
        symbol: Ti
        role: The main product of the titanium chain. Ilmenite is the largest source of titanium concentrate.
      - name: Oxygen
        symbol: O
        role: Bound in the oxide. Reduction with hydrogen or carbon monoxide is the route named for lunar oxygen; an apparent yield of 1.10 wt% is reported by one arXiv paper.
  risk_groups:
    - title: For people
      level: 0
      verdict: Three supplier SDS sheets disagree on classification
      lead: The Teichert SDS lists irritation statements for eyes, skin and the respiratory tract. The Valentine Clays and Pottery Crafts SDS sheets say Not Classified under CLP, and Valentine Clays adds a chronic silica hazard. All three are shown; none is reconciled.
      points:
        - label: The powder
          line: Read the supplier SDS before handling ilmenite powder. Crystalline silica (quartz) is listed as a component in one SDS, and fine particles in air may be ignitable, per that SDS. No GHS H-codes are printed in these sources.
    - title: Lunar oxygen concept
      lead: The hazards of the reduction gases are not covered by the sources read for this profile.
      points:
        - label: Reducing gases
          line: Wikipedia names CO and H2 as the buffers for the lunar reduction reaction. Their handling risks are not in this record.
  why: Ilmenite is an iron-titanium oxide mineral (FeTiO3) and the main titanium mineral concentrate. Wikipedia says lunar ilmenite is a target for water and oxygen extraction by a reduction reaction with CO and H2 buffers. That concept is the reason it is in this collection. The physical data here (density, melting point, hardness) are the ones the sources give; the oxygen yield is reported only as an apparent figure from one arXiv paper.
  uses:
    - where: Titanium and TiO2 feedstock
      line: Wikipedia says more than 80 percent of titanium concentrate comes from ilmenite. USGS reports that in the United States most titanium mineral concentrate is consumed by TiO2 pigment producers.
    - where: Aerospace titanium
      line: USGS reports that the majority of titanium metal was used in aerospace applications. The detailed 2025 consumption data were withheld to protect company data.
    - where: Lunar oxygen (concept)
      line: Wikipedia describes lunar ilmenite as a target for oxygen extraction by reduction with CO and H2 buffers, and gives no yield. The arXiv paper 2601.14719 gives an apparent yield of 1.10 wt% oxygen under hydrogen reduction, with its temperature not stated in the text read.
  can_do:
    - label: Density
      benchmark: density
      line: Calculated density is 4.79 gm/cc (webmineral). Wikipedia gives a specific gravity of 4.7 to 4.79 in the infobox.
    - label: Melting
      benchmark: melting_point
      value: 1710 °C
      line: Wikipedia gives the liquidus of ilmenite as 1710 °C at a peritectic point.
    - label: Hardness
      benchmark: mohs_hardness
      value: 5 to 6 Mohs
      line: Wikipedia gives Mohs hardness 5 to 6 in the infobox and 5.6 to 6 in the text. Webmineral gives 5 to 5.5 on an apatite-knife scale.
    - label: Oxygen
      benchmark: hydrogen_reduction_oxygen_yield
      line: The arXiv paper 2601.14719 gives an apparent 1.10 wt% oxygen for ilmenite under hydrogen reduction. Prior work it cites reports up to 1-2 wt% oxygen via hydrogen reduction at 900 °C for ilmenite-rich regolith.
  compare: Ilmenite is a dense, high-melting oxide with a mid-range hardness, and it is the largest source of titanium concentrate. The USGS names rutile, slag and synthetic rutile as alternative feedstocks. We did not read density or melting data for those in this run, so this profile makes no numeric comparison with them.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Mohs hardness
      benchmark: mohs_hardness
  handling:
    - No handling or hazard data for ilmenite were found in the sources read. Check the supplier's safety data sheet before handling the powder.
    - Wikipedia names CO and H2 as the buffers for the lunar reduction concept. Their hazards are not covered by this record.
  good_for:
    - Titanium feedstock. Wikipedia says more than 80 percent of titanium concentrate comes from ilmenite.
    - Lunar oxygen research. Wikipedia describes ilmenite as a target for oxygen extraction, and one arXiv paper gives an apparent yield of 1.10 wt% oxygen.
  watch_out:
    - 'The Mohs hardness differs between sources: 5 to 6 in the infobox, and 5 to 5.5 on an apatite-knife scale on webmineral.'
    - The USGS production figures are titanium dioxide content, not the mass of ilmenite mineral.
    - The 1.10 wt% oxygen yield is apparent, comes from one paper, and its temperature is not stated in the text read. The lunar highland and south-pole simulants give far lower yields, 0.02 wt% and 0.01 wt%.
  verdict: Ilmenite is a dense iron-titanium oxide with a high liquidus temperature (1710 °C) and a well-documented titanium supply chain. For oxygen extraction, one arXiv paper gives an apparent yield of 1.10 wt% oxygen, while its lunar simulant results are much lower. Energy and temperature data for a working plant are still missing.