Anorthite An

spore: profile
id: anorthite
spore_version: 0.2
family: plagioclase feldspar
name: Anorthite
abbreviation: An
role: feedstock
category: regolith
type: extracted-metals-and-oxygen
summary: |
  Anorthite is the calcium end-member of the plagioclase feldspar series, with the formula CaAl2Si2O8. Webmineral prints a calculated specific gravity of 2.75 gm/cc, and the Handbook of Mineralogy prints a hardness of 6 to 6.5. Wikipedia states that anorthite makes up much of the lunar highlands. No source read in this run describes an extraction process for aluminium, calcium or oxygen from anorthite.
best_for: Reference data for lunar highlands plagioclase. Not yet a sourced feedstock for aluminium, calcium or oxygen extraction in this profile.
weakest_at: Few measured values with units. No melting point, hazard classification or extraction result was found in the sources read.
identity:
  formula: CaAl2Si2O8
  cas: 1302-54-1
  crystal_system: triclinic
  space_group: P1 (low)
  source: hom-anorthite
  where: 'Formula and crystal system from the Handbook of Mineralogy anorthite entry (Triclinic; Cell Data, Space Group P 1 (low)). CaAl2Si2O8 is also printed on webmineral and Wikipedia. CAS 1302-54-1 is listed under Other Identifiers in the PubChem record for CID 56843091. Ideal composition printed by webmineral: SiO2 44.40 %, Al2O3 35.84 %, CaO 19.20 %; element shares Ca 13.72 %, Al 18.97 %, Si 20.75 %, O 46.14 %. Wikipedia''s Occurrence section says it was first described in 1823. Space group conflict: Wikipedia prints P1 (no. 2) and webmineral prints P1,I1.'
tags:
  applications:
    - in-space-manufacturing
properties:
  - benchmark: density
    label: Calculated specific gravity
    value: 2.75
    unit: gm/cc
    scope: material
    conditions:
      basis: calculated value printed by webmineral
      temperature: not stated on the page
    method: Calculated value printed under Calculated Properties on webmineral. Unit printed as gm/cc. Not a measurement.
    status: calculated
    source: webmineral-anorthite
    where: 'Calculated Properties of Anorthite: Specific Gravity of Anorthite = 2.75 gm/cc'
  - benchmark: density
    label: Bulk density from electron density
    value: 2.73
    unit: gm/cc
    scope: material
    conditions:
      basis: bulk density from electron density, printed by webmineral
      temperature: not stated on the page
    method: Calculated value printed under Calculated Properties on webmineral. Unit printed as gm/cc.
    status: calculated
    source: webmineral-anorthite
    where: 'Calculated Properties of Anorthite: Bulk Density (Electron Density) = 2.73 gm/cc'
  - benchmark: hardness_mohs
    label: Hardness (Mohs scale)
    value: 6
    value_high: 6.5
    unit: '-'
    scope: material
    conditions:
      basis: range printed in the Handbook of Mineralogy
      scale: Mohs scale; the scale name is not printed on the page
    method: Handbook of Mineralogy prints Hardness = 6 to 6.5 (the en dash is garbled in the PDF text). Unit recorded as - because the scale is dimensionless.
    status: ground
    source: hom-anorthite
    where: 'Physical Properties: Hardness'
  - benchmark: refractive_index
    label: Refractive index, alpha
    value: 1.573
    value_high: 1.577
    unit: '-'
    scope: material
    conditions:
      wavelength: not stated on the page
      index: alpha
    method: Handbook of Mineralogy prints the alpha index as 1.573 to 1.577. The Greek letter is garbled in the PDF text; the assignment follows the order alpha, beta, gamma.
    status: ground
    source: hom-anorthite
    where: 'Optical Properties: refractive index line (alpha)'
  - benchmark: refractive_index
    label: Refractive index, beta
    value: 1.58
    value_high: 1.585
    unit: '-'
    scope: material
    conditions:
      wavelength: not stated on the page
      index: beta
    method: Handbook of Mineralogy prints the beta index as 1.580 to 1.585. The Greek letter is garbled in the PDF text.
    status: ground
    source: hom-anorthite
    where: 'Optical Properties: refractive index line (beta)'
  - benchmark: refractive_index
    label: Refractive index, gamma
    value: 1.585
    value_high: 1.59
    unit: '-'
    scope: material
    conditions:
      wavelength: not stated on the page
      index: gamma
    method: Handbook of Mineralogy prints the gamma index as 1.585 to 1.590. The Greek letter is garbled in the PDF text.
    status: ground
    source: hom-anorthite
    where: 'Optical Properties: refractive index line (gamma)'
  - benchmark: refractive_index
    label: Calculated refractive index (Gladstone-Dale)
    value: 1.57
    unit: '-'
    scope: material
    conditions:
      basis: Gladstone-Dale calculation printed by webmineral
    method: Calculated value printed on webmineral in the Gladstone-Dale section. Not a measurement.
    status: calculated
    source: webmineral-anorthite
    where: 'Optical Properties, Gladstone-Dale section: Ncalc = 1.57'
  - benchmark: birefringence
    label: Birefringence
    value: 0.011
    value_high: 0.012
    unit: '-'
    scope: material
    conditions:
      wavelength: not stated on the page
    method: Printed by webmineral as bire=0.0110-0.0120. Unit recorded as - because birefringence is dimensionless. Wikipedia prints 0.012 to 0.013 but is not used for properties in this profile.
    status: ground
    source: webmineral-anorthite
    where: 'Optical Properties: bire=0.0110-0.0120'
  - benchmark: molar_mass
    label: Formula mass
    value: 278.203
    unit: g·mol−1
    scope: material
    conditions:
      basis: formula mass printed in the Wikipedia infobox
    method: 'Taken from the Wikipedia infobox, used here for composition only. Sources conflict: webmineral prints Molecular Weight = 277.41 gm, and PubChem''s computed value is 278.21 with no unit printed. See gaps.'
    status: calculated
    source: wikipedia-anorthite
    where: 'Infobox: Formula mass 278.203 g·mol−1'
  - benchmark: photoelectric_absorption_per_electron
    label: Photoelectric absorption per electron (calculated)
    value: 3.05
    unit: barns/electron
    scope: material
    conditions:
      basis: calculated value printed by webmineral
    method: Calculated value printed on webmineral in the photoelectric section. Not a measurement.
    status: calculated
    source: webmineral-anorthite
    where: 'Calculated Properties: PEAnorthite = 3.05 barns/electron'
  - benchmark: photoelectric_absorption_per_volume
    label: Photoelectric absorption per volume (calculated)
    value: 8.32
    unit: barns/cc
    scope: material
    conditions:
      basis: calculated value printed by webmineral, PEAnorthite times electron density
    method: Calculated value printed on webmineral. Not a measurement.
    status: calculated
    source: webmineral-anorthite
    where: 'Calculated Properties: U = PEAnorthite x rElectron Density = 8.32 barns/cc'
  - benchmark: formula_units_per_cell
    label: Formula units per unit cell (Z)
    value: 8
    unit: '-'
    scope: material
    conditions:
      basis: triclinic cell as printed by the Handbook of Mineralogy
    method: Printed as Z = 8 in the cell data. Dimensionless count.
    status: ground
    source: hom-anorthite
    where: 'Cell Data: Z = 8'
corrosion:
  - environment: Weathering of surface rocks
    headline: Wikipedia says anorthite is scarcer in surface rocks than expected, which it attributes to a high weathering potential in the Goldich dissolution series.
    effect: No weathering rate, mass loss or corrosion test result for anorthite was found in the sources read, so this entry is qualitative only.
    conditions:
      basis: qualitative statement only; no test conditions are printed on the page
    source: wikipedia-anorthite
    where: Occurrence section
    rating: unknown
uses:
  - application: in-space-manufacturing
    device: Lunar regolith processing plant (concept only)
    example: Wikipedia says lunar regolith has been hailed as a potential source of oxygen and metals. The page does not name anorthite as the feedstock or name an extraction process.
    source: wikipedia-lunar-regolith
    where: Notes section, note 31
  - application: in-space-manufacturing
    device: Molten salt electrolysis cell for lunar highland regolith (laboratory concept, tested on the LHS-1 simulant)
    example: Schild et al. (Acta Astronautica, 2025) report that molten salt electrolysis of the LHS-1 highland regolith simulant extracted 97–99 % of the oxygen present in the simulant feedstock. The same paper compares the result with electrolysis of anorthosite, the major mineral of highland regolith, and does not report anorthite on its own.
    source: schild2025
    where: Abstract, sentences on the LHS-1 electrolysis and the anorthosite comparison
risks:
  hazards:
    - text: The PubChem record for anorthite (CID 56843091) has no Safety and Hazards section, so no GHS classification was found in the record.
      ghs: []
      source: pubchem-anorthite
      where: 'Record table of contents: no Safety and Hazards heading'
  failure_risks:
    - mode: Brittle fracture along cleavage planes
      trigger: Mechanical stress on a crystal or grain
      consequence: The Handbook of Mineralogy prints perfect cleavage on {001}, less so on {010}, imperfect on {110}, and brittle tenacity, so fragments split along those planes.
      severity: low
      source: hom-anorthite
      where: 'Physical Properties: Cleavage and Tenacity'
  side_effects: []
  handling: []
  mitigations: []
supply:
  - subject: Anorthite as a mineral
    abundance: The Handbook of Mineralogy calls it a widely distributed rock-forming mineral and a rare constituent of mafic plutonic and volcanic rocks. Wikipedia says anorthite makes up much of the lunar highlands.
    producers: []
    critical_lists: []
    recycling: Not found in any source read.
    substitutes:
      - Not found in any source read.
    source: hom-anorthite
    where: Occurrence and Distribution sections
  - subject: Aluminium, for comparison only
    abundance: USGS 2026 prints world bauxite resources of 55 billion to 75 billion tons, and world smelter production of 74,000 thousand metric tons in 2025e (world total, rounded). US net import reliance was 60 % of apparent consumption in 2025e.
    producers: []
    critical_lists: []
    recycling: USGS 2026 says secondary aluminum from scrap is a large share of US supply.
    substitutes:
      - Not found in any source read.
    source: usgs-mcs2026-aluminum
    where: 'Aluminum section: Salient Statistics, World Smelter Production and Capacity table, World Resources paragraph'
documents:
  - title: 'Handbook of Mineralogy: Anorthite (Mineral Data Publishing)'
    type: database
    url: http://www.handbookofmineralogy.org/pdfs/anorthite.pdf
    year: 2001
  - title: 'USGS Mineral Commodity Summaries 2026: Aluminum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
  - title: PubChem compound record, Anorthite (CID 56843091)
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/56843091
  - title: 'Webmineral: Anorthite data page'
    type: database
    url: https://www.webmineral.com/data/Anorthite.shtml
  - title: Characterization of metal products from the molten salt electrolysis of lunar highland regolith simulants (Acta Astronautica, 2025)
    type: paper
    url: https://researchportal.list.lu/publications/detail/characterization-of-metal-products-from-the-molten-salt-electrolysis-of-lunar-highland-regolith-simulants
    year: 2025
gaps:
  - 'Melting point: Wikipedia prints a melting point for pure anorthite, but this profile limits Wikipedia to composition and history, so no melting point is entered. A mineral physics, phase diagram or handbook value is needed.'
  - 'Measured density: webmineral prints a range of 2.72 to 2.75 with an average of 2.73, and the Handbook of Mineralogy prints D(meas.) 2.74 to 2.76, all without a unit. None is entered. Only the calculated values with gm/cc are entered.'
  - Unit cell edge lengths (a = 8.1768, b = 12.8768, c = 14.169) are printed without units on webmineral and the Handbook of Mineralogy. Wikipedia prints them in angstrom but is limited to composition and history, so they are not entered.
  - '2V angle: webmineral prints 2V(Calc)=78 and 2V(Meas)=78 without a unit, and the Handbook of Mineralogy prints 78 to 83 with the degree sign garbled. Not entered.'
  - 'Space group conflict: the Handbook of Mineralogy prints P 1 (low), Wikipedia prints P1 (no. 2) and webmineral prints P1,I1. The Handbook value is entered.'
  - 'Molar mass conflict: Wikipedia prints 278.203 g·mol−1, webmineral prints Molecular Weight = 277.41 gm, and PubChem prints a computed 278.21 with no unit. The Wikipedia value is entered; the others are recorded here only.'
  - 'Non-canonical property names: birefringence, formula_units_per_cell, photoelectric_absorption_per_electron, photoelectric_absorption_per_volume, hardness_mohs and molar_mass are not in spores/property-canon.yaml.'
  - 'Extraction process for aluminium, calcium or oxygen from anorthite: no source read in this run names a process, yield or energy figure for anorthite itself. Schild et al. (2025) describe molten salt electrolysis of the LHS-1 highland simulant, compared with anorthosite, and report 97–99 % oxygen extraction from that simulant; anorthite is not reported separately. The Wikipedia regolith page only calls regolith a potential source of oxygen and metals.'
  - 'Anorthite share in LHS-1: the Wikipedia lunar regolith simulant page names LHS-1 (Lunar Highlands Simulant, Exolith Lab, University of Central Florida) but gives no composition. The statement that anorthite is the main phase in LHS-1 is not verified in this run.'
  - 'Hazards and handling: the PubChem record has no Safety and Hazards section, and no safety data sheet for anorthite was read. Dust exposure limits and handling advice are not sourced.'
  - 'Corrosion and ageing: only a qualitative weathering statement was found on Wikipedia. No weathering rate, leaching rate or ageing test result is entered.'
  - 'Uses: two ISRU concept uses are sourced (a regolith processing plant and molten salt electrolysis of a highland simulant). No ceramic, refractory or industrial use of anorthite itself was read in this run.'
  - 'Supply: no production, trade or country share data for anorthite were found. No critical-minerals listing for aluminium or anorthite was read, so critical_lists is empty.'
  - 'Environment and stress tags: tags.environments and tags.stresses are left out because no source ties anorthite to a lunar-day, shadowed-crater or thermal stress.'
  - 'Media: no image with a licence was read, so the media block is left out.'
  - 'Thermal and mechanical properties: no elastic modulus, thermal conductivity, CTE or specific heat for anorthite was found in the sources read.'
sources:
  webmineral-anorthite:
    kind: database
    title: 'Webmineral: Anorthite data page'
    url: https://www.webmineral.com/data/Anorthite.shtml
  wikipedia-anorthite:
    kind: web
    title: 'Wikipedia: Anorthite'
    url: https://en.wikipedia.org/wiki/Anorthite
  pubchem-anorthite:
    kind: database
    title: PubChem compound record, Anorthite (CID 56843091)
    id: CID 56843091; CAS 1302-54-1
    url: https://pubchem.ncbi.nlm.nih.gov/compound/56843091
  hom-anorthite:
    kind: handbook
    title: 'Handbook of Mineralogy: Anorthite (Mineral Data Publishing)'
    url: http://www.handbookofmineralogy.org/pdfs/anorthite.pdf
    year: 2001
  usgs-mcs2026-aluminum:
    kind: report
    title: 'USGS Mineral Commodity Summaries 2026: Aluminum'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
  wikipedia-lunar-regolith:
    kind: web
    title: 'Wikipedia: Lunar regolith'
    url: https://en.wikipedia.org/wiki/Lunar_regolith
  schild2025:
    title: Characterization of metal products from the molten salt electrolysis of lunar highland regolith simulants
    id: doi:10.1016/j.actaastro.2025.02.021 (Acta Astronautica 232, 1-13, 2025)
    url: https://researchportal.list.lu/publications/detail/characterization-of-metal-products-from-the-molten-salt-electrolysis-of-lunar-highland-regolith-simulants
    year: 2025
    kind: paper
  wikipedia-lunar-regolith-simulant:
    kind: web
    title: 'Wikipedia: Lunar regolith simulant'
    url: https://en.wikipedia.org/wiki/Lunar_regolith_simulant
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 12
  unreachable: 0
  caveats: 4
  note: 'Written by an AI assistant on 2026-11-01 from pages fetched in this run. Seven sources were opened. verify-values passed: 12 of 12 values found in their cited sources. The melting point, uses, supply and extraction parts are thin; see gaps.'
story:
  recipe:
    line: Anorthite is a calcium aluminosilicate mineral with the formula CaAl2Si2O8. Each formula unit combines one calcium atom, two aluminium atoms, two silicon atoms and eight oxygen atoms. The weight shares below are the ideal composition printed by webmineral.
    parts:
      - name: Calcium
        symbol: Ca
        share: 13.72 % by weight (webmineral)
        role: The large cation that sets the calcium end of the plagioclase series. Wikipedia describes the series as a sodium and calcium mix that ends at pure calcium anorthite.
      - name: Aluminium
        symbol: Al
        share: 18.97 % by weight (webmineral)
        role: Part of the aluminosilicate framework. Its role as an extraction target is a concept only; no extraction source is read in this profile.
      - name: Silicon
        symbol: Si
        share: 20.75 % by weight (webmineral)
        role: Forms the silicate framework together with oxygen.
      - name: Oxygen
        symbol: O
        share: 46.14 % by weight (webmineral)
        role: The largest share by weight. Any oxygen-extraction idea depends on this share, but no extraction source is read in this profile.
  risk_groups:
    - title: For people
      level: 0
      verdict: No hazard data found
      lead: No safety data sheet or GHS classification for anorthite was read in this run, so no hazard class can be stated.
      points:
        - label: The mineral
          line: The PubChem record for CID 56843091 has no Safety and Hazards section.
        - label: Dust
          line: No source read gives a dust exposure limit or dust control advice for anorthite.
    - title: For equipment and samples
      level: 1
      verdict: Brittle
      lead: The Handbook of Mineralogy describes brittle tenacity and perfect cleavage on {001}.
      points:
        - label: Cleavage
          line: Perfect on {001}, less so on {010}, imperfect on {110}, according to the Handbook of Mineralogy.
  why: |
    Anorthite (CaAl2Si2O8) is the calcium-rich member of the plagioclase feldspar series. Wikipedia states that it makes up much of the lunar highlands, and it was first described in 1823. It is triclinic with a Mohs hardness of 6 to 6.5 and a calculated specific gravity of 2.75 gm/cc. Its interest for the Moon is the aluminium, calcium and oxygen in its framework, but this profile holds no extraction data for it.
  uses:
    - where: Lunar regolith concept
      line: Wikipedia says lunar regolith has been hailed as a potential source of oxygen and metals. The page does not name anorthite as the feedstock or name an extraction route.
    - where: Molten salt electrolysis of highland simulant
      line: Schild et al. (Acta Astronautica, 2025) report 97–99 % oxygen extraction from the LHS-1 highland simulant by molten salt electrolysis. The paper compares it with anorthosite, not anorthite.
  can_do:
    - label: Density
      benchmark: density
      line: Webmineral prints a calculated specific gravity of 2.75 gm/cc and a bulk density from electron density of 2.73 gm/cc. Both are calculated values, not measurements.
    - label: Hardness
      benchmark: hardness_mohs
      line: The Handbook of Mineralogy prints a hardness of 6 to 6.5.
    - label: Optics
      benchmark: refractive_index
      line: The Handbook of Mineralogy prints refractive indices of 1.573 to 1.577 (alpha), 1.580 to 1.585 (beta) and 1.585 to 1.590 (gamma). Webmineral calls the mineral biaxial negative.
  compare: |
    Anorthite is a silicate mineral and aluminium is a metal, so this profile does not compare them on density or hardness. The USGS 2026 aluminum summary gives world smelter production of 74,000 thousand metric tons in 2025e, which is the existing comparison point for any aluminium route from this mineral. No source read in this run gives an extraction yield or energy figure for anorthite, so no like-for-like comparison is possible yet.
  compare_rows:
    - label: Calculated density
      benchmark: density
    - label: Hardness (Mohs)
      benchmark: hardness_mohs
    - label: Refractive index, alpha
      benchmark: refractive_index
  handling:
    - No safety data sheet or handling guidance for anorthite was read in this run, so this profile gives no handling rule. Read a supplier safety data sheet before handling powdered samples.
  good_for:
    - 'Lunar highlands reference: Wikipedia says anorthite makes up much of the lunar highlands, and it describes the Genesis Rock as composed largely of anorthite.'
    - 'Plagioclase reference data: the calculated density, refractive indices and hardness in this profile come from webmineral and the Handbook of Mineralogy.'
  watch_out:
    - Molar mass conflicts between sources. Webmineral prints 277.41 gm, Wikipedia prints 278.203 g·mol−1, and PubChem computes 278.21 with no unit printed.
    - No melting point is entered. Wikipedia prints one, but this profile limits Wikipedia to composition and history.
    - The extraction role is not sourced. The Wikipedia regolith page calls regolith a potential source of oxygen and metals but names no process for anorthite.
  verdict: Anorthite is a well-characterised calcium plagioclase, and its calculated and optical data can be cited. For the extraction role implied by its category, this profile has no process, yield or energy data, so it should be read as a mineral reference rather than an ISRU feedstock study.