Olivine

Apollo 15 olivine basalt – Photo by Wknight94 talk – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=16937937

Olivine is a major Lunar mineral, with significant concentrations found in most samples. The good news is that the iron variant, fayalite, is the most common type of olivine. We definitely want olivine when we start extracting iron.

Abundance and distribution

• Olivine is present in most Lunar soils but is very variable in abundance (5, pg 249)
• Highland soils are 7% olivine on average with a larger compositional range than mare soils.
• Some mare samples contained a large percentage of olivine. Overall though, the percentage at mare sites varied substantially between samples.

Physical properties

• Magnetic = ??? I’ll keep looking.

Chemical composition

Olivine, a silicate mineral, comes in two basic flavors, iron or magnesium. The iron variant is called fayalite (Fe²⁺₂SiO₄). The magnesium variant is forsterite (Mg₂SiO₄). Both are often found in the same sample of olivine.

• Most olivines found in mare basalts contain 20%-70% fayalite (Lunar Sourcebook, 130).
• Most samples showed 75 to 50 mole percent forsterite (Handbook of Lunar Materials, 32).
• Most compositions of olivine are 50-75% forsterite. (4, chapter X,M)
• None of the olivine samples returned had a fayalite concentration below 20% (Lunar Sourcebook, 131).
• A number of samples did contain fayalite in much higher concentrations (70%-100%)(Lunar Sourcebook).
• Lunar highland samples ranged from 5% to 45% fayalite, with several in the 78%-95% range (Lunar Sourcebook).
• Olivine composition ranges from Fo₇₅-Fo₆₀ with a peak around Fo₆₇ (5, pg 249)

Olivine compositions:

• Fayalite   http://www.handbookofmineralogy.org/pdfs/fayalite.pdf
  • Melting point (degC) = 1025 +- 2 (Handbook of Lunar Materials, 39)
• Forsterite  http://www.handbookofmineralogy.org/pdfs/forsterite.pdf  mostly because it forms with fayalite, not because we plan on using it.
  • Melting point (degC) = 1890 +- 20 (Handbook of Lunar Materials, 39)

Mechanical separation

Not needed for this phase of the project.

Refining

Not needed for this phase of the project.

Data

Proportion of olivine (volume %) from Lunar samples. (90-20μm, not including fused-soil and rock fragments) (Lunar Sourcebook, 123)

• Apollo 11 – 2.1
• Apollo 12 – 5.4
• Apollo 14 – 6.7
• Apollo 15 (Highlands) – 5.9
• Apollo 15 (Mare) – 5.3
• Apollo 16 – 3.9
• Apollo 17 (Highlands) – 11.6
• Apollo 17 (Mare) – 0.2
• Luna 16 – 10.0
• Luna 20 – 6.6
• Luna 24 – 17.5

Analysis of olivine mare basalts (selected samples)(Lunar Sourcebook, 166)

• Apollo 17 (High-Ti)(>9% TiO₂)
  • Iron oxide (FeO) by weight percent range: 27.44% – 28.44%
  • Average FeO by percent weight = 27.94%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.30 – 0.32
• Apollo 11 (High-Ti)(>9% TiO₂)(High-K) (>0.3% K₂0)

• • Iron oxide (FeO) by weight percent range: 26.20%
  • Average FeO by percent weight = 26.20%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.29
• Apollo 11 (High-Ti)(>9% TiO₂) (Low-K)(<0.11% K₂O)
  • Iron oxide (FeO) by weight percent range: 25.40% – 68.70%
  • Average FeO by percent weight = 39.87%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.28 – 0.99
• Apollo 12 ilmenite (<10%MgO, >5% TiO₂)(Low-Ti)(1.5-9% TiO₂)
  • Iron oxide (FeO) by weight percent range: 22.15% – 65.30%
  • Average FeO by percent weight = 43.73%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.24 – 0.91
• Apollo 12 pigeonite [a form of pyroxene] (<10% MgO, <5% TiO₂) (Low-Ti)(1.5-9% TiO₂)
  • Iron oxide (FeO) by weight percent range: 39.60%
  • Average FeO by percent weight = 39.60%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.48
• Apollo 12 olivine (>10% MgO, <5% TiO₂)(Low-Ti)(1.5-9% TiO₂)
  • Iron oxide (FeO) by weight percent range: 21.10% – 33.80%
  • Average FeO by percent weight = 27.45%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.23 – 0.39
• Apollo 15 olivine (>10% MgO, <5% TiO₂)(Low-Ti)(1.5-9% TiO₂)
  • Iron oxide (FeO) by weight percent range: 64.80%
  • Average FeO by percent weight = 64.80%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.91
• Apollo 14 VHK (Very High Potassium)(>0.6% K₂O)(Aluminous, Low-Ti basalts)
  • Iron oxide (FeO) by weight percent range: 24.71% – 49.79%
  • Average FeO by percent weight = 37.25%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.27 – 0.64
• Luna 24 (Very Low-Ti basalts)(<1.5% TiO2)
  • Iron oxide (FeO) by weight percent range: 48.61% – 67.15%
  • Average FeO by percent weight = 57.88%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.60 – 0.97
• Apollo 17 (Very Low-Ti basalts)(<1.5% TiO2)
  • Iron oxide (FeO) by weight percent range: 23.06% – 39.35%
  • Average FeO by percent weight = 28.52%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.25 – 0.46

Abundance of Lunar olivine (percent volume)(Handbook of Lunar Materials, 32)

• Mare basalts = 0%-35%
• Anorthositic rocks = 0%-40% (most samples contained only a few percent)
• Fragmental breccias = 0%-5% (olivine content depends on local rocks)
• Crystalline breccias = 1%-5%
• Soil = 0%-4% (olivine content depends on local rocks)

Iron abundance in typical Lunar olivine (percent weight)(Handbook of Lunar Materials, 33)

• Mare = 27.00%
• Highland = 26.24%

FeO concentrations in olivine (percent weight)(Space Resources: Vol 3 Materials, 29)

• High-Ti mare basalts = 25.4% – 28.8%
• Low-Ti mare basalts = 21.1% – 47.2%
• Highland rocks = 13.40% – 27.3%

Lunar samples % olivine (randomly selected by me) (6)

• Sample 10003 (Apollo 11 mare basalt) = 0.50-0.52%
• Sample 12015 (Apollo 12 mare basalt) = 10.3-62.3%
• Sample 14078 (Apollo 14 KREEP basalt) = 6.5%
• Sample 15261 (Apollo 15 soil) = 2.5%
• Sample 67747 (Apollo 16 highland basalt) = 16.3%
• Sample 70215 (Apollo 17 high-Ti mare basalt) = 6-9.2%

Resources

1. Lunar Sourcebook
2. Handbook of Lunar Materials
3. Space Resources: Vol 3 Materials
4. Extraterrestrial Materials Processing and Construction
5. Lunar Stratigraphy and Sedimentology
6. LPI Lunar Sample Atlas

Not used but relevant