Armalcolite

Named by combining the names of the Apollo 11 astronauts (ARMstrong, Aldrin, COLlins). Armacolite was the first new mineral discovered on Luna. Armalcolite is a metal oxide mineral.

 

Technically, armalcolite is always (FeO₅MgO₅)Ti₂O₅. However, it is also used for minerals whose compositions vary between MgTi₂O₅ and FeTi₂O₅ (Lunar Sourcebook, 148). Armalcolite is mostly found in high TiO₂ rocks but has been found in basalt samples from all missions (Lunar Sourcebook, 148). Armalcolite can be composed of other elements but the Fe-Mg flavor is the most common (Lunar Sourcebook, 148).

I haven’t found a source yet confirming the magnetic properties of armalcolite. So at this point I’m going to assume it’s non-magnetic and move on. I can always come back to it if I find differently.

 

Abundance and distribution

• Found in very small amounts in basalt samples from all missions. (1, pg 148)
• Occurrence is restricted to rocks with high-Ti content that cooled rapidly (1, pg 148)

 

Physical properties

• Probably non-magnetic. I looked and couldn’t find a definitive answer. I’ll keep looking. But the rims of high-Mg ilmenite won’t help.

 

Chemical composition

• Multiple varieties
• Breaks down into a mixture of rutile and magnesium-rich ilmentite at 1,000 °C.
• Often occurs with rims of high-Mg ilmenite (1, pg 148).

 

Mechanical separation

Not needed for this phase of the project.

 

Refining

Not needed for this phase of the project.

 

Data

Analysis of armalcolite (Fe-Mg) in rocks and soils (selected samples)(Lunar Sourcebook, 176)

• Apollo 11 (High-K)(>0.3% K₂0)
  • Iron oxide (FeO) by weight percent range: 15.3% – 16.9%
  • Average FeO by percent weight = 16.1%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.52 – 0.53
• Apollo 11 Fragmental breccias (mainly fragments)

• • Iron oxide (FeO) by weight percent range: 11.9%
  • Average FeO by percent weight = 11.9%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.45
• Apollo 11 Regolith breccias (compressed soil)
  • Iron oxide (FeO) by weight percent range: 14.7%
  • Average FeO by percent weight = 14.7%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.49
• Apollo 11 soil (unknown rock types)
  • Iron oxide (FeO) by weight percent range: 11.32%
  • Average FeO by percent weight = 11.32%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.36
• Apollo 14 soil (unknown rock types)
  • Iron oxide (FeO) by weight percent range: 16.0%
  • Average FeO by percent weight = 16.0%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.77
• Apollo 17 soil (unknown rock types)
  • Iron oxide (FeO) by weight percent range: 15.7% – 16.0%
  • Average FeO by percent weight = 15.85%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.57 – 0.58
• Apollo 17 basalt
  • Iron oxide (FeO) by weight percent range: 14.44% – 16.39%
  • Average FeO by percent weight = 15.62%
  • Ratio of iron to magnesium [Fe/(Fe+Mg)] range = 0.51 – 0.61

 

Resources

1. Lunar Sourcebook