Armalcolite

Armalcolite

Armalcolite – Photo – http://tw.strahlen.org/fotoatlas1/armalcolite_foto.html

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

 

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