Talk:Princess Luna/@comment-28250775-20170721110658/@comment-7345250-20170725003633

[Busts out the igneous petrology notes]

Ackchyually, the lunar highlands are primarily anorthosites, which are upwards of 90% CaAl₂Si₂O₈. There's little titanium to be found in there.

Titanium occurs more frequently in the mafic lunar mares. The TiO₂ content in a sample lunar mare basalt analysis I have on hand is about 10.62wt%, whereas the average FeO content is about 19.21wt%. (Fe₂O₃ does not occur on the moon because Fe³⁺ requires water, so FeO by itself will suffice to represent iron content.) The respective molecular weights of TiO₂ and FeO are 79.90g/mol and 71.85g/mol. Taking this into consideration, simple division shows that, in 100g of lunar mare basalt, there are about 0.13 moles of titanium and 0.27 moles of iron. That's twice as much iron as titanium.

So while titanium is much, much more common on the moon than on earth, lunar rock is not dominated by the metal by any means. However, I think the mineral armalcolite is worth a mention. It is an opaque, hexagonal titanium-rich oxide that was first discovered on the moon and named after Neil Armstrong, Buzz Aldrin, and Michael Collins. I had the privilege of viewing the exotic mineral under a microscope earlier this year, and it says "extraterrestrial" like nothing else I've seen.