[ben_w]

Wikipedia looks like it says [0], by elemental concentration, roughly 42% oxygen, 21% silicon, 12% iron, 8% calcium, 7% aluminium, 6% magnesium, 4% other.

[0] Bar graph with insufficient labels: https://en.m.wikipedia.org/wiki/File:Composition_of_lunar_so...

[imglorp]

Magnesium should be even better for some space apps. In fact, it would sinter better in a vacuum than air.

https://www.deepdyve.com/lp/wiley/sintering-of-magnesium-h06...