Back-of-napkin calculation suggests that it would be ~20 ppm if it were evenly distributed. But as any water is likely concentrated in surface rock and dust, i

Back-of-napkin calculation suggests that it would be ~20 ppm if it were evenly distributed. But as any water is likely concentrated in surface rock and dust, it might be substantially more than that. Still, it may be possible to mine deep water-poor silicates and oxides and process them in a water-free hard-vacuum environment. Time will tell, I guess! Lunar fiberglass is still a highly speculative thing. (But extremely cool, at least in principle, due to its superlative strength and toughness.)