I found this article to be interesting. There's bound to be Titanium rich veins on the surface. Just a matter of finding them. Titanium is a primary metal used in Engines, tools and dies. Many of the present modules being made right now are using hollowed out Al to decrease the weight, but Al doesnt offer the protection from stellar rays or strength like Titanium does. Titanium is also nonmagnetic. This could open up a new resource for Lunar mining. Many uses for it up there.