Lunar Gemstones

When we discuss mineral extraction on the moon we concentrate on the regolith because it's what we know from the Apollo samples. But if, as current theory has it, the moon was created when something very big splashed a huge chunk out of the earth's crust, we should find similar geological processes creating veins of metal ores beneath the lunar surface.

This is a question for geologists and mining engineers. The Apollo program just barely scratched the surface (literally) in only six widespread locations. Everything we know about subselene material comes from a few samples tossed out by impacts.

Another lunar geology question is gemstones. The chemicals are there, and tiny little gemstone crystals are mixed all through the dust. But are there large crystals? Low gravity and an anhydrous environment favor huge crystals of aluminum oxides (rubies, emeralds, and most other gems; not diamonds), but the fast cooling of a smaller body inhibits them. Can we get a handle on what to look for, or do we have to wait until we get there and start digging?