Today I added ore veins to Thunder Moon which is where players can mine the resources necessary for the crafting of many items.
The ore veins are placed with a fairly straightforward fractal, which means the resources will generally appear in clusters underground in groups. Soon, I'll be tweaking the numbers for design control of what depths the various resources will be most commonly found, some of them of course being deep, deep underground.
Speaking of which, and I don't recall if I've mentioned this, but Thunder Moon's terrain is not depth or height limited. There are some precision issues if you go terribly deep, but it's unlikely that will really be a concern.