Board Thread:Questions and Answers/@comment-76.121.146.94-20130404023925/@comment-5627887-20130604145654

84.60.35.207 wrote: Coper is at 40 and above. While Strip-Mining at Level 13 you won't find any!

Or build a Massfabricator to get everything you want ^^

It is likely that if you are only just building MV solar arrays, you do not have enough surplus power to generate UU-Matter in any large quantity, making it more efficient to go out mining than wait for enough UU-Matter to craft whatever it is you need, (3 UU-Matter gives 10 Copper Dust, for example). You are right in that eventually you can forgo actual mining in favour of generating materials, unless you need something UU-matter can't make, such as Lead, Silver, Basalt, Marble, Nikolite etc etc.