Sorry it took so long to get back with you. My husband and I have been in the process of building a new, more ND winter friendly chicken coop, and we have hardly had time to breath, let alone play on the computer. HOpefully it will make for happy chickens!
Whoever has mineral rights to a property basically owns the minerals on the property. I believe that some of the minerals protected would be oil, coal, oil shale, gold, silver, rocks, sand soil, and more. It hasn't really mattered in the past, since the rights go along with the property, unless specifically stated, but now with the bakken oil reserve being hot on everyones minds, some people are selling land, but reserving mineral rights.
I, myself, would not buy land without the mineral rights, the idea bugs me (
), but I suppose to some people it wouldn't matter. I hope that you find what you are looking for in ND!