I highly recommend that if your are even considering selling any minerals, you take the time to talk with a Oil and Gas Lawyer. Some of the letters to purchase minerals state in small print that they are purchasing ALL your minerals. So again this is very serious business. This is something that you can leave to your kids, and their kids, that doesn't cost much to maintain, till they start drilling. So don't think about it today, they are not making any more land. But they sure drill differently since 1918.