Coffeelvr50, There are several ways to find the value of mineral rights and royalty interests. I cover how mineral rights and royalties are valued in my latest Podcast Episode. (Note this is a link to iTunes but it can also be found on Google Play and Stitcher - just search for the Mineral Rights Podcast).
Just to note, there is a difference between a mineral acre and royalty acre which has been answered in detail here on the forum. Here’s a link to one of the latest posts on the subject.
Please let me know if the Podcast episode helps answer your question and please let me know if you have any suggestions or feedback. Right now we are recording regular episodes and I plan on publishing them every other week or so.
Best Regards, Matt Sands Mineral Rights Podcast