With a contract the way your describing, you end up having little to no rights it seems. To me it isn't worth 7K, if they don't extract anything there goes your 12-15 %. Next question is 12 -15 % of what, 100, 1000, 10000, 100000, 1000000?
Id want some sort of figure in writing what they plan on paying you.
Id find an attorney to explain it to you and enter some sort of out clause for you as well and as suggested find other land owners who are using the company to see how it is really going.