Properties for which you are currently receiving a royalty check.
Producing mineral rights that generate monthly revenue are typically more valuable than non-producing minerals. The volumes of oil and gas being produced and the rate at which those rates are declining on a monthly basis are the primary factors in determining the value of a producing property. These properties are evaluated by performing a decline-curve analysis on the production which yields a discounted cash flow calculation estimating what type of return an investor might expect given price expectations and other economic variables.
Properties either leased or unleased that have yet to generate any cash flow.
Non-producing mineral rights have no current production and therefore no cash flow associated with them. They are typically less valuable than producing minerals because they are valued on their very unproven potential. The risk involved with keeping them can many times outweigh the serendipity involved with owning them when the right offer is presented. Valuing these types of minerals is very subjective and determining whether to sell them or not is a very personal decision.