A.G. Davis Ice , 362 F.2d at 936-37; see, e.g., Parrish , 657 F. Supp. at 274 (accepting opinion of value by expert who “was careful to rely on the income generable by the mineral itself (a royalty)—which is correctly attributable to the value of the land—and did not rely on an estimate of an operator’s profit—which would not be attributable to the land”).