Rentals and royalties shall be determined by the authorized officer on the basis of the fair market value, but in no event shall be less than:

(a) A rental of 50 cents per acre or fraction thereof payable in advance until production is obtained.

(b) A minimum royalty of $1 per acre or fraction thereof payable in advance after production is obtained.

(c) A production royalty of 2 percent of the amount or value of the minerals mined, the exact amount of royalty to be fixed prior to the issuance of the lease.