subsequent term of such a lease, the Secretary may issue a 10-year extension of the lease in the interest of conservation or upon a successful showing by the lessee that the lease cannot be successfully operated at a profit or for other reasons. No more than one extension under this subparagraph may be issued. (d) Cumulative acreage limitation No person may take, hold, own, or control at one time, whether acquired directly from the Secretary under this Act or otherwise, hardrock mining leases or licenses for an aggregate of more than 20,480 acres in any one State. (e) Reduction of royalty rate The Secretary— (1) may reduce the royalty rate for a lease upon a showing by clear and convincing evidence by the person conducting mineral activities under the lease that production would not occur without the reduction in royalty