25 U.S.C. § 396a — Leases of unallotted lands for mining purposes; duration of leases

This section covers unallotted lands within an Indian reservation, or lands a tribe, group, or band owns under federal jurisdiction — except any lands specifically excluded from sections 396a through 396g of this title. Since May 11, 1938, these lands may be leased for mining purposes. Two approvals are required: the tribal council or another authorized representative of the tribe must authorize the lease, and the Secretary of the Interior must approve it. A lease can last up to ten years, and can continue beyond that for as long as minerals keep being produced from the land in "paying quantities" — meaning in amounts profitable enough to be worth producing.