30 U.S.C. § 354
Lease of partial or future interests in deposits
Where the United States does not own all of the mineral deposits under any lands sought to be leased and which are affected by this chapter, the Secretary is authorized to lease the interest of the United States in any such mineral deposits when, in the judgment of the Secretary, the public interest will be best served thereby; subject, however, to the provisions of section 352 of this title. Where the United States does not own any interest or owns less than a full interest in the minerals that may be produced from any lands sought to be leased, and which are or will be affected by this chapter and where, under the provisions of its acquisition, the United States is to acquire all or any part of such mineral deposits in the future, the Secretary may lease any interest of the United States then owned or to be acquired in the future in the same manner as provided in the preceding sentence.