Code of Federal Regulations Title 25. Indians § 25.214.7 Operation not permitted until lease approved;  160 acres maximum for single lease

No mining or work of any nature will be permitted upon any tract of land until a lease covering such tract shall have been approved by the Secretary of the Interior and delivered to the lessee. All leases shall be made for such period as the title to the minerals remain in the Osage Tribe, which time will expire April 8, 1931, unless otherwise provided by Congress and shall be subject to cancellation or termination as specified in this part. Leases made by corporations shall be accompanied by an affidavit by the secretary or president of the company showing the authority of its officers to execute leases, bonds, and other papers. No lease shall be made covering more than 160 acres.