Section 212.21 - Execution of leases(a) The Secretary shall not execute a mineral lease on behalf of an Indian mineral owner, except when such owner is deceased and the heirs to or devisee of the estate have not been determined, or if determined, some or all of them cannot be located. Leases involving such interests may be executed by the Secretary, provided that the mineral interest shall have been offered for sale under the provisions of section 212.20(b) (1) through (6) .(b) The Secretary may execute leases on behalf of minors and persons who are incompetent by reason of mental incapacity; Provided, that there is no parent, guardian, conservator, or other person who has lawful authority to execute a lease on behalf of the minor or person with mental incapacity.(c) If an owner is a life tenant, the procedures set forth in 25 CFR part 179 (Life Estates and Future Interests), shall apply.