Section 211.27 - Duration of leases(a) All leases shall be for a term not to exceed a primary term of lease duration of ten (10) years and, absent specific lease provisions to the contrary, shall continue as long thereafter as the minerals specified in the lease are produced in paying quantities. Absent specific lease provisions to the contrary, all provisions in leases governing their duration shall be measured from the date of approval by the Secretary.(b) An oil and gas or geothermal resource lease which stipulates that it shall continue in full force and effect beyond the expiration of the primary term of lease duration ("commencement clause") if drilling operations have commenced during the primary term, shall be valid and shall hold the lease beyond the primary term of lease duration if the lessee or the lessee's designee has commenced actual drilling by midnight of the last day of the primary term of the lease with a drilling rig designed to reach the total proposed depth, and drilling is continued with reasonable diligence until the well is completed to production or abandoned. However, in no case shall such drilling hold the lease longer than 120 days past the primary term of lease duration without actual production of oil, gas, or geothermal resources. Provided, that this extension does not allow a lease to continue past the 10-year statutory limitation. Drilling which meets the requirements of this section and occurs within a unit or communitization agreement to which the lease is committed shall be considered as if it occurs on the leasehold itself. If there is a conflict between the commencement clause and the habendum clause of a lease, the commencement clause will control.(c) A solid minerals lease which stipulates that it shall continue in full force and effect beyond the expiration of the primary term of lease duration if mining operations have commenced during the primary term (commencement clause), shall be valid and hold the lease beyond the primary term of lease duration if the lessee or the lessee's designee has by midnight of the last day of the primary term of the lease commenced actual removal of mineral materials intended for sale and upon which royalties will be paid. If there is a conflict between the commencement clause and the habendum clause of a lease, the commencement clause will control.