43 CFR 3435.1: Coal lease exchanges.

Where the Secretary determines that coal exploration, development and mining operations would not be in the public interest on an existing lease or preference right lease application or portions thereof, or where the Congress has authorized lease exchange for a class or list of leases, an existing lease or preference right lease application may be relinquished in exchange for:

(a) Leases where the Congress has specifically authorized the issuance of a new coal lease;

(b) The issuance of coal lease bidding rights of equal value;

(c) A lease for a mineral listed in subpart 3526 of this title by mutual agreement between the applicant and the Secretary; and

(d) Federal coal lease modifications; or

(e) Any combination of the above.