The lessee may surrender the entire lease, a legal subdivision thereof, an aliquot part thereof (not less than 10 acres) or any bed of the coal deposit therein. A partial relinquishment shall describe clearly the surrendered parcel or coal deposits and give the exact acreage relinquished. If the authorized officer accepts the relinquishment of any coal deposits in a lease, the coal reserves shall be adjusted in accordance with part 3480 of this title.
43 C.F.R. §3452.1-1