43 CFR § 3583.4-1
Leasing units
June 11, 2020
Leasing units may not exceed 640 acres consisting, if the lands are surveyed, of legal subdivisions in reasonably compact form or, if the lands are not surveyed, of a square or rectangular area with north and south and east and west boundaries so as to approximate legal subdivisions, described by metes and bounds and connected to a corner of the public survey by courses and distances. The authorized officer may prescribe a lesser area for any mineral deposit if such lesser area is adequate for an economic mining operation.