E.g., United States v. 237,500 Acres of Land, 236 F. Supp. 44, 55 (S.D. Cal. 1964) (valuing placer mining claims as a whole, then apportioning locators’, lease and option interests). Applying the unit rule can be particularly complex in acquisitions of less-than-fee estates such as easement (Section 4.6.5) or leasehold (Section 4.7) interests, or in acquisitions involving minerals, timber or other natural resources (Section 4.8).