In Andrus v. Shell Oil Co., 446 U.S. 657, 100 S.Ct. 1932, 64 L.Ed.2d 593 (1980), the Supreme Court was called upon to determine whether locations of oil shale made prior to the 1920 Mineral Leasing Act, which withdrew oil shale from discovery under the 1872 general mining law, were valid even though oil shale at that time had no present marketability. The Supreme Court ruled that the locations were valid, noting the long-standing administrative interpretation that had included oil shale within the Act even though there had never been a profitable market for it.