Every mining claim or millsite—

(1) Heretofore located under the mining laws of the United States which shall be entitled to benefits under the first three sections of this Act; or

(2) Located under the mining laws of the United States after the effective date of passage of this Act, shall be subject, prior to issuance of a patent therefor, to a reservation to the United States of all Leasing Act minerals and of the right (as limited in section 6 hereof) of the United States, its lessees, permittees, and licensees to enter upon the land covered by such mining claim or millsite and to prospect for, drill for, mine, treat, store, transport, and remove Leasing Act minerals and to use so much of the surface and subsurface of such mining claim or millsite as may be necessary for such purposes, and whenever reasonably necessary, for the purpose of prospecting for, drilling for, mining, treating, storing, transporting, and removing Leasing Act minerals on and from other lands; and any patent issued for any such mining claim or millsite shall contain such reservation as to, but only as to, such lands covered thereby which at the time of the issuance of such patent were—

(a) Included in a permit or lease issued under the mineral leasing laws; or

(b) Covered by an application or offer for a permit or lease filed under the mineral leasing laws; or

(c) Known to be valuable for minerals subject to disposition under the mineral leasing laws.