Whenever it shall be shown to the satisfaction of the Secretary of the Interior that a tract or tracts of public land, contiguous to a Spanish or Mexican land grant, in the State of New Mexico, not exceeding in the aggregate one hundred and sixty acres, has or have been held in good faith and in peaceful, adverse possession by a citizen of the United States, his ancestors or grantors, for more than twenty years under claim or color of title, and that valuable improvements have been placed on such land, or some part thereof has been reduced to cultivation, the Secretary may, in his discretion, upon the payment of $1.25 per acre, cause a patent or patents to issue for such land to any such citizens: Provided, That where the area or areas so held by any such citizen is in excess of one hundred and sixty acres the Secretary may determine what particular subdivisions, not exceeding one hundred and sixty acres in the aggregate, to any such citizen may be patented hereunder: Provided further, That coal and all other minerals contained therein are reserved to the United States; that said coal and other minerals shall be subject to sale or disposal by the United States under applicable leasing and mineral land laws, and permittees, lessees, or grantees of the United States shall have the right to enter upon said lands for the purpose of prospecting for and mining such deposits: Provided further, That the term "citizen", as used in this section, shall be held to include a corporation organized under the laws of the United States or any State or Territory thereof.