30 U.S.C. § 287
Extension of prospecting permits
Any prospecting permit issued under this subchapter may be extended by the Secretary of the Interior for a period not exceeding two years, upon a showing of satisfactory cause.
( Feb. 7, 1927, ch. 66, § 7 , as added May 7, 1932, ch. 174 , 47 Stat. 151 .)