Subject to the provisos of , any mining location made under the mining laws of the United States, including chapter 12 of this title, on lands of the character described in , except locations made for lands within the exterior boundaries of a prior coal prospecting permit or lease, if based upon a discovery of valuable source material in deposits other than deposits of Leasing Act minerals, shall include the right to mine, remove, and dispose of lignite containing valuable source material and lignite necessary to be stripped or mined in the recovery of source material contained in lignite, subject to the reporting and payment requirements of , and subject to the provisions of the Atomic Energy Act of 1954 [ et. seq.], and upon filing in the land office designated in , an adequate description of his claim or claims containing such lignite: , That nothing in this section shall be construed to limit or restrict the rights acquired by virtue of a mining claim heretofore or hereafter located, under the 1872 Mining Act, as amended, or to impose any additional obligation with respect to the mining and removal of source material which does not occur within any seam, bed, or deposit of lignite.section 541a of this titlesection 541 of this titlesection 541 of this title42 U.S.C. 2011section 541 of this titleProvided