Discovery of valuable minerals is not defined by statute. Ernest K. Lehmann & Assocs. of Mont., Inc. v. Salazar, 602 F.Supp.2d 146, 150 (D.D.C.2009)aff'd, 377 Fed.Appx. 28 (D.C.Cir.2010). In some cases, like the present, claims lie on federal public lands that later become closed by law to new mineral exploration.

“The government presents a prima facie case where a governmental mineral examiner offers expert testimony, based on probative evidence that the discovery of a valuable mineral deposit has not been made within the boundaries of a contested claim.” Ernest K. Lehmann & Assocs. of Mont., Inc. v. Salazar, 602 F.Supp.2d 146, 150 (D.D.C.2009), aff'd,377 Fed.Appx. 28 (D.C.Cir.2010) (citing United States v. Pass Minerals, Inc., 168 IBLA 115, 123 (IBLA 2006)). Once the government has made a prima facie case, the burden shifts to the claimant to establish by a preponderance of the evidence sufficient proof of validity.

“The government presents a prima facie case where a governmental mineral examiner offers expert testimony, based on probative evidence, that the discovery of a valuable mineral deposit has not been made within the boundaries of a contested claim.” Ernest K. Lehmann & Assocs. of Montana, Inc. v. Salazar, 602 F.Supp.2d 146, 150 (D.D.C.2009), aff'd, 377 Fed.Appx. 28 (D.C.Cir.2010) (citing United States v. Pass Minerals, Inc., 168 IBLA 115, 123 (IBLA 2006)). Once the government has made a prima facie case, the burden shifts to the claimant to establish by a preponderance of the evidence sufficient proof of validity.