30 U.S.C. § 28–1

The term “labor”, as used in the third sentence of section 28 of this title , shall include, without being limited to, geological, geochemical and geophysical surveys conducted by qualified experts and verified by a detailed report filed in the county office in which the claim is located which sets forth fully (a) the location of the work performed in relation to the point of discovery and boundaries of the claim, (b) the nature, extent, and cost thereof, (c) the basic findings therefrom, and (d) the name, address, and professional background of the person or persons conducting the work. Such surveys, however, may not be applied as labor for more than two consecutive years or for more than a total of five years on any one mining claim, and each such survey shall be nonrepetitive of any previous survey on the same claim.