The foil fragments were found on one platform mound, the pyramid's summit, and a terrace immediately behind the pyramid, but not in the residential areas. Radiocarbon dates of materials associated with the copper are between ca. B.C. Analyses by Robert Gordon of Yale's department of geology and geophysics showed the copper to be 99.5 percent pure. Small veins of gold and copper do crop out along the coast of central Peru.
Elongated grains indicate that the metal was hammered into foil while cold.