Ceraunia were collected by many persons over the centuries including Michele Mercati, Superintendent of the Vatican Botanical Garden in the late 16th century. He brought his collection of fossils and stones to the Vatican, where he studied them at leisure, compiling the results in a manuscript, which was published posthumously by the Vatican at Rome in 1717 as "Metallotheca". Mercati was interested in Ceraunia cuneata, "wedge-shaped thunderstones," which seemed to him to be most like axes and arrowheads, which he now called ceraunia vulgaris, "folk thunderstones," distinguishing his view from the popular one. His view was based on what may be the first in-depth lithic analysis of the objects in his collection, which led him to believe that they are artifacts and to suggest that the historical evolution of these artefacts followed a scheme.