Contributi italiani alla nascita della Petrografia

At the end of the 18th and in the first decades of the 19th century G. Arduino, G. Marzari Pencati, G. Brocchi, and S. Breislak, italian experts in ore prospecting and exploitation, and interested in Earth sciences, correctly recognized the igneous nature of either intrusive or volcanic bodies within sedimentary sequences on the grounds of field data, in contrast to Werner’s neptunistic ideas. But also renown scholars in the field of Natural History, as L. Spallanzani and G. Gioeni gave relevant contributions to the study of rocks, and at the end of this stage C. Gemmellaro is to be cited, as a successor of Gioeni. Petrography started to develop when rocks, already subdivided by Werner (1774) into groups meeting some criteria of petrographical taxonomy. It reached the stage, as an autonomous discipline from Mineralogy and Geology, within the frame of Natural History, when rocks could be classified on the grounds of the basic works by Cordier (1816), von Leonhard (1823), and Brongniart (1827), who introduced a taxonomic basis, although still affected by inconsistencies and naiveties, related to rocks on the grounds of their compositions and origin.