In addition to these artificial reactive ingredients, the Romans used a natural reactive volcanic sand named harena fossicia wrongly translated as pit sand or simply sand by modern authors. The ingredients testa, carbunculus and harena fossicia were intensively used in Roman buildings. These reactive ingredients must not be confused with the traditional pozzolan whose name originates from the city of Puzzuoli, near Napoli (Mt Vesuvio). According to Vitruvius Book V, 12, the traditional pozzolan was exclusively used for making piers into the sea or foundations for bridges, whereas harena fossicia, carbunculus and testa produced the concrete for buildings on land.