This paper documents the results of in situ analysis of 306 lava paving stones and 74 possible source rocks using pXRF. Data were collected from sites both in the city of Rome—on major roads beyond the city (including the Viae Flaminia, Cassia, Clodia, Praenestina and Appia)—and in the city of Ostia. Comparison of the pXRF data with lava compositional data from the geological literature allows broad identification of possible sources. The results point to quite distinctive patterns of exploitation for the city of Rome and Ostia, utilizing the Alban Hills lava flows, and the roads of the middle Tiber Valley, drawing on lava flows associated with the Vico and Sabatini volcanoes. The results show the potential of pXRF to produce data to elucidate the exploitation of lava flows for paving the Roman roads.

This paper reports on geochemical data collected using a He‐enabled handheld portable XRF (HHpXRF) from lava paving stones in Trajan's Forum (Hemicycle) and the Via Biberatica (Rome). Issues relating to HHpXRF field use and calibration are also addressed in detail. By means of this instrument, 355 analyses of the paving stones were collected and the data were processed using the standard techniques of igneous petrology and petrography. Provenancing was based on comparisons between the HHpXRF data and geological data from the abundant literature on Roman volcanic rocks. These comparisons placed the provenance of the paving stones in the Colli Albani, south‐east of Rome. Further analysis using Zr/Y versus Nb/Y discriminant diagrams suggests that the paving stones were quarried from two sources, both of which are represented in Trajan's Forum and the Via Biberatica. The diagrams suggest that the sources lie within the Faete and Vallerano lava complexes. The latter were probably transported to the construction site by barge on the River Tiber and the former were easily accessible by carts along the Via Appia. The study establishes the potential of HHpXRF equipment for non‐destructive analysis of paving stones both in Rome and at other sites in central Italy, and challenges a number of assumptions about the supply of building materials to Rome based on intuition alone.

A helium‐enabled Niton X‐ray analyser (HHpXRF) study of 296 lava stepping stones from ancient Pompeii showed that their surfaces were contaminated with superficial deposits of Zn and Pb. Recent research has shown that concentrations of these elements are highest in urban areas, where they were attributed to tyre dust and leaded petrol, respectively. The distribution of these elements on the stepping stones is represented on maps of the site. Zn pollution is most abundant in areas visited by tourists and is attributed mostly to wear from their rubber‐soled footwear. Pb pollution is attributed to the movement of onsite vehicles using leaded petrol.