The Geochemical Fingerprint of Tufo Lionato Blocks from the Area Sacra di Largo Argentina: Implications for the Chronology of Volcanic Building Stones in Ancient Rome

We use trace element discrimination diagrams to provide a geochemical fingerprint for Tufo
Lionato, the volcanic rock most commonly used in the ancient Roman dimension stone technique.
Based on the comparison of their geochemical signatures, we identify different rock facies
of Tufo Lionato employed since the fourth to third centuries and through the second
century BCE in the construction of the temples of the Area Sacra di Largo Argentina. These
rock facies correspond to two previously identified building stones: Aniene Tuff and
Monteverde Tuff, named after their supposed source areas located in the Aniene River Valley
and in the homonymous locality of the Tiber River Valley, respectively. However, the results of
our study demonstrate previous misidentification of these volcanic rocks in the different construction
phases of Temple C, providing a revision of the dating system currently accepted
for the diffusion of Tufo Lionato architecture. We show that the Aniene facies has been
exploited since the end of the fourth century BCE and that it was employed along with Tufo
Giallo della Via Tiberina in the podium and staircase of Temple C, whereas observations at
Largo Argentina suggest that the ‘Monteverde Tuff ’ was only sporadically used in the early
phases of the dimension stone construction technique.