A review of available analytical methods to detect ancient salt production

In ancient historical records, the significance of salt (NaCl) has consistently held considerable prominence. Consider, for instance, its pivotal role in the genesis and evolution of the city of Rome (Giovannini, 1985). According to Dionysius of Halicarnassus (Roman Antiquities, 2.53–55), one of the first wars undertaken by Romulus was against Veii, also for control of the saltworks located at the mouth of the Tiber River, which were then controlled by that city. Venice owes a substantial portion of its early growth to the trade in salt, an essential commodity sourced from diverse corners of the Mediterranean (Hocquet, 1979, 2022). Unfortunately, salt is also highly soluble in water; therefore, its presence is difficult to prove. Research on the methods of salt production, trade, and consumption in antiquity has long suffered from enforced oblivion due to the difficulty of identifying its traces in the archaeological record. In the past two decades, the field of archaeology has witnessed a proliferation of sophisticated methodologies derived from the so-called hard sciences. Physics and chemistry have offered the possibility, if not to directly identify salt crystals, at least to identify their proxies, understood as the physicochemical consequences of their presence. Various tools and methods have been applied to case studies, with differing degrees of success. The primary aim of this contribution is to present a state-of-the-art review (Booth et al., 2022; Efron and Ravid, 2018) of these methods, elucidating the strengths and shortcomings inherent to each approach. The intention is to provide an overview of the subject to facilitate the choice of the appropriate analytical method for researchers who need it and to suggest some new methodological approaches to the scientific community that could advance the field of study.