A pottery workshop in Pompeii unveils new insights on the Roman ceramics crafting tradition and raw materials trade

Highlights

• Via dei Sepolcri workshop produced Thin Walled pottery in Pompeii until the 79 CE.

• Different clayey raw materials were used for the pottery in the two production phase.

• Ischia Clays and alluvial clays supported Phase 1 production.

• High-CaO clays from Salerno province were exploited during the Phase 2.

• A complicate pattern of raw materials trade existed in Campania region.

Abstract

Recent excavations of the Via dei Sepolcri ceramic workshop in Pompeii provide an exceptional window into ancient Roman material culture. The remarkable ceramic objects found here, and importantly, the raw geological materials used in their production, afford a unique opportunity to gather information about each aspect of the organisation of the workshop and the ceramics production cycle, including those which are normally erased by the firing process. The exceptional nature of this site provides interesting insights into the system of raw material procurement, a facet poorly explored thus far due to the lack of ancient historical sources.

The study is based on the investigation of 40 samples including pottery fragments, unfired, fired and overfired sherds and their source materials by means of optical microscopy, X-ray diffraction, Inductively Coupled Plasma Mass Spectroscopy, Raman and FTIR spectroscopy; in addition, Sr–Nd isotopic and paleontological analyses completed the raw material characterisation.

The workshop experienced two different periods of activity starting from the beginning of 1st century CE; in a first phase they produced a variegated repertoire of Thin Walled pottery using local alluvial sediments and clays imported from Ischia island. In a second phase (probably from 62 to 63 CE to 79 CE), the workshop became larger and more specialised, the Thin Walled types drastically decreased and the artisans exclusively utilized clayey sediments from outcrops near Mt. Picentini in the Salerno province.

As complementary materials, the ceramic production also utilized local volcanic sands for tempering and decorative purposes along with a presumed imported red earth pigment for decorative finishing.

Firing conditions, as inferred from mineral assemblages in the pottery, were not strictly controlled in either production phase as estimated firing temperatures vary widely from approximately 800 to 1000 °C. Likewise, atmospheric conditions in the kiln, as inferred from the variable occurrence of Fe²⁺ and Fe³⁺ oxides, were not carefully controlled in either production phase.

When compared with data from the larger framework of coeval regional and extra-regional pottery productions, the data obtained suggest that the existing paradigm of the Exploitable Threshold Model, which implies a maximum distance of 7–8 km between the source of raw materials and their usage in production centres, may need to be revised by at least an order of magnitude where sea routes and ports were readily available, as was the case in Pompeii and the surrounding Bay of Naples.

Introduction

The ancient city of Pompeii, founded at the end of the 7th century BCE, is one of the most well-known archaeological sites in the world. The history of the city is closely associated with the nearby Somma-Vesuvius volcanic complex, which experienced a cataclysmic eruption in 79 CE, destroying the city and burying it under several meters of pumice, ash, and pyroclastic flows, thus abruptly ending all human activities there. The ancient city was completely lost until its accidental rediscovery in 1592. Since the first archaeological excavations there in 1748, investigations on the large number of preserved archaeological materials have provided an outstanding snapshot of the material culture and technological skills of the ancient Pompeians and revealed new and evocative insights into the life of the ancient city.

Among the archaeological remains, researchers have devoted their attention particularly to pottery since it represents a useful proxy for dating events, revealing production methods, illuminating technological progress, and tracking commercial pathways. The archaeological site of Pompeii represents an exceptional opportunity for reliable reconstructions of the ancient past there thanks to the well-constrained chronology of events and the good state of preservation of the pottery.

A brief review of the abundant literature on Pompeian pottery indicates that, despite the presence of a port which could have fostered the importing of both amphoric and non-amphoric pottery, the majority of the samples preserved in Pompeii's repositories are thought to have been produced very near the Bay of Naples in the area known as the ager Pompeianus (Peña and McCallum, 2009a, 2009b). Several studies, the most recent of which are supported by archaeometric analyses, focused on interesting aspects of the production of pottery in Pompeii both in the Pre-Roman and Roman periods (e.g. Schneider et al., 2010; Giannossa et al., 2012, 2014, 2015, Scarpelli et al., 2014, 2015). In particular, Peña and McCallum (2009a, 2009b) explored several interesting aspects of pottery production and circulation in Pompeii, including the first attempt to locate the possible source(s) of the clayey raw materials used.

Ceramic production in Pompeii during the Roman period and until the 79 CE eruption is characterized by two workshops located at Porta di Nocera and Via dei Sepolcri near Porta Ercolano (Fig. 1) since archaeological materials found there indisputably prove that the workshops were active at the very moment of the 79 CE eruption. The Via di Nocera workshop (Regio I, 20, 2–3), discovered in 1958–1959 by A. Maiuri and then studied by Cerulli Irelli (1977), produced oil lamps and little pots called frittili. A new research program exploring this workshop recently found additional archaeological remains related to the manufacturing processes, including unfired vessels and raw materials that were ready to be used before the eruption (Cavassa et al, 2017, 2018; Cavassa and Lemaire, 2019). The second workshop (Fig. 1), discovered in 1838, was in the northern sector outside the town, close to Porta Ercolano necropolis along Via dei Sepolcri. In 1855 it was first described by Ernst Breton as a “pottery factory with a very remarkable kiln structure where cooking pots were produced” (Breton, 1855).

The present study reports and interprets the archaeological and archaeometric data from recent excavations (2012–2014) performed in the Via dei Sepolcri workshop (Cavassa et al., 2013, 2014a, 2014b, 2015a, 2015b, 2017, 2018; Cavassa and Lemaire, 2019). The site represents an exceptional archaeological context where excavations and material analyses reveal the life and the organization of the workshop from the first half of the 1st century CE up to the volcanic eruption and abandonment. In particular, the unused raw materials, unfired finished pottery, and fired vessels found in the workshop captured the last instant of its activity. To date, this is the first occurrence of ceramic raw materials found in any Pompeii excavations, which prompted a detailed analytical investigation of the pertinent samples for every step of production.

We studied the recovered specimens using a multi-disciplinary approach that illuminates the entire pottery production cycle, including the selection of raw materials, their preparation by tempering, the shaping and decoration of the pottery, and the firing conditions in the kilns. The primary objective of this work was to characterise the ceramic production collected at Via dei Sepolcri workshop by means of a rigorous archaeometric approach that includes mineralogical, petrographic, spectroscopic and chemical analyses focused on the technological peculiarity of the Pompeian ars vasaria. Then, considering that we have a unique opportunity to address all phases of pottery production from unearthed raw materials to unfired vessels to the final fired products, we explore and discuss the economic aspects of raw material procurement and the sophisticated technology of the pottery production at Pompeii and, more generally, in the Roman world.

The most relevant economic questions addressed by archaeologists and historians and often supported by archaeometric studies concern the trade of pottery (both raw materials and finished products) which allows for some estimation of both the sophistication and the routes of ancient commerce (Peacock, 1982). Actually, numerous studies on Roman pottery support that the finished ceramics travelled from medium to long distances (from hundreds to thousands kilometers) as already suggested by Pliny the Elder (NH 35, 160). Other written sources noted the role of mercatores and negotiatores responsible for medium-to-long-distance economic circuits, whereas over short distances the most efficient distribution systems were the periodic markets called nundinae (Aubert, 1994; Peacock, 1982). The determination of the source of the clayey raw material is an important goal of this research in order to identify the potential supply system and commercial trading paths to Pompeii.

Archaeometric investigations provide an independent means to both confirm what is known about ancient trade from written records, and to draw inferences about trade where written records are absent. These investigations can unveil various technological aspects (raw materials selection and manipulation, decorative embellishment, firing procedures, etc.) preserved inside the pottery (Maritan, 2019; Maritan et al., 2015).

The selection of raw materials also involved another economic sector of pottery manufacturing, namely the pre-production system. Unfortunately, as far as we are aware, there are no historical written sources related to the strategies of procurement and trading of raw materials in Roman times. The reason why this important aspect of the ceramic production has been disregarded by ancient writers is still unclear; common opinion is that workshops were located in close proximity to the sources of raw materials (Peacock, 1982). A comprehensive study is still needed.