Il commercio del marmo nell'Adriatico tardo antico (IV-VI secolo d.C.). Scambi, maestranze, committenze

This thesis aims to explore the potential of archaeological and written sources to analyse the diffusion of marble artefacts of Constantinopolitan origin in the Mediterranean during Late Antiquity (4th-6th century A.D.), focusing on the Adriatic regions. Implementing a holistic approach, it argues that different classes of data are of limited value and must be appreciated as cogs in a far broader exchange mechanisms. The theoretical frameworks underlying most research designs devoted to the study of the commerce of marble in Antiquity remain primarily site-specific rather than being devised to examine specific historical issue. A similar approach presupposes that the circulation of marble artefacts took place in an economic, political and cultural vacuum. Moreover, a lot of studies tended to emphasize the movement of objects, underestimating or ignoring the existence of itinerant artisans. The object of this work is to draw on different kinds of sources relating to the commerce of marble to freshly appraise the value of this phenomenon to understand the mechanisms of artistic and building patronage in the early Byzantine period in the Adriatic and in the neighbouring regions. The early Byzantine period was marked by a substantial exploitation of quarries, linked to a significant construction boom whose origins lay undoubtedly in the building of Constantinople and its stunning triumph as the capital of the Eastern Roman Empire. To be sure, the quarries of the Aegean and of Asia Minor had already been substantially worked during the Roman period; the new centre of power only reactivated the quarrying of known sources, whose production had been momentarily interrupted by the crisis in the second half of the third century. The quarries on the islands of Prokonnesus (nowadays Marmara, Turkey) and of Thasos (Greece) had already been worked during the imperial period, and their were in great part dependent on the imperial treasury. Their products were exported all over the Mediterranean, where many other quarries of great, medium and little importance were active, from Spain to Asia Minor. Diocletian's transformation of Nikomedeia into a Tetrarchic capital was a prelude of sorts to the ultimate mission of the Prokonnesian quarries: to cloak the new capital in marble so that the glory of Constantinople would blaze out to all reaches of the Mediterranean. The researches carried out since the '70s on the island of Prokonnesus have revealed an extremely rich sampling of pieces in all phases of their production. The Prokonnesian quarries made pieces to order, tied to the large scale-municipal building programs of Theodosius I and his family, and also manufactured column shafts, together with column bases, capitals and liturgical furnishings (ambos, ciboria, panels decorated with a central chrismon flanked by crosses, altar tables…). With respect to the latter, the Corinthian capital represents a highly standardized product line, whose crafting process has been reconstructed with great skill, showing the extent to which fifth-century capitals differ with respect to their stages of production from those of the second century. All these sculptures were widely exported and were copied, both imitatively and in a cruder style, in other varieties of marble and local stone, as attested even for the products of Thasos. These various types of marble were assembled within single structures, either through combined orders or through a single order placed with large entrepôts that gathered different varieties of marble. A clear example of these composite exports is offered by the Marzamemi wreck (Capo Passero, Sicily), whose cargo was composed by bases, shafts, and capital made of Prokonnesian marble, an ambo in breccia or verde antico from Thessaly, and an altar table of a finer marble. It is uncertain if the cargo ship was loaded in a single location, or if it stopped at two (or more) different yards. A similar situation is attested even in many other cases, as - for example - the Acheiropoietos in Thessaloniki, Sant'Apollinare in Classe and San Vitale at Ravenna, and the basilica built at Parenzo (Pore?, Croatia) by the archbishop Euphrasius. Alongside architectural elements and liturgical furnishings of unmistakable Costantinopolitan origin, in many early Byzantine buildings is attested the presence of elements manufactured by local artisans, not necessarily imitating the products of the workshops of the imperial capital. Turning our attention to the written sources, we note that the imperial authorities had a primary role in the exploitation and the use of marble. The great imperial building projects were directly managed by the emperor, and the same is true for the emperor's gift-giving. In addition to imperial largesse, however, there was a market: for example, Gregory of Nazianzus happens to tell us that one of his enemies in Constantinople in 379/380 A.D. was a priest who had come to Constantinople from Thasos, with money supplied by his Church in order to buy "Prokonnesian slabs". These must have been slabs for a chancel-screen in the marble of the island of Prokonnesus. At the beginning of the 7th century A.D., the Miracula Demetrii show the bishop pf Thenai in Byzacena obtaining an ambo and a ciborium from a ships' captain, even if thanks to the miraculous and providential help of Saint Demetrius. The episode attest that marble was obtainable from the open market. As well as in the entire Mediterranean, after the 4th century A.D. the circulation of marble artefacts in the Adriatic seems to loose progressively its commercial character, acquiring that of a hallmark of the imperial intervention in sites or regions that, for their strategic, economic and political importance, attracted the investments of the central government. This is clear at Ravenna, where the flood of Prokonnesian marble started under Theoderic (as attests the letter with which Amalasuintha asks the emperor to send to her the marmora she bought at Constantinople) and reached its acme during the Justinianic period. Even in many other cases, the diffusion of architectural elements and liturgical furnishings of Prokonnesian marble follows the Byzantine reconquest, and - in spite of its diversity - early Byzantine sculpture presents an incontestable homogeneity of inspiration, reaffirming the unity of the Empire (and of the Orthodox world). In Apulia and in the Marche, the Costantinopolitan marble elements are non particularly numerous, but their diffusion is of particular significance: they could be attributed, even if in a tentatively way, to imperial patronage, or to the presence of important military officials (as in the case of Ancona). At Siponto, the beautiful marble-screens decorating the local episcopal church were probably imported by bishop Laurentius, related to Justinian according to a later Medieval hagiographic tradition. At Rome, the not numerous Prokonnesian marble objects reached the ancient imperial capital during the first decades of the 6th century A.D., in the context of intense diplomatic relations between the Papacy and the Empire. In other cases, as at Parenzo, the picture is rather different: the great heterogeneity of the marble elements in the basilica suggests that Euphrasius purchased the column shafts, the bases and the capitals in a Ravennate entrepôt, where the available supply did not permit a homogeneity. Moreover, the bishop recruited local artisans, who realized part of the liturgical furnishings, probably working Prokonnesian marble. From a general point of view, in the early Byzantine period the economic impact of the commerce of marble was no longer comparable to what have been in the earlier centuries. However, it had acquired a marked symbolical meaning, especially in the Western provinces of the reunified empire of Justinian