When we think of Venetian glass, our minds leap to the blazing furnaces of Murano, to delicate filigree and the vivid colours of the Renaissance. This iconic and universally recognised image tells only part of the story. For centuries, the earlier chapter — its Early Medieval origins — remained in the shadows, considered merely a prelude to Murano’s later greatness.

Recent discoveries show that the history of glass in Venice is far older, more complex and technologically more advanced than previously imagined. A nearly forgotten past is resurfacing through minute fragments.

The key to this new understanding is an archaeometric study published in Archaeological and Anthropological Sciences by researcher Margherita Ferri (Department of Humanities, Ca’ Foscari University of Venice). The study analyses an assemblage of Early Medieval glass from San Pietro di Castello, the ancient island of Olivolo — one of the city’s founding nuclei and, at the time, strategically located near the entrance to the harbour, controlling access to the lagoon.

The research, conducted in collaboration with Elisabetta Gliozzo (Department of History, Archaeology, Geography, Art and Performing Arts – SAGAS, University of Florence) and Eleonora Braschi (CNR – Institute of Geosciences and Earth Resources), is based on Early Medieval glass fragments unearthed during archaeological excavations carried out in the early 1990s by the Superintendency for Archaeology, Fine Arts and Landscape for the Metropolitan City of Venice, with which Ca’ Foscari’s Department of Humanities collaborates.

The scientific analysis of these glasses, dated from the sixth to the ninth centuries and comprising 45 samples — including vessels, production waste, and a steatite crucible — provides us with a view of Early Medieval Venice as a lively hub of international trade and remarkable technological progress.

This offers a fresh perspective on Venice’s origins: a city that was advanced, connected, and innovative as early as the eighth century — a key hub in the Early Medieval Mediterranean, capable of extensive trade and mastering the most sophisticated technologies of its era.

A new technology

The history of technology is marked by epochal transitions. One of the most significant in the ancient world was the shift from natron-based glass — the recipe inherited from the Roman Empire — to plant-ash glass. This change, triggered by difficulties in sourcing Egyptian natron, opened a new era for European glassmaking. The long-standing question for archaeologists has been: who was at the forefront of this revolution?

“The answer emerging from the excavations at San Pietro di Castello is surprising,” explains Margherita Ferri.
“Here we have fragments of plant-ash glass dating back as early as to the eighth century. But the real twist is another: chemical analysis attributes these ancient fragments to Syro-Levantine production. This means that Venice 1,300 years ago not only was aware of this new technology, but its trade networks were so efficient that it imported cutting-edge materials produced hundreds of kilometres away. This places Venice among the very first centres in Italy to embrace and master this technology, revealing a remarkably receptive and well-connected city.”

In addition, within a single blue tessera, scientists identified the coexistence of two different opacifying agents: calcium antimonate — an ancient technology no longer in use after the fourth century — and lead stannate, the more modern technique. How can one tiny mosaic tessera contain technologies separated by centuries? The answer, revealed by analysis, lies in a practice we consider modern: recycling. Craftspeople melted down an older Roman tessera to recover its material and reuse it, blending past and present.

Furthermore, to produce blue, Venetian artisans did not use pure, refined cobalt pigment. Instead, they exploited metalworking slag — a by-product rich in cobalt. This choice reveals not only a sophisticated understanding of material properties, but also an intelligent reuse-based economy: a proto–circular economy of sorts.

Early Medieval Venice and its trade networks

Analyses of the provenance of raw glass present a vivid picture of Venice as an international commercial crossroads. The finds reveal an almost equal proportion of glass originating from the two main production regions of the period: Egypt and the Levant (today’s coasts of Syria, Lebanon, Palestine, and Israel).

Venice’s trade routes were dynamic and adaptable, responding to shifting geopolitical and production conditions in the Mediterranean. The lagoon was not simply a recipient of goods but played an active role in a complex, evolving network of exchanges.

But how did these new technologies and exotic objects arrive in Venice? Were they meant as raw materials to be processed in local workshops, or as finished luxury goods? The answer is: both, showcasing a remarkably sophisticated supply network.

Evidence for raw-material trade comes from plant-ash beakers. Their chemical composition suggests a Syro-Levantine origin for the raw material. Their shape, however, is identical to that of beakers produced locally using the older natron-based technique. This indicates that Venetian artisans imported raw glass and worked it in accordance with local styles. In contrast, finding a conical-based glass—common in Syrian production but not made in the Adriatic during that period—indicates the direct import of finished luxury goods.

Early Medieval Venice therefore, managed a mixed supply chain, importing both raw materials for its workshops and high-value finished goods for direct consumption.