Cubes of cast Roman glass containing traces of gold – MUSEUM OF SOUTHWEST JUTLAND
Oct. 4 () –
Ancient craftsmen from the earliest Viking Age, around the year 700, used sophisticated and sustainable methods when they gave new life to ancient Roman glass mosaics as precious blue glass beads.
This is the conclusion of a study published in the journal Archaeological and Anthropological Sciences by scientists at Aarhus University.
The Danish Ribe –the oldest city in Scandinavia– It was an important trading center in the Viking Age. In the early 8th century, a trading post was established on the north side of the River Ribe, where merchants and artisans flocked from far and wide to make and sell products such as brooches, costume buckles, combs, and colored glass beads.
When glass became a rare commodity in the early Middle Ages, colored glass cubes, called tesserae, were plucked from mosaics in abandoned Roman and Byzantine temples, palaces, and baths, transported north, and traded. in emporium cities like Ribe, where bead makers melted them into large pots and shaped them into beads.
Until now, archaeologists assumed that pearl makers used opaque white tesserae as raw material for the production of opaque white beads.
But a geochemist and an archaeologist from Aarhus University together with a museum curator from Ribe have made a startling discovery, According to the university in a statement.
The chemical composition of white Viking beads from an early workshop showed that glassmakers had found a more sustainable way to save time and wood for their furnaces: crush gold-gilt transparent glass cubes, re-melt them at low temperature, stir to trap air in the form of bubbles, and finally wrap the glass around an iron mandrel to form beads and produce opaque white pearls created in a short time using minimal resources.
Of course, the glazier salvaged the valuable ultra-thin gold sheets attached to the surface of the gold mosaic stone before re-melting the glass, but the new finds show that some gold inevitably ended up in the crucible. Tiny flecks of gold on the white beads, the many air holes (which is why the beads are opaque), as well as the fact that there are no chemical color markers present, the researchers show that, in fact, it was the gold mosaic stones that was the raw material for the beads.
Such traces of gold were found not only on the white beads but also on the blue ones from the same workshop. Chemistry shows that the glazier’s recipe consisted of a mixture of blue and gold mosaic stonesyes It was necessary to mix them because Roman blue mosaic stones contained high concentrations of chemicals that made them opaque and therefore ideal for mosaics, but not blue beads. By thus diluting the chemicals, the result was the clear, deep blue glass we know from Viking Age beads.
