New method solves old mystery: Hafnium isotopes clinch origin of high-quality Roman glass

July 09, 2020

Glass is an immensely interesting archaeological material: While its fragility and beauty is fascinating in itself, geochemical studies of invisible tracers can reveal more than what meets the eye. In a new international collaboration study from the Danish National Research Foundation's Centre for Urban Network Evolutions (UrbNet), the Aarhus Geochemistry and Isotope Research Platform (AGiR) at Aarhus University and the Danish-German Jerash Northwest Quarter Project (Aarhus University and University of Münster), researchers have found a way to determine the origin of colourless glass from the Roman period. The study is published in Scientific Reports.

The Roman glass industry was prolific, producing wares for drinking and dining, window panes and coloured glass 'stones' for wall mosaics. One of its outstanding achievements was the production of large quantities of a colourless and clear glass, which was particularly favoured for high-quality cut drinking vessels. The fourth-century Price Edict of the emperor Diocletian refers to colourless glass as 'Alexandrian', indicating an origin in Egypt. However, large amounts of Roman glass are known to have been made in Palestine, where archaeologists have uncovered furnaces for colourless glass production. Such furnaces have not been uncovered in Egypt, and hitherto, it has been very challenging to scientifically tell the difference between glass made in the two regions.

Now, an international collaboration led by Assistant Professor Gry Barfod from UrbNet and AGiR at Aarhus University has found the solution. Their work on Roman glass from the Danish-German Jerash Northwest Quarter Project in Jordan shows that the isotopes of the rare element hafnium can be used to distinguish between Egyptian and Palestinian glass and provide compelling evidence that the prestigious colourless glass known as 'Alexandrian' was indeed made in Egypt. Two of the co-authors of the publication, Professor Achim Lichtenberger (University of Münster) and Centre Director at UrbNet Professor Rubina Raja, head the archaeological project in Jerash, Jordan. Since 2011, they have worked at the site and have furthered high-definition approaches to the archaeological material from their excavations. Through full quantification methods, they have over and again shown that such an approach is the way forward in archaeology, when combining it with in context studies of various material groups. The new study is yet another testament to this approach.

"Hafnium isotopes have proved to be an important tracer for the origins of sedimentary deposits in geology, so I expected this isotope system to fingerprint the sands used in glassmaking", states Gry Barfod. Professor at Aarhus University Charles Lesher, co-author of the publication, continues: "The fact that this expectation is borne out by the measurements is a testament of the intimate link between archaeology and geology."

Hafnium isotopes have not previously been used by archaeologists to look at the trade in ancient man-made materials such as ceramics and glass. Co-author Professor Ian Freestone, University College London, comments, "These exciting results clearly show the potential of hafnium isotopes in elucidating the origins of early materials. I predict they will become an important part of the scientific toolkit used in our investigation of the ancient economy."

Fact box:

The sand along the Mediterranean coast of Egypt and Levant (Palestine, Israel, Lebanon and Syria) originates from the Nile and is ideal for glass production because it naturally contains the amount of lime needed to keep the glass stable and not degradable. In the Levant, they made transparent glass by adding manganese - it was good, but not perfect. The second type of Roman glass, which scientists now show came from Egypt, the glassmakers made transparent by adding antimony (Sb), which made it crystal clear; therefore, this was the most valuable glass.
-end-


Aarhus University

Related Glass Articles from Brightsurf:

Glass tables can cause life-threatening injuries
Faulty glass in tables can cause life-threatening injuries, according to a Rutgers study, which provides evidence that stricter federal regulations are needed to protect consumers.

The nature of glass-forming liquids is more clear
Researchers from The University of Tokyo have found that attractive and repulsive interactions between particles are both essential to form structural order that controls the dynamics of glass-forming liquids.

Experimental study of how 'metallic glass' forms challenges paradigm in glass research
Unlike in a crystal, the atoms in a metallic glass are not ordered when the liquid solidifies.

On-demand glass is right around the corner
A research group coordinated by physicists of the University of Trento was able to probe internal stress in colloidal glasses, a crucial step to control the mechanical properties of glasses.

Glass from a 3D printer
ETH researchers used a 3D printing process to produce complex and highly porous glass objects.

Making glass more clear
Northwestern University researchers have developed an algorithm that makes it possible to design glassy materials with dynamic properties and predict their continually changing behaviors.

Researchers use 3D printer to print glass
For the first time, researchers have successfully 3D printed chalcogenide glass, a unique material used to make optical components that operate at mid-infrared wavelengths.

New family of glass good for lenses
A new composition of germanosilicate glass created by adding zinc oxide has properties good for lens applications, according to Penn State researchers.

In-depth insights into glass corrosion
Silicate glass has many applications, including the use as a nuclear waste form to immobilize radioactive elements from spent fuel.

New research questions the 'Glass Cliff' and corroborates the persistent 'Glass Ceiling'
Are women more likely to be appointed to leadership positions in crisis situations when companies are struggling with declining profits?

Read More: Glass News and Glass Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.