The secret of making the perfect "Alexandrian" glass is revealed

A joint team of researchers from Denmark and Germany used a new method for the analysis of hafnium isotopes to study the composition of the so-called "Alexandrian" glass, which was widely used in ancient Rome and was considered ideal. The study first proved that this glass was made in Egypt.

The study was published in the journal Scientific Reports, and Phys.org briefly talks about it. It is known that glass was very much appreciated in ancient Rome. Glass industry in this state was at an extremely high level. Not only household items, but also jewelry were made of glass.

Surprisingly, colorless glass was considered the most valuable at that time. The more transparent it was, the more expensive it was. In written sources, it is referred to as "Alexandrian glass." For example, this is exactly what it is called in the decree of the emperor Diocletian, who ruled in the 4th century.

The name itself indicates its Egyptian origin. However, until now, archaeologists could not find any evidence of this. During excavations in Egypt, never found furnaces in which transparent glass could be made.

Moreover, in the territory of modern Palestine such stoves were found. Yes, and previous analysis of artifacts showed that glass was produced in the countries of the Levant. This is a region along the coast of the Mediterranean Sea, in the territory of which Israel, Lebanon and Syria are now located.

There really is a lot of sand, which is ideal for glass production. It contains such an amount of lime that it is necessary for the glass to maintain a stable structure. Transparent glass was produced in the Levant, adding manganese to it. It was a good product, but not perfect. It was inferior in quality to the "Alexandrian" glass.

To solve a long-standing mystery, the researchers applied a fundamentally new method. They conducted an analysis of artifacts, comparing the concentration of hafnium isotopes in them - a rare chemical element.

This finally allowed to divide Roman glass into two different types - "Palestinian" and "Alexandrian". The presence of hafnium isotopes proved that the latter was actually made in Egypt, and not in the Levant.

“Hafnium isotopes turned out to be an important indicator of the origin of sedimentary deposits in geology, so we expected that isotopic analysis would identify sand that was used in glass production,” said co-author Charles Loesher of Aarhus University. “This expectation was confirmed by measurements, which indicates a close links between archeology and geology. "

Moreover, the researchers were finally able to discover the secret of the perfect purity of the "Alexandrian" glass. It turned out that the Egyptians during its production did not add manganese to the composition, as in the Levant, but antimony. This is what made the glass crystal clear and, therefore, the most valuable.

Source: https://rg.ru/