Chemical analyses uncover secrets of an ancient amphora

From FECYT - Spanish Foundation for Science and Technology

A team of chemists from the University of Valencia (UV) has confirmed that the substance used to hermetically seal an amphora found among remains at Lixus, in Morocco, was pine resin.

The scientists also studied the metallic fragments inside the 2,000-year-old vessel, which could be fragments of material used for iron-working.

In 2005, a group of archaeologists from the UV discovered a sealed amphora among the remains at Lixus, an ancient settlement founded by the Phoenicians near Larache, in Morocco. Since then, researchers from the Department of Analytical Chemistry at this university have been carrying out various studies into it components.

The latest study, published recently in the journal Analytical Letters, focuses on the resinous material that sealed the vessel.

There are remains of a circular rope-effect decoration around the mouth of the amphora, and on which some fingerprints of the craftsman who moulded it can still be seen.

It would probably have been sealed with a lid of cork or wood, of which nothing remains, possibly including a ceramic operculum, such as those found nearby.

"We have studied the substance that was used to seal the container using three different techniques, and we compared it with pine resin from today", José Vicente Gimeno, one of the authors of the study and a senior professor at the UV, tells SINC.

The results confirm that the small sample analysed, which is 2,000 years old, contains therpenic organic compounds (primaric, isoprimaric and dehydroabietic acids), allowing this to be classified as resin from a tree from the Pinus genus.

The researchers have identified some substances that indicate the age of resins, such as such as 7-oxo-DHA acid, although this kind of compound was not abundant in the sample due to the amphora's good state of preservation.

In addition, Gimeno says that the archaeological resin of the amphora found was hard and blackish with yellow spots, unlike present-day resin, which is more malleable and orangey in colour, similar to the fresh sap of the tree.

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