RARE PURPLE PIGMENT DISCOVERED BY ARCHEOLOGISTS IS MORE VALUABLE THAN GOLD

These days, purple is connected to opulent royalty. There is a long history of this association. Since purple was one of the hardest-to-find and most labour-intensive dyes, Roman emperors wore it as a symbol of their wealth and power approximately 2,000 years ago. One of the most sought-after materials in the world of Ancient Rome was a dye known as Tyrian Purple, which was made from snails. In 2023, a group of archaeologists in Carlisle, England, made the startling discovery of discovering a lump of Tyrian Purple that had been preserved for centuries in the drains of a Roman bathhouse from the third century.

Archaeologists discovered multiple intaglio-carved jewels in the bathhouse's drains. A peculiar lump with a soft, organic interior was also found by them. Testing turned up beeswax and bromine, which are signs of Tyrian Purple. Juicing snails from the Purpura haemostoma and Murex brandaris species produced Tyrian Purple.

It's "a complex process which involves extracting the liquid while the mollusc is still alive and exposing it to sunlight for a specified period of time, during which the dye changes colour," according to the University of Chicago Library. To make one gram of dye, up to 12,000 molluscs are required. The colour was claimed as theirs by the Roman emperors, and few others could have afforded it. 

It was actually worth more than gold, pound for pound. With the fall of the empire, the recipe for creating the rich hue was lost. Excavating the site, Wardell Armstrong's Frank Giecco says, "Tyrian Purple was the most expensive and sought-after colour in the world for millennia." The idea that the structure was somehow connected to the Septimius Severus Imperial Court in York and may have been related to an Imperial visit to Carlisle is strengthened by its presence in Carlisle as well as additional evidence from the excavation.

It's the only example of a solid sample of the pigment in the form of leftover paint pigment that we are aware of, and it may be the only one in the entire Roman Empire that is located in Northern Europe. Examples of it can be seen in high-status painted coffins from the Roman province of Egypt as well as wall paintings from places like Pompeii.

The "Uncovering Roman Carlisle" excavation has been in progress in the northern city, which is located next to Hadrian's Wall, since 2021. The UNESCO World Heritage site, Hadrian's Wall, was the Roman Empire's walled northern border in Britain. The excavations came about as a result of the previously unknown remains of a bathhouse or mansion for Roman officials being found in 2017.

Since then, Wardell Armstrong archaeologists have discovered numerous indications of Roman habitation, such as ceramics and a stone sculpture honouring the Empress Julia Domna. In particular, Septimus Severus, an emperor who made military visits to England and passed away in York in 211 CE, was the husband of Julia Domna. The bathhouse may have been built, or at least used, as a result of the emperor's visit to the UK.