The Purple Dye That Powered the Ancient Phoenician Empire

To the ancient mind, the color purple was a wondrous thing, perhaps never before seen. Yet some seafaring traders had entire rolls of cloth dyed with it, fleeces of purple wool and fabrics woven with purple threads. The secret of how to make this magical color was closely kept, but the ancient Phoenicians made it famous as they roamed, raided, traded and colonized the coastlines and islands of the ancient Mediterranean Sea.

The name "Phoenician" may even have meant "purple people," from an ancient Greek word for the color of the mythical phoenix. And the mysterious purple dye may have been one reason for the Phoenicians' success.

The Phoenicians were traders from the eastern Mediterranean whose city-states rose after about 1200 B.C., when many neighboring Bronze Age powers collapsed under mysterious circumstances. The biblical cities of Tyre and Sidon, now in Lebanon, were Phoenician, and the dye and color became known as "Tyrian purple" as a result.

Not only was the dye bright purple—a color unmatched in the ancient world—but it stayed fast and bright, even after fabrics made with it were washed. Its shade was determined during the dyeing process, giving a range of hues from almost red to deep blue. The dark blue tekhelet dye used to color garments for Hebrew religious ceremonies was also a form of Tyrian purple. Another common name was "Royal purple," because it was so highly prized that only kings could afford it, and under the Romans, Tyrian purple was more valuable than gold.

Archaeologist Golan Shalvi of the University of Chicago and the University of Haifa, who recently studied an ancient purple dye factory in Israel, explains why the dye was so sought after: "It was of exceptional high quality, required advanced knowledge to produce, and relied on rare resources," he says. "Purple dye is a perfect example of what makes a product luxurious."

And chemist and archaeologist Chris Cooksey, an expert on Tyrian purple, says knowledge of the dye would have been a valuable secret for the Phoenicians. "Tyre was the center of trade in many items, including dyes, textiles, ebony, honey, oil, spices, wines, metals, precious stones, cattle and human slaves," he says. "Having a local purple dye manufacture could only have been an advantage."

The secret was mucus extracted from shellfish—in particular, from just three species of sea-snails, called murex, that still live on rocks around the Mediterranean. But Tyrian purple was expensive because the yield was very low, Cooksey explains. "Each shell needs to be broken at the correct point so that the color precursor can be obtained," he says. An experiment found that 12,000 specimens of the shellfish Murex brandaris were needed to make just 1.2 grams of the dye—about half a thimbleful.

For the Phoenicians, one answer was to build more purple factories. Their ruins—including stone troughs rinsed by seawater where the gathered sea-snails were dumped and sorted—have now been found on the coast of Tunisia at what was once the Phoenician (or Punic) colony of Carthage, and at other places throughout the Mediterranean. But Carthage was the peak of Phoenician power, and it was defeated in three bloody Punic Wars against Rome. Tyre and Sidon had already fallen to the armies of Alexander the Great, and in 64 B.C., the Romans seized the region from its Seleucid rulers.

"Royal purple" then became "Imperial purple" and a hallmark of Roman nobility. During the Byzantine Empire, to be "born in the purple" meant being born to a ruling emperor.

"Purple was a status symbol for the Roman emperors and the powerful representatives of the emergent power, the Catholic Church," says Maria Melo of NOVA University at Lisbon in Portugal, a conservation scientist who studies ancient dyes. Purple was used whenever authority was displayed, and in rituals with high visual impact. It also became associated with Jesus Christ. "Purple achieved the status of a sacred color," she says.

University of Chicago historian Carolina López-Ruiz, the author of Phoenicians and the Making of the Mediterranean, says murex purple was first discovered by the Minoans on Crete, but the Phoenicians spread it widely through trade. "It existed in the Bronze Age; but the Phoenicians were the ones who exported this technology and exported its products." The dye had no doubt helped Phoenician trade, but the color purple was not the only thing they sold, she says.

Murex purple was superseded by synthetic dyes in the 19th century, but it took years to replicate its most appealing features, like staying fast within threads. The original is still made as a boutique item, and at least one tech startup hopes to recreate Tyrian purple without sea-snails as an ingredient. The company notes that many shorelines around the Mediterranean today are still littered with millions of shells from the ancient industry.

The Nobel Prize-winning chemist Roald Hoffmann, an emeritus professor at Cornell University, has spent more than 20 years investigating Tyrian purple—including making it from sea-snails amid the ruins of a Phoenician purple factory on Israel's coast. He notes that two important items of Phoenician trade were murex purple and glass, which the Phoenicians learned about from ancient Egypt or Mesopotamia. However, the production of glass was perfected by the Phoenicians and it was traded by them throughout the ancient world. But both murex purple and glass required a basic knowledge of chemistry to manufacture, and Hoffmann suspects this knowledge gave the Phoenicians an edge.

"The Phoenicians in general were masters of a lot of things, and I've wondered if their control of primitive chemistry, as exhibited in the making Royal purple, does not exhibit a broader interest in technology," he says. Such knowledge would also help with primitive metallurgy, and objects made from metal were another trade item the Phoenicians were famous for. "I think the conditions were there," he says.