Archaeologists Uncover Unusually Large Chunk of Rare ‘Egyptian Blue’ in Nero’s Palace

Archaeologists in Rome have discovered beautiful, ancient paint—but not just any paint. Known as “Egyptian Blue,” it’s among the oldest synthetic pigments in the world, with the newly found ingot weighing more than five pounds.

Archaeologists excavating the Domus Aurea, Emperor Nero’s vast imperial residence in ancient Rome, have discovered containers still carrying the splendid pigments artisans used to decorate the palace complex almost 2,000 years ago. Among the brilliant colors, researchers were most excited to find a rare chunk of Egyptian blue pigment. The Colosseum Archaeological Park announced the discovery in a January 20 Facebook post.

“The fascination conveyed by the depth of blue of this pigment is incredible,” Alfonsina Russo, Director of the Colosseum Archaeological Park, said in the Facebook post. “The Domus Aurea once again moves [us] and restores the brilliance of the colors used by the painters who skillfully decorated the rooms of this precious and refined imperial palace.”

The archaeologists unearthed two tubs that, among other things, were used to process the colorful pigments while the palace was under construction. Presumably from within the tubs, they recovered an amphora containing yellow ocher, tiny jars with red pigments such as realgar and red ocher, and an ingot of Egyptian blue.

Unlike yellow and red ocher, Egyptian blue is a synthetic color achieved by heating a mixture of limestone, chemical compounds, and copper-containing minerals. Its earliest production and use dates back over 5,000 years ago to ancient Egypt; in Roman times, the pigment was produced in southern Italy. In fact, it’s the oldest synthetically-made color known to scientists. Archaeologists typically discover the ancient remnants of Egyptian blue pigment in the form of powder or tiny spheres, but the rarity of the recent specimen lies in its size: a whopping 5.29 pounds (2.4 kilograms).

Remnants of Egyptian blue previously uncovered in Pompeii suggest that the pigment was used in spaces of luxury and wealth, according to the Colosseum Archaeological Park. The context of the recent discovery within Nero’s imperial residence further affirms this suggestion, and provides insight into the refinement and specialization of the artisans who were employed to decorate it.

Scientists previously thought that the recipe for Egyptian blue was lost after the fall of the Roman Empire and only truly rediscovered in the early 1800s by the British chemist Humphry Davy. A 2020 study, however, revealed that Italian Renaissance painter Raphael used the pigment in his 1512 fresco, Triumph of Galatea. Perhaps the recipe hadn’t been lost after all.

Either way, the brilliant color connects artists and artisans across the vast annals of human history. Even some modern shades of blue used by artists today are called Egyptian blue in homage to the ancient pigment.