• Pompeii’s newly uncovered “Blue Room” shrine was lavishly painted using rare and costly Egyptian blue pigment.
• Researchers estimate six to 10 pounds of pigment cost up to 90 percent of a soldier’s annual salary.
• The small shrine’s extravagant materials signal immense household wealth, despite its modest size within the villa.

As any Pompeii guide will tell you, the mosaics may catch the eye, but among the city’s elite, wall paintings were a far greater status symbol. In this context, no color was more coveted and costly than Egyptian blue, so-named because ancient Egyptians had been manufacturing it since the late 4th millennium B.C.E. as an affordable alternative to grinding down lapis lazuli.

In the summer of 2024, a domestic shrine room was discovered inside a two-story house that once belonged to an extremely wealthy Pompeii family. Fifteen tall amphorae rested against the walls and piles of construction materials suggested the house was under renovation when Vesuvius erupted in 79 C.E., but it was the walls that piqued the archaeologists’ interest: they were covered in Egyptian blue paint and featured elaborate depictions of goddesses, sphinxes, and winged griffins.

The small space was duly labelled the Blue Room and a recent study by the Archaeological Park of Pompeii and the Massachusetts Institute of Technology (MIT) has not only confirmed the presence of Egyptian blue (along with naturally derived red, green, yellow, and white pigments), but also estimated the amount of precious paint used and its value at the time.

In the Roman Empire, Egyptian blue was typically traded in the form of small pellets, which were ground into a useable powder, and researchers estimate between six and 10 pounds were used to coat the Blue Room. Using prices quoted by Pliny the Elder (who died in nearby Stabiae during the eruption), the researchers estimate this much paint would have cost 93 to 168 denarii, perhaps equivalent more than 1,000 loaves of bread or 90 percent of a Roman foot soldier’s annual salary. As the paper published in Heritage Science on March 3 notes, this is before the costs of specialist labor are factored in.

The amphorae inside the blue room. Photo: courtesy Archaeological Park of Pompeii.

The kicker? The Blue Room was one of the smallest rooms in the entire house, which included a thermal bath complex, garden courtyard, and banquet hall. “While the use of Egyptian blue as a base layer across the entire shrine could be interpreted as a reduction in the perceived value of Egyptian blue,” the researchers wrote. “We suggest that this choice by the owners speaks less to the value of the pigment and more to the substantial wealth of the household.”

When illuminated, Egyptian blue emits near-infrared luminescence. To confirm the use of the pigment, two pictures were taken using modified night-vision goggles: one in natural light and the other while shining LED light on the wall. By subtracting the natural light image from the LED image, researchers were left with the glowing signal of Egyptian blue. Researchers called the new technique “a key advancement in non-invasive field analysis of Egyptian blue.” The quantity of paint was calculated by multiplying the surface area of the walls by the average thickness of Egyptian blue.

Egyptian blue is considered the first synthetic pigment in human history. Created by firing sand, calcium carbonate, and copper-loaded minerals at more than 1500 degrees Fahrenheit, it became the most widely used blue pigment across the ancient Mediterranean and West Asia for thousands of years. By the 1st century C.E., the main production region for the pigment in the entire Roman Empire was Puteoli, a commercial port 20 miles from Pompeii.