ROME, ITALY—Artnet reports that a chunk of a rare and valuable pigment known as Egyptian blue was uncovered near workshops associated with the construction of the Emperor Nero’s Domus Aurea, or "Golden House," in Rome. The sprawling imperial residence, which was built in the 60s a.d., contained more than 100 rooms that were lavishly decorated with marble statues and vivid frescoes. Archaeologists recently excavated a room used by workers and artists to prepare and store the colorful materials used in these artworks, including yellow ocher and a red mineral called realgar. Among the finds was an incredibly large six-pound ingot of Egyptian blue, which is normally only found in powder form or small pieces. The use of Egyptian blue in painting dates back to the third millennium b.c. in Egypt and Mesopotamia. It became a popular color in the paintings that lined the walls of the homes of Rome’s richest citizens. Egyptian blue is not a naturally occurring pigment, but is created by mixing lime and silica with minerals containing copper and sodium carbonate and heating them at very high temperatures. The Roman architect Vitruvius recorded this process in his first-century b.c. work De architectura. For more on the Domus Aurea, go to "Golden House of an Emperor."
