5,000-Year-Old Egyptian Blue Technology May Have Been Made in Iran
TEHRAN — Nearly 500 artifacts discovered at two archaeological sites in northwestern Iran are helping researchers investigate one of the ancient world’s most remarkable technological achievements: the production and use of Egyptian blue, the earliest known synthetic pigment.
The artifacts, dating to the Iron Age II period, were found at Hasanlu during the Hasanlu Project and at nearby Dinkha Tepe during archaeological expeditions led by the Penn Museum from the 1950s to the 1970s.
Made from molded Egyptian blue paste, they include beads, vessels, furniture elements and decorative objects, revealing that the pigment had uses in ancient Iran that extended well beyond its traditional role as a paint.
Egyptian blue was developed in ancient Egypt about 5,000 years ago and became widely used because of its exceptionally stable blue color. Its presence in northwestern Iran roughly 2,000 years later, however, raises important questions about technological exchange, trade and the movement of people and materials across the ancient Near East.
Researchers from the University of Pennsylvania are now examining the Iranian artifacts to determine how the pigment was produced, where its raw materials originated and whether Egyptian blue was manufactured locally in northwestern Iran.
“If the pigment was made in northwestern Iran, then this is the earliest example of its production outside of Egypt,” archaeometallurgist Vanessa Workman said.
Egyptian blue is a synthetic material whose color comes from crystals with the same chemical composition as the rare naturally occurring mineral cuprorivaite. Because cuprorivaite is extremely uncommon in nature, the presence of the compound in archaeological objects generally indicates deliberate human production.
The manufacturing process required considerable technological knowledge. Ancient craftspeople combined a copper-bearing material with silica, usually quartz sand, an alkali such as plant ash or natron, and calcium carbonate such as limestone. The mixture was ground into a fine powder and heated at a controlled temperature inside a closed container.
Small changes in the recipe or production conditions could produce a related green pigment, demonstrating that ancient artisans had learned to manipulate the chemical composition and crystal structure of materials to obtain a desired color.
The scale and variety of Egyptian