Egyptian blue

Synthetic · Ancient Egypt to the Roman period

Source material

Ground quartz, lime, copper and an alkali, heated together

Geography

Ancient Egypt; later used across the ancient Mediterranean world

Earliest documented use

Around the third millennium BCE

Cost & availability

Required deliberate high-temperature manufacture rather than simple mining or grinding, but became widely produced and traded once the process was established.

Production (historical summary)

Ground quartz sand, a copper source, lime and an alkali flux were combined and heated to around 800-900°C, fusing into a blue glass-like material that was then ground into pigment.

Stability & lightfastness

Highly stable once fired; resistant to fading, alkalis and most acids. (excellent)

Replacement / obsolescence

The technique for producing it was gradually lost after the Roman period and was only rediscovered and chemically understood by modern researchers in the 19th and 20th centuries.