https://hyperallergic.com/366307/egyptian-blue-the-first-synthetic-pigment/

Egyptian Blue: The First Synthetic Pigment

The first human-made blue pigment emerged in ancient Egypt, then disappeared for centuries until it was rediscovered in Pompeii.

Allison MeierApril 3, 2017

Amphora with cover decorated with Egyptian blue pigment (Egypt, New Kingdom, 1380-1300 BCE) (via Walters Art Museum/Wikimedia)

In a series for the first day of each month, Hyperallergic is exploring some firsts in art, from the earliest known depictions of things to pioneers in the visual fields.

The Virgin Mary is often depicted in Renaissance paintings draped in a robe of blue, chosen not just for its heavenly tones, but for the rarity of the lapis lazuli pigment that colored her clothing. Yet long before this hue of ground semi-precious stones, there was a synthetic blue pigment widely used in ancient Egypt. This blue's creation, loss, and rediscovery cover centuries of human history, from the tombs of Egyptian kings, to the 19th-century archaeological digs at Pompeii, to the modern forensics lab.

Painting from the Tomb of Nebamun (via British Museum/Wikimedia)

Egyptian blue is the earliest-known synthetic pigment, meaning it was not a color already found in nature (such as the precious lapis lazuli, which was mined in today's Afghanistan). It was formed by heating quartz sand, copper, an alkali, and lime (or lime-heavy sand) into calcium copper silicate, a highly stable chemical compound. The Pigment Compendium: A Dictionary of Historical Pigments states that it was "used extensively from 4th dynasty Egypt until the end of the Roman period in Europe, as well as in certain other rare exceptions." So after such a long use, including tomb ceilings as the night sky and the blue skin of the god Osiris, why did such an innovative hue disappear?

Partly it was the fall of the Roman Empire, but even before then it had gone slightly out of favor. Roman Egyptian artists tended to use more reds, yellows, and whites, sometimes even painting over preparatory blue drawings. Egyptian blue is believed to have vanished during the Dark Ages, except for strange, sporadic survivals, like in the blue of a 1524 painting by Giovanni Battista Benvenuto. Finally, as the Royal Society of Chemistry explains, samples of the pigment were found in 1814 at Pompeii, leading researchers to link the Roman ruins to this rediscovered Egyptian invention.

The reason it's easily identified is it has a distinct optical property. According to Yale University, Egyptian blue "fluoresces in the near infrared region of the electromagnetic spectrum when irradiated with visible light." The unique quality has resulted in scientists considering contemporary applications, like as an ink for use at a nanometer scale, or as a luminescent dusting power for forensics on complex surfaces. A couple of centuries after its retrieval from history through Pompeii, this blue may have its own scientific significance as a material of discovery.

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