Egyptian Blue — the world's first synthetic pigment.
In Egyptian, the word < wAD > means "blue, blue-green, and green." For instance, in the Egyptian term for the Mediterranean — < wAD wr > "great green, blue-green, or blue."
The Egyptians, like many other ancient peoples, greatly valued the color blue. It may not have been feasible to the Egyptians to import large quantities of Lapis Lazuli from as far away as modern Afghanistan to grind up to use as a pigment.
The oldest artifact known to be colored with Egyptian Blue is dated to the late pre-Dynastic Naqada III period (~ 3250 BCE) on an alabaster bowl excavated at Nekhen (Hierakonpolis). It's rather likely that the manufacture of Egyptian Blue predates this. The alabaster bowl is now housed in the Boston Museum of Fine Arts. In the Middle Kingdom (2050–1652 BCE) it continued to be used as a pigment in the decoration of tombs, wall paintings, furnishings, and statues, and by the New Kingdom (1570–1070 BCE) began to be more widely used in the production of numerous objects. Its use continued throughout the Late period and Greco-Roman period with the last known possible manufacture and use (for some centuries) being two Roman churches. In the first, the Church of San Clemente, the pigment appears in a Byzantine fresco The Ascension of Christ, dating from ca 850 CE. The poor quality of the pigment would tend to exclude it from being sourced from a reclaimed batch of genuine old Roman stock, so it seems that the pigment was most likely produced concurrently with the fresco. A mixture of Egyptian Blue and Lapis Lazuli also appeared in some 8th century wall paintings in the San Saba Church. This could also be the first occurrence of lapis lazuli as a pigment in European painting.
No written information exists in the Egyptian corpus about the manufacture of Egyptian blue, it was first mentioned only in Roman literature by Vitruvius during the 1st century BCE. He refers to it as "coeruleum." He described the manufacture of it in his work 'De Architectura' — grinding sand, copper, and natron, and heating the mixture, shaped into small balls, in a furnace. Lime is necessary for the production as well, but probably lime-rich sand was used. Theophrastus gives it the Greek term κύανος (kyanos, blue) which originally probably referred to lapis lazuli. Only in the beginning of the 19th century was interest renewed in learning more about its manufacture. The first recorded use of "Egyptian blue" as a color name in English was in 1809. Humphry Davy in 1815, W. T. Russell, and F. Fouqué all investigated its manufacture.
The process of making Egyptian Blue was thought to be lost to history. But modern scientists analyzed its chemistry and figured out how to recreate it. Egyptian blue is scientifically known as calcium copper silicate (CaCuSi4O10) or (CaOCuO[SiO2]4) - calcium copper tetrasilicate or 'cuprorivaite.' The manufacture of it is now known to be multi-phasal: heating together quartz sand, a copper compound, calcium carbonate, and a small amount of an alkali (ash from salt-tolerant, halophyte plants or natron) at temperatures ranging between 800 and 1,000 °C (1,470 and 1,830 °F) (depending on the amount of alkali used) for several hours.
It is not believed the Egyptians were aware of the need for lime in the manufacture of Egyptian Blue, but that it was a natural by-product of some other material used in the process. It is also not known the exact source of the copper before the New Kingdom era. During and after the New Kingdom era, different types of bronze filings were used.
Egyptian Blue has been found in 3rd Milienium BCE West Asia as artifacts and inlays, but not as a pigment. It was found in the Mediterranean area at the end of the Middle Bronze Age, and traces of tin were found in its composition which suggests the use of bronze scrap instead of copper ore as the source of copper. Egyptian Blue was used extensively during the Roman period — a pot containing the unused pigment was unearthed in 1814 in Pompeii attests to this. It has also been found as unused pigment in the tombs of a number of ancient painters. Etruscans also used it in their wall paintings. Chinese blue is related and is suggested as having Egyptian roots. In 2009, researchers reported evidence for the use of Egyptian Blue in an 11th century mural altarpiece in the Church of Sant Pere at Terrassa in Spain. Egyptian Blue was used by Medieval painter Raphael in his painting, Triumph of Galatea. Other Medieval painters used the pigment as well.
A few examples of Egyptian Blue are shown below. If you'd like to know more, please feel free to use your favorite search engine to learn much more.