Egyptian Blue ( CaCuSi4O10 or CaO.CuO.4SiO2) is a pigment used by Egyptians for thousands of years. It is considered to be the first synthetic pigment. The pigment was known to the Romans by the name caeruleum. Vitruvius describes in his work 'de architectura' how it was produced by 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. After the Roman era Egyptian Blue was not used anymore. For animal and plant pigments, see Pigment, biology. ... Marcus Vitruvius Pollio (born ca. ...
The ancient Egyptian word wedjet signifies blue, and the same word is used for the human eye, as in the Eye of Ra. In Egyptian mythology, Buto (papyrus colored--referring to the color of the cobra) was a snake (especially cobra) goddess and patron of the oracle in the city of the same name. ... Hieroglyphic version of the Eye of Horus The Eye of Horus (originally, The Eye of Ra) is an ancient Egyptian symbol of protection and power, from the deity Horus or Ra. ...