Egyptian blue

Egyptian blue, also known as calcium copper silicate (CaCuSi4O10 or CaOCuO(SiO2)4 (calcium copper tetrasilicate)) or cuprorivaite, is a pigment used in ancient Egypt for thousands of years. It is considered to be the first synthetic pigment. It was known to the Romans by the name caeruleum – see also the English word cerulean. After the Roman era, Egyptian blue fell from use and the manner of its creation was forgotten. Egyptian blue, also known as calcium copper silicate (CaCuSi4O10 or CaOCuO(SiO2)4 (calcium copper tetrasilicate)) or cuprorivaite, is a pigment used in ancient Egypt for thousands of years. It is considered to be the first synthetic pigment. It was known to the Romans by the name caeruleum – see also the English word cerulean. After the Roman era, Egyptian blue fell from use and the manner of its creation was forgotten. The ancient Egyptian word wꜣḏ signifies blue, blue-green, and green. The first recorded use of 'Egyptian blue' as a color name in English was in 1809. Egyptian blue is a synthetic blue pigment made up of a mixture of silica, lime, copper, and an alkali. Its color is due to a calcium-copper tetrasilicate CaCuSi4O10 of the same composition as the naturally occurring mineral cuprorivaite. It was first synthesized in Egypt during the Fourth Dynasty and used extensively until the end of the Roman period in Europe, after which its use declined significantly. The term for it in the Egyptian language is ḫsbḏ-ỉrjt, which means artificial lapis lazuli (ḫsbḏ). It was used in antiquity as a blue pigment to color a variety of different media such as stone, wood, plaster, papyrus, and canvas, and in the production of numerous objects, including cylinder seals, beads, scarabs, inlays, pots, and statuettes. It is also sometimes referred to in Egyptological literature as blue frit. Some have argued that this is an erroneous term that should be reserved for use to describe the initial phase of glass or glaze production, while others argue that Egyptian blue is a frit in both the fine and coarse form since it is a product of solid state reaction. Its characteristic blue color, resulting from one of its main components—copper—ranges from a light to a dark hue, depending on differential processing and composition. Apart from Egypt, it has also been found in the Near East, the Eastern Mediterranean, and the limits of the Roman Empire. It is unclear whether the pigment's existence elsewhere was a result of parallel invention or evidence of the technology's spread from Egypt to those areas. The ancient Egyptians held the color blue in very high regard and were eager to present it on many media and in a variety of forms. They also desired to imitate the semiprecious stones turquoise and lapis lazuli, which were valued for their rarity and stark blue color. Use of naturally occurring minerals, such as azurite, to acquire this blue, was impractical, as these minerals were rare and difficult to work. Therefore, to have access to the large quantities of blue color to meet demand, the Egyptians needed to manufacture the pigment themselves. The Egyptians developed a wide range of pigment varieties, including what is now known as Egyptian blue, which was the first of its color at the time of its development. This accomplishment was due to the advancement of Egypt as a settled agricultural society. This stable and established civilization encouraged the growth of a nonlabor workforce, including clerics and the Egyptian theocracy. Egyptian pharaohs were patrons of the arts, and consequently were a stimulus for the advancement of pigment technology. The earliest evidence for the use of Egyptian blue, identified by Egyptologist Lorelei H. Corcoran of the University of Memphis, is on an alabaster bowl dated to the late pre-dynastic period or Naqada III (circa 3250 BC), excavated at Hierakonpolis, and now in the Museum of Fine Arts, Boston. In the Middle Kingdom (2050–1652 BC), 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 BC), began to be more widely used in the production of numerous objects. Its use continued throughout the Late period, and Greco-Roman period, only dying out in the fourth century AD, when the secret to its manufacture was lost.