what is egyptian blue

Egyptian blue is a synthetic blue pigment that was used in ancient Egypt for thousands of years. It is considered to be the first synthetic pigment and was made by heating a mixture of silica, lime, copper, and an alkali. The pigment was used extensively from the early dynasties in Egypt until the end of the Roman era. Egyptian blue was associated with the sky and the river Nile, and thus came to represent the universe, creation, and fertility. It was relatively inexpensive to produce and was traded throughout the Roman Empire. Egyptian blue ceased to be used as a pigment with the fall of the Roman Empire, but modern researchers are discovering new applications for it. Egyptian blue luminesces in the infrared range, and recent experiments have shown that finely ground Egyptian blue can be used as a biomarker in medical imaging devices. Egyptian blue is completely stable in all vehicles and is completely lightfast. It was mixed with different pigments and used with lime on frescoes. Egyptian blue contains copper, which is rated as toxic from prolonged exposure if inhaled or ingested, so care should be used in handling the dry powder.