gems, analytical, Egyptian blue

Fouqué discusses the ancient artificial pigment commonly known as Egyptian blue, examining its mineralogical and chemical nature and its relationship to the blue substance then termed “Vestorian blue.” He considers specimens of the pigment from ancient Egyptian objects and compares their physical and optical characteristics with artificially prepared material. Particular attention is given to the crystalline blue compound produced by heating mixtures containing silica, lime, and copper, and to the conditions necessary for its formation. Microscopic and mineralogical examination demonstrates that the color is associated with a definite crystalline copper-bearing silicate rather than merely with a glass colored by copper. Fouqué discusses experimental reproduction of the material and its relationship to pigments used in antiquity, contributing to the identification of Egyptian blue as a deliberately manufactured crystalline substance. The paper is an early scientific investigation of the composition and manufacture of one of the most important synthetic blue materials of the ancient world.