A synthetic inorganic colorfast pigment having coarse, irregular particles and ranging in color from a powdery blue to a royal blue. It is composed of a double silicate of calcium and copper, prepared by heating a mixture of silica, copper salts, and calcite in a sodium carbonate flux, forming a stable blue frit. Egyptian blue is stable in all types of media and is unaffected by acids or alkali. It was used by the ancient Egyptians over 5000 years ago as a pottery glaze and watercolor pigment in wall paintings. Similar materials, later manufactured in Italy and called Pompeian blue and Pozzuoli blue, have similar chemical compositions and optical properties.一種不會褪色的合成無機顏料，粒子粗糙且不規則，顏色範圍從粉藍到皇家藍。它由矽酸鈣及矽酸銅雙矽組成，在碳酸鈉助熔劑中加熱矽石、銅鹽、方解石的混合物，形成穩定的藍色熔塊。埃及藍在所有媒材中都很穩定，不受酸或鹼影響。五千多年前古埃及人便開始使用埃及藍，當時做為陶器釉料及壁畫的水彩顏料。之後義大利製造出類似材料，即龐貝藍和波佐利藍，具相似的化學成分及光學性質。