A colorful, glassy material made by grinding quartz or sand with sodium, potassium, calcium, magnesium and/or copper oxide. The resulting substance is formed into the desired shape, such as a bead, amulet, or sculpture, then fired. During firing, the pieces harden and develop a glassy finish with bright colors, blue-green being the most common. The ancient Egyptians perfected faience-making, perhaps in an attempt to imitate the colors of turquoise and other gemstones. Web resources here and here.
Statuette of a Hippopotamus. Faience. Ca. 1981–1885 BCE. Metropolitan Museum of Art, New York.