“Side by side with the production of metals, the Egyptians and the inhabitants of Mesopotamia perfected the arts of making glazed pottery... and the production of glass. ...vessels were baked in tall closed furnaces. "Egyptian blue" was made in Egypt by heating silica with malachite and lime... applied with soda as a blue glaze on faience, and the blue glass is also colored with copper. Some early... Egyptian and Babylonian blue glass are coloured with cobalt.”