Blue, blue, cobalt blue

Pale blue pottery was the height of fashion in the New Kingdom of Egypt three thousand years ago and in particular during the reign of Amenhotep III and Ramesses II. The color is due to cobalt that may have been derived from a mineral mined at an oasis in the eastern Sahara Desert, or so Colin Hope, an expert in blue painted pottery, believed. Jennifer Smith, professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis, crawled into the mine to obtain a pristine sample of those minerals for analysis. Her findings suggest that the ancient miners knew precisely which ores to dig to obtain cobalt and the artisans they supplied found a way to concentrate the mineral.