Chemical analyses of Egyptian blue pigments of the second millennium B.C. have established that those containing cobalt invariably contain elevated concentrations of aluminum, magnesium, manganese, iron, nickel, and zinc. The correlation holds true in pottery, paint, glass, and faience. Past attempts to identify the source of the cobalt used in Egypt have foundered on the problem of finding an ore with all of the above-mentioned elements, or on the fact that some other correlations expected from the proposed sources were not detectable in the manufactured materials. Analyses just completed show that the cobalt in the alum from the Dakhla Oasis is invariably accompanied by all of the elements associated with it in Egyptian pigments. The elemental proportions are similar to those observed in Egyptian New Kingdom faience. It is therefore suggested that the cobalt employed in New Kingdom Egypt and in the Mycenean world, where similar correlations have been observed, came from the Great Western Oases in Egypt. Cobalt used in Egypt during the first millennium B.C. shows no clear correlations with other elements and resembles the cobalt detected in Mesopotamian pigments of all time periods, which presumably came from Iran.