five different categories of Egyptian blue forms and the vessels associated with them: large round flat cakes, large flat rectangular cakes, bowl-shaped cakes, small sack-shaped pieces, and spherical shapes. No tin was found in the samples analyzed, which the authors suggest is an indication that use of scrap copper was possible instead of bronze. Qantir In the 1930s, Mahmud Hamza excavated a number of objects related to the production of Egyptian blue at Qantir, such as Egyptian blue cakes and fragments in various stages of production, providing evidence that Egyptian blue was actually produced at the site. Recent excavations at the same site uncovered a large copper-based industry, with several associated crafts, namely bronze-casting, red-glass making, faience production, and Egyptian blue. Ceramic crucibles with adhering remains of Egyptian blue were found in the excavations, suggesting again it had been manufactured on site. These Egyptian blue 'cakes' possibly were later exported to other areas around the country to be worked, as a scarcity of finished Egyptian blue products existed on site. For example, Egyptian blue cakes were found at Zawiyet Umm el-Rakham, a Ramesside fort near the Libyan coast, indicating in fact that the cakes were traded, and worked at and reshaped away from their primary production site. Connections with other vitreous material and with metals Egyptian blue is closely related to the other vitreous materials produced by the ancient Egyptians, namely glass and Egyptian faience, and it is possible that the Egyptians did not employ separate terms to distinguish the three products from one another. Although it is easier to distinguish between faience and Egyptian blue, due to the distinct core of faience objects and their separate glaze layers, it sometimes is difficult to differentiate glass from Egyptian blue due to the very fine texture that Egyptian blue occasionally could have. This is especially true during the New Kingdom, as Egyptian blue became more refined and glassy and continued as such into the Greco-Roman period. Since Egyptian blue, like faience, is a much older technology than glass, which only begins during the reign of Thutmose III (1479–1425 BC), changes in the manufacture of Egyptian blue undoubtedly were associated with the introduction of the glass industry. Analysis of the source of copper used in the manufacture of Egyptian blue indicates a relationship with the contemporaneous metal industry. Whereas in the earlier periods, it is most probable that copper ores were used,