Evidence for the Metallurgical Origins of Glass at Two Ancient Egyptian Glass Factories
- PDF / 136,237 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 107 Downloads / 234 Views
Evidence for the
Metallurgical Origins of Glass at Two Ancient Egyptian Glass Factories
Jennifer L. Mass, Mark T. Wypyski, and Richard E. Stone Introduction Studying the raw materials used by ancient glassmakers provides information about ancient glassmaking practices, the relationship between glassmaking and other craft technologies (silicate-based or non-silicate-based), and the trading patterns of specific cultures. Colored opaque glasses are of particular interest because they were among the first mass-produced and mass-distributed glasses. They are also important because several hypotheses suggest that the first colored opaque glasses were derived from metallurgical slags.1–3 Previously reported compositions and microstructures of colored opaque Roman glasses support the use of a silver-refining by-product (litharge, PbO) as the source of lead antimonate (Pb2Sb2O7), the colorant/ opacifying agent used in opaque green and yellow Roman glasses.4,5 Several authors have addressed the direct formation of vitreous silicate objects from metallurgical slags.6,7 This article will review current theories on the relationship between ancient metallurgy and glassmaking, and discuss our findings on ancient Egyptian colored opaque glasses. The ancient Egyptian glasses discussed in this article are from two New Kingdom (1550–1070 B.C.) glass factories, Malkata and Lisht. There have been many comprehensive studies of
38
second-millennium-B.C. Egyptian glass compositions, and Brill and Sayre have previously examined glasses from Malkata and Lisht.8 Our article, however, presents an in-depth study of the raw materials
used for glassmaking at Malkata and Lisht. Note that all of the glasses discussed in this work are soda-lime-silica glasses (Na2O-CaO-SiO2), although the source of the soda for the Egyptian wares appears to have been different from the source for the Roman wares.9
Colored Opaque Glasses in Antiquity Opaque glasses have been found in third- and fourth-millennium-B.C. archaeological contexts, but they do not occur in significant quantities until the middle of the second millennium B.C.10 These glasses were prized in antiquity as inexpensive replacements for precious stones such as lapis lazuli, carnelian, and turquoise. Colored opaque glasses were used in the production of small vessels, amulets, inlays, jewelry, and mosaics. The opaque glasses produced from the middle of the second millennium B.C. to the middle of the Roman Imperial period (2nd century A.D.) were typically white, yellow, light blue (turquoise), green, and red. The blue and white glasses were opacified with white calcium antimonate crystallites (Ca2Sb2O7 and CaSb2O6). The green and yellow glasses were opacified with yellow lead antimonate crystallites (Pb2Sb2O7). Copper (II) ions in solution in a colorless transparent glass render it a translucent blue; they were added to the opaque white and yellow glasses to transform them, respectively, into opaque blue and green glasses. Red opaque glasses were colored and opacified with metallic copper par
Data Loading...
