Ancient glassmakers: Egyptians crafted ingots for Mediterranean trade.

When pharaohs ruled Egypt, high-status groups around the Mediterranean exchanged fancy glass items to cement political alliances. New archaeological finds indicate that by about 3,250 years ago, Egypt had become a major glass producer and was shipping the valuable material throughout the region for reworking by local artisans.

This discovery settles a more-than-century-old debate over whether ancient Egyptians manufactured raw glass themselves or imported it from Mesopotamia, say Thilo Rehren of University College London and Edgar B. Pusch of the Pelizaeus-Museum Hildesheim in Germany in the June 17 Science.

The oldest-known glass remains come from a 3,500-year-old Mesopotamian site, which some researchers took as an indicator that ancient Egypt's glass depot was located there. However, excavations at Qantir, a village on the eastern Nile Delta, have yielded remnants of a glassmaking factory in operation just after that time, the two archaeologists report.

"Rehren and Pusch convincingly show that the Egyptians were making their own glass in large, specialized facilities that were under royal control,' remarks archaeologist Caroline M. Jackson of the University of Sheffield in England, in a commentary published with the new report.

Workers at Qantir have so far uncovered pieces of hundreds of pottery containers, some with glass chunks attached to them. Other finds include waste products from glass production. Chemical analyses of these materials provided data about glassmaking ingredients used at the site.

This evidence reflects a two-stage glassmaking process, the scientists assert. In the first stage, Egyptians crushed quartz pebbles into an alkali-rich plant ash and heated the mixture at relatively low temperatures in small clay vessels that were probably recycled beer jars. Next, they removed the resulting glassy material from the jars and ground it into powder, then cleaned and colored it red or blue with metal oxides.

In the second stage, workers poured this powder through clay funnels into ceramic crucibles and melted it at high temperatures. After cooling, they broke the crucibles to remove puck-shaped glass ingots.

Rehren and Pusch propose that Egyptians exported these ingots to workshops throughout the Mediterranean, where artisans reheated the glass and fashioned it into decorative items. The chemical composition of glass vessels and other artifacts found at various elite Mediterranean sites dating to around the time of Rameses II matches that of the Egyptian ingots, Jackson points out.

Indirect evidence of ancient Egyptian glassmaking also exists. For example, at the ancient Egyptian city of Amarna, archaeologists found ceramic vessels from more than 3,300 years ago that may have served as ingot molds. Also, a Bronze Age shipwreck discovered off Turkey's coast in 1987 contained glass ingots fitting the dimensions of the Amarna containers.