a b s t r a c tThe South Caucasus was a major center of metal production in the Late Bronze and Early Iron Ages. Nowhere is this more clear than in the hills and mountains in the southeastern Black Sea region (ancient Colchis), where exceptionally large numbers of metal production sites have been found. Chemical and microscopic analysis of slagged technical ceramics at these sites illuminates several aspects of both raw copper and tin bronze alloy production. Copper ores were smelted in a complex multi-stage process designed to extract metal from sulfide ores. Technical ceramics served as containers for a range of different reactions, from the first phase of smelting, in which the copper sulfides were likely consolidated into a matte, though later stages of matte processing and metal copper production in smaller crucibles. In addition, a single crucible fragment, recovered from a late 2nd millennium BC slag heap, demonstrates that tin bronze was created by the direct addition of cassiterite tin ore, probably of alluvial origin, to metallic copper. The crucible's context, the use of cassiterite ore rather than tin metal, and a review of local geology suggests that the tin used in this crucible came from nearby, with the most likely source being the Vakijvari and Bzhuzhi gorges roughly 10e15 km away. While a single fragment does not speak to the regularity of this practice, at the very least it raises the possibility that the Colchian bronze industry was based on local rather than imported tin.

Many of the arguments for how and why people began to use iron in Southwest Asia rely on assumptions about the technology and relative organization of copper and iron smelting. However, research on the technological transformations of the Late Bronze Age and Early Iron Age suffers from a lack of investigation of primary metal production contexts, especially in regions outside the Levant. The current research examines metal production debris from a large number of smelting sites in western Georgia, and addresses questions of technology and resource utilization through detailed examination of few select sites. Through the chemical and mineralogical analysis of slag samples, we demonstrate the existence of an extensive copper-production industry and reconstruct several key aspects of the smelting technology during the Late Bronze Age and Early Iron Age. Combining a statistical analysis of slag mineralogy with other lines of evidence, we argue that copper was extracted from sulfide ores through a process of roasting and smelting in deep pit furnaces. The data also suggest that metalworkers at different sites exploited different ore sources within the same ore body. These results form a fundamental basis for further examination of spatial and chronological patterns of technological variation, with implications for models of Near Eastern copper production in this crucial period. Intriguing evidence of bloomery iron smelting, though currently undated, reinforces the region's potential to provide data on a key technological transformation.

Studies of metal production frequently show a correlation between scale and organizational complexity. The remarkably rich landscapes of metal-producing sites of late 2 nd-early 1 st millennium BC Colchis provide an unprecedented opportunity to reexamine this apparent correlation. Investigations of copper smelting sites show that industries with a large aggregate output can be the result of numerous small groups of metalworkers acting independently. Spatial data on site distributions, estimates of productive output, and archaeometric data on ore procurement patterns were integrated to reconstruct the organization of production. Judicious use of a portable X-ray fluorescence spectrometer (pXRF) showed that not only were smelting sites highly dispersed, but also that metalworkers at different sites were using ores from geologically distinct deposits. This innovative approach helped to reconstruct the organization of production in a distinctive metal production landscape, bridging an enduring divide between landscape-scale and microscopic investigations of craft production.