Catching the light: studying the polishing techniques of the Neolithic calcedony beads from the Levant and Upper Nubia

Abstract

Since the pioneering experiments of A. Gwinett and L. Gorelick in the 80s to solve enigmatic questions of ancient Mesopotamian and Egyptian lapidary technologies, little works has been dedicated to the study of ancient hard semiprecious stone beads (quartz, carnelian, agate, amazonite, obsidian, etc.). Rarer are studies of Neolithic assemblages of the Levant and the Nile Valley that gave rise to the development of beads production by full-time specialized craftsmen long before the early Urban societies. Beyond addressing the artisans¿ skills and know-how, technological studies of hardstone beads are fundamental to reassess the techno-symbolic and social systems of the Neolithic communities. However, this task is quite challenging due to the scarcity of clearly identified Neolithic workshops, therefore the analyses are made on final products, the complex biographies of beads, and the lack of experimental referential that require, among other things, skillful experimenters. Our paper focuses on the polishing stage of chalcedony beads from the Pre-pottery Neolithic Levant and the Middle Neolithic Upper Nubia. This stage, that implies the application of successive techniques (abrasion, polish and luster/shining), is one of the most time-consuming in the chaîne opératoire yet critical for determining the products¿ quality(e)s. For this purpose, the method we applied combines optical and confocal microscopy with metrology software. To interpret the results, we applied the same analytical protocol on ethnographic chalcedony beads manufactured in traditional Indian and Yemeni workshops. As the Neolithic beads, the ethnographic ones were knapped prior to their surface treatments. By comparing the archaeological samples with the ethnographic specimens, the aims are to determine if the Neolithic beads have received successive polishing treatments including the luster, and to identify gestures and any potential use of mechanical devices.