Highlights• Quartz-rich raw materials were extensively exploited in the African Early Stone Age.• Few studies have characterized quartzitic outcrops as primary source areas.• Macroscopic, petrographic, and EDXRF data used to fingerprint quartzitic outcrops at Oldupai.

International audienceThis paper details the results of a survey of the obsidian sources on the island of Giali in the Dodecanese, Greece, together with a review of these raw materials' use from the Mesolithic to the Late Bronze Age (ninth to second millennium Cal bc). Elemental characterization of 76 geological samples from 11 sampling locations demonstrates the existence of two geochemically distinct sources, termed `Giali A', and `Giali B'. The latter material, available in small cobble form on the island's southwestern half, seems to have only been exploited by local residents during the Final Neolithic (fourth millennium Cal bc). In contrast, Giali A obsidian comprises a distinctive white-spotted raw material, available in large boulders on the northeastern half of Giali, whose use changed significantly over time. During the Mesolithic to later Neolithic it was mainly used for flake-based tool-production by local Dodecanesian populations. Further away, handfuls of Giali A obsidian are documented from Early Neolithic to Early Bronze Age sites in Crete, the Cyclades, and western Anatolia. The distribution of this material is likely indicative of population movement, and regional socio-economic interaction more generally, rather than a significant desire for, and trade of, the material itself. This changed in the Middle Bronze Age (second millennium Cal bc), when Giali A obsidian was reconceptualized as a valued raw material, and used by Cretan palace-based lapidaries to make prestige goods. This radical shift in traditions of consumption resulted from Cretan factions appropriating Anatolian and Egyptian elite value regimes and craft practices as a means of creating new means of social distinction within a larger Eastern Mediterranean political arena

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