The macroscopic aspects of the volcanic glasses are used by archaeologists in the initial sorting of their material. The parameters are not only colours (grey, black, red, brown, yellow, green,…), but textures (smooth to rough), transparency (translucent, semi-opaque, opaque), appearance (milky, metallic, shiny, dull), zonation (bedded, cloudy, dapple,…), heterogeneity (ashes, spherulites,…). We are currently building up a photo gallery using 2mm thick slices of raw material with a standard description of these aspects of the different volcanic glasses. This macroscopic analysis together with the technological study allows the accurate definition of samples used to define the geological sources exploited by ancient groups.
Our corpus is composed of 86 slices for central Anatolian sources (Obsidian Use Project) and we are conducting similar approach for Eastern Anatolian obsidians (GeObs Project).