The Pigment Production Site of the Ancient Agora of Kos (Greece): Revisiting the Material Evidence

A late-Hellenistic production site was found at the eastern stoa of the agora of Kos. The presence of destroyed fire-structures indicates pyrotechnological processes, related to pigment manufacture and metallurgy. Pigment production included the treatment of natural earths and the manufacture of the artificial material Egyptian blue. Among the excavation’s finds were hollow tubular litharge rods, amorphous lead lumps and drops, and a small quantity of silver, which point to lead production and silver separation through cupellation. The co-existence of the two separate manufacturing activities at the same site may have been beneficial in supplying the workshop with raw materials and fuel. The strategic location of the production site in the commercial centre of the ancient town, with its connection to the port, would have facilitated trade. The production debris from the Koan site underlines the relationship between pigment manufacture and metallurgy

Colourful earth: Iron-containing pigments from the Hellenistic pigment production site of the ancient agora of Kos (Greece)

The red, brown, yellow and green pigment lumps from the Hellenistic pigment production site of the ancient agora of Kos (Dodecanese, Greece) are the focus of this paper. A selection of pigments is examined through a combination of analytical techniques, including SEM-EDS on uncoated samples, X-ray powder diffraction, FTIR and pRaman spectroscopy. Through the study of raw pigments deriving from the context of a production site, the aim is to approach pigment manufacturing contextually during the Hellenistic period. The examined red pigments were characterised as red earths (rubricae, μίλτοι), with their colour primarily attributed to hematite. However, significant variance was observed in their chemical and mineralogical composition, reflecting on their final colour. Interestingly, two of the red samples contained lead tetroxide in addition to hematite. The colour of the brown pigments was attributed to a complex mixture of iron oxides. The chemical and mineralogical composition of the two yellow lumps showed that they are of different origin; the first, composed of goethite and quartz, can be characterised as a yellow earth (sil, ὢχρα) and the second corresponds to the mineral jarosite. A green-coloured lump was characterised as a type of celadonitic rock. The variance in the composition of the examined pigments indicates the treatment techniques carried out at the site and the preferences of the local craftspeople. The finds from the Koan workshop illustrate the complex and sophisticated nature of pigment production, suggesting an intertwined relationship with mining and metallurgy

Egyptian Blue Pellets from the First Century BCE Workshop of Kos (Greece): Microanalytical Investigation by Optical Microscopy, Scanning Electron Microscopy-X-ray Energy Dispersive Spectroscopy and Micro-Raman Spectroscopy

This paper aims to expand our understanding of the processes involved in the production of the artificial pigment Egyptian blue through the scientific examination of pigments found in the first century BCE workshop of the Greek island of Kos. There, 136 Egyptian blue pellets were brought to light, including successfully produced pellets, as well as partially successful and unsuccessful products. This study is based on the examination of eighteen samples obtained from pellets of various textures and tones of blue, including light and dark blue pigments, coarse and fine-grained materials, and one unsuccessful pellet of dark green/grey colour. The samples were examined by optical microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), and micro-Raman spectroscopy. These complementary microanalytical techniques provide localised information about the chemical and mineralogical composition of this multicomponent material, at a single-grain level. The results shed light on the firing procedure and indicate possible sources for raw materials (beach sand, copper alloys), as well as demonstrating the use of a low-alkali starting mixture. Moreover, two different process for the production of light blue pigments were identified: (a) decreased firing time and (b) grinding of the initially produced pellet and mixing with cobalt-containing material