The Study of Attic Black Gloss Sherds using Synchrotron X-ray Diffraction

We have studied the mineral composition of the gloss and the ceramic body of three pieces of Attic Greek pottery by applying the technique of high-resolution powder diffraction using synchroton X-rays. The measurements were performed on Stations 2·3 and 9·1 at the Synchrotron Radiation Source, Daresbury Laboratory. High quality powder patterns from the bulk of the ceramics and from the gloss surfaces have been obtained. The diffraction results show interesting variations of mineral composition between the gloss of the different sherds as well as variations between the bulk and the gloss. This makes phase identification and comparison between different fabrics less ambiguous. Spinel minerals are present in the gloss which are absent in the main body of the ceramics. Diffraction lines from one surface match the patterns of hematite, magnetite/maghemite and hercynite, while solid solutions of spinel structures appear to be present in the gloss layer of another sample. Crystallite particle sizes and lattice parameters of the minerals in the gloss layer have been accurately determined. Supplementary scanning electron microscopy (SEM) reveals the gloss thickness to be approximately 20μm but with variations down to 5μm. Analysis of the diffraction profile for the hematite component reveals a particle size in the order of 0·027μm.