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 o f three pieces of Attic Greek pottery by applying the techniques of high-re solution powder diffraction using synchrotron x-rays. The measurements were performed on Stations 2.3 and 9.1 at the Synchrotron Radiation Source, Dar esbury Laboratory. High quality powder patterns from the bulk of the cerami cs 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. Thi s 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 pa tterns of hematite, magnetite/maghemite and hercynite, while solid solution s of spinel structures appear to be present in the gloss layer of another s ample. Crystallite particle sizes and lattice parameters of the minerals in the gloss layer of another sample. Crystallite particle sizes and lattice parameters of the minerals in the gloss layer have been accurately determin ed. Supplementary scanning electron microscopy (SEM) reveals the gloss thic kness to be approximately 20 mum but with variations down to 5 mum. Analysi s of the diffraction profile for the hematite component reveals a particle size int he order of 0.027 mum.