gems, ancient gems, glyptic, archaeology, archaeogemology, quartz, species, treatment nomenclature, Near Eastern, Western Asiatic, cylinder seals, Classical world

Scholars of glyptics frequently face two related problems; firstly, naming the materials of gems they wish to describe and secondly, understanding the terms used by other scholars, past and present. Ideally materials should be scientifically identified by gemmological or laboratory techniques, such as refractive index or specific gravity measurements, X-ray powder diffraction or X-ray fluorescence analysis, but this is seldom possible. It is perhaps fortunate that many intaglios and cameos of Classical and post-Classical periods have been worked from quartz. This mineral is of common occurrence and its distinctive physical properties ofhardness, compact structure, lack of cleavage and vitreous to subvitreous lustre make it a most suitable material for engraving. These properties also enable it to be easily identified and often scholars can be confident of recognising quartz by simple visual inspection. However, it is not always easy to differentiate between quartz and some other materials such as glass. Furthermore, distinguishing between the many varieties of quartz which are identified by variations in colour, translucency and patterning etc, may be problematic leading to confusion and inconsistencies in terminology; these problems are perhaps most acute for the almost innumerable varieties of microcrystalline quartz. The situation is further complicated by the widespread occurrence of quartz, which has led to regional traditions in naming varieties from local sources and to broader geographical differences in approach. In addition, the approaches and requirements of different eroups ofscholars, suchas gemmologists, mineralogistsand geologists, to the complex subject of quartz nomenclature are diverse; for instance, the terminology applied to a specimen at source may not be appropriate for a small part of it worked as a gemstone.