gems, jade, jadeite, fei cui, Japan, geology

This chapter represents a foray into a very different aspect of Tectonic Archaeology. Previous descriptions dealt with sanukite and obsidian sources produced during volcanic eruptions in the Japanese Islands (BOX 4 and Chapter 6). These stones were mainly used by prehistoric peoples for utilitarian objects. Here, we will look at the more ornamental stones that are referred to under the catch-all term ‘jade’. For millennia, jades have been valued in many cultures in both China and Japan. The favoured types and sources of jades have changed over time, as has our knowledge of the stones themselves. One of the greatest problems in dealing with archaeological jades is the correct identification of the stones in order to trace their source and thereby understand the social relations underlying their patterns of procurement, production, and consumption. In the last 15 years, the field has been upset by increasingly detailed chemical analyses of so-called jadeites. This impacts the gemological world more than geological, but what ramifications does it hold for archaeology? Plate Tectonics is crucial for understanding the formation and distribution of the true jades: nephrite and jadeitite. Their tectonic contexts determine the minerals available for their composition. True jade mineralogy will be detailed below in relation to their host rocks, dolomitic limestone (dolostone) and serpentenite. Metamorphic processes (Chapter 2.5) are integral to the formation of both host rocks and jade products, while the processes of exhumation and obduction (Chapter 2.5.3, 2.7) determine where the true jades are found in the world today.