ESHS/HSS Annual Meeting

Non-invasive Research into the Origins of Ceramic Raw Materials: a Challenge

• In Event: Minescapes 2: Mining for Blue

English Abstract

Constituting only a few thousandths of an object by weight, coloring agents nevertheless circulated in long-distance trade for centuries because their precursors are geologically rare, especially in usable form. Lapis lazuli is the iconic example, with a single mine supplying material for millennia.
This paper analyzes enamels made from such raw materials through a two-step approach. First, mobile X-ray fluorescence and light-scattering spectroscopies (Raman and luminescence) are used to identify coloring elements; associated major, minor, and trace elements; crystalline phases; and the composition of the glass matrix. Second, spectral features are evaluated to distinguish those linked to geological context from those resulting from historical selection and purification processes, since certain elements may reflect specific methods of extraction.
The paper examines blue coloring (and green produced with added yellow pigments) using lapis lazuli and cobalt across Egyptian, Norman (Sicily), Islamic (Ottoman, Mamluk), Chinese, Japanese, and European productions. In many cases, limited geological data on ancient mines and sparse historical documentation prevent certain attribution of a colorant’s geological source, particularly when isotopic analysis—more precise but destructive—is not possible. However, where detailed geological information exists, source identification becomes feasible. For example, the presence or absence of uranium, zinc, or bismuth can differentiate cobalt mined within the same region, such as the Erzgebirge in Saxony (Freiberg: uranium; Schneeberg: bismuth).

Author

• Philippe Colomban, Sorbonne Université