gems, garnet, red garnet, Dark Age garnet, Sweden

Mellis presents a nondestructive mineralogical investigation of 41 red stones from Merovingian- and Carolingian-period jewelry found in Sweden, undertaken both to establish whether the stones were actually garnets and, if possible, to determine their geographical origin. Because of the cultural and historical importance of the objects, the examination was restricted chiefly to refractive index, color and absorption spectra, specific gravity, anomalous birefringence, inclusions, and, for some specimens, single-crystal X-ray study. The small polished garnet plates are described individually, with detailed observations of their optical properties and inclusions, including various types of needles, prismatic and plate-like crystals, opaque minerals, zircon, and other phases. Chemical compositions were estimated from physical and optical properties and compared with established garnet compositional groups; the examined stones include pyrope-rich and almandine-rich varieties and mixtures of the principal garnet components. Mellis explores whether inclusions and composition can identify the geological environment and source of the stones, comparing the archaeological specimens particularly with garnets from Bohemia and other known occurrences. He concludes that inclusions alone cannot, at the existing state of knowledge, provide a reliable determination of geographical provenance, although inclusions combined with chemical composition can exclude certain geological environments and help characterize possible source rocks. The study demonstrates the value of detailed mineralogical examination of archaeological garnets while emphasizing the limitations of assigning ancient worked stones to specific deposits solely from their observable mineralogical properties.