Original paper
Electron microprobe analysis and X-ray diffraction methods in archaeometry: Investigations on ancient beads from the Sultanate of Oman and from Sri Lanka
Rösch, Cordelia; Hock, Rainer; Schüssler, Ulrich; Yule, Paul; Hannibal, Anne
European Journal of Mineralogy Volume 9 Number 4 (1997), p. 763 - 783
45 references
published: Jul 23, 1997
manuscript received: Aug 1, 1995
DOI: 10.1127/ejm/9/4/0763
Abstract
Abstract Beads from graves of the Samad Culture, Sultanate of Oman, and from an ancient craftsmen quarter of the old kingdom of Ruhuna, excavated in Sri Lanka, were investigated using electron microprobe analysis and X-ray powder diffraction. Both experimental methods were optimized towards a non-destructive analysis of archaeological finds. Based on their analysis, the beads from Oman can be divided into those made from natural rocks or minerals, metal, glass, Egyptian Blue and synthetic enstatite. Preferred natural rock types are serpentinite, chloritite and massive chlorite amphibolite which occur in the Samail Ophiolite of Oman and indicate a local production of these beads. Garnet beads are almandine-pyrope-rich and are interpreted as imports from the Sri Lanka/India area. Metal beads are made from pure Ag, ± pure Au or from Ag-Au-Cu alloys. Reddish-brown glass beads from Oman are Na-rich and coloured by Cu present in the glass matrix. Opaque red glass beads from Sri Lanka are commonly K-rich and coloured by tiny cuprite droplets which recrystallized from the melt and which are intensively disseminated within the glass matrix. Blue-white-blue and brown-white-brown sandwich beads from Oman and Sri Lanka are stylistically similar, but differ in composition of the white glass. Parts of the glass beads from Oman is partially or completely altered to form smectite. A cogged wheel bead from Oman was cut from steatite and then hardened by transformation of the steatite to synthetic enstatite during firing at about 1000°C. Large amounts of microbeads from a Samad grave also consist of synthetic enstatite and most probably were produced from Mg-rich clay by firing. Comparable beads have been recovered from excavations in the Indus area, especially Harappa, but also in the Arabian Emirates
Keywords
archaeometry • beads • Oman • Sri Lanka • glass weathering • Egyptian Blue