Nuclear microscopy of rubies: trace elements and inclusions

Abstract

The concentrations of trace elements (e.g. Ti, V, Cr, Fe and Cu) in ornamental rubies have been linked to the country of origin for natural stones [1,2]. These broad-beam PIXE results show relatively large variations between stones from one country, which might indicate that they stem from different geological environments in a country, or that there are inclusions or surface contaminations present in individual stones. PIXE elemental maps were used to find contamination and inclusion free regions on rubies from Mong Hsu, Burma, and from Thailand. Trace element concentrations were determined in these surface areas. The results indicate that the Fe-concentrations in Mong Hsu rubies have previously been overestimated due to the presence of surface contaminations. Cu is consistently present at a few hundred ppm level in these stones and not observed in any of the four Thai rubies, while it was observed sporadically in broad-beam measurements. The depth profiling capabilities of the proton microprobe were employed for the analysis of liquid and mineral inclusions in rubies, and some preliminary results are reported. © 1995.