corundum, geology.11, inclusions.5, Myanmar (Burma).12, trapiche ruby, gems

After a comparison of the geologic occurrences of trapiche emerald and trapiche ruby, and a discussion of the various theories proposed for their formation, this article presents the results of an investigation of the chemical compositions, and the solid and fluid inclusions, of six trapiche rubies from Mong Hsu. The study used advanced analytical techniques such as energy- and wavelength-dispersive spectrometry and “cold” cathodoluminescence. The authors identify 12 minerals not previously reported as inclusions in trapiche rubies or as components of their skeletal “arms.” The rubies show a chemical zonation that can be linked to variations in the chemical composition of the growth fluid. The chromium content, in particular, appears to be related to variations in the circulation of metasomatic fluids rich in REE (rare-earth element) fluorides.