Optical and Mössbauer Study of Brazilian Emeralds

Emerald samples from two different locations in Brazil have been analyzed using transmission 57 Fe Mossbauer spectroscopy, X-ray diffraction, electron microprobe analysis, and optical methods. Mossbauer spectra were decomposed into four subspectra associated with Fe ions at different sites. We found that Fe 2+ substitutes both Al and Be sites in different proportions (varying with the origin of emerald samples); and about 1/3 of iron ions in Fe 3+ valence state are primarily located at two different sites.