CRYSTAL-GROWTH OF EMERALD BY FLUX METHOD

Emerald crystals have been formed in two binary fluxes of Li2O-MoO3 and Li2O-V2O5 using the slow cooling method and the temperature gradient method under various conditions. In the flux of Li2O-MoO3 carried out in the range of 2~5 of molar ratios (MoO3/Li2O), emerald was crystallized in the temperature range from 750 to 950°C, and the suitable crystallization conditions were found to be the molar ratio of 3~4 and the temperature about 900°C. In the flux of Li2O-V2O5 carried out in the range of 1.7~5 of molar ratios (V2O5/Li2O), emerald was crystallized in the temperature range from 900 to 1150°C. The suitable crystals were obtained at the molar ratio of 3 and the temperature range of 1000~1100°C. The crystallization temperature rised with an increase in the molar ratio of the both fluxes. The emeralds grown in two binary fluxes were transparent green, having the density of 2.68, the refractive index of 1.56, and the two distinct bands in the visible spectrum at 430 and 600 nm. The emerald grown in Li2O-V2O5 flux was more bluish green than that grown in Li2O-MoO3 flux. The size of the spontaneously nucleated emerald grown in the former flux was larger than the latter, when crystallized by the slow colling method. As for the solubility of beryl in the two fluxes, Li2O-V2O5 flux was superior to Li2O-MoO3 flux whose small solubility of SiO2 caused an experimental problem to the temperature gradient method. The suitability of the two fluxes for the crystal growth of emerald by the flux method was discussed from the view point of various properties of above-mentioned two fluxes. © 1979, The Chemical Society of Japan. All rights reserved.