Study On Mineralogy And Treatment Of Emeralds From Yunnan Province

Base on pioneers'achievement, this paper did a thorough work on emeralds from Yunnan, especially the samples with zone structure,on crystallography, chemical composition and crystal structure, visible spectrum and infrared spectrum, fluid inclusions testing etc,also treatment was carried on.A great deal of rich liquid phase inclusions with kinds of formation styles and character were fond in crystal. Results of fluid inclusions testing testified high temperature and low salinity concentration during earlier growth period.Then, temperature dropped down, and salinity concentration began to heighten. Needle-like black tourmaline, dolomite(contains V) arsenopyrite and zone structure together were considered as characteristic inclusions. Chemical composition analysis revealed emeralds from Yunnan were rich in V,poor of Cr. V³⁺,Cr³⁺ and alkali ions increased during the last crystal growth period.Visible spectrum datum showed that color was caused by V³⁺, and Cr³⁺,Fe³⁺ had a tiny effect upon hue.Infrared spectrum results proved thatâ…¡type water was dominant in samples. the swing of the pendulum relationship was detected betweenâ… andâ…¡type water. Due to abundance in alkali ions in deep green outer layers, especially Na+,â…¡type water wave stronger than light green core. As well,â… type water reversed. By heat treatment, it was fond thatâ… type water began to escaped between 400⁴50℃, as forâ…¡type water at round about 800℃,which attributed to alkali metals irons in the ring channels.The worse transparency caused by lots of cranny in emeralds had a particularly bad influence to its value. In heating treatment, A lot of rich liquid phase fluid inclusions broken andâ… type water in crystal dispersed, which destroyed the structure, and caused much more cranny. So, heat treatment was unsuitable to emeralds enhancement. In organic compound filling experiments, with colorless, transparent, closest refractive index, polystyrene was the best choise,and Neutral gum next. Polystyrene's characteristic absorption peak was 3030cm-1,and Neutral gum'sabsorption belt was about 2850—3000 cm-1,which indicated that we can detect them through Infrared spectrum.