Gemological And Mineralogical Characteristics Of Lavender Jadeite From Myanmar

Lavender jadeite is a important color type of jadeite,mainly produced in Myanmar,the transparency of lavender jadeite is usually poor.This paper systematically reviewed previous studies on lavender jadeite and collected representative samples of lavender jadeite of Myanmar to systematically study and analyze its macroscopic characteristics,conventional gemological properties,microscopic characteristics,main and trace elements test and spectral characteristics,and obtained certain research progress and understanding:Myanmar lavender jadeite can be divided into two types:the type?of lavender jadeite has primary structure and metamorphic deformation structure,particle size generally larger than 0.3mm,up to 1cm;The type?of lavender jadeite has late filling structure,and occurs metasomatism with early minerals,the particle size is generally 50?m,with.The main mineral of Myanmar lavender jadeite is jadeite,which can contain secondary minerals such as torendrikite,calcite,celsianite,and chlorite.The refractive index of lavender jadeite is 1.66;Lavender jadeite shows fluorescence inertia under long and short wave ultraviolet light.The gravity of samples contents ranges from 3.30-3.35;The Mohs hardness index is 7,in line with basic gemological characteristics of jadeite.The lavender,green and colorless parts of jadeite in early Myanmar jadeite has banding structure in imaging under the cathodoluminescence microscope and electron backscattered diffraction,indicating that jadeite is formed by precipitation crystallization in a fluid environment.Electron probe test showed that the contents of Cr₂O₃,Fe O,Ca O,and Mg O in jadeite minerals in lavender part were generally low,and their contents ranged from 0-0.04;0-0.12;0-0.29 and 0-0.19(wt%),respectively,which were lower than that of green jadeite minerals in the same sample.The content of Al₂O₃is slightly higher than that of green jadeite,with a content of 24.43-25.80(wt%),indicating that the elements of Cr,Fe,Ca,Mg and Al are isomorphic substitution.The trace element test results show that the element Mn of lavender jadeite is significantly higher than that of other jadeite colors,the range is 17.60-1853.24ppm,and the more obvious the lavender tone,the higher the element Mn of jadeite,UV-vis spectrum show that 580nm absorption peak,which is caused by the d-d orbital electron transition of Mn3+ions.It shows that Mn³⁺ion is the principal chromatic element of lavender jadeite.The results of Raman spectrum test showed that the intensity of the 1040cm^-1Raman peak is stronger than the 989cm^-1Raman peak in lavender,green and colorless jadeite,and the intensity of the two peaks is almost the same in the green region.In addition,a large number of fluid-melt inclusions can be seen in jadeite minerals.The laser Raman spectroscopy shows that the type?of lavender jadeite is crystallized from the system between fluid and melt containing H₂O,N₂,CH₄and H₂S as volatiles,which indicates that jadeite is formed by crystallization in the fluid-melt system.The type?of lavender jadeite is the early product in the early formation process,which is directly crystallized from the fluid-molten system.The type?of lavender jadeite is formed by the later hydrothermal process.After the formation of lavender jadeite is susceptible to the later geological effect and evolve into other colors;fragmentation makes lavender jadeite white;when the later rich Fe,Cr fluid into the lavender jadeite fissure and metasomatism can lead to lavender evolution into white or green;secondary minerals formed at a later stage also cause the lavender color of the lavender jade to be obscured by the green,yellow,and red secondary minerals.