Comparison of Mineralogical Characteristic between "Blue Water" Variety Jadeite from Guatemala and "Oil-Green" Variety Jadeite from Myanmar

Guatemala is the second largest jadeite producer after Myanmar. The appearance of "blue water" variety jadeite from Guatemala is similar to "oil-green" variety jadeite from Myanmar. With more and more "blue water" variety jadeite appearing in the jadeite market, it is confusing to distinguish between "blue water" variety jadeite and "oil-green" variety jadeite. Therefore, the comparative study is of great significance. The physical properties, structure, mineral components and chemical compositions of "blue water" variety jadeite samples from Guatemala and "oil-green" variety jadeite samples from Myanmar were compared by means of rock thin section observation, X-ray powder diffraction spectrometer, laser Raman spectrometer, scanning electron microscope and electron microprobe. The results show that the main mineral component of "blue water" variety jadeite from Guatemala is jadeite, with fine particles, fine structure, and developed mylonitic structure and it also contains a lot of impurity minerals such as omphacite and albite. The mineral component of "oil-green" variety jadeite from Myanmar is pure jadeite, and its particles are relatively coarse.The particle size is uniform, and has a columnar granular mosaic structure and may contain mineral impurities omphacite.The backscattered electron images show that the particles of both jadeite samples have rhythmic annulus structure: The belt in jadeite samples from Guatemala is mainly composed of 2-3 layers, and the omphacite is mechanically penetrated and interspersed and to replace the early-stage jadeite particles; The belt of jadeite samples from Myanmar develops 3-5 layers of ring-band structure, and omphacite is filled with jadeite particles in the form of veins or is replaced as an island by jadeite particles. The results of electron microprobe showed that the Jd(NaAlSi₂O₆)content of particles in samples from Myanmar is higher than that of samples from Guatemala, while the content of WEF (the total content of three minerals of Ca₂Si₂O₆, Mg₂Si₂O₆ and Fe₂Si₂O₆)is lower than that of samples from Guatemala. In addition, the CaO and MgO contents of the jadeite particles and omphacite particles of samples from Guatemala are higher than those of samples from Myanmar. It is speculated that the Ca and Mg of the ore-forming minerals in the two producing are as may differ.