The Study On Gemmological And Mineralogical Characteristics Of Green Nephrite In HuaLian,Taiwan

China has a long history of jade culture, nephrite takes the first place of the“Four famous jade and it maks itself having a broad market and being fond of by themajority of consumers.In this article we will use testing means including Polarizingmicroscope,Scanning electron microscopy, Electron microprobe, X-ray powderdiffraction (XRD), Fourier transform infrared spectrometer to discuss thegemmologicaland mineralogical characteristics of Green Nephrite in Hualian,Taiwan.Scientific、comprehensive and systematic research has a great significance inimproving the scientific content and visibility of nephrite in Hualien, Taiwan.The result of the observation shows that the color of green nephrite ranges fromlight green to dark green,the color is relatively pure but distributed unevenly. Blackmetal mineral impurities can be seen inside. They are lipidic-silky luster and aretranslucent–opaque. The green nephrite’s index of refraction are1.61,with a relativedensity from2.96to3.02and a hardness from6to7.The major constituent mineral of green nephrite is ether tremolite or actinolite.Besides that,the Taiwan green nephrite also contains secondary minerals includinggrossular,chromite and chlorite. The result of Electron microprobe shows that themain components of green nephrite are MgO、SiO、CaO，a small amount of FeO andtrace amounts of Cr2O3、MnO、K2O、Na2O、Al2O3、TiO2. According to thecomparison of the sample data we can surmise that the depth of the color of greennephrite has a positive correlation with the content of FeO,and also when it containsgrossular,the color will be more brightly colored.The results of X-ray diffraction support the calculation results of the EMPAdata, the major constituent mineral of green nephrite is ether actinolite or tremolite.The diffraction lines of the surrounding rock is consistent well with the serpentinestandard data,it contain little tremolite.It indicates that the green nephrite andsurrounding rock growing closely.The mineral composition transit during the thecontact portion，the surrounding rock has been alterated.The research of FTIR shows that, the band of OH in green nephrite areseperated and move to the direction of lower wave.According to the analysis ofprevious studies we can speculate that it is because of the the effect of Fe replacingMg.The result Missing the stretching vibration of the adsorbed water and lack ofsignificant absorption band,it indicates that during the forming process of greennephrite the water didn’t occupy too much internal space or adsorbe on the surfaceof green nephrite.The structure of the sample was observed by polarized light microscopy andscanning electron microscopy.It has two kinds of structure: Felt like metacryststructure, Parallel fibers metacryst structure. The overall structure of green nephriteis schistosity structure,and the surrounding rock is massive structure.Comparing with the former data we kown that the characteristics of greennephrite from different place of origin are similar and hard to classify.We can onlydistinguish them through the gemological characteristics and mineral composition.The endemism of secondary minerals can be treated as the identificationof the characteristics for distinguish between other nephrite.The green nephrite in Hualian,Taiwan is fond of by the majority of consumers,itis because of its strong colors,delicate structure and special optical effects.As thefeatures of its beauty and rarity,when it comes to a high quality green nephrite,it willcontain a high economic value and the value of the more rare green nephrite cat’seye is the highest of all.