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Gemological And Mineralogical Study Of White Nephrite From Dakeximu Region In Russia

Posted on:2011-11-17Degree:MasterType:Thesis
Country:ChinaCandidate:X F LiuFull Text:PDF
GTID:2180360302492901Subject:Gemology
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Dakeximu region is an major origin of white nephrite in Russia,and study of the white nephrite from this region have the typical significance and value for overall understanding white nephrite in Russia.This paper studys its gemmological and mineralogical systematically by observing samples,testing gemological properties and using electron microprobe,X-ray powder diffraction,Infrared spectrometry,SEM (scanning electron microscope),LA-ICP-MS and other modern testing methods and means.The results show that colors of shanliao nephrite from Dakeximu region are mostely white,grey-white,grey and brown. The shanliushui and ziliao nephrite usually have the skin which ofen show reddish brown and sepia.The main mineral constituent of nephrite is tremolite and a little apatite, diopside, anorthite, clay mineral .Its structure contains felt-shaped cryptocrystalline blastic texture,nematoballistic texture, foliaceous blastic texture,radiated or broom-shaped blastic texture, recrystal texture, cataclastic texture. Nematoballistic texture is the most common. The tremolite of white nephrite mainly assumes fibrous,prismatical,foliaceous which the length varies, weak directional, non-directional distribution. The interior of nephrite ofen have cracks which serious influence the nephrite, quality. The main mineral constituent of adjacent rock is diopside, and it usually show cataclastic texture in tremolite-forming region by geological formation and metasomatism.The main components of tremolite are SiO2,MgO,CaO and the minor components are Na2O,Al2O3,FeO,etc,which coincide with the data of tremolite in adjacent rock. The trace element content of the white nephrite from Dakeximu region in the mass is very low. The relatively high content of trace elements is Zn,Ti,V,Be,etc,followed by Sc, Ga, Rb, Sr, Cs, Ba, Pb,etc,and the low content of trace elements is Mo, Cd, Sb, Hf, Ta、Bi、Th、U,etc.The rare-earth element belongs to the enrichment of LREE and the distribution curve is right deviation.Eu both has positive and negative anomalies.The diopside of white nephrite,which basically have the same chemical composition with the diopside that compose the adjacent rock,belongs to metasomatic relict residue. According to test results and production of the former talents,this paper has carried on the discussion to nephrite,s origin.The nephrite may be generated by diopside,s or dolomite-marble,s metasomatic alteration.The processing of white nephrite from Dakeximu region includes five tranditional steps: selecting materials, designing, roughhewing, fine carving and polishing. The quality values can be considered from some aspects including whiteness, texture, transparence, clarity, craftwork, size, shape, gambling, etc.
Keywords/Search Tags:tremolite, Gemological and Mineralogical characteristics, white nephrite, Dakeximu
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