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The Study On Gemological Characteristic Of Green Nephrite In Canada

Posted on:2010-08-11Degree:MasterType:Thesis
Country:ChinaCandidate:H HuangFull Text:PDF
GTID:2120360272488173Subject:Gemology
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Canada is one of the countries that first develop and make use of green nephrite. It has abundant green nephrite resources and its reserves take the first place in the world. Its market prospect is very brilliant. This essay, by combining the research results of the former talents, makes a systematic and detailed research on the gemological characteristic, mineral components and structural features of green nephrite in Canada. Moreover, it makes a intensive analysis on the aspects including the differences and relations among the green nephrite of different deposit and the identification characteristic between the green nephrite and its imitations. Also, it discusses the quality evalution and the classification system of green nephrite according to its color, structure, clarity and craftwork.The result of the observation test shows that the green nephrite can be green, bottle green and black green colors. Their colors are relatively well distributed. They are lipidic-waxy luster, and are often sub-translucent-opaque. Their index of refraction are from 1.607 to 1.622, with a relative density from 2.974 to 3.001 and a hardness from 6 to 7. The samples all have less absorption lines which are inert to fluorescence, and do not change their colors under a color filter.Green nephrite consists of tremolite- actinolite isomorphism series of mineral, mainly tremolite. It has six kinds of structure: felt-shaped cryptocrystalline ballistic structure, fascicules ballistic structure, lamina-shaped ballistic structure, broom-shaped ballistic structure, radiated ballistic structure, recrystal structure. The special structure of green nephrite can strengthen the mechanical and binding force among its component mineral particles, and thus can enhance its ability of avoiding being torn into pieces, which is the reason for its high toughness.The result of EPMA shows that the main components of green nephrite are MgO , SiO2 , CaO, and few FeO. The color of green nephrite is proportional to the content of FeO. From the cell parameter calculated from the test of XRD we can see that the b0 value of green nephrite is in direct proportion with the proportion of Fe2+ taking place of Mg2+. The research of FTIR shows that because the effect of Fe replacing Mg, the band of OH in green nephrite are seperated and move to the direction of lower wave. These analysis shows that many features of green nephrite are closely connected to the Fe content inside them.The comparison shows that the characteristics of green nephrite from different deposit are similar and hard to classify. The jades that are similar to green nephrite can be distinguished from their characteristics including color, luster, transparence, index of refraction, relative density, hardness and structure, etc.The manufacture of green nephrite includes four tranditional steps: selecting materials, designing, carving and polishing. Their values depend on the quality of the green nephrite, the craftwork, the supply-demand relations and the regional differences. The quality evalution of green nephrite in Canada can be considered from seven aspects including color, transparence, structure, clarity, cranny, size, craftwork. According to the standard of quality evalution, we can make classifications on the green nephrite in Canada from two aspects including their materials and finished products.
Keywords/Search Tags:Canada, green nephrite, component, structure, gemological characteristic
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