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Study Of Gemological Mineralogy Of Green Nephrite From New Zealand

Posted on:2016-01-03Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y ZhaoFull Text:PDF
GTID:2180330461995685Subject:Materials engineering
Abstract/Summary:PDF Full Text Request
New Zealand nephrite is protected by national policy. The raw materials are not allowed to export, and they can only be sold and exported after processing into finished goods. The nephrite business history of New Zealand has only about 30 years. It has entered the Chinese market only a short time. But it is popular with consumers because of its bright color, less waterline, unique black and green dot design. The existing researches on nephrite in New Zealand are very few and the study samples are all from the market. The specific origin is not clear. They had not made comprehensive analysis and research on the gemological characteristics of New Zealand nephrite.Based on the previous studies, this paper made comprehensive research on gemological and mineralogy characteristics of the New Zealand nephrite with modern test methods such as electron microscope, scanning electron microscope, electron probe and X-ray powder diffraction, infrared spectrum analysis, trace elements test.New Zealand nephrite mineral mining area is located in southern New Zealand. Its native mine belongs to serpentine deposit, and genetic type is because of the ultrabasic rock alteration. The deposit is output in the form of lens.With the polarizing microscope, we can see the main components of New Zealand nephrite are tremolite, and the impurity minerals are Albite, Chlorite, Pyroxene and Maucherite. The tremolite grain is very small, with cryptocrystalline texture. According to the relative size it can be divided into porphyroblast structure; According to the size of mineral particle it can be divided into fine granular blastic texture and micro granular blastic texture; According to the mineral crystal-habit, the relationship between the morphology and mineral particles it can be divided into felt granular blastic texture, microscopic flake blastic texture, bunchy blastic texture and vein-structure. The structure is mainly the block structure, distributed in particles, few directional structures such as gneissic schistosity, schistosity, lineation, etc.Electron microprobe analysis indicates that the main mineral composition of New Zealand nephrite is tremolite, and the impurity minerals are Albite, Chlorite, Pyroxene and Maucherite. The result of X-ray powder diffraction is consistent with the standard spectrum of tremolite. Some samples show the diffraction peaks of the albite and the clay mineral, no diffraction peaks of the Maucherite and Pyroxene, which explained that the content may be less than 1%. Scanning electron microscopy shows that among nephrite samples felt blastic texture has the best quality, strongest tenacity, the firmest structure. It is because the crack of felt structure is difficult to extend. LA-ICP-MS experiment’s results show that the sample with higher Cr and Ni ‘s green tone are more bright. Infrared spectrum analysis results showed that the infrared spectrums between nephrite in different regions are similar, and there’s only a small difference.
Keywords/Search Tags:New Zealand, nephrite, structure, mineral component
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