加拿大北极矿碧玉的宝石矿物学研究

发布时间：2018-06-16 03:32

本文选题：北极矿碧玉 + 矿物组成　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：近年来,碧玉因其色如翡翠、润如羊脂而在国内珠宝玉石市场上掀起一阵购买热潮。其中加拿大碧玉因其产量大、块度大、颜色浓艳等特点受到国内从业者的青睐。尽管前人对于各个产地碧玉的研究较为全面,但是针对同一产地不同矿区的碧玉研究甚少,且未对加拿大碧玉中的水线、褐色团块、绿斑以及黑点进行深入研究。因此本课题将在前人研究基础上,运用常规宝石学特征测试、偏光显微镜镜下观察、电子探针分析、X射线粉晶衍射分析、扫描电子显微镜、红外光谱分析以及LA-ICP-MS等测试手段对加拿大北极矿碧玉的矿物组成、化学成分以及颜色成因进行深入研究和分析,总结加拿大各矿区碧玉特点并与其它产地碧玉进行对比,以此探讨碧玉的产地特征。加拿大北极矿矿区位于不列颠哥伦比亚省北部迪斯湖区域内,碧玉产出在超基性、基性岩(以蛇纹岩为主)与围岩接触带上或附近,与古生代中期至三叠纪时期岩石有关。偏光镜下观察结果显示,北极矿碧玉主要矿物成分为透闪石,次要矿物包括：石榴石、辉石以及阳起石,在北极矿样品中未发现在其他矿区样品中普遍存在的铬铁矿。扫描电子显微镜结果显示,北极矿碧玉的结构与透明度、韧性之间存在一定关系。透闪石纤维定向排列程度越高透明度越高,水线处透闪石纤维定向程度较周围透闪石要高,因此透明度高；纤维状交织状排列、结构紧密者韧性高；平行定向排列者韧性较低；片层状结构松散者韧性低。电子探针结果显示,北极矿碧玉主要矿物成分为透闪石,黑点成分为含铬钙铁榴石,绿斑成分为铬钙铝榴石,其次还含有一定量的辉石,且辉石仅在北极矿样品中出现,白色、褐色水线及团块成分均为透闪石,白色部分透闪石Fe含量较低,褐色部分透闪石Fe3+含量较高。LA-ICP-MS测试显示,北极矿碧玉绿色主要与Fe、Cr有关,其中微量元素Cr决定绿色的鲜艳程度。Fe2+决定碧玉呈现绿色,Fe3+是碧玉呈现黄色调的主要原因。
[Abstract]:In recent years, Jasper has caused a buying boom in the domestic jewelry and jade market because of its jadeite and lanolin. Among them, Canadian Jasper is favored by domestic practitioners because of its large output, large block size, strong color and other characteristics. Although the previous studies on Jasper from different areas are relatively comprehensive, there are few studies on Jasper from different mining areas in the same area, and no in-depth study on the waterline, brown lump, green spot and black spot in Canadian Jasper. Therefore, on the basis of previous studies, this paper will apply conventional gemology characteristic testing, polarizing microscope, electron probe analysis, X-ray powder diffraction analysis, scanning electron microscope, Infrared spectrum analysis and LA-ICP-MS were used to study and analyze the mineral composition, chemical composition and color origin of Canadian Arctic Jasper. In this paper, the origin characteristics of Jasper are discussed. The Canadian arctic mining area is located in the Lake Disc area in northern British Columbia. Jasper is produced in the ultrabasic, the basic rock (mainly serpentine) is in contact with or near the surrounding rock, which is related to the rocks from the middle Paleozoic to the Triassic. The results of polarimetric observation show that the main mineral composition of the Arctic Jasper is tremolite and the secondary minerals include garnet pyroxene and actinolite. There is no chromite commonly found in other mineral samples in the Arctic ore samples. The results of scanning electron microscope show that there is a certain relationship between the structure, transparency and toughness of Arctic Jasper. The higher the orientation degree of tremolite fiber is, the higher the transparency is, and the higher the orientation degree of tremolite fiber is at the waterline, the higher the transparency is; Loose lamellar structures have low toughness. The results of electron microprobe showed that the main mineral composition of the Arctic mineral Jasper was tremolite, the black spot component was chromium-containing calcium iron garnet, the green spot component was chrome calcium aluminite, and the second was pyroxene, and the pyroxene was only found in the Arctic ore sample. The composition of brown water line and mass is tremolite, the Fe content of white tremolite is relatively low, and the Fe 3 content of brown part tremolite is higher. LA-ICP-MS test shows that the green of Arctic Jasper is mainly related to Feo Cr. Among them, trace element Cr determines the bright degree of green. Fe2 determines the green color of Jasper and Fe3 is the main reason for the yellowish tone of Jasper.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P619.28

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