危地马拉绿色系列翡翠的宝石矿物学特征研究

发布时间：2018-05-19 09:54

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

【摘要】：危地马拉翡翠矿床位于北美—加勒比板块碰撞带内,原生矿床产于莫塔瓜河谷深断裂带南北两侧的白垩纪蛇纹岩带之中,长度可达200千米。南北两侧的硬玉岩在岩石组合、形成的温度压力条件和地质年代等方面均有较大差别。本文在收集了危地马拉常见的绿色系列翡翠(包括蓝绿色、浅灰绿色、墨绿色)样品的基础上,运用常规宝石学、薄片观察、阴极发光、电子探针、X射线粉晶衍射、紫外—可见光光谱、红外光谱等方法,对危地马拉绿色系列翡翠典型样品的基本宝石学性质、结构特征、矿物组成、化学成分、谱学特征及颜色成因等进行研究。蓝绿色翡翠,油脂光泽—玻璃光泽,微透明,折射率点测为1.66,相对密度3.22-3.31;斑状变晶结构,叠加糜棱结构;矿物组成为绿辉石、硬玉、多硅白云母,少量褐帘石、榍石、金红石、锆石。浅灰绿色翡翠,油脂光泽—玻璃光泽,不透明,折射率点测为1.67-1.68,相对密度为3.26-3.30,可见“翠性”;碎裂结构,局部残留柱粒状镶嵌结构;矿物组成为硬玉,少量黑云母、斜黝帘石。墨绿色翡翠,玻璃光泽,半透明,折射率点测为1.66,相对密度3.27-3.34;显微变晶结构,叠加糜棱结构;矿物组成为绿辉石、硬玉,少量石榴石。蓝绿色翡翠的红外反射光谱主要显示硬玉特征峰,主要峰值为1081 cm-1、954 cm-1、582 cm-1、524 cm-1、470 cm-1、435cm-1,;浅灰绿色翡翠与标准硬玉红外光谱基本相同,主要峰值为1086 cm-1、954 cm-1、590 cm-1、534 cm-1、522 cm-1、471 cm-1、435 cm-1;墨绿色翡翠主要显示绿辉石的红外光谱,主要峰值为1064cm-1、961 cm-1、562 cm-1、521cm-1、455 cm-1、441 cm-1。蓝绿色、浅灰绿色翡翠的紫外—可见光谱具有紫区434nm的吸收峰;墨绿色翡翠具有436nm处吸收峰及Cr3+引起的红区693nm、670nm、656nm处吸收峰,使其在透射光下显示纯正的绿色。
[Abstract]:The Jade deposit in Guatemala is located in the collision zone between North America and the Caribbean plate. The primary deposit occurs in the Cretaceous ophiolite belt on the north and south sides of the Motagua valley deep fault zone, and its length can be up to 200 km. The jadeite rocks on both sides of north and south are different in rock assemblage, temperature and pressure conditions and geological age. On the basis of collecting the common green series of jadeite jade (including turquoise, light gray green, dark green) in Guatemala, conventional gemmology, thin slice observation, cathodic luminescence, electron probe X-ray powder diffraction are used in this paper. The basic gemstone properties, structural characteristics, mineral composition, chemical composition, spectral characteristics and color origin of typical samples of Guatemala green jadeite were studied by UV-Vis spectroscopy and infrared spectroscopy. Blue-green jadeite, greasy gloss-glass gloss, slightly transparent, refractive index point 1.66, relative density 3.22-3.31; porphyry metamorphic structure, superimposed chyme structure; mineral composition: opyroxene, jadeite, polysilicon Muscovite, a small amount of cinnamon, sphene, rutile, Zircon. Light grayish green jadeite, grease luster-glass gloss, opacity, refractive index point of 1.67-1.68, relative density 3.26-3.30, can be seen as "verdant"; fragmentation structure, local residual columnar granular mosaic structure; mineral composition is jadeite, a small amount of biotite, oblique tetrahedrite. Dark green jadeite, glass gloss, translucent, refractive index point measured 1.66, relative density 3.27-3.34, microalloyed structure, superimposed chyphon structure, mineral composition of pyroxene, jadeite, a little garnet. The infrared reflectance spectrum of blue-green jadeite mainly shows the characteristic peak of jadeite, the main peak value is 1081 cm-1954 cm-1582 cm-1524 cm-1470 cm-1435cm-1, and the infrared spectrum of grayish green jadeite is basically the same as that of standard jadeite. The main peak value is 1086 cm-1954 cm-1590 cm-1534 cm-1522 cm-1471 cm-1435 cm -1 and the main peak value is 1064cm-1961 cm-1562 cm-1521cm-1455 cm-1441 cm -1. The UV-Vis spectra of blue-green and grayish green jadeite have the absorption peak of 434nm in purple region, and the absorption peak of 436nm and 670 nm ~ 656 nm of red region caused by Cr3 in black green jadeite jade, which makes it appear pure green under transmitted light.
【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】：P619.281

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