翡翠的皮壳组成及其与内部玉石质量关系初步研究

在对广东南海平洲、广州花都国际翡翠展销会等翡翠原料集散地大量现场考察的基础上,选取了具有黄色色调、白色和灰黑色皮壳的翡翠原石样品,经肉眼和偏光显微镜观察、X射线粉末衍射和电子探针测试,研究了不同颜色系列翡翠原石皮壳的矿物组成和化学成分特征。结果表明,不同颜色翡翠皮壳的主要矿物均为硬玉,次要矿物则有所不同。黄色皮壳含高岭石、三水铝石、软锰矿和赤铁矿等,白色皮壳含高岭石和水钙铝榴石,黑色皮壳则含高岭石和绿泥石类矿物。与内部玉石成分相比,皮壳中的主要化学成分硼（Na2O）和w（SiO2）有所降低,而w（CaO）和w（MgO）及Fe的质量分数则相对增加;黄色皮壳翡翠中Fe的质量分数越高,则皮壳的黄色色调越深,但皮壳的化学成分受环境影响较大,难以用于判断其内部玉石质量。仅初步总结了翡翠皮壳矿物组成与其内部玉石质量的关系。     

真假翡翠毛料的鉴别

因为翡翠毛料外部有一层皮壳,人们无法直接观察判别内部的质量。不法商人常利用这一特征,在皮壳上做假,以假乱真,谋取暴利。真假翡翠毛料的鉴定,是翡翠鉴定中难度最大,涉及知识面最广,经验最为重要的鉴定技术。近年来,我们在鉴测过程中,通过看、掂、照、刻、敲、触、烧、测试等一系列方法,来鉴别真假翡翠毛料,同时总结出假翡翠毛料的常见类型、做假的方法,并制定了一套鉴别程序。     

翡翠原石可赌性的探讨

翡翠称玉中之王。悲翠原石（赌石）的研究一直引起业界的重视。本文通过翡翠原石（赌石）皮壳的外表特征、颜色分布迹象、裂绺特点,探讨翡翠原石的可赌性及其对翡翠原石评价的影响。     

和田玉仔料与仿和田玉仔料的肉眼鉴识

收集十几块和田玉仔料和数十块仿和田玉仔料样品,进行肉眼与镜下观察。简要总结和田玉仔料与仿和田玉仔料以及染色和田玉仔料的肉眼鉴别要领。     

蓝色翡翠的呈色机制探讨

近期广东市场上出现了一种来自缅甸的蓝色翡翠样品,该样品目前未见相关报道。为了确定其定名,通过常规宝石学测试、红外光谱和X射线粉末衍射测试对样品进行分析,表明样品的主要矿物组成为硬玉,质量分数约97．1％,检测鉴定结论为翡翠。为了对蓝色翡翠呈色机制进行研究,通过紫外一可见吸收光谱测试,表明可见光区480nm以后逐渐增强的吸收带是其产生蓝色的原因;采用电子探针进行化学成分测试,表明蓝色的成因与钒离子有关。根据3d过渡金属离子的晶体场理论和翡翠晶体场理论的研究,可以推测：由于翡翠结构中M1位的Al3＋被过渡金属离子钒（V4＋）替代,目l起八面体结构畸变而导致蓝色的产生,因此,蓝色是过渡金属离子钒（v4＋）产生的原生色。     

翡翠赌石的地质预测

玉中之王的翡翠,是市场上最受欢迎和利润最高的宝石之一,但又是最难鉴定和经营风险最大的行业。特别是外部具有一层风化皮壳的翡翠毛料－俗称赌石,更是神秘莫测,至今尚未成为一门学科。作者试图以地质学为基础,结合前人的实践经验,在了解赌石来源,鉴定皮壳真伪和判别场区、场口基础上,主要通过皮壳表面的颜色、成分、结构和裂隙等四个方面的特征,对赌石内部质量进行预测,从而更科学地对赌石进行正确的评价。     

B货翡翠的红外光谱特征及鉴定意义

在对9个B货翡翠样品进行常规宝石学特征描述的基础上，进行了红外光谱测试。结果表明B货翡翠最主要的吸收峰是2959（或2966），2931（或2924）和2895cm^-1这一组，而1510，1581，1609cm^-1和3040，3060cm^-1这两组谱带可作为鉴定B货翡翠的辅助谱带，但不是必要的谱带。研究结果可为准确鉴定B货翡翠提供进一步的资料。     

“新型”处理翡翠（注蜡）实验及鉴定

近年来,翡翠市场上出现了一种“新型”处理翡翠（注蜡）。这种注蜡翡翠与未注蜡翡翠在肉眼上无明显差别,且结构未遭到破坏,但在紫外荧光灯下和红外光谱中有异常现象。这对实验室检测定名及销售市场产生了很大的困扰。为此,在对“新型”处理翡翠（注蜡）实验研究的基础上,采用宝石学常规检测、高倍率放大观察和光谱学测试对30件注蜡前、后的翡翠样品进行了综合研究。结果显示,肉眼（放大）观察时,这种注蜡翡翠的颜色、结构基本未遭破坏,但在紫外荧光灯和DiamondViewTM下具有蓝白色荧光,红外光谱中具有2850,2920,2956cm-1处的强吸收峰。根据“GB／T16553-2010”《珠宝玉石鉴定》中翡翠优化处理定名的相关规定,本研究的注蜡翡翠应定名为翡翠。     

翡翠赌石内部色彩及裂隙的探讨

长期以来,翡翠赌石内部色彩及裂隙的存在情况很难把握,是珠宝界一大尖端课题,解决这一课题具有很大的科学和经济意义。文章通过分析皮壳以及运用交叉学科的有关原理来探讨赌石内部色彩及裂隙的存在问题。     

B货翡翠的漫反射红外傅里叶变换光谱法鉴别

对酸处理后注蜡和注胶的翡翠（Ｂ货），漫反射红外傅里叶变换光谱法是一个有用的非破坏的识别手段，因此，ＤＲＩＦＴ光谱法可用来鉴别天然的未经处理的翡翠与打蜡翡翠（Ａ货）。ＤＲＩＦＴ光谱中表现出的强吸收峰可用于检测胶和蜡的存在。利用ＤＲＩＦＴ光谱法对１０个翡翠样品进行综合研究。结果表明，其中一些翡翠样品已经过了酸处理、注蜡或注胶处理。该研究结果已被基础宝石学测试和Ｘ射线光电子分光光度法（ＸＰＳ）检测所证实     

危地马拉翡翠宝石矿物学特征及其与缅甸翡翠的对比研究

危地马拉目前已成为仅次于缅甸的第二大翡翠原料供应地。这两个产地翡翠辨别的需求愈发迫切,且应用意义较大。采用显微镜观察、电子探针分析及背散射电子照相获得危地马拉蓝水料翡翠的矿物成分及结构构造特征,结合两产地翡翠产出的大地构造环境、自然地理环境、原石特征与矿物成分特征等进行对比分析。总体上,危地马拉翡翠次生原石有一定的磨圆,呈次棱角状,“皮”(风化皮)厚度较薄,较少出现翻砂现象,由“皮”向里,极少甚至几乎不存在“红雾”。相对地,缅甸翡翠次生原石发育显著的球状风化,原石通常有较好的磨圆度,棱角状不明显,“皮”厚度可达数厘米,用手压磨有显著的翻砂现象, “皮”“肉”之间偶可见“红雾”。硬玉与绿辉石成分判别图显示危地马拉翡翠中硬玉和绿辉石呈相对富Ca、贫Na的特征,而缅甸翡翠中硬玉和绿辉石整体呈相对贫Ca、富Na的特征。在Fe含量上,危地马拉翡翠中硬玉的Fe含量较缅甸翡翠中硬玉的Fe含量偏低,而危地马拉翡翠中绿辉石的Fe含量较缅甸翡翠中绿辉石的Fe含量偏高。对翡翠外观特征的充分对比和对判别图的综合分析可应用于实际中翡翠产地的区分。     

从翡翠原石交易看翡翠市场的发展趋势

以翡翠原石投标为主体的缅甸珍宝玉石交易会（俗称“公盘”）一直是翡翠价格风向标,翡翠原石价格的上涨必然会推动成品价格的迅速跟进.通过对翡翠市场爆发式增长后的近几年原石交易特点的分析,发现所谓“原石价格上涨”完全是市场炒作的结果,一些玉商为了维护自身利益,聘请“枪手”投标,中标后又违约拒绝领标,造成原石投标交易现场火爆,价格屡创新高,但实际成交率却很低.从翡翠成品市场的反应来看,虽然价格有所上涨,但涨幅并不与媒体夸张的报道相适应.分析认为,玉商在翡翠原石交易中的行为需要进一步规范;在原石供应短缺和玉商极力维护自身利益的情况下,翡翠的价格不可能大幅度波动;高档翡翠因原料近于枯竭,价格还有进一步的上涨空间;在产能过剩的市场环境中,翡翠市场重归活跃尚待时日.     

Mechanical twinning of jadeite – an indication of synseismic loading beneath the brittle–plastic transition

The orientation distribution of mechanically twinned jadeite crystals in a metagranite from the Sesia Zone, Western Alps, is evaluated to derive the orientation of the principal stress directions for a prominent stage of ductile deformation at ca. 300 to 350 °C that has been interpreted to reflect synseismic loading and postseismic creep by Küster and Stöckhert (1999). It is tested whether the orientation distribution can be used to obtain information on the magnitude of differential stress if the critical shear stress for twinning is known. Assuming that the critical shear stress of 140 MPa determined by Kollé and Blacic (1982) for mechanical twinning of clinopyroxene in the (100) [001] system holds true for jadeite, and assuming a homogeneous stress field as a first approximation, differential stresses of the order of 1-2 GPa are inferred for metagranites with ca. 15% jadeite, and of 0.5 GPa for jadeitite with 80% of jadeite. Notwithstanding the uncertainty for the critical resolved shear stress for jadeite, these unexpectedly high values are suspected to be due to a combination of the following effects: (1) an inhomogeneous stress field in the polyphase material with curved stress trajectories, (2) stress concentration in jadeite due to load transfer from the quartz matrix, and (3) minor reorientation of the jadeite crystals in the flowing quartz matrix. Hence, absolute values of differential stress cannot be derived from the orientation distribution of twinned jadeite in polyphase rocks. Notwithstanding the failure in deriving reliable absolute values, a short period with exceptionally high stress must have occurred, and is fully consistent with the microstructural record of other minerals. It is proposed that the mechanical twinning of jadeite was caused by a short-lived stress peak and flow at laboratory strain rates related to quasi-instantaneous loading of the uppermost level of the ductile lower crust during brittle failure of the brittle upper crust in a major seismic event.     

Microfabric characteristics and rheological significance of ultra-high-pressure metamorphosed jadeite-quartzite and eclogite from Shuanghe, Dabie Mountains, China

Quantitative analysis of the structural evolution of jadeite‐quartzite, a rare ultra‐high pressure (UHP) rock type from the Dabie Mountains of eastern China, sheds light on the formation and evolution of UHP orogenic belts worldwide. Geological mapping of the Shuanghe area, where jadeite‐quartzites crop out, was carried out to determine the spatial relationships between different UHP rocks within this orogen. The deformation mechanisms of jadeite‐quartzite, geodynamical parameters (stress, strain, strain rate), and microstructure including lattice preferred orientation (LPO) were determined from six jadeite‐quartzite samples from the Shuanghe area. LPOs of clinopyroxene (jadeite and omphacite), garnet, rutile and quartz from these jadeite‐quartzite samples are compared with those of three eclogites preserving different degrees of deformation from the Shuanghe area. Microstructural LPOs of jadeite, omphacite, garnet, rutile and quartz were determined using electron backscattered diffraction (EBSD) analysis. Quartz fabrics were largely recrystallized during late, low‐grade stages of deformation, whereas garnet shows no strong LPO patterns. Rutile fabrics show a weak LS fabric along [001]. Jadeite and omphacite show the strongest eclogite facies LPO patterns, suggesting that they may provide important information about mantle deformation patterns and control the rheology of deeply subducted continental crust. Microstructural data show that the jadeite LPO patterns are similar to those of omphacite and vary between L‐ and S‐types, which correlate with prolate and oblate grain shape fabrics (SPO); quartz LPOs are monoclinic. Microstructural analysis using TEM shows that the dominant slip systems of jadeite in one sample are (100)[001], (110)[001] and (1 1 0)1/2[110], while in another sample, no dislocations are observed. Abundant dislocations in quartz were accommodated by the dominant slip system (0001)[110], indicating basal glide and represents regional shearing during the exhumation process. This suggests that dislocation creep is the dominant fundamental deformation mechanism in jadeite under UHP conditions. The protoliths of jadeite‐quartzite, metasedimentary rocks from the northern passive continental margin of the Yangtze craton, experienced the same deep subduction and were deformed under similar rheological conditions as other UHP eclogite, marble and paragneiss. Experimental UHP deformation of quartzo‐feldspathic gneiss with a chemical composition similar to the bulk continental crust has shown that the formation of a jadeite–stishovite rock is associated with a density increase of the host rock similar to the eclogite conversion from basaltic protoliths. The resulting rock can be denser than the surrounding mantle pyrolite up to depths of 660 km (24 GPa). Thus, processes of deep continental subduction may be better‐understood through understanding the rheology and mechanical behaviour of jadeite. Jadeite‐quartzites such as those from the Shuanghe may be exhumed remnants of deeply‐subducted slabs of continental crust, other parts of which subducted past the ‘depth of no return’, and remain in the deep mantle.     

大别山超高压变质岩的显微构造与有效黏度

超高压变质岩提供了研究大陆俯冲隧道中岩石的变形机制和流变差异性的窗口。文章使用电子背散射衍射技术分析了大别山超高压变质带的榴辉岩和长英质片麻岩的显微构造。榴辉岩中的石榴子石基本呈无序分布,绿辉石发育较强烈的晶格优选定向,[001]轴的极密平行或近平行于拉伸线理,(100)面的法线近垂直于面理,退变榴辉岩中角闪石的(100)[001]组构可能继承了绿辉石的晶格优选定向。退变榴辉岩和长英质片麻岩中的石英记录了(0001)低温底面滑移和{1010}中温 柱面滑移,反映了超高压变质岩折返到中地壳的韧性变形;而斜长石的(001)<110>和(010)[100]组构形成于折返到下地壳的角闪岩相变质条件（>600℃）。根据主要矿物的流变律计算了俯冲与折返过程中无水矿物的有效黏度变化。俯冲过程中,钠长石=硬玉+石英的分解反应以及石英-柯石英相变导致长英质片麻岩的有效黏度和密度都显著增高,有利于陆壳深俯冲。但是折返过程中由于温度较高,这两个反应带来的有效黏度变化较小。>80 km深度,石榴子石的流变强度>硬玉>绿辉 石>柯石英,俯冲上地壳的流变由柯石英和硬玉控制,下地壳的流变由绿辉石和石榴子石控制。超高压变质岩流变强度的差异有助于上—下地壳力学解耦,使相对低密度、低黏度的上地壳物质在俯冲隧道内快速折返。     

采用便携式近红外矿物分析仪鉴别注胶翡翠

目前,采用传统的中红外光谱技术鉴别不透明注蜡与注胶翡翠有一定的难度。采用便携式近红外矿物分析仪检测鉴定了翡翠、注蜡与注胶翡翠样品,对其近红外反射光谱进行了分析与研究,同时对微透明样品作了中红外透射光谱的比对测试。研究结果表明,采用BJKF-1型便携式近红外矿物分析仪,能获得较好的透明或不透明翡翠、注蜡与注胶翡翠样品的近红外反射光谱,三者的近红外光谱特征存在着明显的差异。利用这些特征可有效地鉴别翡翠、注蜡翡翠与注胶翡翠。     

高温高压合成翡翠的溶胶-凝胶法粉料制备的工艺方法探索

采用溶胶-凝胶法合成具有翡翠成分的玻璃料,再对其进行高温高压处理,实现玻璃体向晶质硬玉的转化,从而得到合成翡翠。从金属醇盐浓度、pH值、去离子水的添加量、水浴温度四个方面探讨了最佳凝胶条件。常规宝石学特征测试、偏光显微镜下岩矿薄片分析、X射线粉末衍射和傅里叶变换红外光谱表明,合成翡翠与天然翡翠的常规宝石学性质相近,其结晶矿物为硬玉,样品的结晶转化程度较好,具有硬玉的标准红外特征吸收峰。     

阴极发光在翡翠研究中的应用

通过对多个翡翠及其他玉石标本进行阴极发光实验,观察不同品种的翡翠、处理翡翠制品以及翡翠的相似玉石品种在阴极发光镜下的荧光颜色、发光强度、环带特点、颗粒形态和裂隙状况等的不同特征,来有效鉴别翡翠、处理翡翠及翡翠的相似品。同时依据不同类型翡翠在阴极发光下的特征,对翡翠的品质、颜色等的划分提供依据。     

缅甸翡翠矿石化学成分及其意义

通过对翡翠矿石化学成分研究，我们可以了解翡翠类质同象关系的存在、划分翡翠矿石类型、探讨翡翠呈色机理，特别是对其微量元素和稀土元素进行研究，证明物质来源于蛇绿岩化橄榄岩以及可能的成矿环境，对进一步加强翡翠研究和指导翡翠找矿起到极其重要的作用。