小秦岭金矿含金石英脉中黄铁矿晶体的表面微形貌研究

利用微分干涉显微镜、扫描电镜、透射电镜等对小秦岭金矿含金石英脉中黄铁矿晶体的表面微形貌进行了研究。黄铁矿晶体的{210}面上发育自由生长层，表明{210}面是F面，其生长机理受二维成核层生长所制约。除简单的五角十二面体外，其他形态黄铁矿晶体的{210}面上也发育有自由生长层。{210}面上的正条纹有些是由{100}面上生长层的边缘台阶在{210}面上叠堆形成，另一些正条纹则是{210}面上生长层边缘台阶堆叠的产物。透射电镜和电子衍射花样研究表明，负条纹黄铁矿晶体是由30～50nm大小的核团经自动定向附生作用形成，每个核团不是单晶体，而是由许多早先在溶液中形成的小微晶聚合而成。这些特征表明负条纹黄铁矿晶体是在溶液过饱和度极高和温度梯度小的理想环境中形成，它的形成与杂质无关。PBC理论和唐纳-哈克定律能较好地解释自然界中黄铁矿晶体{100}面上普遍发育自由生长层、而{210}面上自由生长层极为罕见的原因。除日本释迦内矿区黑矿之上的浮岩凝灰岩中产生出负条纹黄铁矿晶体外，在石英脉型金矿床中也有负条纹黄铁矿晶体产出。     

广西龙头山金矿床黄铁矿标型特征及其地质意义

广西龙头山金矿床是大瑶山成矿带内重要的金矿床,矿区发育大量不同类型的黄铁矿。根据黄铁矿的产出特征,将黄铁矿划分为5个世代,对应着5个成矿阶段:电气石-石英-硫化物阶段(Ⅰ)、石英-黄铁矿-黄铜矿阶段(Ⅱ)、石英-多金属硫化物阶段(Ⅲ)、石英-黄铁矿-闪锌矿阶段(Ⅳ)、石英-黄铁矿阶段(Ⅴ)。不同阶段黄铁矿晶形均以{100}为主,少见{210};金含量与{210}含量呈正相关。黄铁矿晶胞参数为5.411 86~5.415 52,变化幅度不大,与钴含量呈正相关,主成矿阶段受金含量影响而变大。形貌及砷含量变化特征表明,{210}和金含量随砷含量降低而升高,说明砷含量降低利于{210}的出现,且金与砷不存在正相关关系。形貌特征及微量元素特征均反映主成矿阶段温度应220℃,且多集中于300℃的范围;δFe—δS图解及矿床地质特征表明,成矿热液主要为岩浆热液。综合分析认为,龙头山金矿床为中-高温岩浆期后热液矿床。     

黄铁矿晶体形态标型在金矿评价中的意义

黄铁矿晶体形态是金矿床矿物学填图的良好指示参数之一.黄铁矿的微形貌特征具有指示其形成环境的意义.在金矿床中,早期成矿阶段结晶的a{100}或e{hk0}形态黄铁矿含金性较差;主成矿阶段形成的ae、aeo、ao、oa、oe等聚形晶,以及{310}、{320}等e黄铁矿含金性较好.黄铁矿形态沿矿体空间可以表现出分带性.其垂向分带趋势为:矿体上部以o{111}晶形为主,矿体中部以e{hk0}形为主,矿体下部主要以a{100}形占主导,或分别以其晶面发育的聚形为主.但不同矿床,甚至同一矿床的不同矿脉,这种分带的表现也不完全一致.因此,应用此分带模式进行深部矿体预测时,应具体情况具体分析.     

α-石英晶体腐蚀形貌三维空间变化规律与晶体对称研究

通过对α-石英自然晶面六方柱面(100)和(010)、菱面体正形面(101)与菱面体负形面(011)、以及介于上述自然晶面之间的切面进行腐蚀形貌的观察研究发现,石英晶体同种单形的晶面(切面)腐蚀坑形态相同,但方位可以有变化,不同单形的晶面(切面)腐蚀坑形态不同;同一单形的正形与负形腐蚀坑形状不同;蚀坑形态能够反映晶体的对称性。α-石英晶体各晶面(切面)的蚀坑形态在三维空间分布的投影图可用于岩石中α-石英晶体的定向及缺陷研究。这一观察研究对厘清α-石英晶体腐蚀形貌立体全方位的对称关系、指导岩石中α-石英晶体的定向研究具有理论与实际意义。     

岫岩陨石坑石英的冲击变质特征

直径1.8 km的岫岩陨石坑位于辽宁省岫岩县苏子沟镇。坑区基岩为下元古界变质岩,由变粒岩、片麻岩、角闪岩、透闪岩和大理岩等岩石组成。坑内充填的撞击角砾岩石英颗粒呈现典型的冲击变质特征,其中包括沿着石英(0001)、{10 11}、{10 12}和{10 13}等方向发育的多组面状变形页理,以及石英发生相转变形成二氧化硅玻璃和柯石英。产出在二氧化硅玻璃中的针状和粒状柯石英表明从二氧化硅熔体中结晶形成。石英面状变形页理的发育特点限定冲击压力高达35 GPa,而二氧化硅熔体玻璃的存在表明冲击压力高达50 GPa。当压力释放和温度升高,二氧化硅熔体首先被形成。随着压力进一步释放到2.5～13 GPa,柯石英从二氧化硅熔体中结晶析出。岫岩陨石坑中石英面状变形页理和柯石英的存在提供了矿物冲击变质的诊断性证据。     

湖南湘西金矿及外围石英脉包裹体特征与石英脉含金性研究

以湖南湘西金矿及其外围(东部)脉石英为例，研究了脉石英包裹体的气、液相成分特点，提出包裹体中的CO2、HCO3^-、CO2／H2O、HCO3^-／Cl^-及离子总浓度(∑1)可作为评价石英脉含金性的标志，并总结出石英脉含金性评价的矿物学特征，预测了湘西金矿外围四个工作区的成矿远景。     

石英黄铁矿中群体包裹体微量元素研究--以胶东焦家式金矿床为例

采用ICP-MS测定了胶东焦家、马塘、东季和红布金矿床黄铁矿、石英及其群体包裹体的微量元素组成。结果表明,黄铁矿包裹体与石英包裹体均富集Cu、Pb和Zn等成矿元素,反映了成矿流体的特征;不同成矿阶段成矿流体特征有差异,石英黄铁矿化阶段、黄铁绢英岩化阶段、石英多金属矿化阶段石英及其包裹体微量元素含量均高于成矿较差的钾长石化阶段的石英及其包裹体;与陆壳微量元素丰度相比,黄铁矿及石英中Cu、Pb、Zn、Ag和Au等成矿元素富集;与地热卤水及斑岩铜矿卤水微量元素含量相比,黄铁矿及石英包裹体中以Cu为代表的成矿元素均较其它元素相对富集,反映了成矿流体中富集成矿元素的特征。上述结果表明,可以采用ICP-MS测定黄铁矿及石英包裹体微量元素来研究成矿流体的特征。     

粤西河台金矿床富硫化物石英脉Rb-Sr等时线年龄讨论

河台金矿床产于河台韧性剪切带中 ,成矿作用分为韧性剪切变质成矿期的韧性剪切变质成矿阶段和热液蚀变成矿期金石英脉阶段、金硫化物阶段和方铅矿闪锌矿碳酸盐脉阶段。金的成矿主要发生在金石英脉阶段和金硫化物阶段 ,形成的矿石有蚀变糜棱岩型和富硫化物石英脉型。富硫化物石英脉单矿物石英中富含以富CO2 液相为主的流体包裹体、流体熔融包裹体及熔融包裹体。与以往用流体包裹体热爆法和压碎法提取Rb、Sr的方法不同 ,本文用石英全溶法测得富硫化物石英脉中石英的Rb Sr等时线年龄为 172± 2Ma(1σ) ,初始比值为 0 .72 816± 0 .0 0 0 96 ,对比已有的同位素年龄数据及区域成矿特征 ,认为这一年龄值可能代表了河台金矿床的成矿年龄。     

天然金刚石平行{100}的正常生长

利用同步辐射对天然金刚石晶体进行了形貌学研究，在的完整晶体内观察到晶体以平行{100}生长为主的正常生长，而不是前人所常见的平行{111}生长。生长带方向平行于(100)、（100）和（010）、（010）。生长带分布在偏离晶体中心的曲面内。由生长带的分布与形态可以观察到晶体不同晶面生长速度具有明显差异。     

石英傅立叶变换漫反射红外光谱在成矿作用研究中的应用——以山西繁峙义兴寨金矿床为例

作为热液成因矿床中最为主要的贯通性矿物,石英的内部结构和成分在不同成矿阶段会产生系统性变化.石英粉末漫反射红外光谱1 200 cm-1～400 cm-1指纹谱段对此变化较为敏感,可以用来指示不同成矿阶段石英与成矿的关系.研究对山西义兴寨金矿1 070 m中段MO#脉、1*脉,2#脉,3#-4#矿体,M3#脉,950 m和830 m中段的5#脉和6#脉41件不同成矿阶段的石英粉末进行漫反射红外光谱测试,并利用1 070 m中段各矿脉石英粉末光谱特征参数进行矿物学填图.结果表明.非对称伸缩振动谱带1 085 cm-1半高宽值与石英晶格中的类质同像替换浓度有关,类质同像杂质浓度愈高,1 085 cm-1半高宽相对愈大;填图结果指示该值与金品位值的分布对应性较好.对称伸缩振动谱带800cm-1和780 cm-1的吸收强度与石英所经历的构造差应力呈正相关关系,填图结果表明800 cm-1和780 cm-1吸收强度高值区与金品位高值区的分布几乎趋于一致.红外结晶指数表征石英晶体的结晶程度,随着成矿温度逐渐降低,石英的结晶程度从无序逐渐向有序转化,红外结晶指数也随之减小.     

东伙房金矿中黄铁矿和石英的某些标型特征及其找矿意义

主要对黄铁矿及石英的某些标型特征进行研究，并推测成矿的有利部位，研究发现，本区成矿阶段的黄铁矿为ｎ＋ｐ混合型，ｐ型含量愈高，矿化愈好，金品位高值区与热电系数标志值５００～７００部位吻合，主成矿阶段出现（１００）＋（３２１）＋（２１０）＋（３２１）及（１００）＋（２１０）＋（１１１）黄铁矿聚形，石英热发光强度大（大于０．５Ｒ）发光曲线峰多（双峰），总积分强度大于４．３Ｒ是本区主成矿阶段的一个标志。     

石英结晶学优选与应用

石英集合体的结晶学优选可由位错滑移、双晶滑移、定向成核与生长等形成,其中位错滑移是塑性变形岩石中石英结晶学优选产生的最重要的机制。影响变形石英结晶学优选的因素有温度、应变速率、应变、差应力、水、复矿物岩石中各种矿物间的相互作用、初始结晶学方向等。系统总结了石英晶体变形与滑移系,结晶学优选的测量与表达,多种条件下石英的结晶学优选,以及在判断剪切方向、计算运动学涡度、判定变形温度、分析变形历史等方面的应用,并认为应用石英组构作运动学和动力学解析时需与其它微观、宏观现象相结合。     

高纯石英的研究进展及发展趋势

石英是一种在地壳上大量分布,有着广泛工业用途和广阔应用前景的矿物。当石英晶体形成演化时,受结晶时环境条件、流体性质、结晶后遭受改造(如变质作用、构造变形和热扰动等)等影响,杂质元素如P、Ti、Ge、Al、B、Be、Ca、Na、K、H、Li等会或多或少存在于石英晶体中,因此在自然界不存在纯SiO₂组分的石英。同时,基于石英的微量元素组成,可以反演石英源区和形成演化过程,并用于研究岩石及矿床成因等科学问题。石英晶体内部杂质元素以类质同象替代、气液包裹体、矿物包裹体(不能按尺度分,应该按照状态划分存在形式)3种形式存在。石英中杂质元素的种类、含量、赋存形式,特别是包裹体特征将直接影响石英资源的品质和工业用途。本文还系统地阐述了石英的发光特性、工艺性能以及高纯石英的质量分类与标准和高纯石英原料来源等方面的内容。在本研究中,通过光学显微镜和激光拉曼测试,初步地查明了苏北张锦庄石英砂和广西姑婆山花岗岩石英中流体包裹体的分布和矿物包裹体的种类,这是开展后续研究的基础。高纯石英是优质石英资源经纯化加工得到的高品质石英原材料,可用于石英玻璃、石英坩埚、半导体、高温灯管、光纤、精密光学、微电子和太阳能等高新技术产业中。研究高纯石英原料的评价体系、理想源岩和形成机制有益于持续性地供给高纯石英原料, 极大地提高了石英原料的工业附加值。     

X-ray topographic study of quartz crystals twinned according to japan twin law

Quartz crystals twinned according to Japan twin law were investigated by means of X-ray topography in order to understand the origin of characteristic morphology of twin crystals. It is demonstrated that the flattened and elongated morphology characteristic of quartz twins is due to preferential growth at twin junctions where dislocations with the Burgers vector direction 〈11 \(\overline {\text{2}} \) 1〉 concentrate, and that such preferential growth operates only when {10 \(\overline {\text{1}} \) 1} faces meet at the twin junction. Once {10 \(\overline {\text{1}} \) 0} faces appear at the twin junction due to the change of growth conditions, the effect diminishes sharply and the characteristic morphology becomes less pronounced. This leads to the conclusion that the characteristic morphology of quartz crystals twinned according to Japan twin law is formed at the earlier stage of growth and becomes less pronounced at the later stage of growth.     

超临界流体的快速泄出:来自霓辉石英脉的证据

河南外方山地区熊耳群火山岩中新发现了一种霓辉石英脉群,脉表现出独特的矿物组合及晶体特征,如霓辉石英脉具有复杂的矿物组成,表现出强烈的不平衡特点;霓辉石英脉具明显的对称分带特征,各分带中矿物组成及特征显著不同;存在具熔蚀边结构的钾长石-霓辉石集合体团块;霓辉石具在明显核幔结构,内核化学成分与幔边部存在较大差异;钾长石晶体元素分布存在似"文象"结构,表现出Fe元素的熔体分离特征;脉中矿物普遍发育环带结构;霓辉石英脉交代致密火山岩围岩形成蚀变带,新生大量榍石、霓辉石等矿物且含量随着与脉壁距离的增加急剧减少,显示出强烈的流体/气体扩散交代作用.霓辉石英脉独特的矿物组合及晶体特征反映了其成因的复杂性以及生长环境的变化.根据霓辉石英脉矿物的特点,推测其源于流体、熔体和晶体的混合物,并经历了快速侵位、快速冷却的过程,因而能够保存流体演化各阶段的结晶信息,保留不同成因的晶体群.外方山霓辉石英脉矿物可划分为捕虏晶亚群、熔体晶体群、超临界流体亚群、热液晶体亚群和凝聚晶体亚群等.外方山霓辉石英脉矿物晶体群的深入研究可能有助于揭示岩浆熔体向流体转换的机制及侵位机制,进而可揭示岩浆-流体成矿作用.     

Inverted high-temperature quartz

Fifty-two samples of inverted high-temperature quartz from volcanic rocks were investigated by Guinier-Jago powder diffractometry and differential scanning calorimetry (DSC). Quartz megacrysts from Clear Lake and Cinder Cone, California show a variability of ?2.5 ° K in their α-β transition temperature (T _α-β). Quartz phenocrysts and quartz from crystalline rocks give a range of 0.5 ° K in T _α-β. Neutron activation analysis of single crystals demonstrates that Al is the principal impurity (17–380 ppm). Its concentration is inversely correlated with T _α-β. A very small variation was found in the a and c lattice parameters among the specimens of volcanic quartz studied. This variation does not correlate with Al content or transition temperature. Mean values at 22 ° C (a=4.1934±0.0004 Å, c=5.4046±0.0006 Å) are similar to those of quartz grown at low temperatures. Enthalpy of the α-β transition (ΔH _α-β), obtained over 9.0 ° from DSC runs, is dependent upon sample grain size and for a crushed powder with zero hysteresis (T _α-β on heating=T _α-β on cooling) is 92.0 ±1.4 cal/mol. In contrast, a single piece of quartz requires ΔH _α-β be 107.7±1.4 cal/mol and has a T _α-β hysteresis of 1.1 ° K. Regression of published data provides equations for the variation of the molar volume (cc/mol) of quartz with v. These equations imply a ΔV _α-β of 0.205±0.031 cc/- mol. Expressions are also provided for the temperature dependence of the thermal coefficient of expansion, α, the compressibility, β, and (?/gb/?T)_p (which is identically -(?α/?P) _T ). DSC heat capacity measurements over the range 400 to 900 ° K were fitted to extended Maier-Kelley type expressions to give: $$\begin{gathered} C_P = 10.31 + 9.116 \times 10^{ - 3} T - \frac{{1.812 \times 10^5 }}{{T^2 }} \hfill \\ - {\text{5}}{\text{.630}} \times 10^{ - 2} {\text{ }}\frac{T}{{(T - 848)}} - 0.3553\frac{T}{{(T - 848)^2 }} \hfill \\ - 0.9011\frac{T}{{\left( {T - 848} \right)^3 }} \hfill \\ (400{\text{ to 842}}^ \circ {\text{K), and}} \hfill \\ C_P = - 318.8 + 0.2532T \hfill \\ {\text{ + }}\frac{{8.687 \times 10^7 }}{{T^2 }} + 0.1603\frac{T}{{\left( {T - 848} \right)^4 }} \hfill \\ \end{gathered} $$ (851 to 900 ° K), which together with the values of ΔH _α?β measured over the range 842–851° K give 7875.3 cal/mol for H₉₀₀-H₄₀₀. The behavior of α, β, and C _p as a function of T emphasizes that structural changes which occur at the α?β transition do so over a broad temperature interval.     

Shock induced planar deformation structures in quartz from the Ries crater,Germany

Crystalline rocks from breccias of the Ries basin, Germany, contain highly deformed quartz. Various planar deformation structures could be observed and classified into five different types: (1) Decorated planar elements, (2) Non-decorated planar elements, (3) Homogeneous lamellae, (4) Filled lamellae, (5) Planar fractures. All these structures are parallel to crystallographic planes: {10¯13}, {10¯12}, {10¯11}, {0001},{11¯21}, {11¯22}, {21¯31}, {51¯61}, {10¯10}. The most typical and most abundant planar structures are decorated and nondecorated planar elements parallel to {10¯13} and {10¯12}. Planar fractures are parallel to {0001} and {10¯11} and form at lower stress levels, probably earlier than the planar elements.Quartz containing planar elements, especially of the non-decorated type, has lower density, index of refraction and birefringence than normal quartz. This quartz is apparently a mixture of an amorphous phase and crystalline quartz, the amount of which can be calculated using average density or refractive index.Comparison of planar quartz structures found in tectonites and those produced artificially under static or dynamic high pressure conditions demonstrates that Ries quartz closely resembles deformed quartz recovered from shock wave experiments. The planar structures found in Ries quartz have been formed by shock wave actions with peak pressures in the 100–400 kbar range.Planar elements are explained to be traces of gliding processes during shock loading visible due to the fact that a high pressure phase (stishovite and/or a stishovite-like glass phase) has been produced along the glide planes. Upon pressure release most of the high pressure phase was transformed into an SiO₂-glass (diaplectic glass).In comparison with experimental data the amount of residual crystalline quartz as well as type and orientation of planar structures in the quartz grains are clues to estimate the peak pressures responsible for these deformations. Shock waves with peak pressures exceeding about 400 kbar completely transform quartz into diaplectic SiO₂-glass.     

鄂东南付家山脉石英矿杂质特征及其用作高纯石英原料的潜力

作为战略性矿产资源之一,高纯石英已广泛应用于集成电路、半导体芯片、太阳能等高新技术产业中,但是能够生产高纯石英的原料矿床极为稀缺,我国尤为紧缺高纯石英原料矿。鄂东南地区是湖北省脉石英矿床的主要分布区。本文针对鄂东南付家山脉石英矿床,通过光学显微镜、扫描电子显微镜观察了脉石英的脉石矿物类型和包裹体特征,采用电感耦合等离子发射光谱法(ICP-OES)对原矿进行了微量元素分析,旨在获得付家山脉石英矿床的杂质元素特征,进而评价矿床用作高纯石英原料的潜力。结果表明,付家山脉石英矿石SiO₂含量大于99.95%,杂质元素主要为Al、K、Fe、Ti、Ca等,脉石矿物主要有白云母、钾长石、铁氧化物等,流体包裹体较为发育。杂质元素分析结果表明,付家山脉石英原矿质量达到低端高纯石英标准,经传统工艺提纯后,可能具有生产中高端高纯石英的潜力。     

Systematics of internal zircon morphology in major Variscan granitoid types

The internal morphologies of zircon crystals from different types of granitoids (alkaline, calcalkaline and anatectic) are revealed by cathodoluminescence imaging and are described in terms of growth rates of the crystal faces relative to each other. Zircons in the alkaline granitoids are characterized by high and constant growth rates of {010} relative to the pyramidal forms and by symmetric grwoth of {011}. Zircons in the calcalkaline and anatectic granitoids are characterized by fluctuating or gradually decreasing relative growth rates of {010}, by asymmetric and highly variable growth of {011}, and by a tendency of {110} to become grwoth-inhibited. Corrosion events are interspersed during zircon growth in the calcalkaline magmas. In the calcalkaline and anatectic magmas, a discontinuity breaks the morphological evolution at late stages of crystallization. The discontinuity coincides with a sharp drop in cathodoluminescence. The growth behaviour of each crystal form is analysed and compared with predictions made by the periodic bond chain (PBC) theory. It is argued that the relative growth rate of {010} depends on supersaturation, that the growth rates of {011} faces are changed in response to different ratios of adsorbing cations (Na, K, Al), and that {110} faces become growth-inhibited by the adsorption of H₂O or trace elements enriched in the residual liquid. Morphological and chemical discontinuities at late stages of crystallization are reasonably explained by the formation of larger growth units (from smaller ionic entities) in the residual liquid. Important factors controlling the zircon morphology in different types of granitoids are: high cooling rates (alkaline magmas), magma mixing (calcalkaline magmas), enrichment of H₂O and trace elements in residual liquids (calcalkaline and anatectic magmas), and the major element chemistry of the magma, possibly the ratio of Na and K to Al (agpaicity).     

An X-ray excited optical luminescence study of a zoned quartz crystal from an emerald-bearing quartz vein,Hiddenite, North Carolina,USA

The optical luminescence excited with synchrotron radiation along a preferential orientation of a quartz crystal has been investigated. It is found that the crystal is composed of two distinct regions, only one of which luminesces upon X-ray excitation. This luminescence is generally uniform and exhibits emission bands in the blue (470 nm with a shoulder at 522 nm) and in the UV (340 nm) regions of the spectrum. The branching ratio for the intensity of these bands is sensitive to the excitation energy across the Si K-edge. XANES spectra collected by partial luminescence yield (PLY) suggest that both emission bands originate from the de-excitation of Si atoms in the quartz. The possible defect sites within the crystal structure that could account for the observed luminescence are investigated and discussed. Additional experiments are proposed to verify this assignment of the optical emission bands.