河南祁雨沟金矿床自然金{110}自形晶的发现及其成矿意义

在东秦岭华北板块南缘祁雨沟金矿床中发现罕见的两颗粗粒自然金{110}自形晶体,产出于矿床晚期蚀变矿化阶段,出现在晶洞中,均可见10个发育完好的晶面。晶体是在溶解主成矿期自然金基础上的再生产物,是在中偏碱性热液溶解了已结晶的金,在天水加入后的酸性条件下,于方解石开始结晶后结晶生长的。共生矿物除石英、方解石等,并有多种Bi-硫盐和Bi,碲化物。在一定量碲的存在下,铋起着完好粗粒自然金成长的“催化剂”的作用。{110}自形晶金出现在富矿地段,系局部现象,也是指导矿床勘查及矿山开采的重要标志之一。

山西石英岩的结晶特征与加热相变

为了解释山西石英岩并非所谓的胶结硅石,采用场发射扫描电镜-能谱仪和XRD研究了原矿石的石英晶体大小、分布和杂质特征以及煅烧后的显微结构。结果表明,山西石英岩系显晶和微晶石英构成的复合型石英岩,白色区域为自形石英晶体;红色区域含有纳米尺度的石英晶体、伴生矿物球状和针状铁、锰氧化物。经1 450℃保温3 h煅烧后的试样约有30%转化为方石英和产生液相分离现象。

新西兰北岛红树林沉积物中黄铁矿微观形貌特征及其环境指示意义

为探究红树林沉积环境自生黄铁矿形貌特征及其分布规律,利用新西兰北岛红树林沼泽区三个不同植被带采集的沉积物柱状样品,在偏光显微镜及扫描电镜下对其不同深度沉积物样品中黄铁矿数量及形貌特征进行了分类、统计。结果表明:①三个植被带沉积物样品中均存在莓球状黄铁矿、团块状黄铁矿、结核状黄铁矿及晶粒状黄铁矿,且结核状黄铁矿占比最高;②莓球状黄铁矿平均粒径7.77μm,微晶形态以八面体和五角十二面体型为主;③相比光滩区、内部林区两个植被带,红树林林缘区沉积物的莓球状黄铁矿粒径变幅较大,自形晶含量最高。初步判断本研究区沉积环境属于贫氧沉积环境,红树林林缘区水环境动荡,黄铁矿发育程度较高。相比中国海南省、厦门红树林湿地及美国西海岸Elkhorn Slough盐沼湿地沉积环境,本研究区红树林沉积环境更封闭,促进了自形晶的广泛发育。

西藏列廷冈铁多金属矿床地质特征

1地质概况矿区地处念青唐古拉弧背断隆带南侧,属那露果-新嘎果Ag、Pb、Zn成矿远景区(西藏地调院,2012)。矿区出露地层主要为早三叠世查曲浦组(T1ch)及第四系残坡积物和冲洪积物。查曲浦组岩性主要为大理岩夹矽卡岩,主要分布在矿区北部。矿区构造以断层构造为主,但规模均较小。矿区岩浆岩类型多样,从基性-中。

西南印度洋龙旂热液区(49.6°E)硫化物的矿物学特征

不同的构造环境必然会产生不同的热液循环系统。在超慢速扩张的西南印度洋(SWIR),不仅扩张速率不同于快速扩张脊,中脊扩张机制(动力)、岩浆供应的规模与形式、海底基岩的类型等也都有所不同,这就使得SWIR的热液活动系统在热液循环、岩水反应、物质来源、热液喷出的规模与频率等诸多方面都必将有其独特性。然而,由于受调查工作的限制。

我国首次发现钒砷锗石

1988年12月我们在四川廿孜某多金属矿床中发现了钒砷锗石。这种矿物首先由Н·М·Мнтряева等(1968)发现于苏联。在我国则属首次发现。与钒砷锗石共生的矿物,除方铅矿、闪锌矿外,还有锌锑黝铜矿、黄铁矿、黄铜矿、斑铜矿、铜蓝、自然金、银金矿、硫铜银矿、硫汞银铜矿、钡长石、钡冰长石、重晶石。

Simulation and experimental validation of three-dimensional dendrite growth

A three-dimensional （3-D） modified cellular automaton （MCA） method was developed for simulating the dendrite morphology of cubic system alloys. Two-dimensional （2-D） equations of growth velocities of the dendrite tip, interface curvature and anisotropy of the surface energy were extended to 3-D system in the model. Therefore, the model was able to describe the morphology evolution of 3-D dendrites. Then, the model was applied to simulate the mechanism of spacing adjustment for 3-D columnar dendrite growth, and the competitive growth of columnar dendrites with different preferred growth orientations under constant temperature gradient and pulling velocity. Directional solidification experiments of NH4Cl-H2O transparent alloy were performed. It was found that the simulated results compared well with the experimental results. Therefore, the model was reliable for simulating the 3-D dendrite growth of cubic system alloys.

广西隆安县凤凰山锰—银矿床中发现多种银矿物

广西隆安县凤凰山锰—银矿床于1987年由广西第四地质队发现。该矿床产于寒武系清溪组的构造破碎带中。目前普查工程揭露控制矿体已有一定的规模,含银品位超过工业指标要求。经过银的赋存状态专题研究,对矿石作了百余块光薄片鉴定和相当数量的电子探针分析以及单矿物分析、光谱分析、化学多项分析、X射线衍射分析等,查明了银的赋存状态。发现该矿床原生矿中的银矿物有以下十种:深红银矿。

Super Performance InGaP/GaAs HBT with Novel Structure

A kind of super performance InGaP/GaAs HBT with f T=108GHz and f max =140GHz is demonstrated.The excellent frequency performance results from the novel structure of the U shaped emitter,together with self aligned emitter and LEU(lateral etched undercut) technologies.The HBT with the novel structure shows a distinguished performance with BV CEO up to 25V.And excellent performance of low V offset of 105mV and V knee of 0 50V is great favor of low power applications.The differences due to the different structure are also compared.

Cellular automaton simulation of dynamic recrystallization behavior in V-10Cr-5Ti alloy under hot deformation conditions

The deformation behavior of V-10Cr-5Ti alloy was studied on the Gleeble-1500 thermomechanical simulator at the temperatures of 950-1350℃, and the strain rates of 0.01-10 s^-1. Based on the Arrhenius model, dislocation density model, nucleation model and grain growth model, a numerical cellular automaton (CA) model coupling simulation of hot deformation is established to simulate and characterize the microstructural evolution during DRX. The results show that the flow stress is fairly sensitive to the strain rate and deformation temperature. The error between the predicted stress by the Arrhenius model and the actual measured value is less than 8%. The initial average grain size calculated by the CA model is 86.25 μm, which is close to the experimental result (85.63 μm). The simulations show that the effect of initial grain size on the dynamic recrystallization microstructure evolution is not significant, while increasing the strain rate or reducing the temperature can refine the recrystallized grains.

Phase field simulation of solidification under supergravity

In order to understand the influence of supergravity on the microstructure of materials,crystal nucleation,dendritic growth,and polycrystal solidification under supergravity are investigated by using the modified nucleation theory and phase field models.Firstly,supergravity is considered in the nucleation theory by using pressure-dependent Gibbs free energy.It is found that the critical radius decreases and the nucleation rate increases when supergravity rises.Secondly,anisotropic heat transport is proposed in the phase field model to investigate the influence of supergravity on dendritic growth.Phase field simulations show that supergravity promotes the secondary dendritic growth in the direction parallel to supergravity.Finally,a multiply phase field model with pressure-dependent interfacial energy is employed to simulate the polycrystalline solidification under supergravity.Due to the depth-dependent pressure by supergravity,crystal grains are significantly refined by high pressure.In addition,gradient distribution of grain size is obtained in the solidification morphology of polycrystalline,which is consistent with previous experimental observations.Results of this work suggest that supergravity can be used to tune the microstructures and properties of materials.