scholarly journals Genesis of Carbonate Breccia Containing Invisible Gold in Taebaeksan Basin, South Korea

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1087
Author(s):  
Sang-Gun No ◽  
Maeng-Eon Park ◽  
Bong-Chul Yoo ◽  
Seung-Han Lee
Keyword(s):  
South Korea ◽  
Carbonate Rock ◽  
Gold Deposits ◽  
Invisible Gold ◽  
Gold Particles ◽  
X Ray ◽  
Taebaeksan Basin ◽  
The Matrix ◽  
Backscattered Electron

The Yemi breccia developed and is distributed within the Paleozoic carbonate rock (Maggol Formation) in the central part of the Taebaeksan Basin, South Korea. Explanation for the genesis of the Yemi breccia has been controversial. We investigated the petrological and mineralogical properties of the breccia and the matrix materials at 60 outcrops. The Yemi breccia is divided into crackle, mosaic, and chaotic breccias based on morphology. In addition, these are divided into blackish, reddish, grayish, and white to pinkish matrix breccias according to the materials of the matrix. Quartz, calcite, pyrite, hematite (after pyrite), and minor epidote, chlorite, and opaque materials mainly comprise the matrix materials. The pyrite grains from the Yemi breccia can be divided into two types based on the mineral texture: diagenetic and hydrothermal. We analyzed the chemistry of pyrite and hematite (after pyrite) from the Yemi breccia with an electron probe X-ray microanalyzer (EPMA). Invisible gold was detected within the pyrite grains by EPMA and disseminated micron-sized isolated gold particles were discovered by backscattered electron (BSE) images. The texture of Au-bearing pyrite and gold particles in the Yemi breccia is especially well matched with pyrite and gold from the Shuiyindong Carlin-type hydrothermal gold deposits, China. Therefore, we suggest an important role of hydrothermal fluid in karstification within the Paleozoic carbonate rock.

Role of Heat Treatment in Magnetic Properties of Fe-Co-Ni-Al-Cu-Ti Alloy

2012 ◽  
Vol 510-511 ◽  
pp. 394-398 ◽  
Author(s):  
S. Imran ◽  
M.S. Awan ◽  
M.N. Sarwar ◽  
S. Akhtar ◽  
M. Farooque
Keyword(s):  
Heat Treatment ◽  
Magnetic Properties ◽  
Single Phase ◽  
Permanent Magnets ◽  
X Ray ◽  
Casting Technique ◽  
Alloy Casting ◽  
The Matrix ◽  
Metallurgical Structure

Anisotropic (Fe-24Co-15Ni-7.5Al-3Cu-0.3Ti) permanent magnets were prepared by alloy casting technique. Samples were characterized for structural, microstructural and magnetic properties using x-ray diffractrometer (XRD), Scanning electron microscope (SEM) equiped with energy dispersive x-ray spectrometer and DC magnetometer. There is a relation between metallurgical structure and magnetic properties. The magnetic properties of this type of alloy depend on heat-treatment that is controlling the cooling rate in the presence of magnetic field and double aging. How magnetic properties vary with heat treatment is discussed in this work. XRD studied revealed that the alloy was single phase (bcc) with (110) as the major crystallographic plane. Optical and SEM micrographs showed the presence of (Ti,S)-rich precipitates which are randomly distributed in the matrix. Their composition was analyzed by EDX analysis.

Investigation of Carbon Fiber/Polyphenylenesulfone Composites by Method of X-Ray Photoelectron Spectroscopy

2019 ◽  
Vol 816 ◽  
pp. 37-42
Author(s):  
Z.K. Kalazhokov ◽  
A.V. Naumkin ◽  
Azamat Zhansitov ◽  
S.Yu. Khashirova ◽  
K.H. Kalazhokov ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Carbon Fibers ◽  
Photoelectron Spectroscopy ◽  
Surface Region ◽  
Dominant Factor ◽  
Fiber Concentration ◽  
X Ray ◽  
The Matrix ◽  
Bulk Part

The surfaces of polyphenylenesulfone samples with the addition of carbon fibers were studied by X-ray photoelectron and Auger-electron spectroscopy. The state of carbon atoms on the surface, the electronic structure, and the distribution of carbon fibers in the surface region as a function of the concentration of the additive were studied. It is shown that with 10 mass. % carbon fiber addition, the transformation of peaks is mainly associated with an increase in the number of carboxyl groups in the matrix, while with a carbon content exceeding 10 mass. %, the increasing role of differential vertical charging becomes the dominant factor. A further increase in the carbon fiber concentration leads to an increase in the conductivity of the bulk part and, consequently, to a decrease in the charge layer without carbon fiber, and therefore, to a decrease in the broadening effect of the C 1s carbon peak.

X-ray spatial resolution in electron microbeam analysis

1991 ◽  
Vol 49 ◽  
pp. 462-463
Author(s):  
John T. Armstrong ◽  
Paul K. Carpenter
Keyword(s):  
Spatial Resolution ◽  
X Rays ◽  
X Ray ◽  
Excitation Potential ◽  
Sample Density ◽  
The Matrix ◽  
Backscattered Electron ◽  
X Ray Absorption ◽  
Critical Excitation ◽  
Secondary Fluorescence

The spatial resolution of characteristic x-ray production from electron bombardment in thick specimens is dependent upon the rate of energy loss of the primary electrons, the degree of electron scattering, the degree of x-ray absorption by the matrix, and the extent of secondary fluorescence of the x-rays by higher energy characteristic and continuum x-rays. The x-ray spatial resolution in thick specimens is much coarser than the secondary or backscattered electron resolution, typically being of the order of a fraction of a μm to several μm when secondary fluorescence is not significant, or as much as 100 to 200 μm when it is. The size of the excited volume of x-ray production is dependent upon the accelerating potential of the electron beam, the critical excitation potential, and the sample density. The size of the excited volumes of different elements’ x-ray lines can be considerably different in the same matrix, due to differences in critical excitation potential; the emitting volumes can vary even more, due to differences in mass absorption.

Microstructure of Magnesium-Aluminum Metal Matrix Composites Reinforced with 2wt.% SiC Particles

2011 ◽  
Vol 413 ◽  
pp. 207-212
Author(s):  
Run Lan Zhang ◽  
Xiang Rong Liu ◽  
Tan Wei Zhou ◽  
Jian Li Yang
Keyword(s):  
Optical Microscope ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aluminum Metal ◽  
Sic Particles ◽  
The Matrix ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
Aluminum Metal Matrix Composites

SiCp/Mg-Al composites with 5μm 2wt.% SiC particles as reinforcement were prepared under the protection of inorganic flux. The microstructures, textures and components of the composites were investigated using optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and backscattered electron imaging (BSE). The results indicate that SiC particles are mainly distributed along grain boundaries, retarding grain growth and conducing to the refinement of the matrix. Interfacial reaction can occur between SiCp and Mg but not between SiCp and Al. There are α-Mg and β-Mg17Al12 phases, γ-MgAl phase, α-Al and β-Al3Mg2 phases in SiCp/Mg-Al composites with the Mg/Al ratio of 4/1, 1/1, 1/4 respectively.

Lateral resolution of the electron microbeam analysis

1978 ◽  
Vol 36 (1) ◽  
pp. 542-543
Author(s):  
H.J. Dudek
Keyword(s):  
Quantitative Analysis ◽  
Depth Resolution ◽  
Lateral Resolution ◽  
Cylindrical Particle ◽  
Correction Procedure ◽  
X Ray ◽  
Element Concentrations ◽  
Microbeam Analysis ◽  
The Matrix

The chemical inhomogenities in modern materials such as fibers, phases and inclusions, often have diameters in the region of one micrometer. Using electron microbeam analysis for the determination of the element concentrations one has to know the smallest possible diameter of such regions for a given accuracy of the quantitative analysis.In th is paper the correction procedure for the quantitative electron microbeam analysis is extended to a spacial problem to determine the smallest possible measurements of a cylindrical particle P of high D (depth resolution) and diameter L (lateral resolution) embeded in a matrix M and which has to be analysed quantitative with the accuracy q. The mathematical accounts lead to the following form of the characteristic x-ray intens ity of the element i of a particle P embeded in the matrix M in relation to the intensity of a standard S

Analysis and lattice imaging of a transitional event on garnets

1978 ◽  
Vol 36 (1) ◽  
pp. 270-271
Author(s):  
J.Y. Laval
Keyword(s):  
Yttrium Iron Garnet ◽  
Reciprocal Lattice ◽  
Transitional Zone ◽  
Lattice Imaging ◽  
Yttrium Iron ◽  
X Ray ◽  
Ionic Process ◽  
The Matrix ◽  
High Resolution Technique ◽  
Iron Garnet

The exsolution of magnetite from a substituted Yttrium Iron Garnet, containing an iron excess may lead to a transitional event. This event is characterized hy the formation of a transitional zone at the center of which the magnetite nucleates (Fig.1). Since there is a contrast between the matrix and these zones and since selected area diffraction does not show any difference between those zones and the matrix in the reciprocal lattice, it is of interest to analyze the structure of the transitional zones.By using simultaneously different techniques in electron microscopy, (oscillating crystal method microdiffraction and X-ray microanalysis)one may resolve the ionic process corresponding to the transitional event and image this event subsequently by high resolution technique.

Thickness and composition determinations from T.E.M. specimens using both x-ray and backscattered electron data

1984 ◽  
Vol 42 ◽  
pp. 576-577
Author(s):  
M.D. Ball ◽  
H. Lagace ◽  
M.C. Thornton
Keyword(s):  
Electron Microscope ◽  
Atomic Number ◽  
Transmission Electron Microscope ◽  
Convenient Method ◽  
Flow Chart ◽  
X Ray ◽  
Intensity Measurements ◽  
Transmission Electron ◽  
Electron Intensity ◽  
Backscattered Electron

The backscattered electron coefficient η for transmission electron microscope specimens depends on both the atomic number Z and the thickness t. Hence for specimens of known atomic number, the thickness can be determined from backscattered electron coefficient measurements. This work describes a simple and convenient method of estimating the thickness and the corrected composition of areas of uncertain atomic number by combining x-ray microanalysis and backscattered electron intensity measurements.The method is best described in terms of the flow chart shown In Figure 1. Having selected a feature of interest, x-ray microanalysis data is recorded and used to estimate the composition. At this stage thickness corrections for absorption and fluorescence are not performed.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

The role of silicon in forages: A quantitative X-Ray study

1987 ◽  
Vol 45 ◽  
pp. 416-417
Author(s):  
Janet H. Woodward ◽  
D. E. Akin
Keyword(s):  
Sodium Acetate ◽  
Dry Matter ◽  
Acetate Buffer ◽  
Plant Tissues ◽  
Sodium Acetate Buffer ◽  
X Ray ◽  
Dry Matter Digestibility ◽  
Percent Composition

Silicon (Si) is distributed throughout plant tissues, but its role in forages has not been clarified. Although Si has been suggested as an antiquality factor which limits the digestibility of structural carbohydrates, other research indicates that its presence in plants does not affect digestibility. We employed x-ray microanalysis to evaluate Si as an antiquality factor at specific sites of two cultivars of bermuda grass (Cynodon dactvlon (L.) Pers.). “Coastal” and “Tifton-78” were chosen for this study because previous work in our lab has shown that, although these two grasses are similar ultrastructurally, they differ in in vitro dry matter digestibility and in percent composition of Si.Two millimeter leaf sections of Tifton-7 8 (Tift-7 8) and Coastal (CBG) were incubated for 72 hr in 2.5% (w/v) cellulase in 0.05 M sodium acetate buffer, pH 5.0. For controls, sections were incubated in the sodium acetate buffer or were not treated.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

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