• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.109-121
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• 1992

For the purpose of mineralogical and chemical study on the topazes from various localities of world(Brzail, China, India, Nigeria and Sri Lanka), electron microprobe analysis(EPMA), neutron activation analysis(NAA), X-ray diffractometry, Raman spectroscopy, etch test, scanning electron microscopy, refractive index, specific gravity, fluid inclusion were performed. The chemical composition in topaz was discussed along with its physical and structural properties. Variations in the unit-cell dimension and physical properties of topaz were found to have a close relations in the unit-cell dimension and physical properties of topaz were found to have a close relationship with extent of substitution of $OH^-\;for\;F^-$. According to neutron activation analyses, the trace elements had no effects on the physical properties of topaz. Raman spectra showed that the peaks of topaz were different in intensity from one locality to another. Etching defects in topaz includes negative crystal defect o point-bottom pit(India, Nigeria) and net work defect of curl-bottom pit(Brazil, China). Fluid inclusions in topaz may be classiffied into liquid $CO_2$-bearing inclusion, gaseous inclusion, halite, sylvite-bearing inclusion and liquid inclusion. The results of this study can be useful to devising artificial coloring methods for topaz with different mineralogical compositions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.11a
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• pp.43-46
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• 2006

The Hwangtoh is one of the traditional construction material used in wall, plastering material, and ondol (Korean underfloor heating system) with stone and wood. It is an important greenness material and it has much advantages such as; high storage of heat, auto-purification, antibiotic ability, and emission of far infrared rays. But, it is not developed and not used in modern construction because of its low strength and properties of dry shrinkage crack. According to the recent researches and studies, it is evaluated for natural pozzolanic material like flyash or pozzolan. It's possibility on construction material is high because it's chemical and mineralogical proportion is like as Metakaolin and Kaolinite. In this point of view, this study aims to analyze the physical properties on Hwangtoh mortar through an experiment with various activation condition of Hwangtoh, which is natural pozzolanic material, for the purpose of increase the using possibility in construction material.

• YAKHAK HOEJI
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• v.29 no.2
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• pp.96-102
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• 1985

Innovated utilization of Korean kaolins as pharmaceuticals is attempted, for which relevant properties including adsorptive behaviours are observed in connection with their mineralogical structures. In practice, physico-chemical properties are assessed by means of IR, XRD and thermal analysis including DTA, TG and DSC. Elemental analysis of the ore specimens under investigation is carried out in conventional manners. It is found that the chemical compositions are varied significantly with sampling sites and primary classifications. The clay ores thus analyzed are mainly composed of halloysite species. Proper benefication of the raw clays is necessary so that authentic requirements for medicinal use may be satisfied. White-colored premium grade halloysite could be utilized as therapeutics with relative ease after purification. Evidence indicates that gibbsite-like impurities are intercalated between the 1 : 1 layered moieties. Thermal behaviours may be characterized in such a fashion that loss of free water occurs near 100.deg. C and further heatings result in liberation of bound water near 500.deg. C, with subsequent transformation into amorphous metastable entities. Through thermal activation, enhanced pharmaceutical effects could be envisaged.

• Journal of the Mineralogical Society of Korea
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• v.27 no.2
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• pp.63-72
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• 2014

This study is conducted to investigate mineralogical characteristics and estimate firing temperature and condition of earthenwares in the 5-6th Century which are found at ancient tombs in Gyo-dong, Gyo-ri, Changnyeong-eup, Changnyeong-gun, Gyeongsangnam-do, TKorea by applying petrological methods. For this study, mineralogical analysis, microtexture observation and chemical analysis were conducted. According to observations using a polarization microscope, the potshreds are mainly composed of quartz and feldspar and consist of some felsic volcanics, tempers, opaques and mullite, hematite and spinel were found under XRD and FTIR analysis. The flow pastes are observed in many potshreds, and it indicate that this textures made by the mixing process or the pottery made from the mixture of 2 sorts of clays at least. They dose not show the features of the potshreds firing under temperature of $1,200-1,300^{\circ}C$ rather than the earthenware firing under relatively low temperature of $1,000^{\circ}C$ approximately because of the existence of a number of pores and the crystals of the specific minerals. The growths mostly of mullite on the surface and into the cracks of the potshreds indicate that the firing condition was not uniform to make even temperature and oxidation. Most of the pottery shreds have felsic volcanic fragments and some of them have cristobalite which is formed at the temperature of more than 1,470^{\circ}C$. But considering the estimated firing temperature, these are not formed during firing but included in the original clay.

• Journal of the Mineralogical Society of Korea
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• v.26 no.2
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• pp.87-99
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• 2013

The occurrence, mineralogical characteristics, and origin of the dolomite ores were investigated from major dolomite mines in South Korea. Mineralogical and textural properties of the ores and associated minerals were analyzed using X-ray diffraction, thin section petrography, and scanning electron microscopy. Dolomite ores were light to dark gray in color and mainly composed of dolomite in varying particle size with minor amounts of calcite, quartz and micas. Calcite, quartz, illite, feldspar, kaolin minerals, and chlorite occurred in local veins, dikes and alteration zones. Sepiolite and wollastonite occurred in the altered part of some mine. Asbestos minerals such as chrysotile and tremolite, however, were not identified in the present study. Reddish brown to yellow clay materials were mainly composed of illite, occasionally associated with kaolin minerals and smectite. These clay minerals might be a product of the local hydrothermal alteration related to the dyke intrusion and subsequent weathering. As well indicated in the previous studies, mineral composition, texture, and occurrence of the dolostone beds suggest their formation through the diagenesis of carbonate sediments deposited in the shallow sea during the Precambrian to Paleozoic period.

• Journal of the Mineralogical Society of Korea
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• v.17 no.3
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• pp.201-208
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• 2004

$CaSiO_3$-garnet phase was observed in the phase transformation sequences on a natural hedenbergite, (Ca, Fe)$ SiO_3$ between 14 and 24 GPa when quenched from $～1200^{\circ}C$. Bulk modulus K = 155 GPa, $V_{\Phi}$ = 6.58 km/sec and other elastic properties of the $CaSiO_3$-garnet were obtaiend on the basis of the systematics of structural analogs in varius garnet phases and relationship of $KV_{m}$ = constant and $V_{\Phi}$$M^{$\frac{1}{2}$}$ = constant. The quenchable garnet phase apears to be stabilized by the considerable amount of Mn and other cations, and shows a wide stability range. As one of the host minerals of Ca composition, $CaSiO_3$-garnet would be one of the important mineral phases in the mantle transition region.

• Journal of the Mineralogical Society of Korea
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• v.29 no.2
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• pp.35-45
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• 2016

Clays, which are abundant in nature and eco-friendly, have been utilized throughout human history due to their characteristic physicochemical properties. Recently, a variety of clays such as montmorillonite, kaolinite, sepiolite and layered double hydroxide with or without chemical modification have been extensively studied for potential application in industries. Clays that possess a large specific surface area, high aspect ratio, nanometer sized layer thickness and controllable surface charge could be utilized as polymer fillers after appropriate chemical modifications. These modified clays can improve mechanical and gas barrier properties of polymer materials but also provide sustained antibacterial activity to polymer films. Furthermore, engineered clays can be utilized as scavengers for chemical or biological pollutants in water or soil, because they have desirable adsorption properties and chemical specificity. In this review, we are going to introduce recent researches on engineered clays for potential applications in future industries such as food packaging and environmental remediation.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.211-220
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• 2012

The numerical modeling and simulation have been used increasingly as tools for examining and interpreting the bulk structure and properties of materials. The use of molecular dynamics (MD) simulations to model the structure of materials is now both widespread and reasonably well understood. In this research, we introduced the numerical method to calculate the physico-chemical properties such as a diffusion coefficient and a viscosity of clay mineral. In this research, a series of MD calculations were performed for clay mineral and clay-water systems, appropriate to a saturated deep geological setting. Then, by using homogenization analysis (HA), the diffusion coefficients are calculated for conditions of the spatial distribution of the water viscosity associated with some configuration of clay minerals. This result of numerical analysis is quite similar to the previous experimental results. It means that the introduced numerical method is very useful to calculate the physico-chemical properties of clay minerals under various environmental conditions.

• Journal of the Mineralogical Society of Korea
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• v.18 no.2
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• pp.83-92
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• 2005

Dissolution rate of minerals may differ from climates configuration, but weathering rate of feldspars is generally proved to be relatively higher The result of geochemical reaction modeling indicates the acid water of pH 4.5 excluding any other variables, was 2.3 times higher than that in ordinary rain of pH 5.7. This result proved that pH is very important factor in preservation of granite cultural properties. To prevent the weathering of stone cultural properties, weathering characteristics of stones should be studied first and constitution of dry environments, using water repellent or oil coating, isolating water which cause chemical weathering reaction like hydration and oxidization should be considered. Considering the long-term reactions between granite and rain, selection of materials, which can bring neutralization and non-oxidization conditions, are very important in using cleaning agents and biological controls.

• Journal of the Mineralogical Society of Korea
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• v.28 no.2
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• pp.109-126
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• 2015

Because fault gouge developed at the center of fault is recognized as one of the most important weak sites, it is evident that clay mineralogy and physical properties greatly affect the rock stability. The purpose of this study is to establish the relationship of mineralogy and physical factors that control rock stability in fault zones. We analyzed a total of 51 samples from 16 main faults which were selected from a Korea fracture map, using XRD, SEM, and physical analyses like unit weight, friction and cohesion properties. Though it is considered that the most common clay minerals comprising fault gouge are kaolinite, illite and smectite, clay mineralogy slightly varies depending on lithology: illite > smectite > kaolinite and chlorite in volcanic rocks, kaolinite and chlorite > illite > smectite in sedimentary rocks, and illite > smectite > kaolinite and chlorite in abundance, respectively. Friction angle decreases with increasing clay content. Cohesion increases with increasing clay content below the 45 % region while it decreases with increasing clay content at the region higher than 45%, with some scatters in the data. It is likely that these results are ascribed to the physical heterogeneity of fault gouges with varying content of different clay minerals.