• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.107-109
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• 2009

Micromagnetism explores magnetic configurations in nano-scales to visualize the details of magnetic domain structures, and also can produce snapshots of complex remanence or other magnetic states. The particle shape has a profound effect on the magnetic hysteresis. For instance, octahedral magnetite showed higher coercivity and squareness than cubic magnetite.

• 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.

• 한국해양학회지
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• v.30 no.4
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• pp.271-278
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• 1995

A study of heavy mineral sands in terms of heavy mineral group and concentration has been carried out by analyzing 88 grab samples from the continental shelf off the southeast coast of Korea. Heavy mineral groups seem to be outlined and classified into four regions in the study area: 1) the western region; high concentrations of stable minerals, such as opaque mineral, magnetite, garnet and ZTR, 2) Korean Trough region; moderate concentrations of stable minerals, 3) the eastern region; abundant altered mineral and amphibole with minor of pyroxene concentration, and 4) the northeastern shelf-break region; low concentration of stable minerals with abundant altered minerals. The sedimentologic natures of four major heavy mineral regions (groupings) seem to be influenced by physical, dynamic and hydraulic milieu and also aerial and/or subaqueous weathering processes. It seems to be, further, plausible that shallow marine waves and currents associated with neritic dynamic condition of transgressive sea might be very effective on the concentration and groupings (sorting) of heavy min-erals in the surficial sediments of the continental shelf. The pyroxene-abundant heavy mineral suite (group), in fact, seems to suggest a sediment source from Japanese Islands.

• Journal of the Mineralogical Society of Korea
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• v.19 no.3 s.49
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• pp.197-207
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• 2006

In the coal-bearing formations of the Janggi Group, which are reported as typical clastic sediments, several beds of volcaniclastic rocks are actually found in the Yeongil area. The coal-bearing formations generally exhibit alternating lithologic characteristics of pyroclastic and epiclastic sedimentary facies. Tuff and tuffaceous sandstone rich in pumice fragments are characteristic in the coal-bearing fermations. Diagenetic minerals found in the pyroclastic rocks of the upper and lower coal-bearing formations are montmorillonite, clinoptilolite, opal-CT, and quartz. Several tuffaceous beds correspond to the low-grade ores of zeolites and bentonite, and moreover, these ores mostly occur as thin beds less than 1 m in thickness. Thus, the potential of altered tuffaceous rocks as the resources typical of zeolite and bentonite seems to be low. However, based on mineral composition and CEC determinations, it can be evaluated that these tuffaceous rocks mostly have the promising potential for utilization as the absorbent-functional mineral resources such as acid clays, if these low-grade ores plus adjacent tuffaceous rocks are collectively exploited.

• Economic and Environmental Geology
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• v.12 no.3
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• pp.127-146
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• 1979

Though tungsten minerals have been mined for over fifty years in Korea, which has become one of the worlds largest tungsten producers since 1951, knowledge of their mineralogy and geochemistry is somewhat limited to the school of tungsten students. There is a considerable amount of literature throughout the world on the tungsten mineralogy, the geochemical behaviour of tungsten, the nature of tungsten deposits and geological environments for tungsten mineralisation. Commonly known tungsten minerals such as scheelite and wolframite belong to one of two series, the scheelite or the wolframite series, as the primary tungsten minerals. Secondary tungsten minerals are known rather rare, however, some of them plays an important role-of exploration guide in search for tungsten deposits. The geochemistry of tungsten is imperfectly known, and apparently the behaviour of tungsten in geological processes has been the subject of few studies. Recently, some aspects of the fundamental geochemistry of tungsten has been worked out and compiled the data in broad the up to date by many authors. In order to facilitate the better understanding and future exploration of tungsten deposits, an attempt has been made to summarise the existing knowledge of the fundamental geochemistry of tungsten, together with its common geochemical association with various types of tungsten deposits.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.107-115
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• 2010

Removal and mineralization of dissolved uranium by bacteria in KURT (KAERI Underground Research Tunnel), Korea Atomic Energy Research Institute (KAERI) was investigated. Two different bacteria, IRB (iron-reducing bacteria) and SRB (sulfate-reducing bacteria) was used, and minerals formed by these bacteria were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Compared to uranyl ions, ferric ions were preferentially reduced by IRB, showing that there is no significant reduction and removal of uranium. However, uranium concentration considerably decreased by addition of Mn(II). Results show that a sulfide mineral such as mackinawite (FeS) is formed by SRB respiration through combination of Fe(II) and S without manganese sulfide formation. In the presence of Mn(II), however, uranium is removed effectively, suggesting that the sorption and incorporation of uranium could be affected by Mn(II) onto the sulide minerals.

• Journal of the Mineralogical Society of Korea
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• v.29 no.4
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• pp.209-220
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• 2016

Clay minerals are a major player to determine geochemical cycles of trace metals and carbon in the critical zone which covers the atmosphere down to groundwater aquifers. Molecular dynamics (MD) simulations can examine the Earth materials at an atomic level and, therefore, provide detailed fundamental-level insights related to physicochemical properties of clay minerals. In the current study, we have applied classical MD simulations with clayFF force field to dioctahedral clay minerals (i.e., gibbsite, kaolinite, and pyrophyllite) to analyze and compare structural parameters (lattice parameter, atomic pair distance) with experiments. We further calculated vibrational power spectra for the hydroxyls of the minerals by using the MD simulations results. The MD simulations predicted lattice parameters and interatomic distances respectively deviated less than 0.1~3.7% and 5% from the experimental results. The stretching vibrational wavenumber of the hydroxyl groups were calculated $200-300cm^{-1}$ higher than experiment. However, the trends in the frequencies among different surface hydroxyl groups of each mineral was consistent with experimental results. The angle formed by the surface hydroxyl group with the (001) plane and hydrogen bond distances of the surface hydroxyls were consistent with experimental result trends. The inner hydroxyls, however, showed results somewhat deviated from reported data in the literature. These results indicate that molecular dynamics simulations with clayFF can be a useful method in elucidating the roles of surface hydroxyl groups in the adsorption of metal ions to clay minerals.

• Journal of the Mineralogical Society of Korea
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• v.21 no.3
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• pp.289-295
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• 2008

We studied the difference between the clay mineral content in the bulk marine sediments (absolute clay mineral composition) and clay mineral content only in total clay minerals (relative clay mineral composition) of the Yellow Sea marine sediments, and correlated the relationship between their distribution patterns. We used 56 Yellow Sea Surface sediments collected at the second cruise in 2001 of KORDI, and determined the absolute mineral composition using the quantitative X-ray diffraction analysis. Yellow Sea surface sediments consist of primary rock forming minerals including quartz (average 44.7%), plagioclase (15.9%), alkali feldspar (10.0%), hornblende (2.8%) together with clay minerals (illite 15.3%, chlorite 2.6% and kaolinite 1%) and carbonates (calcite 1.7%, aragonite 0.6%). Absolute clay mineral contents are very high in the region extending from the southeast of Sandong Peninsula to the southwest of Jeju Island. In contrast, it is very low along the margin of the Yellow Sea. Such distribution patterns of absolute clay mineral content are very similar to those of fine-grained sediments in the study area. The average relative clay mineral composition of illite, chlorite, and kaolinite is respectively 80.3%, 14.9% and 4.8%. The distribution pattern of relative mineral composition shows very different phenomenon when compared with those of absolute mineral composition, and also do not exhibit any positive relationship with that of fine-grained sediments in which clay mineral composition is abundant. Therefore, we suggest that the relative clay mineral compositions and their distribution patterns must be used very carefully when interpreting the origin of sediment provenance.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.1-9
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• 1993

A study was carried out to investigate the genesis and mineralogical characteristics of clay minerals in three different types of soil derived from the gray shale distributed in Kyeongbuk Province in Korea. The soils have been developed from parent materials of residuum (Daegu series, Sirye series), colluvium(Banho series), and alluvium (Bigog series) of the same origin of parent rock with a topographical sequence. The investigation mainly focussed on the mineralogical aspects of primary minerals of asnd and silt fractions, identification and quantification of clay minerals, and characterization of hydroxy-interlayered mineral (HIM) along with their chemical composition. The identification was done through analyses of chemical, X-ray diffraction, and thermal methods. The major clay minerals in the soils are illite, vermiculite, kaolin and HIM, while chlorite and mixed layer minerals such as illite/chlorite and illite/vermiculite were coexisted as a subsidiary minerals. The distribution of clay minerals, however, varies according to the location and types of parent material. In the soils derived from the parent material of residuum, the upper soil (Daegu series) shows higher of 2:1 type minerals such as illite, vermiculite, and HIM than 1:1 type mineral rich in the lower soil(Sirye series). Soils developed from the parent material of colluvium and alluvium were high in illlte and mixed layer minerals, but low in HIM compared with the residual soils. The predominant weathering sequence of the clay minerals in each soil could be inferred as follows according to the minerlogical distribution and quantification of clay minerals : Daegu series, illite ${\rightarrow}$ vermiculite ${\rightarrow}$ HIM ; Sirye series, vermiculite ${\rightarrow}$ kaolin minerals ; Banho sereies and Bigog series, illite ${\rightarrow}$ illlte/vermiculite and/or illite/chlorlte mixed layer ${\rightarrow}$ vermiculite.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.245-252
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• 2011

콜롬비아는 안데스 산맥의 북단에 위치하며 NS 방향의 단층대를 기준으로 지질 환경의 차이가 크다. 단층대를 기준으로 동부지역은 원생대 변성암류와 이를 피복하는 고생대 변성퇴적암류가 주로 분포하며, 서부 지역은 고생대 퇴적암류, 중생대 화성암류, 제 3 기 화산양류 및 퇴적암류가 주로 분포한다. 지화학이상대는 6개 그룹으로 분류되며, 철 (Fe), 귀금속(Au, Ag, Pt), 기초금속(Cu, Pb, Zn), 희유금속(Sn, Cr, Co, Mn, Mo, Ni, Nb, W, V, Mg, Ti, Be, REE, Ga, Zr, Hf, Se, Te, Ta, Cd, In, Li 등) 빛 핵원료자원인 U 이상대로 구성된다. 콜롬비아의 주요 부존자원은 석탄, 니켈, 금 및 에메랄드이다. 에메랄드, 석탄 및 니켈은 세계적인 매장규모와 생산량을 보인다. 콜롬비아는 탐사가 거의 수행되지 않은 지역이 전 국토의 49%에 달해 광물부존 잠재성은 현재보다 크게 높을 것으로 보인다. 따라서 최근 콜롬비아와의 광물자원 협력이 강화되고 있는 시점에서 미탐사 지역을 대상한 공동탐사를 지화학 이상대가 확인된 지역을 중심으로 수행하여 신규광체를 확보하고, 광물자원 협력을 강화함으로써 공동개발 여건을 마련할 필요가 있다고 판단된다.