• Journal of Conservation Science
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• v.23
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• pp.25-37
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• 2008

This study focuses on identification of mineralogical and geochemical characteristics and interpretation of raw material sources for prehistoric chlorite beads excavated from Geoseokri site in Boseong and Buntori site in Haenam, Korea. These prehistoric beads consist of three grayish blue ring-shaped beads, one dark green tubular bead and one greenish black tubular bead that show acicular-columnar and fibrous microtexture. The beads are composed of $SiO_2$, $Al_2O_3$, MgO and FeO as majors and a trace amount of $K_2O$, CaO and Na_2O$. Mineral species is mostly chlorite with a small amount of quartz and feldspar. Quantitative analysis indicates that the grayish blue ring-shaped beads and the dark green tubular bead belong to clinochlore and the greenish black tubular bead does to the boundary between clinochlore and sheridantie. Chlorite is a hydrous phyllosilicate mineral and it shows various microtexture of acicular, sheeted, earthy, granular andfibrous shapes. As its hardness is 2, chlorite is easily engraved due to its softness. It has aesthetic worthy as it shows green, black and greenish gray colors and pearly to greasy luster as well. These factors would lead to the extensive use of chloritic beads as ornaments from prehistoric times. Though the mineral sources of the chlorite beads can be found in central western region of Chungnam and Iwon of Hamnam, those areas are too distant from the two relic sites. Instead, chlorite ores commonly occur as altered products in wall rock alteration zone of every hydrothermal deposit. Therefore, it is probable that raw materials of chlorite were supplied from neighboring hydrothermal environment rather than far deposits. The result needs further study to verify raw material provenance interpretation, supply, manufacture and distribution on the basis of archaeological points of view.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.1
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• pp.1-10
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• 2020

The atomic structures of silicate liquids at high pressure provide insights into the transport properties including thermal conductivities or elemental partitioning behavior between rocks and magmas in Earth's interior. Whereas the local electronic structure around silicon may vary with the arrangement of the nearby oxygens, the detailed nature of such relationship remains to be established. Here, we explored the atomic origin of the pressure-induced changes in the electronic structure around silicon by calculating the partial electronic density of states and L₃-edge X-ray absorption spectra of SiO₂ polymorphs. The result showed that the Si PDOS at the conduction band varies with the crystal structure and local atomic environments. Particularly, d-orbital showed the distinct features at 108 and 130 eV upon the changes in the coordination number of Si. Calculated Si XAS spectra showed features due to the s,d-orbitals at the conduction band and varied similarly with those observed in s,d-orbitals upon changes in the crystal structures. The calculated Si XAS spectrum for α-quartz was analogous to the experimental Si XRS spectrum for SiO₂ glass, implying the overall similarities in the local atomic environments around the Si. The edge energies at the center of gravity of XAS spectra were closely related to the Si-O distance, thus showing the systematic changes upon densification. Current results suggest that the Si L_2,3-edge XRS, sensitive probe of the Si-O distance, would be useful in unveiling the densification mechanism of silicate glasses and melts at high pressure.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.3
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• pp.157-167
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• 2021

Lead (Pb) is one of the key trace elements, exhibiting a peculiar partitioning behavior into silicate melts in contact with minerals. Partitioning behaviors of Pb between silicate mineral and melt have been known to depend on melt composition and thus, the atomic structures of corresponding silicate liquids. Despite the importance, detailed structural studies of Pb-bearing silicate melts are still lacking due to experimental difficulties. Here, we explored the effect of lead content on the atomic structures, particularly the evolution of silicate networks in Pb-bearing sodium metasilicate ([(PbO)_x(Na₂O)_1-x]·SiO₂) glasses as a model system for trace metal bearing natural silicate melts, using ²⁹Si solid-state nuclear magnetic resonance (NMR) spectroscopy. As the PbO content increases, the ²⁹Si peak widths increase, and the maximum peak positions shift from -76.2, -77.8, -80.3, -81.5, -84.6, to -87.7 ppm with increasing PbO contents of 0, 0.25, 0.5, 0.67, 0.86, and 1, respectively. The ²⁹Si MAS NMR spectra for the glasses were simulated with Gaussian functions for Qⁿ species (SiO₄ tetrahedra with n BOs) for providing quantitative resolution. The simulation results reveal the evolution of each Qⁿ species with varying PbO content. Na-endmember Na₂SiO₃ glass consists of predominant Q² species together with equal proportions of Q¹ and Q³. As Pb replaces Na, the fraction of Q² species tends to decrease, while those for Q¹ and Q³ species increase indicating an increase in disproportionation among Qⁿ species. Simulation results on the ²⁹Si NMR spectrum showed increases in structural disorder and chemical disorder as evidenced by an increase in disproportionation factor with an increase in average cation field strengths of the network modifying cations. Changes in the topological and configurational disorder of the model silicate melt by Pb imply an intrinsic origin of macroscopic properties such as element partitioning behavior.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.1
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• pp.65-73
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• 2022

The proper estimation of physical and chemical properties of Earth materials and their structures at high pressure and high temperature conditions is key to the full understanding of diverse geological processes in Earth and planetary interiors. Multi-anvil press - high-pressure generating device - provides unique information of Earth materials under compression, mainly relevant to Earth's upper mantle. The quantitative estimation of the relationship between the oil load within press and the actual pressure conditions within the sample needs to be established to infer the planetary processes. Such pressure-load calibration has often been based on the phase transitions of crystalline earth materials with known pressure conditions; however, unlike at high temperature conditions, phase transitions at low (or room) temperatures can be sluggish, making the calibration at such conditions challenging. In this study, we explored the changes in Al coordination environments of permanently densified pyrope glasses upon the cold compression using the high-resolution ²⁷Al MAS and 3QMAS NMR. The fractions of highly coordinated Al in the cold compressed pyrope glasses increase with increasing oil load and thus, the peak pressure condition. Based on known relationship between the peak pressure and the Al coordination environment in the compressed pyrope glasses at room temperature, we established a room temperature pressure-load calibration of the 14/8 HT assembly in 1,100-ton multi-anvil press. The current results highlight the first pressure-load calibration of any high pressure device using high-resolution NMR. Irreversible structural densification upon cold compression observed for the pyrope glasses provides insights into the deformation and densification mechanisms of amorphous earth materials at low temperature and high pressure conditions within the subducting slabs.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.1
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• pp.41-50
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• 2022

To study the properties of Sr²⁺ exchange into zeolite A with increasing the molar concentration of Na⁺ in given exchange solution, four single crystals of fully dehydrated Sr²⁺- and Na⁺- exchanged zeolite A were prepared by the bath method using mixed ion-exchange solutions. The Sr(NO₃)₂:NaNO₃ molar rations of the ion exchange solution were 1:1(crystal 1), 1:100(crystal 2), 1:250(crystal 3), and 1:500 (crystal 4), respectively, with a total concentration of 0.05 M. The single-crystals were then vacuum dehydration at 623 K and 1×10^-4 Pa for 2 days. Their single-crystal structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Pm3-m, at 100(1) K, and were then refined to the final error indices of R₁/wR₂=0.047/0.146, 0.048/0.142, 0.036/0.128, and 0.040/0.156 for crystals 1, 2, 3, and 4, respectively. In crystals 1 and 2, the 6 Sr²⁺ ions are found at three different crystallographic sites. In crystal 3, 1 Sr²⁺ and 10 Na⁺ ions are found in large cavity and sodalite unit. In crystal 4, only 12 Na⁺ ions occupy three equipoints. The degree of Sr²⁺ ion-exchange decreased sharply from 100 to 16.7 to 0% as the initial Na⁺ concentration increase and the Sr²⁺ concentration decrease. In addition, the unit cell constant of the zeolite framework decreased with this lower level of Sr²⁺ exchange.

• Economic and Environmental Geology
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• v.55 no.5
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• pp.531-540
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• 2022

Various iron minerals that precipitate in acid mine drainage have a great influence on the concentration change and mobility of trace elements in the drainage during phase transition to other minerals as well as the precipitation process. This study investigated the change of mineral properties and the behaviors of trace elements influenced by pH and time for the precipitates collected from the acid mine drainage treatment system of the Dalsung mine, where schwertmannite is mainly precipitated. However, the main mineral precipitated in the drainage was goethite, suggesting schwetmannite has already undergone a phase transition to goethite to some extent, and it was observed that at higher pH, the peak width at half maximum of XRD peak was narrower. This can be interpreted as the transformation of small amount of amorphous schwetmannite to goethite or an increase in the crystallinity of goethite, and it showed that the higher the pH, the greater this change was. The concentration of Fe was also greatly affected by the pH values, and as the pH increased, the concentration of Fe in the drainage decreased. With increasing time, the Fe concentration increased and then decreased, which can be interpreted to indicate the dissolution of schwertmannite and precipitation of goethite. This mineral change probably resulted in the rapid increase of the concentration of S at initial stage, but its concentration was stabilized later. The concentration of S is also related to the stability of schwetmannite, showing a high concentration at a low pH at which schwertmannite is stable and a low concentration at a high pH at which goethite is stable. The trace elements present as cations in the drainage also showed a close relationship with the pH, generally the lower the pH, the higher the concentration, due to the solubility changes by the pH, and the precipitation and the changes in mineral surface charge at high pH. On the other hand, in the case of As, existing as an anion, although it showed a high concentration at low pH, its concentration increased with time at all pH values, which is probably related to the concentration of Fe which can be coprecipitated in the drainage, and the increase of As concentration with time is also considered to be related to the decrease in schwertmannite rather than the mineral surface charge.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.1
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• pp.55-72
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• 2023

This study aims to identify the fault zone architecture and geometric and kinematic characteristics of the Yeongdeok Fault, based on the geometry and kinematic data of various structural elements obtained by detailed field survey and anisotropy of magnetic susceptibility (AMS) of the fault rocks. The Yeongdeok Fault extends from Opo-ri, Ganggu-myeon, Yeongdeok-gun to Gilgok-ri, Maehwa-myeon and Bangyul-ri, Giseong-myeon, Uljin-gun, and cuts various rock types from the Paleo-proterozoic to the Mesozoic with a range of 4.6-5.0 km (4.77 km in average) of right-lateral offset or forms the rock boundaries. The fault is divided into four segments based on its geometric features and shows N-S to NNW strikes and dips of an angle of ≥ 54° to the east at most outcrops, even though the outcrops showing the westward dipping (a range of 54°-82°) of fault surface increase as it goes north. The Yeongdeok Fault shows the difference in the fault zone architecture and in the fault core width ranging from 0.3 to 15 m depending on the bedrock type, which is interpreted as due to differences in the physical properties of bedrock such as ductility, mineral composition, particle size, and anisotropy. Combining the results of paleostress reconstruction and AMS in this and previous studies, the Yeongdeok Fault experienced (1) sinistral strike-slip under NW-SE maximum horizontal principle stress (σ_Hmax) and NE-SW minimum horizontal principle stress (σ_Hmin) in the late Cretaceous to early Cenozoic, and then (2) dextral strike-slip under NE-SW maximum horizontal principle stress (σ_Hmax) and NW-SE minimum horizontal principle stress (σ_Hmin) in the Paleogene. It is interpreted that the deformation caused by the Paleogene dextral strike-slip movement was the most dominant, and the crustal deformation was insignificant thereafter.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.418-428
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• 2007

Physical and chemical properties of the aggregate by-products including sludge and crushed dust samples collected from the 21 private companies throughout the country were analyzed to evaluate possible usage of the by-products as artificial soil materials for plantation. The pH of the materials ranged from 8.0 to 11.0. The organic matter content was $2.85g\;kg^{-1}$, and the total nitrogen content and available phosphate content were low as 0.7 percents and $12.98mg\;kg^{-1}$, respectively. Exchangeable $Ca^{2+}$, $Mg^{2+}$, $K^+$, and $Na^+$ were 2.29, 0.47, 0.02 and $0.05cmol\;kg^{-1}$, respectively. Heavy metal contents were lower than the limits regulated by environmental law of Korea. Textural analysis showed that most of the materials were silt loam with low water holding capacity ranged from 0.67 to 7.41 percents, and with low hydraulic conductivity ranged from 0.4 to $2.8m\;s^{-1}$. Mineralogical analysis showed that the aggregate by product materials were mostly composed of silicate, alumina and ferric oxides except calcium oxide dominant materials derived from limestones. The primary minerals were quartz, feldspars and dolomites derived from granite and granitic gneiss materials. Some samples derived from limestone material showed calcite and graphite together with the above minerals. According to the result, it can be concluded that the materials could be used as the artificial soil material for plantation after proper improvement of the physico-chemical properties and fertility.

• Economic and Environmental Geology
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• v.55 no.4
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• pp.377-388
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• 2022

Laboratory-scale experiments were performed to identify the As removal mechanism of the residual slag generated after the mineral carbonation process. The residual slags were manufactured from the steelmaking slag (blast oxygen furnace slag: BOF) through direct and indirect carbonation process. RDBOF (residual BOF after the direct carbonation) and RIBOF (residual BOF after the indirect carbonation) showed different physicochemical-structural characteristics compared with raw BOF such as chemical-mineralogical properties, the pH level of leachate and forming micropores on the surface of the slag. In batch experiment, 0.1 g of residual slag was added to 10 mL of As-solution (initial concentration: 203.6 mg/L) titrated at various pH levels. The RDBOF showed 99.3% of As removal efficiency at initial pH 1, while it sharply decreased with the increase of initial pH. As the initial pH of solution decreased, the dissolution of carbonate minerals covering the surface was accelerated, increasing the exposed area of Fe-oxide and promoting the adsorption of As-oxyanions on the RDBOF surface. Whereas, the As removal efficiency of RIBOF increased with the increase of initial pH levels, and it reached up to 70% at initial pH 10. Considering the PZC (point of zero charge) of the RIBOF (pH 4.5), it was hardly expected that the electrical adsorption of As-oxyanion on surface of the RIBOF at initial pH of 4-10. Nevertheless it was observed that As-oxyanion was linked to the Fe-oxide on the RIBOF surface by the cation bridge effect of divalent cations such as Ca²⁺, Mn²⁺, and Fe²⁺. The surface of RIBOF became stronger negatively charged, the cation bridge effect was more strictly enforced, and more As can be fixed on the RIBOF surface. However, the Ca-products start to precipitate on the surface at pH 10-11 or higher and they even prevent the surface adsorption of As-oxyanion by Fe-oxide. The TCLP test was performed to evaluate the stability of As fixed on the surface of the residual slag after the batch experiment. Results supported that RDBOF and RIBOF firmly fixed As over the wide pH levels, by considering their As desorption rate of less than 2%. From the results of this study, it was proved that both residual slags can be used as an eco-friendly and low-cost As remover with high As removal efficiency and high stability and they also overcome the pH increase in solution, which is the disadvantage of existing steelmaking slag as an As remover.

• Economic and Environmental Geology
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• v.56 no.2
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• pp.125-138
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• 2023

Most of previous cesium (Cs) sorbents have limitations on the treatment in the large-scale water system having low Cs concentration and high ion strength. In this study, the new Cs sorbent that is eco-friendly and has a high Cs removal efficiency was developed by improving the coal mine drainage treated sludge (hereafter 'CMDS') with the addition of Na and S. The sludge produced through the treatment process for the mine drainage originating from the abandoned coal mine was used as the primary material for developing the new Cs sorbent because of its high Ca and Fe contents. The CMDS was improved by adding Na and S during the heat treatment process (hereafter 'Na-S-CMDS' for the developed sorbent in this study). Laboratory experiments and the sorption model studies were performed to evaluate the Cs sorption capacity and to understand the Cs sorption mechanisms of the Na-S-CMDS. The physicochemical and mineralogical properties of the Na-S-CMDS were also investigated through various analyses, such as XRF, XRD, SEM/EDS, XPS, etc. From results of batch sorption experiments, the Na-S-CMDS showed the fast sorption rate (in equilibrium within few hours) and the very high Cs removal efficiency (> 90.0%) even at the low Cs concentration in solution (< 0.5 mg/L). The experimental results were well fitted to the Langmuir isotherm model, suggesting the mostly monolayer coverage sorption of the Cs on the Na-S-CMDS. The Cs sorption kinetic model studies supported that the Cs sorption tendency of the Na-S-CMDS was similar to the pseudo-second-order model curve and more complicated chemical sorption process could occur rather than the simple physical adsorption. Results of XRF and XRD analyses for the Na-S-CMDS after the Cs sorption showed that the Na content clearly decreased in the Na-S-CMDS and the erdite (NaFeS₂·2(H₂O)) was disappeared, suggesting that the active ion exchange between Na⁺ and Cs⁺ occurred on the Na-S-CMDS during the Cs sorption process. From results of the XPS analysis, the strong interaction between Cs and S in Na-S-CMDS was investigated and the high Cs sorption capacity was resulted from the binding between Cs and S (or S-complex). Results from this study supported that the Na-S-CMDS has an outstanding potential to remove the Cs from radioactive contaminated water systems such as seawater and groundwater, which have high ion strength but low Cs concentration.