김상건 Sanggeon Kim , 손상보 Sangbo Son , 권기덕 Kideok D. Kwon

DOI: Vol.37(No.2) 13-22, 2024

X-ray absorption near-edge structure (XANES) spectroscopy can provide qualitative insights into the coordination chemistry of calcium (Ca) across a variety of geological materials. However, systematic studies on Ca K-edge XANES spectral features and the Ca coordination parameters are rare. This study investigated potential correlations between the spectral features of Ca K-edge XANES and the coordination parameters of Ca for selected Ca-bearing minerals (anorthite, aragonite, calcite, diopside, dolomite, grossular, monohydrocalcite, perovskite, and wollastonite), employing density functional theory (DFT) calculations. DFT calculations accurately reproduced the main features of their experimental Ca K-edge XANES spectra for representative silicates, carbonates, and titanates. No strong correlation was observed between XANES peak positions vs. Ca-O distances (or Ca coordination numbers). However, a significant correlation was noted between the peak intensity of post-edge peaks vs. the effective coordination number of Ca in minerals of similar chemical compositions. These results show the potential, yet limited, applicability of XANES spectra for molecular-level research of Ca-bearing geomaterials, and highlight the critical role of DFT computations in interpretating XANES spectra.

칼슘, X-선 흡수 스펙트럼, 밀도범함수이론, 유효배위수, Calcium, X-ray absorption spectrum, Density functional theory, Effective coordination number

박선영 Park Sun Young , 이경북 Lee Kyungbook , 최지영 Choi Jiyoung , 박주영 Park Ju Young

DOI: Vol.37(No.2) 23-34, 2024

It is essential to know the mineral composition of core samples to assess the possibility of gas hydrate (GH) in sediments. During the exploration of gas hydrates (GH), mineral composition values were obtained from each core sample collected in the Ulleung Basin using X-ray diffraction (XRD). Based on this data, machine learning was performed with 3100 input values representing XRD peak intensities and 12 output values representing mineral compositions. The 488 data points were divided into 307 training samples, 132 validation samples, and 49 test samples. The random forest (RF) algorithm was utilized to obtain results. The machine learning results, compared with expert-predicted mineral compositions, revealed a Mean Absolute Error (MAE) of 1.35%. To enhance the performance of the developed model, principal component analysis (PCA) was employed to extract the key features of XRD peaks, reducing the dimensionality of input data. Subsequent machine learning with the refined data resulted in a decreased MAE, reaching a maximum of 1.23%. Additionally, the efficiency of the learning process improved over time, as confirmed from a temporal perspective.

가스 하이드레이트, XRD, 광물 조성, 기계학습, Gas hydrate, Mineral composition, Machine learning

안현호 Hyeonho An , 양기호 Kiho Yang , 고영탁 Youngtak Ko , 이용문 Yongmoon Lee , 정재우 Jaewoo Jung

DOI: Vol.37(No.2) 35-46, 2024

This study investigated the origin and mineralogical-geochemical characteristics of a small ferromanganese (Fe-Mn) nodule sample obtained from the abyssal seafloor of the Magellan Seamount cluster. To this end, X-ray diffraction and X-ray fluorescence analyses were conducted. The dark brown Fe-Mn oxides constituting the nodule had a homogeneous texture without distinguishable layers, forming around three distinct nuclei. The oxides had a low average Mn/Fe ratio of 0.73 (0.24-1.10) and were characterized by high Co content (0.41-0.85 wt.%, average = 0.58 wt.%) as well as low Ni (0.06-1.24 wt.%, average = 0.55 wt.%) and Cu (0.27-1.02 wt.%, average = 0.59 wt.%) concentrations. The maximum age of the nodule was estimated at 0.52 Ma, suggesting that it began forming during the transition from the glacial to the interglacial periods in the middle Pleistocene. The Fe-Mn oxide layer comprised vernadite, smectite, quartz, and feldspar, while the nuclei were composed of soft sediments. The presence of vernadite, a typical hydrogenetic Fe-Mn oxide mineral, along with the low Mn/Fe ratio, high Co content, and low Ni and Cu concentrations, indicates that Fe-Mn nodules on the abyssal seafloor of the Magellan Seamount cluster in the western Pacific Ocean formed through hydrogenetic processes.

서태평양, 마젤란 해산군, 수성기원 망가니즈 단괴, 유용 광물 자원, Western pacific, Magellan seamount cluster, Hydrogenetic ferromanganese nodule, Prospective mineral resources

김영규 Yeongkyoo Kim

DOI: Vol.37(No.2) 47-57, 2024

Jarosite, a mineral belonging to the alunite family, is found in various low pH environments and can incorporate cations or oxyanions into its structure, either by coprecipitation or substitution. This mineral is sensitive to pH changes and can easily transform into goethite upon geochemical changes, such as an increase in pH. This transformation can release toxic ions from the jarosite, potentially causing additional environmental damage. In addition to potassium (K), sodium (Na) and ammonium (NH4) can also substitute for cations in jarosite. The formation of jarosites containing these and other cations is significant not only for acid mine drainage but also for the smelting industry. In this study, three different types of jarosites containing various cations were synthesized and the phase transformation of each jarosite to goethite upon pH change were compared. All the jarosites were sensitive to pH changes, showing much higher rates of phase change at pH 8 than at pH 4. At the relatively low pH of 4, the phase transformation of K-jarosite, which is most stable in structure, to goethite was the slowest. For the other two jarosites, the cations have either smaller or larger radii than K ions, resulting in differences in structural stability and they showed more rapid transformations to goethite. However, at pH 8, K-jarosite exhibited a much more rapid transformation to goethite than the other jarosites, which was also evident from the rapid increase in K ions in aqueous solution. The mineral transformation behavior of K-jarosite at higher pH is significantly different from that at lower pH, indicating that the mechanism of the transformation to goethite differs between these conditions, which requires further investigation. The results of this study indicate that the mineral transformation of jarosite in acid mine drainage or smelter waste disposal may significantly influence the behavior of heavy metals. This research provides valuable insights for predicting the behavior of heavy metals in smelting industry waste disposal.

자로사이트, 양이온, 침철석, 상변화, 중금속 용출, Jarosite, Cation, Goethite, Phase transformation, Heavy metal leaching

김수현 Suhyun Kim , 양기호 Kiho Yang

DOI: Vol.37(No.2) 59-66, 2024

This study aimed to understand the mineral characteristics of the sediment from the summit of Magellan Seamount KC-7. In December 2023, approximately 20 years after the Korea Institute of Ocean Science and Technology conducted an initial field investigation of the sediment from the summit of seamount KC- 7 in 2004, were obtained and subjected to mineralogical analysis to determine the essential sedimentary environmental characteristics of the seamount summit. For this purpose, smear slide analysis through a polarized microscope and X-ray diffraction analysis were conducted. The total length of the obtained sediments was 672.7 cm, and they were generally composed of calcareous ooze. In the lower part of the sediments (283.7-672.7 cm), Discoaster groups and coccoliths were predominantly observed. However, in the upper part above 283.7 cm, both coccoliths and foraminifera began to appear together, and in the uppermost sediments (0-151.7 cm), foraminifera became dominant, and the grain size of the sediments increased. This reflects a shift in the marine environment from high temperature and eutrophic conditions to low temperature and oligotrophic conditions as the seamount moved to its current position, aligning with the present oligotrophic environment of the western Pacific. The sediments comprised clay minerals, quartz, feldspar, and calcite. Examining the content changes of the four major mineral groups with depth, calcite was the most predominant, averaging 89.8 wt%. However, towards the upper layers, there was a trend of increasing clay content (up to 12.1 wt%) and decreasing calcite content (down to 85.1 wt%). This indicates that while the sedimentation mechanism remained unchanged, there has been a gradual influx of aeolian sediments.

서태평양, 마젤란 해산군, 정상부 퇴적물, 광물 조성, 고환경 복원, Western pacific, Magellan seamount cluster, Summit sediments of seamount, Mineral compositions, Reconstruction of paleoenvironment

김효임 Hyo-im Kim , 이범한 Bum Han Lee

DOI: Vol.37(No.2) 67-76, 2024

In light of the development of modern high-tech industries, where human sustainability is becoming increasingly important, anorthosite needs to be reevaluated not only for its potential as a new source of aluminum, but also as a primary resource with a wide range of industrial applications. In particular, a relatively simple chemical composition with a high CaO content and Al₂O₃/SiO₂ ratio, along with its relatively low impurity levels and chemically stable nature offers significant advantages in industrial processes. Thus, anorthosite is considered as an important industrial resource in the age of energy transition. In this review, we examine the mineralogical and geochemical characteristics of anorthosite that determines their stability and reactivity In light of the development of modern high-tech industries, where human sustainability is becoming increasingly important, anorthosite needs to be reevaluated not only for its potential as a new source of aluminum, but also as a primary resource with a wide range of industrial applications. In particular, a relatively simple chemical composition with a high CaO content and Al₂O₃/SiO₂ ratio, along with its relatively low impurity levels and chemically stable nature offers significant advantages in industrial processes. Thus, anorthosite is considered as an important industrial resource in the age of energy transition. In this review, we examine the mineralogical and geochemical characteristics of anorthosite that determines their stability and reactivity Based on their characteristics, we propose the potential use of utilizing the anorthosite as an alternative to the Bayer process which has the limitations. We also explore its application as the eco-friendly geo-synthetic materials, and as the new materials for carbon dioxide storage and utilization. As the demand for aluminum applications accelerates, anorthosite is gaining their importance in the geological industry and clean energy field. Therefore, advanced and extensive research on anorthosite complex occurring in the Hadong and Sancheong regions of Korea is critical to obtain opportunities to enhance economic advantages through efficient utilization of national resources and to lead to sustainable development.

회장암, 하동-산청 회장암 복합체, 자원잠재성, 탄산염안정화, 알루미늄, Anorthosite, Hadong-Sancheong anorthosite complex, Resource potentiality, Carbonate sequestration, Aluminum ore

유봉철 Bong Chul Yoo , 호르게아꼬스타 Jorge Acosta

DOI: Vol.37(No.2) 77-85, 2024

Recently, the world has been declaring global carbon neutrality to curb carbon emissions, a major factor in global warming. Therfore, high-tech and clean energy industries such as renewable energy, electric vehicles, batteries, and semiconductors are rapidly developing. The Korean government selected total 33 critical minerals on based of evaluating the supply risk and economic impact of raw minerals essential for national high-tech industries (semiconductors, secondary battery, etc). Among these critical minerals, Copper, Zinc and lead have been used as basic materials in human life from the past to the present and in addition, they are currently used as an essential material for mobile phones, electric vehicles, and batteries. So, I would like to introduce the Las Bambas copper mine within Apurimac porphyry copper metallogenic belt of Peru, which have the world’s 2nd (copper), 4th (zinc) and 5th (lead) largest reserves of these critical minerals. Las Bambas copper mine is the world’s largest mine with copper reserves of more than 1 billion tons and is joint venture project mine invested by MMG (Minerals and Metals Group, 62.5%), Guoxin international investment company (22.5%) and CITIC metal company (15.0%). This mine mainly produces copper and also produces gold, silver and molybdenum as a by-product. The ore grade of this mine has 0.77% Cu, 0.06 g/t Au, 3.93 g/t Ag and 178 ppm Mo. Mineral resource and ore reserve of this mine have 10.5 million ton Cu (0.61% Cu) and 6.9 million ton Cu (0.73% Cu). So, this mine life is about more than 20 years. The copper mineralization of this mine occurs as skarn type and vein type related with lower limestone of Ferrobamba formation and Cenozoic monzonites.

핵심광물, 라스 밤바스 광산, 지질, 산출광물, 광화작용, Critical mineral, Las bambas mine, Geology, Mineralogy, Mineralization