• Economic and Environmental Geology
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• v.55 no.2
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• pp.171-181
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• 2022

The Geochang Au-Ag deposit is located within the Yeongnam Massif. Within the area a number of hydrothermal quartz and calcite veins were formed by narrow open-space filling of parallel and subparallel fractures in the granitic gneiss and/or gneissic granite. Mineral paragenesis can be divided into two stages (stage I, ore-bearing quartz vein; stage II, barren calcite vein) by major tectonic fracturing. Stage I, at which the precipitation of major ore minerals occurred, is further divided into three substages (early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early, marked by deposition of pyrite with minor pyrrhotite and arsenopyrite; middle, characterized by introduction of electrum and base-metal sulfides with minor sulfosalts; late, marked by hematite with base-metal sulfides. Fluid inclusion data show that stage I ore mineralization was deposited between initial high temperatures (≥380℃ ) and later lower temperatures (≤210℃ ) from H₂O-CO₂-NaCl fluids with salinities between 7.0 to 0.7 equiv. wt. % NaCl of Geochang hydrothermal system. The relationship between salinity and homogenization temperature indicates a complex history of boiling, fluid unmixing (CO₂ effervescence), cooling and dilution via influx of cooler, more dilute meteoric waters over the temperature range ≥380℃ to ≤210℃. Changes in stage I vein mineralogy reflect decreasing temperature and fugacity of sulfur by evolution of the Geochang hydrothermal system with increasing paragenetic time. The Geochang deposit may represents a mesothermal gold-silver deposit.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.1
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• pp.51-64
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• 2022

For effective preservation of the rocks, which bearing plant fossils at Gumkwangdong Formation, Pohang, the properties of rock and treatment of chemicals were examined in an artificial weathering test. The rocks are diatomaceous siliceous mudstone, which contain a small amount of smectite and has developed laminated layers. The rocks react with water, the d₀₀₁ spacing of smectite was increased. On the one hand, the physical properties of the rock samples, such as surface hardness, improved after the application of ethyl silicate-based stone strengthener. On the other hand, the spacing of interlayer of swelling clay minerals decreased and spacing of laminae layer increased. When the ethyl silicate-based stone strengthener was applied after pretreatment with a swelling inhibitor, interlayer and spacing of laminae changes were similar to those when only the stone strengthener was treated. The effect of the swelling inhibitor was almost negligible. When the rocks that have been conserved with chemicals react with water, spacing of laminae has widened much, whereas when the rocks was in contact with moisture only, there was little change. In addition, if it is placed in the outdoor after conservation treatment, although it occurs slightly slower than the untreated rock, the separation of the lamination layer and the pulverization of the rock occur within a very short time. Consolidation is required to improve the physical properties of fossil rock, but when exposed to rain and undergoing freeze-thaw process, the effect is lost very quickly. Therefore, regardless of the chemical treatment, it is a priority to prevent direct rainfall contact with the rock.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.1
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• pp.75-81
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• 2022

Given that China's resource research, exploration and development and resource economy policies are closely related to Korea's industrial competitiveness in the field of global mineral energy resources, it is important to establish the domestic and overseas resource development strategies. In 2020, China will revise and set standards for mineral resources to ensure efficiency in exploration and development and storage management. China's Ministry of Natural Resources has established the National Mineral Resources Plan (2021-2025), aiming to achieve national goals and strategies, and local governments at all levels are also establishing and implementing regional mineral resources plans. As a result, the supervision and management of geological mineral exploration activities have been strengthened, and the safety of industrial production management in the field of geological mineral exploration and development has been strengthened. China has developed guidelines for high-quality geological exploration, surveying and mapping, improved the level of geological mineral exploration and strengthened the mining supervision and management system. According to China's standardization of mineral resources such as solid mineral resources and petroleum gas mineral resources, a new standard system for resource management will be established in China to improve scientific understanding, rational management and utilization.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.4
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• pp.277-291
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• 2021

A mineral phase contained in a rock sample can be categorized into several crystal populations with distinct origins and crystal growth histories. A detailed textural and mineralogical investigation on a clinopyroxene megacryst-bearing porphyritic dike with glassy chilled margins (tachylyte) in the southeastern Ulleung Island was conducted to decipher its crystal populations. During this study, we have measured glass and mineral major element compositions using electron microprobe analyzer. Tachylyte has a homogeneous trachyandesitic composition without any significant alteration characteristics, suggesting that its composition may represent the original melt composition of the dike. Clinopyroxene and plagioclase larger than 0.5 mm are antecrysts equilibrated with a more primitive melt composition than trachyandesitic tachylyte. Meanwhile, clinopyroxene and plagioclase microlites (<0.5mm) are regarded as primocrysts crystallized in-situ. According to our results, all clinopyroxenes in the Stage I Dodong Basalt are sectored into basal and prismatic parts, whose compositional ranges systematically vary: [Mg+Si+Fe]_basal ↔ [Al+Ti+Na]_prism. Therefore, we suggest that the effect of the elemental partitioning caused by the clinopyroxene sector zonation in Stage I volcanism should be considered in the future works.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.753-765
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• 2021

The Dongwon Au-Ag deposit is located within the Paleozoic Taebaeksan province, Okcheon belt. Mineral paragenesis can be divided into two stages (stage I, ore-bearing quartz veins; stage II, barren carbonate veins) by major tectonic fracturing. Stage I, at which the precipitation of major ore minerals occurred, is further divided into three substages(early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early, marked by deposition of pyrite with minor magnetite, pyrrhotite and arsenopyrite; middle, characterized by introduction of electrum and base-metal sulfides with minor sulfosalts; late, marked by argentite, Cu-As (and/or Sb) and Ag-Sb sulfosalts with base-metal sulfides. Fluid inclusion data show that stage I ore mineralization was deposited between initial high temperatures (≥430℃) and later lower temperatures (≤230℃) from fluids with salinities between 6.0 to 0.4 wt. percent equiv. NaCl. The relationship of salinity and homogenization temperature suggest that ore mineralization at Dongwon was deposited mainly due to fluid boiling, cooling and dilution via influx of cooler, more dilute meteoric waters. Changes in stage I vein mineralogy reflect decreasing temperature and fugacity of sulfur by evolution of the Dongwon hydrothermal system with increasing paragenetic time. The Dongwon deposit may represents a Korean-type and/or Au-Ag type mesothermal/epithermal gold-silver deposit.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.2
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• pp.141-151
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• 2022

The 16 natural zeolites collected from Mongolia (6 types), the United States (1 type), and Korea (9 types) were characterized by XRD, XRF, TGA, DTA, and CEC analysis. All 16 samples are composite minerals. Two or more mineral phases co-exist and consist primarily of minerals such as clinoptilolite, heulandite, mordenite, and chabazite. In certain samples, minerals like illite and quartz were present as impurities. The XRF analysis showed that the 16 natural zeolites contain SiO₂, Al₂O₃, K₂O, CaO, Na₂O, MgO, and Fe₂O₃ oxides. The cation exchange capacity of the U-1 sample was 223.3 meg/100 g, which is higher than the rest of the samples. M-6 sample in Mongolian natural zeolite and K-1 sample in Korean natural zeolite showed the highest cation exchange capacity at 166.6 meg/100 g. As a result of thermal differential and thermos gravimetric analysis, all 16 samples showed excellent thermal stability up to 600℃.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.4
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• pp.265-275
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• 2021

Findings of microplastics and nanoplastics from diverse natural environments have increased demand for research of the fate and transport of the potentially toxic plastic particles in soils and groundwater. Weathering of microplastics would generate a significant amount of nanoplastics, but nanoplastics research is scarce because of technical difficulties in detecting nanoplastics in environments and analyzing nanoplastics adsorption to mineral surfaces. In the current study, we tested a possibility using quartz crystal microbalance (QCM) for application to nanoplastics adsorption analysis on mineral surfaces. In silica (SiO₂)-packed column experiments, a measurable adsorption capacity for polystyrene nanoparticles often requires injection of unrealistically high ionic strengths or concentrated nanoplastic particles. The current test shows that QCM can measure polystyrene nanoplastics adsorbed onto SiO₂ surface under the low ionic strengths and nanoplastics concentrations, where typical column experiments cannot. QCM is a promising tool for understanding the interaction between nanoplastics and mineral surfaces and thus transport of nanoplastics in soils and groundwater.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.4
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• pp.219-226
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• 2021

We examined component analysis and lead isotope ratio analysis to find out the relationship between the excavation and the production site of 25 bronze weapons from prehistoric ages. All 25 bronze weapons are ternary alloys of copper-tin-lead and lead is artificially added. The lead isotope ratios of 25 bronze weapons show that bronze are made by raw materials in the southern regions of the Korean Peninsula, including northern China. The raw materials of narrow-shaped bronze dagger are supplied in zone 1-3 and northern China. In addition, provenance of lead for bronze halberd and pearhead are the rest of the region except for zone 1 and zone 4. Silver are enriched in most samples and zinc and cobalt are deficient. Arsenic and antimony detected only specific samples and can be used as critical parameter for provenance study. Lead isotopes and trace elements of archaeological bronzes will provide conservation scientist with useful tool to study the provenance of raw materials

• Economic and Environmental Geology
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• v.54 no.2
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• pp.199-212
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• 2021

The Sebyeonggwan Hall (National Treasure No. 305) is located on the Naval Headquarter of Three Provinces in Tongyeong, and it has partly undergone with several rebuilding, remodeling, repairing and restorations since it's the first establishment in Joseon Dynasty (AD 1605) of ancient Korea. This study focuses on 50 foundation stones that comprise the Sebyeonggwan. These stones are made of six rock types and currently have various shapes of the surface damages. As the foundation stones, the dominant rock type was dacitic lapilli tuffs, and provenance-based interpretation was performed to supply alternative stones for conservation. Most of the provenance rocks for foundation stones showed highly homogeneity with their corresponding stones of petrography, mineralogy and magnetic susceptibility. According to surface deterioration assessments, the most serious damages of the stones were blistering and scaling. The deterioration mechanism was identified through the analysis of inorganic contaminants, and the primary reason is considered salt weathering caused by sea breeze and other combined circumstances. Based on the mechanical durability of the stones, there was no foundation stone that required the replacement of its members attributed to the degradation of the rock properties, but conservation treatment is considered necessary to delay superficial damage. The foundation stones are characterized by a combined outcome of multiple petrological factors that caused physical damage to surfaces and internal defects. Therefore, it's required to diagnosis and monitoring the Sebyeonggwan regularly for long-term preservation.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.2
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• pp.147-156
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• 2021

We report fluid inclusion study results of copper-bearing quartz veins in Zogdor area, which is located within the Gurvansayhan island arc terrane of Southern Mongolia. At the Zogdor area, structurecontrolled copper mineralization is hosted in granodiorite-porphyry, which emplaced in the late Cretaceous formation. Within this granodiorite porphyry, copper-bearing quartz veins are associated with the hydrothermal alteration that includes quartz-epidote-magnetite, and quartz-magnetite in the propylitic zones. The veins are classified into two types, according to their mineral composition, which occur mainly as chalcopyrite, rare amounts of bornite, magnetite, and pyrite. Fluid inclusions in the quartz veins from the quartz-magnetite±chalcopyrite and quartz-epidote-magnetite veins are two-phase aqueous inclusions having bubble sizes of 5-30 vol.%, evident salinities of 2.0-22.6 wt.% NaCl, and homogenization temperatures of 107-270℃. Based on mineral assemblages of the observed veins, along with the geochemical properties and alteration faces of the host rock, fluid inclusion data show that the study area corresponds to propylitic alteration zone in the porphyry Cu related mineralization.