하상범 Sangbeom Ha , 김부근 Boo-keun Khim , 조현구 Hyen Goo Cho , 에스터콜리자 Ester Colizza

DOI: Vol.31(No.1) 1-12, 2018

A gravity core (RS14-C2) was collected at site RS14-C2 in the continental slope to the east of Pennell-Isellin Bank of the Ross Sea (Antarctica) during PNRA XXIX (Rosslope II Project) Expedition. In order to trace the sediment source, magnetic susceptibility (MS), sand fraction, and clay mineral compositions were analyzed, and AMS 14C ages were dated. Core sediments consist mostly of hemipelagic sandy clay or silty clay including ice-rafted debris (IRD). AMS 14C age of core-top indicates the modern and Holocene sediments. Based on AMS 14C dating, sediment color, MS and sand fraction, core sediments are divided into interglacial and glacial intervals. The interglacial brown sediments are characterized by low MS and sand fraction, whereas the glacial gray sediments are characterized by high MS and sand fraction. Among clay mineral compositions of core sediments, illite is highest (61.8~76.7%), and chlorite (15.7~21.3%), kaolinite (3.6~15.4%), and smectite (0.9~5.1%) are in decreasing order, and these compositions are also divided into the interglacial and glacial/deglacial intervals. During the glacial period, the high content of illite and chlorite indicate sediment supply from the bedrocks of Transantarctic Mountains under the Ross Ice Sheet. In contrast, because of decreasing supply of illite and chlorite by the glacial retreat, smectite and kaolinite contents increased relatively during the interglacial period. During the interglacial period, smectite may be transported additionally by the northeastward flowing surface current from the coast of Victoria Land in the western Ross Sea. Kaolinite may be also supplied to the continental slope by the Antarctic Slope Current from the kaolin-rich metasedimentary rock outcropped on the Edward VII Peninsula.

점토광물, 퇴적물 기원, 빙하기, 간빙기, 로스해, clay mineral, sediment provenance, glacial, interglacial, Ross Sea

김주혁 Juhyeok Kim , 손상보 Sangbo Son , 권기덕 Kideok D. Kwon

DOI: Vol.31(No.1) 13-22, 2018

Aluminum silicates (Al₂SiO₅) undergo phase transitions among kyanite, andalusite, and sillimanite depending on temperature and pressure conditions. The minerals are often used as an important indicator of the degree of metamorphism for certain metamorphic rocks. In this study, we have applied classical molecular dynamics (MD) simulations and density functional theory (DFT) to the aluminum silicates. We examined the crystal structures as a function of applied pressure and the corresponding stabilities based on calculated enthalpies at each pressure. In terms of the lattice parameters, both methods showed that the volume decreases as the pressure increases as observed in the experiment. In particular, DFT results differed from experimental results by much less than 1%. As to the relative stability, however, both methods showed different levels of accuracy. In the MD simulations, a transition pressure at which the relative stability between two minerals reverse could not be determined because the enthalpies were insensitive to the applied pressure. On the other hand, in DFT calculations, the relative stability relation among the three minerals was consistent with experiment, although the transition pressure was strongly dependent on the choice of the electronic exchange-correlation functional.

Al₂SiO₅, 고전분자동력학 시뮬레이션, 밀도범함수이론, 동질이상, computational mineralogy, classical molecular dynamics, density functional theory, polymorphs

이장존 Jang Jon Lee , 김재환 Jae Hwan Kim , 한민수 Min Su Han

DOI: Vol.31(No.1) 23-32, 2018

Noerok ia a green pigment used in Joseon dynasty, and its main usage was for forming foundation layers of Dancheong, the ornamental paintings on the surface of traditional buildings in Korea, such as the Daeung-jeon(main hall) of Bulguk-sa temple. In this research, we investigated the mineralogical characteristic changes of Noerok, a traditional Korean pigment, depending on its firing temperature. The Noerok that we experimented on was mined from Noeseong Mountain, Pohang where it is locally reserved. The major composition mineral is Celadonite, and the main constituent elements are Fe, Si, K and Mg, that refers to the existence of Fe-rich mica. As a result of phased firing experiment from 105℃ to 1000℃, the color was changed from green to pale green, then to brown, and finally to red in order. In the thermal analysis, endothermic reaction induced by the dehydration of crystalline water was confirmed at around 616℃. In the mineralogical change, the crystal surface [(111) and (021)] of the mineral collapsed at temperatures above 600℃, and iron oxide was formed at 1000℃ or higher. Therefore, it is estimated that the crystallization temperature of Noerok is below 60 0℃, and it is also considered that it has undergone the alteration phase up to stage I, based on the presence of only a celadonite.

뇌록, 안료, 뇌성산, 소성온도, 셀라도나이트, Noerok, Pigment, Noeseong Mountain, Firing temperature, Celadonite

정기영 Gi Young Jeong , 조현구 Hyen Goo Cho , 도진영 Jin Young Do

DOI: Vol.31(No.1) 33-46, 2018

Traditional inorganic pigments applied to dancheong, buddhist painting, and wall painting were produced from natural minerals which were later replaced by synthetic pigments, resulting in the loss of the recipe to prepare mineral pigments. This study examined the domestic occurrence and mineralogical characteristics of green and blue mineral pigments required for the conservation of cultural heritage. Cuprous green-blue mineral pigments were found as the weathering products of waste dumps and ores of abandoned Cu-Pb-Zn sulfide mines. Mineralogical analyses using X-ray diffraction and scanning electron microscopy identified diverse hydrous copper sulfate pigments of green (brochantite and devilline) and blue color (linarite, bechererite, and schulenbergite) with minor green pigments of antlerite and atacamite commonly associated with cerussite, smithsonite, anglesite, and cuprite. Noerok, a green silicate pigment, replaced the fractured basalt lava. Celadonite was responsible for the green color of Noerok, closely associated with opal in varying ratio. Glauconite, green silicate pigment, was identified in the Yellow Sea sediments. Malachite and azurite, the most important green and blue pigments of Korean cultural heritage, were not identified in this study.

안료, 녹색, 청색, 광물, 구리, 공작석, 남동석, 셀라도나이트, 해록석, Pigment, green, blue, mineral, copper, malachite, azurite, celadonite, glauconite

김진우 Jin Woo Kim , 이범한 Bum Han Lee , 김진철 Jin Cheul Kim , 김현나 Hyun Na Kim

DOI: Vol.31(No.1) 47-55, 2018

Talc, hydrous magnesium phyllosilicate, is one of the most popular industrial minerals due to their chemical stability and adsorptivity. While micro-sized talc has long been used as a filler and coating, nano-sized talc recently is attracting attention as additives for improving the stability of nanocomposites. In this study, we produced the nano-sized talc powder by mechanical method using high energy ball mill and investigated the changes in particle size and crystallinity with increasing milling time up to 720 minutes. X-ray diffraction results show that the peak width of talc gradually as the milling proceeded, and after 720 minutes of pulverization, the talc showed an amorphous-like X-ray diffraction pattern. Lase diffraction particle size analysis presents that particle size of talc which was ~12 μm decreased to ~0.45 μm as the milling progressed, but no significant reduction of particle size was observed even after grinding for 120 minutes or more. BET specific surface area, however, steadily increases up to the milling time of 720 minutes, indicating that the particle size and morphology change steadily as the milling progressed. Scanning electron microscope and transmission electron microscope images shows that layered particles of about 100 to 300 nm was aggregated as micro-sized particles after pulverization for 720 minutes. As the grinding time increases, the particle size and morphology of talc continuously change, but the nano-sized talc particles form micro sized agglomerates. These results suggest that there is a critical size along the a, b axes in which the size of plates is reduced even though the grinding proceeds, and the reduction of plate thickness along the c axis leads the increase in specific surface area with further grinding. This study could enhance the understanding of the mechanism of the formation of nano-sized talc by mechanical grinding.

활석, 고에너지 볼 밀, 나노입자, 입도 분석, 재응집, talc, high-energy ball mill, nanoparticles, particle size analyzer, agglomerates

오일환 Il-hwan Oh , 허철호 Chul-ho Heo

DOI: Vol.31(No.1) 57-65, 2018