• Economic and Environmental Geology
• /
• v.12 no.2
• /
• pp.51-73
• /
• 1979

The zinc-lead deposits at the Yeonhwa I mine were investigated in terms of ore-forming geologic setting, structural style of ore control, geometry of individual orebodies, zoning, paragenesis and chemical composition of skarn minerals, as well as metal grades and ratios of selected orebodies. The Yeonhwa I mine is characterized by a large swarm of chimney type massive orebodies with thin skarn envelopes, boldly developed through a thick sequence of Pungchon Limestone, the overlying Hwajeol Formation, and the underlying Myobong Slate of Cambrian age. Nearly 20 orebodies of similar shape, but of varying size are arranged in a V-shaped pattern with northwest and northeast trends, clearly indicating an outstanding ore control by a conjugate system of fractures with these trends. Important orebodies are the Wolam 1, 2, 3, and 5 orebodies in the west, and the Namsan 1, 2, 3. and 5 orebodies in the east, among others. The Wolam 1 orebody, which was observed from the -360 level through the -240, -120, and 0 levels to the surface outcrops (totaling a vertical height of about 500m), shows a vertical variation in skarn mineralogy, ranging from pyroxene-garnet zone on the lower levels. through pyroxene (without garnet) zone on the intermediate levels, and finally to rhodochrosite vein on the upper levels and surface. Microprobe analyses of pyroxene and garnet on a total of 14 mineral grains revealed that pyroxenes are manganoan salitic in most samples, with downward increase of Fe and Mn, whereas garnets are highly andraditic, containing fractions of subordinate grossular with downward decrease of Fe. This indicates a reverse relationship of Fe-contents between pyroxene and garnet with depth. Ore minerals are major sphalerite, subordinate galena, and minor chalcopyrite. Sulfide gangue minerals include major pyrrhotite, and minor pyrite and marcasite of later age. Two types of variational trends in metal grades and ratios with depth are present on the plots of assay data from the Wolam orebodies: one is a steady upward increase in Pb, Zn, and Pb:Zn ratios, with a terminal decline at the top of orebody: the other is an irregular or sinusoidal change. The former is characteristic of chimney-type orebodies, whereas the latter is of vein· shaped orebodies. The Pb grades show large variations among orebodies and from level to level, whereas the Zn grades are relatively constand or less variable.

• Economic and Environmental Geology
• /
• v.49 no.2
• /
• pp.77-88
• /
• 2016

Chrysotile is a 1:1 sheet silicate mineral belonging to serpentine group. It has been highlighted studies because of uses, shapes and structural characteristics of the fibrous chrysotile. However, it was designated as Class 1 carcinogen, so high attentions were being placed on detoxification studies of chrysotile. The objectives of this study were to investigate changes of mineralogical characteristics of chrysotile and to suggest detoxification mechanism of chrysotile by thermal decomposition. Samples for this study were obtained from LAB Chrysotile mine in Canada. The samples were heated in air in the range of 600 to $1,300^{\circ}C$. Changes of mineralogical characteristics such as crystal structure, shape, and chemical composition of the chrysotile fibers were examined by TG-DTA, XRD, FT-IR, TEM-EDS and SEM-EDS analyses. As a result of thermal decomposition, the fibrous chrysotile having hollow tube structure was dehydroxylated at $600-650^{\circ}C$ and transformed to disordered chrysotile by removal of OH at the octahedral sheet (MgOH) (Dehydroxylation 1). Upon increasing temperature, it was transformed to forsterite ($Mg_2SiO_4$) at $820^{\circ}C$ by rearrangement of Mg, Si and O (Dehydroxylation 2). In addition, crystal structure of forsterite had begun to transform at $800^{\circ}C$, and gradually grown 3-dimensionally to enstatite ($MgSiO_3$) by recrystallization after the heating above $1,100^{\circ}C$. And then finally transformed to spherical minerals. This study showed chrysotile structure was collapsed about $600-700^{\circ}C$ by dehydroxylation. And then the fibrous chrysotile was transformed to forsterite and enstatite, as non-hazardous minerals. Therefore, this study indicates heat treatment can be used to detoxification of chrysotile.

• Economic and Environmental Geology
• /
• v.29 no.3
• /
• pp.235-246
• /
• 1996

Placer gold in collected heavy minerals from several localities in Huongkhe area, is consistently very finegrained (${\leq}100$ to $400{\mu}m$). The size and size distribution show somewhat differences at Dongdo and Hoahai : at Dongdo, predominant relatively larger and wide distribution; at Hoahai, characteristic relatively finer and narrow distribution range. The morphology of gold grains is divided into the four groups assumed by the dimension ratio : spherical, subprismoidal, prismoidal, and irregular. The gold grains at Dongdo show wide morphological distribution, whereas, at Hoahai, spherical form is predominant (${\approx}75%$). Three main types of gold are classified based on their chemical composition and mode of occurrence: type I (electrum; fineness=568~931), type II (amalgam; fineness=671~927), and type III (native gold; fineness=923~999). Type I gold contains, relatively high and variable silver contents (${\approx}11$ to 58 atomic % Ag), and has been classified into two subtypes based on their silver contents (type IA, ${\approx}11{\sim}39$ atomic % Ag; type IB, ${\approx}40{\sim}58$ atomic % Ag). However, type I gold would have been generally original compositions of electrum which originated at the provenance deposits. Mercury reacts with gold and silver to form amalgam (type II gold) which has variable Hg contents (1.2~30.5 atomic % Hg). The mercury contents in gold grains at Hoahai (10.9~30.5 atomic % Hg) are higher than those at Dongdo (5.8~21.1 atomic % Hg). The gold grains from the area generally exhibit a high-purity gold (type III) rim. The individual rims on the various grains range from <1 to $80{\mu}m$ in thickness and have silver contents of <10 atomic percent Ag, even though the core compositions range from ${\approx}11$ to 58 atomic percent Ag. The rim of gold most likely is responsible for the commonly cited cases of gold from placer deposits assaying at higher values of fineness than the gold in the corresponding source lode. The gold-rich rim in the Huongkhe area apparently forms by a combination of self-electrorefining and preferential dissolution of silver under oxidizing nature during the weathering and transport process. All data of gold grains in the Huongkhe area suggest that the transport distances and/or time of placer gold at Hoahai are generally farther than those at Dongdo. The mercurian gold bearing provenance deposits at Dongdo and Hoahai would be suggest nearest epithermal gold-silver vein-type.

• Journal of Food Hygiene and Safety
• /
• v.25 no.4
• /
• pp.354-359
• /
• 2010

In the present study, we investigated the chemical composition, antioxidant activities and nitrite scavenging ability in leaf and root of Youngia sonchifolia Max. The leaf powder contained 4.3% of water, 53.9% of crude carbohydrate, 21.6% of crude protein, 3.5% of crude fat and 16.7% of crude ash. The root powder contained 4.8% of water, 65.9% of crude carbohydrate, 17.4% of crude protein, 3.2% of crude fat and 8.7% of crude ash. The major mineral elements both in leaf and root powder were potassium, calcium, and magnesium. Contents of unsaturated fatty acids were higher than those of saturated fatty acids both in leaf and root powder. Total polyphenol and flavonoid contents of methanol extract in leaf were 3,922.4 mg/100 g and 1,903.2 mg/100 g respectively. In comparison, total polyphenol and flavonoid contents of methanol extract in root powder were 1,898.4 mg/100 g and 359.8 mg/100 g. The antioxidative activities of several solvents extract of leaf and root powder were investigated by measuring electron-donating ability using 1,1-diphenyl-2-picrylhydrazyl (DPPH). Of the each extracts, ethyl acetate extract of leaf and root powder showed relatively higher antioxidant activity; 94.3% in the leaf powder and 92.9% in the root powder. Nitrite scavenging ability was also highest in the ethyl acetate extract of leaf (45.4%) and root powder (28.8%). These results suggest that ethyl acetate extract of Youngia sonchifolia Max. can be used as a functional materials.

• Journal of Fisheries and Marine Sciences Education
• /
• v.23 no.3
• /
• pp.410-424
• /
• 2011

This study was investigated for the purpose of obtaining basic data which can be applied to processing of canned sea mussel using tomato paste. Shell were washed, and then steamed and shucked. Sea mussel meat was prepared with ratio of sea mussel 90g, tomato paste sauce 65g(tomato paste 42%, gum guar 1.0%, salt 2.0%, starch syrup 2.0%, cooking wine 1%, water 52%). The sea mussel meats were packed with vacuum seamer in 301-3 can, and then sterilized for various F0 value(F0 8-12 min.) in a steam system retort at $118^{\circ}C$. The factors such as pH, VBN, amino-N, total amino acid, free amino acid, chemical composition, color value (L, a, b), texture profile, TBA value, mineral, sensory evaluation and viable bacterial count of the canned sea mussel produced with various sterilization condition(F0 8-12 min.) were measured. The same element was also measured during preservation. The results showed that the product sterilized at F0 8 min. and preserved for 90 days were the most desirable.

• Korean journal of food and cookery science
• /
• v.19 no.5
• /
• pp.603-608
• /
• 2003

In approximate composition, crude protein, lipid, ash, crude fiber, and N-free extract constituted 14.70%, 3.10%, 6.90%, 18.20%, and 57.10%, respectively, in Korean safflower flowers, compared to 12.60%, 2.70%, 5.80%, 16.40% and 62.50%, respectively, in Chinese safflower flowers. This indicated that Korean safflower flowers surpassed their Chinese counterparts except in terms of N-free extract. Free sugars such as fructose, glucose, and sucrose were proven to be dominant in both domestic and Chinese safflower flowers, while little xylose was contained. For content of polyphenolic compound, Korean safflower flowers contained 13.85% water soluble extract and 9.70% MeOH extract, compared to 9.39% and 7.04%, respectively, for the Chinese variety, confirming the higher levels in the Korean variety. For fatty acids, (Ed- the following results are not presented in ratio form) saturated fatty acids and unsaturated fatty acids comprised 6.80% and 93.20% in Korean safflower flowers and 16.0% and 84.0% in Chinese safflower flowers, respectively. Linoleic, oleic, and palmitoleic acids comprised 75.30%, 11.60%, and 3.40% in Korean safflower flowers, and 66.70%, 11.20%, and 6.10% in the Chinese variety, respectively. Of amino acids, essential amino acids comprised 46.67% in Korean safflower flowers and 36.79% in the Chinese variety. Moreover, total essential amino acids in Korean safflower flowers were higher than those of their counterparts. Non-essential amino acid comprised 65.17% in the Korean variety and 54.49% in the Chinese. In terms of mineral content, Korean safflower flowers contained more Ca, Cu, Fe and Mn than those of China, while Chinese safflower flowers contained more A1, Ba, Mg, K, Na, Zn, Sr and P.

• Journal of agriculture & life science
• /
• v.46 no.6
• /
• pp.105-115
• /
• 2012

The detailed proximate, fatty/amino acid, mineral composition, texture, color, chemical and taste compounds of six oysters (four kinds of cultured oysters and two kinds of wild oysters) in Korea were investigated. Length and weight of the shell removed cultured and wild oysters were 4.7~5.1 and 3.0~4.2 cm, and 5.9~9.1 and 2.6~5.5 g, respectively. The proximate compositions were not significantly different between cultured and wild oysters. Amino nitrogen and volatile basic nitrogen content of these ones were 232.8~258.2 and 160.5~213.9 mg/100 g, 9.5~12.0 and 7.8~9.5 mg/100 g, respectively. As a texture characteristic of muscle, shearing force were 95~114 and 105~132 g. Amounts of total amino acids of cultured and wild oysters were 9,004~10,198 and 8,165~8,942 mg/100 g, respectively. Major amino acids and inorganic ions were aspartic acid, glutamic acid, proline, alanine, leucine, phenylalanine, lysine, arginine and K, Na, Ca, Fe, S, P, Zn. Major fatty acids of these ones were 16:0, 18:0, 16:1n-9, 18:1n-9, 22:1n-9, 16:4n-3, 20:5n-3 and 22:6n-3, and there was little difference between the two groups. Amounts of free amino acids of cultured and wild oysters extracts were 1,444~1,620 and 1,017~1,277 mg/100 g, respectively, and major ones were taurine, glutamic acid, glycine, alanine, tryptophan, ornithine and lysine. There is a little difference in glycine, tryptophan, ornithine and arginine contents, but TMAO and TMA contents were low in amount, and were not significantly different between the two groups.

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

• The Journal of the Petrological Society of Korea
• /
• v.28 no.3
• /
• pp.157-169
• /
• 2019

Pseudotachylytes, produced by frictional heating during seismic slip, provide information that is critical to understanding the physics of earthquakes. We report the results of occurrence, structural characteristics, scanning electron microscopic observation and geochemical analysis of pseudotachylytes, which is presumed to have formed after the Late Cretaceous in outcrops of the Paleoproterozoic granitic gneiss on the Bulil waterfall of the Jirisan area, Yeongnam massif, Korea. Fault rocks, which are the products of brittle deformation under the same shear stress regime in the study area, are classified as pseudotachylyte and foliated cataclasite. The occurrences of pseudotachylyte identified on the basis of thickness and morphology are fault vein-type and injection vein-type pseudotachylyte. A number of fault vein-type pseudotachylytes occur as thin (as thick as 2 cm) layers generated on the fault plane, and are cutting general foliation and sheared foliation developed in granitic gneiss. Smaller injection vein-type pseudotachylytes are found along the fault vein-type pseudotachylytes, and appear in a variety of shapes based on field occurrence and vein geometry. At a first glance fault vein-type seudotachylyte looks like a mafic vein, but it has a chemical composition almost identical to the wall rock of granitic gneiss. Also, it has many subrounded clasts which consist predominantly of quartz, feldspar, biotite and secondary minerals including clay minerals, calcite and glassy materials. Embayed clasts, phenocryst with reaction rim, oxide droplets, amygdules, and flow structures are also observed. All of these evidences indicate the pseudotachylyte formed due to frictional melting of the wall rock minerals during fault slip related to strong seismic faulting events in the shallow depth of low temperature-low pressure. Further studies will be conducted to determine the age and mechanical aspect of the pseudotachylyte formation.

• Economic and Environmental Geology
• /
• v.54 no.6
• /
• pp.709-716
• /
• 2021

In this study, an adsorbent prepared by natural drying of iron hydroxide-based sludge collected from settling basin at a mine drainage treatment facility located in Gangneung, Gangwon-do was used to remove fluoride in an artificial fluoride solution and mine drainage, and the adsorption characteristics of the adsorbent were investigated. As a result of analyzing the chemical composition, mineralogical properties, and specific surface area of the adsorbent used in the experiment, iron oxide (Fe₂O₃) occupies 79.2 wt.% as the main constituent, and a peak related to calcite (CaCO₃) in the crystal structure analysis was analyzed. It was also identified that an irregular surface and a specific surface area of 216.78 m²·g^-1. In the indoor batch-type experiment, the effect of changes in reaction time, pH, initial fluoride concentration and temperature on the change in adsorption amount was analyzed. The adsorption of fluoride showed an adsorption amount of 3.85 mg·g^-1 16 hours after the start of the reaction, and the increase rate of the adsorption amount gradually decreased. Also, as the pH increased, the amount of fluoride adsorption decreased, and in particular, the amount of fluoride adsorption decreased rapidly around pH 5.5, the point of zero charge at which the surface charge of the adsorbent changes. Meanwhile, the results of the isotherm adsorption experiment were applied to the Langmuir and Freundlich isotherm adsorption models to infer the fluoride adsorption mechanism of the used adsorbent. To understand the thermodynamic properties of the adsorbent using the Van't Hoff equation, thermodynamic constants 𝚫H° and 𝚫G° were calculated using the adsorption amount information obtained by increasing the temperature from 25℃ to 65℃ to determine the adsorption characteristics of the adsorbent. Finally, the adsorbent was applied to the mine drainage having a fluoride concentration of about 12.8 mg·L^-1, and the fluoride removal rate was about 50%.