• Economic and Environmental Geology
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• v.26 no.1
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• pp.11-20
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• 1993

In the present study, three representative hydrothermal clay deposits, named the Seongsan, Ogmaesan and Haenam deposits, were selected for oxygen and hydrogen isotope studies. Oxygen and hydrogen isotopic compositions of quartz, sericite, alunite and kaolin minerals from Seongsan, Ogmaesan, Haenam deposits and surrounded rocks of clay deposits have been measured. The ${\delta}^{18}O$ values of quartz, kaolin, sericite and alunite in the Seongsan mine are +8.4 to +11.1‰, +3.6 to 5.4‰, +4.8 to +5.8‰ and + 3.0 to +6.6‰, respectively. In the Ogmaesan mine, the ${\delta}^{18}O$ values of quartz, kaolin, sericite and alunite are +8.0 to +13.6‰, +2.8 to +6.7‰, +4.8 to +8.4‰ and +0.9 to +2.4‰, respectively. The ${\delta}^{18}O$ values of the Haenam mine range from +7.9 to +10.1‰ for quartz and from +4.5 to +6.5‰ for sericite. The ${\delta}^{18}O$ values of the whole-rocks range from + 3.0 to + 7.8‰ for the granitic rocks. The ${\delta}^{18}O$ values of the whole-rocks range from + 3.2 to + 10.7‰ for the volcanic rocks. The 8D values of kaolin, sericite and alunite in the Seongsan mine are -78 to -86‰, -71 to -90‰ and -43 to -77‰, respectively. In the Ogmaesan mine, the ${\delta}D$ values of kaolin, sericite and alunite are -73 to -80‰, -74 to -88‰ and -57 to -98‰, respectively. The ${\delta}D$ values of the Haenam mine range from -76 to -85‰ for sericite. The ${\delta}D$ values of the whole-rocks range from -77 to -105‰ for the granitic rocks. The ${\delta}D$ values of the wholerocks range from -76 to -100‰ for the volcanic rocks. The main result obtained oxygen and hydrogen isotope data can lead to the following interpretations on the origin of hydrothermal fluids in the clay deposits: Through the oxygen isotopic study, the formation temperature of the clay deposits was estimated from the coexisting minerals such as quartz-kaolin minerals and -sericite. Formation temperature of the acidic alteration zone is 165 to $280^{\circ}C$ in the Seongsan deposits, 175 to $250^{\circ}C$ in the Ogmaesan deposits and 250 to $350^{\circ}C$ in the Haenam deposits. Three clay deposits has been formed by magmatic water mixed with meteoric water. Furthermore, from this isotopic data, it is clarified that kaolin minerals and alunite are hypogene in origin, and has been formed by oxidation of hydrogen sulfide in the steam-heated environment, and that alunite has been produced in the spectacular solfataric alteration observed at the surface of some present-day hydrothermal systems. Oxidation of the $H_2S$ is thought to be generated when the vapor phase generated by boiling of the deep-seated water under the water table.

• Economic and Environmental Geology
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• v.25 no.4
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• pp.397-416
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• 1992

In the present study, three clay deposits, named the Seongsan, Ogmaesan and Haenam deposits, were investigated. The altered zones are recognized in the hydrothermally altered rocks of the clay deposits from the center of the alteration to the margin: Kaolin, Kaolin-Quartz, Quartz, Sericite and Chlorite zones in the Seongsan deposits; Quartz zone, Alunite zone, Kaolin zone, Sericite zone and Chlorite zone in the Ogmaesan deposits; Quartz zone, Pyrophyllite zone, Sericite zone and Chlorite zone in the Haenam deposits. These zones can be grouped into two types of alteration: Acidic alteration such as Pyrophyllite zone, Alunite zone, Quartz zone, Kaolin zone, Kaolin-Quartz zone and a part of Sericite zone; Propylitic alteration such as Chlorite zone and a part of Sericite zone. All clay deposits belong to high-sulfidation (acid-sulfate) system. The rocks of the acidic alterations are composed of pyrophyllite, alunite, kaolin minerals, sericite, quartz and pyrite. On the basis of bulk chemical compositions, it was found that some components such as $SiO_2$, $TiO_2$, $Fe_2O_3$, FeO, MgO, CaO, $K_2O$ and $Na_2O$ were mobilized considerably from the original rocks. The mobility of these major elements is related to, and controls, mineral assemblages in each altered zone. Polytypes of sericite are determined as $2M_1$ and 1M by X-ray diffraction method. The amount of $2M_1$ is nearly equal to that of 1M in the Seongsan deposits whereas $2M_1$ is less and higher than that of 1M in the Ogmaesan and the Haenam deposits. These facts indicate that formation temperature of sericite is relatively high in the Haenam deposits, moderate in the Seongsan deposits, and low in the Ogmaesan deposits. The ratios of Na/(K+Na) for alunite in the Ogmaesan deposits determined by electron microprobe analyzer (EPMA) are higher than those in the Seongsan deposits. Thus, the alunite of the Ogmaesan deposits must have been formed from the solutions with relatively high aqueous Na/(K+Na) ratios and low pH at a high temperature rather than that of the Seongsan deposits. From all data, it is clarified that alunite is hypogene in origin, and has been formed by oxidation of hydrogen sulfide in the steam-heated environment, and that alunite has been produced by the spectacular solfataric alteration observed at the surface of some present-day hydrothermal systems.

• Journal of the Korean Ceramic Society
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• v.16 no.3
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• pp.164-168
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• 1979

In the previous paper, it was reported that formation of desirable calcium alunimate(CA) in clinker was considerably affected by sulfur-contaminated alumina which was prone to form a disadvantageous mineral, $C_4A_3S$. In this study, however, sulphate-free alumina cement was made from sulfur-free alumina refined from alunite and corresponding materials. The major minerals in the clinker were identified by X-ray diffraction patterns as calcium aluminate (CA), calcium dialuminate $(CA_2)$ and dicalcium alumino silicate $(C_2AS)$. The formation of CA was more effective with decreasing contents of silica to 2 per cent or less and sulfur in the refined alumina. Physical properties of prepared alumina cement such as setting time, stability and compressive strength were measured. The values were similar to those of commercial alumina cements.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.123.1-123
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• 2000

• Journal of the Mineralogical Society of Korea
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• v.6 no.2
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• pp.122-144
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• 1993

The Kimhae napseok clay deposit was studied to characterize its mineralogy and genesis. Geology of the deposit is composed of Tertiary volcanic rocks and granodiorite. Tertiary volcanic rocks consist of andesitic tuff with minor interstratified tuffaceous shale, and rhyodacitic tuff. The main ore body of 2.4 to 4 m in thickness developed parallel to the bedding of andesitic tuff bed. Its strike and dip are $N70^{\circ}E-N85^{\circ}E$ and $16^{\circ}NW-32^{\circ}NW$, respectively. Two alteration zones; the propylitic zone of albite-epidote-chlorite-quartz assemblage and advanced argillic zone of pyrophyllite-dickite-alunite-diaspore assemblage are developed. Correlation of $SiO_2$ to $Al_2O_3$ shows no relation in propylitic zone, while a negative linear relation in advanced argillic zone. Chemical variation shows that $SiO_2$, $Al_2O_3$, MgO, CaO, $Na_2O$ and $K_2O$ were leached out during hydrothermal alteration. Pyrophyllite, the most abundant mineral in advanced argillic zone, occurs as low temperature 2M polytype. It is closely associated with dickite, diaspore and alunite. The Hinckley index of dickite is 0.83 showing moderate crystallinity. Na content is increasing in the M site with the increasing content of cations in the R-site. the mole percent of Na replacing K in alunite ranges from 53.2 to 71.6. It is also found that pyrophyllite grows in the dissolution site of diaspore. Plagioclase was albitized. Lowering of pH caused mainly by sulfide and sulfate decomposition resulted in preferential leaching of Si. It is inferred that aluminum released from plagioclase in the volcanic rocks as well as from the tuffaceous shale intercalated in andesitic tuff were the main sources of aluminum required for the formation of clay deposit. pH in hydrothermal fluid decreased from propylitic zone to advanced argillic zone with increasing degree of alteration. Based on experimental data reported in the literature and mineral assemblages, the formation temperature of the deposit ranges 270 to $320^{\circ}C$.

• Economic and Environmental Geology
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• v.28 no.6
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• pp.571-577
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• 1995

Several acid-sulfate clay deposits associated with silicic magmas occur in the Haenam area of the southwestern part of Korea. Geology of the studied area consists of tuffs, granitic rocks, quartz porphyry, rhyolite, andesite and sedimentary rocks. The granitic rocks and quartz porphyry intruded tuffs and sedimentary rocks. The rhyolite and tuffs around the mines have undergone hydrothermally weak or strong alteration. Gold contents with major and trace elements have been determined for a total of sixty-seven specimens of fresh igneous rocks, wall rocks and minerals such as dickite and alunite by graphite furnace atomic absorption spectrometer and inductively coupled plasma. Gold is enriched in the alunite vein and the silicified zone, but is depleted in dickites and hydrothermally altered rocks with dickite of the Seongsan deposit. Gold is especially concentrated near the faults or conjunction area of two faults. High content of gold is shown in the mineral assemblages of alunitequartz- pyrite in the alunite vein and silicic zone of the Seongsan deposit compared with that of minerals and rocks from another deposits distributed in the studied area. Gold content in tuffs and dickites with pyrite is generally low. Gold content in silicified tuff tends to show positive correlations with content of As, Hg and Sb. Variation trends of Cd, Hg and Sb are similar to those of gold content. From the result of gold content variations, gold may be transported and concentrated by mineralizing solutions ascending along the cracks like fault. Therefore, it is important to survey alunite vein and silicified zone at the conjunction of faults, and to analyze pathfinder elements such as As, Hg and Sb for geological and geochemical exploration of gold in the studied deposits.

• Economic and Environmental Geology
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• v.50 no.1
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• pp.15-26
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• 2017

Advanced argillic, argillic, and phyllic zones are the most important alteration patterns to predict the hidden ore body during exploration of hydrothermal deposits. We examined the quantitative relationship between the spectral absorption characteristics and the mineral content of the synthetic mixtures such as alunite-kaolinite and illite-kaolinite using short wavelength infrared (SWIR) spectroscopy. In the alunite-kaolinite mixtures, the spectral absorption characteristics of the alunite was highly correlated with the Hull quotient reflectance(0.99) and the kaolinite had the highest correlation with the Gaussian peak(0.92). Illite-kaolinite mixtures are essential for Gaussian deconvolution because of the overlap of absorption region. Illite and kaolinite mixtures indicate the high correlation of 0.93 and 0.98, respectively. The error ranges in the alunite-kaolinite(8%) and illite-kaolinite mixtures(5%) derived from SWIR were smaller than the ones(29% and 26%) obtained from X-ray diffraction(Rietveld) analysis. These results show that SWIR spectroscopic analysis is more reliable than XRD Rietveld analysis in terms of quantification of allowed minerals.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.82.2-82
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• 2002

• Proceedings of the Petrological Society of Korea Conference
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• 2009.05a
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• pp.124-128
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• 2009

• Journal of the Mineralogical Society of Korea
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• v.7 no.1
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• pp.14-24
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• 1994

The Sungsan clay deposits have been formed by the hydrothermal alteration of volcanic and volcanoclastic rocks of the Hwangsan Formation of Cretaceous age. Claystones are mainly composed of dickite, alunite, illitic minerals and tosudite. The mineralogical properties of clay minerals have been studied using X-ray diffraction analysis, electron microscopy, electron microprobe analysis, and infrared absorption analysis. The physicochemical condition for the clay deposits also have been studied by the activity diagrams and mineral assemblages. Dickite, the dominant mineral in clay deposits, occurs generally as massive aggregates. It shows book-structure of well-defined hexagonal plates. Chemistry of dickite agrees with its ideal formula. Peak depth ratios in infrared absorption spectra were used for discrimination between pure and mixture of kaolin minerals. Five hydrothermal alteration zones are divided according to the mineral assemblages. From center to margin, alunite, dickite, illite and albite zones are discernible. Quartz zone occurs as small lenticular form in dickite zone. The formation of dickite and illite zones are promoted by decreasing $a_{k^+}$. An increase in $a_{H_{2}SO_{4}}$ or $a_{K_{2}SO_{4}}$ is required for the formation of alunite zone. Estimated temperature of formation ranges 110-270 $^{\circ}C$