• Economic and Environmental Geology
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• v.12 no.4
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• pp.181-195
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• 1979

The Nambu orebodies of the Okbang tungsten mine are hosted in the Precambrian amphibolite and Weonnam formation. These orebodies can be classified into two types; The scheelite-bearing ore vein occurring in the amphibolite (the Nambu 1, 2 adits) and tungsten-bearing quartz vein along the contact between the amphibolite and the Weonnam formation (the Young-ho, -1, -2, -3 levels). The scheelite-bearing ore vein in the amphilbolite is discontinuous, narrow, and highly irregular in geometry, occurring only within the amphibolite with which of the vein is graduational. Based on these feature of the mode of occurrence, the origin of this ore type might be attributed to a potential segregation of tungsten ore fluid in situ from hornblenditic basic magma of the host rock. Tungsten-bearing quartz vein, however, is considered to have deposited along the N30-60E trending fractures as a later hypothermal vein after the hornblendite was emplaced. The principal ore mineral is scheelite with minor amount of wolframite, and the gangue minerals are quartz, and small amounts of fluorite, pyrrhotite, chalcopyrite and calcite. Fluid inclusion study of minerals from the Nambu orebody reveals that the fluids in fluorite of the scheelite-bearning ore vein attained a temperature range of $208{\sim}256^{\circ}C$ and those in quartz from the tungsten-bearing quartz vein a temperature range of $220{\sim}357^{\circ}C$. The real formation temperatures can be somewhat higher than filling temperatures, if pressure correction is made. Chemical analysis of 8 amphibolitc samples on major and some trace elements indicate that the amphibolite is igneous origin. On a Niggli diagram (al-alk)versus c, the analytical values are plotted on an igneous field, and on a Niggli diagram mg versus c they follow a karroo igneous trend line. According to the Ba, Cr, and Ni versus Niggli mg plots suggested by Leake (1964), Okbang amphibolite fall outside a pelitic field and compare favorably with his plots form ortho-amphibolites. Analitical values of $MoO_3$ of 8 samples of scheelite minerals from the Nambu orebody indicate that the tungsten-bearing quartz vein (type n) of Nambu orebody shows a range from 1. 69% to 4.38% which is higher than 0.94%~3.25% $MoO_3$ for the scheelite-bearing ore vein (type I). This fact indicates that the type II was deposited in a lower $fO_2/higher$ $fO_2$ environment and under lower temperature than the type I. Analysis of major components $WO_3$, MnO, and FeO of 6 samples of wolframite from the type II veins revealed that they contain 73.35~76.2% $WO_3$, 7.94~11.63% MnO, and 10.53~14.82% FeO. MnO/FeO ratios of wolframite shows the range of 0.85~1.17 which suggests a slightly higher temperature type of deposits than other major tungsten deposits in the country.

• Economic and Environmental Geology
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• v.3 no.2
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• pp.55-73
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• 1970

The district investigated covers the central and southern portions of the Uiryong Quadrangle amounting to $40km^2$ in area and is bounded approximately by geographical coordinates of $128^{\circ}$ 28' $40^{{\prime}{\prime}}{\sim}128^{\circ}$ 24' 25"E in longitude and $35^{\circ}10{\prime}{\sim}35^{\circ}14^{\prime}06^{{\prime}{\prime}}N$ in latitude. The purpose of this investigation was to provide basic information in drawing up a comprehensive development plan of the copper ore deposits known to exist in the HamanKumbuk district with special emphasis given to the ascertainment of geological and paragenetic characteristics. The area consists chiefly of shale, sandy shale and chert, all belong to Kyongsang System of Cretaceous age. Intruded into these rocks are andesite, granodiorite, basic dikes, and acidic dikes. The mineralization which took place in the area, consists of mostly fissure-filling vein deposits, numbering several tens, with varying magnitudes. The fissures and shear zones created in rocks, such as chert and granodiorite, hosted the deposition of mineralizing vapors and/or hydrothermal solutions along their openings. The strike lengths of these veins vary from 50 to 600 meters in extension and 0.1 to 3 meters in width. Although the degree of fluctuation in width is great, it averages 0.3m. The stuctural patterns, which apparently affected the deposition of veins, are fissure patterns, trend NS to $N30^{\circ}W$, and steep-pitching tension fractures as well as normal fault pattern. Ore minerals associated with vein matters are primarily chalcopyrite and small amounts of scheelite, cobaltiferous arsenopyrite, and gold and silver intimately associated with sulphide minerals. Associated with these ore mineral are pyrite, pyrrhotite, magnetite, specularite and arsenopyrite. Gangue minerals noted are quartz, calcite, chlorite, tourmaline and hornblende. In terms of the compositions of associated minerals, the vein deposits in the district could be grouped under the following four categories: 1. Pyrrhoitite, Arsenopyrite, Gold and Silver Bearing Copper Vein (Type I) 2. Calcite-Scheelite-Copper Vein (Type II) 3. Magnetite-Pyrite-Copper Vein (Type III) 4. Tourmaline Copper Vein (Type IV) Of the four types, the first and the fourth are presently yielding relatively higher grades: of copper ores and concentrates. The estimated ore reserves total some 222,000 metric tons with the following breakdown in terms of metal contents: Name of Mines Au(g/t) Ag(g/t) Cu(%) Reserves(M/T) Kunbuk 15.92 78.69 6,074 60.498 Cheil Kunbuk - - 1.040 60,847 Haman - - 2.688 101,204 222,549 As rehabilitation of old workings and/or exploration of veins at depth proceed, additional estimation of ore reserves may become apparent and necessary. With regard to the problem of beneficiation and upgrading of low-grade ores in the district, it would be advisable to make decisions on location, treating capacity and mill flowsheet after sufficient amount of exploration is completed as suggested in the report.

• Economic and Environmental Geology
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• v.2 no.1
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• pp.1-12
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• 1969

In the Sangdong Mine area, Taebaegsan series (Pre-Cambrian) and Chosun System (Cambro-ordovician) are widely distributed. The Chosun System consists of Yangdug Series (Jangsan Quartzite and Myobong Slate) and The Great Limestone Series (Pungchon Limestone, Shesong Shale, Hwajeol Formation and Dongjeom Quartzite). The mineralized zone containing the main ore body of the Sangdong Mine was developed in the Myobong Slate formation. The result of the field and microscopic study on the mineral paragenesis and it's wall rock alteration in the tungsten ore deposit shows the following features. The orogenic movements of the Post-Chosun System in the Hambaeg Geosyncline are closely related to the tungsten ore deposition in the area, the ore minerals are composed mainly of scheelite, powelite molybdenite and sulfide minerals, and gangue minerals are hornblende, diopside, garnet, quartz, phlogopite, tremolite, biotite, muscovite, fluorite, etc., main ore body was enriched by scheelite bearing quartz vein filling into interstices of formerly mineralized zones, and the minor faults, faults of N $60^{\circ}-70^{\circ}W$, $45^{\circ}-60^{\circ}NE$ and joints, which were formed at the end of the mineralization and the slate. Country rock of the ore body was altered into the following several zones from the outside to the inside; lowgrade recrystalline aureole, silicified sericite zone, and diopside-hornblende zone. Under the microscopic observation of 195 samples taken from throughout ore body can be classified into 10 different groups by their mineral paragenesis as shown in table 2. The garnet-diopside group is primary skarn and it shows gradational change to the groups of later stage by the successive processes of metasomatism. From the stage of quartz-bearing group, the dissemination of scheelite is seen. The crystallization of scheelite in the bed started with the quartz deposition and continued to the last stage when quartz vein intruded into the main ore body. In the field and the under ground investigation a durable limestone bed in thickeness about 20 meters and their remnants in ore body are observed and under microscope calcite remnants are recognized. Hence it is posturated that the ore material moved up through the faults, shear zones or feather cracks and was assimilated with the interbeded limestone, after that the body was affected by the successive differentiated ore solution by gradational increasing in $SiO_2$, $K_2O$ and $H_2O$. Evidently this ore deposit shows the features resulted from pyrometasomatic processes.

• Economic and Environmental Geology
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• v.42 no.1
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• pp.1-8
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• 2009

The Haman mineralized area is located within the Cretaceous Gyeongsang Basin along the southeastern part of the Korean peninsula. Almost all occurrences in the Haman area are representative of copper-bearing polymetallic hydrothermal vein-type mineralization. Within the area are a number of fissure-filling hydrothermal veins which contain tourmaline, quartz and carbonates with Fe-oxide, base-metal sulfide and sulfosalt minerals. The Gunbuk, Jeilgunbuk and Haman mines are each located on such veins. The ore and gangue mineral paragenesis can be divided into three distinct stages: Stage I, tourmaline + quartz + Fe-Cu ore mineralization; Stage II, quartz + sulfides + sulfosalts + carbonates; Stage III, barren calcite. Equilibrium thermodynamic data combined with mineral paragenesis indicate that copper minerals precipitated mainly within a temperature range of $350^{\circ}C$ to $250^{\circ}C$. During early mineralization at $350^{\circ}C$, significant amounts of copper ($10^3$ to $10^2\;ppm$) could be dissolved in weakly acid NaCl solutions. For late mineralization at $250^{\circ}C$, about $10^0$ to $10^{-1}\;ppm$ copper could be dissolved. Equilibrium thermodynamic interpretation indicates that the copper in the Haman-Gunbuk systems could have been transported as a chloride complex and the copper precipitation occurred as a result of cooling accompanied by changes in the geochemical environments ($fs_2$, $fo_2$, pH, etc.) resulting in decrease of solubility of copper chloride complexes.

• Economic and Environmental Geology
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• v.36 no.2
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• pp.75-87
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• 2003

The Haman-Gunbuk mineralized area is located within the Cretaceous Gyeongsang Basin along the southeastern part of the Korean peninsula. Major ore minerals, magnetite, scheelite, molybdenite and chalcopyrite, together with base-metal sulfides and minor sulfosalts, occur in fissure-filling tourmaline, quartz and carbonates veins contained within Cretaceous sedimentary and volcanic rocks anu/or granodiorite (118{\pm}$3.0 Ma). The ore and gangue mineral paragenesis can be divided into three distinct stages: Stage 1, tourmaline+quartz+Fe-Cu ore mineralization; Stage II, quartz+sulfides+sulfosalts+carbonates; Stage 111, barren calcite. Earliest fluids are recorded in stage I and early por-tions of stage II veins as hypersaline (35~70 equiv. wt.% NaCl+KCl) and vapor-rich inclusions which homogenize from ~30$0^{\circ}C$ to $\geq$50$0^{\circ}C$. The high-salinity fluids are complex chloride brines with significant concentrations of sodium, potassium, iron, copper, and sulfur, though sulfide minerals are not associated with the early mineral assemblage produced by this fluid. Later solutions circulated through newly formed fractures and reopened veins, and are recorded as lower-salinity(less than ~20 equiv. wt.% NaCl) fluid inclusions which homogenize primarily from ~200 to 40$0^{\circ}C$. The oxygen and hydrogen isotopic compositions of fluid in the Haman-Gunbuk hydrothermal system represents a progressive shift from magmatic-hydrothermal dominance during early mineralization stage toward meteoric-hydrothermal dominance during late mineralization stage. The earliest hydrothermal fiuids to circu-late within the granodiorite stock localiring the ore body at Haman-Gunbuk could have exsolved from the crystal-lizing magma and unmixed into hypersaline liquid and $H_2O$-NaCl vapor. As these magmatic fluids moved throughfractures, tourmaline and early Fe, W, Mo, Cu ore mineralization occurred without concomitant deposition of othersulfides and sulfosalts. Later solutions of dominantly meteoric origin progressively formed hypogene copper and base-metal sulfides, and sulfosalt mineralization.

• Economic and Environmental Geology
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• v.15 no.1
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• pp.17-32
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• 1982

The Wolak tungsten-molybdenum deposits are tungsten-molybdenum bearing quartz veins which filled the fractures in Pre-Cambrian pebble-bearing calcareous hornfels, hornfels and Cretaceous granite. There are two vein groups in this mine, Dongsan vein group in the west and Kwangcheon vein group in the east. The ore minerals are wolframite, scheelite, molybdenite, native bismuth, bismuthinite, pyrite, arsenopyrite, chalcopyrite, cubanite, stannite, pyrrhotite, sphalerite, galena, marcasite, Pb-Bi sulfosalt and ilmenite. Quartz, calcite, beryl, fluorite, muscovite, rhodochrosite and siderite are gangue minerals. Fluid inclusion studies were carried out for the quartz, beryl, scheelite, early and late fluorite. Fluid inclusion studies reveal that liquid-gas inclusions are most common and occur in all of the minerals examined. Filling degree of the inclusions in the late fluorite is much higher than that of the inclusions in quartz and early fluorite. Liquid $CO_2$ bearing liquid-gas inclusions occur in quartz and early fluorite. Liquid, gas and solid phase inclusions occur in quartz, beryl and scheelite. Salinities of inclusions in quartz and beryl from Dongsan vein group range from 3.9 to 8.0, from 5.3 to 7.7 wt.% NaCl equivalent respectively. Salinities in the late fluorite range from 1.5 to 3.2 wt.% NaCl equivalent. In Kwangcheon vein group salinities range from 3.9 to 9.6 wt.% NaCl equivalent in quartz, from 2.8 to 7.3 wt.% NaCl equivalent in early fluorite, from 1.3 to 1.5 wt.% NaCl equivalent in late fluorite. Homogenization temperatures of inclusions range from $239^{\circ}$ to higher than $360^{\circ}C$ in quartz, over $360^{\circ}C$ in scheelite, from $288^{\circ}C$ to higher than $360^{\circ}C$ in beryl, and from $159^{\circ}$ to $202^{\circ}C$ in late fluorite of the Dongsan vein group. In Kwangcheon vein group, homo genization temperatures of inclusions range from $240^{\circ}C$ to higher than $360^{\circ}C$ in quartz and from $240^{\circ}$ to $328^{\circ}C$ in early fluorite. As a whole, in Dongsan and Kwangcheon vein groups it seems that there are no distinct differences in mineralogy, salinities and homogenization temperatures. No distinct variations in homogenization temperatures are revealed through about 300 m vertically in both district. The faint trend of increase in salinities in the lower level can be detected. The salinity, $CO_2$ content and the temperature of ore fluid were much higher in the early vein stage and then dropped off in the late stage of mineralization as represented by the quartz and fluorite inclusion data.

• Journal of the Mineralogical Society of Korea
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• v.31 no.4
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• pp.307-323
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• 2018

The Inseong Au-Ag and base metal deposit, located in Chungchengbuk-do, Korea, consists of series of quartz veins filling fissures. The deposit occurs in Hwanggangri meta-sediment formation, a lime pebble-bearing phyllite, in the Okcheon Supergroup. Abundant ore minerals in the deposit are pyrite, arsenopyrite, sphalerite, chalcopyrite and galena. The gangue minerals are quartz, calcite and chlorite. Hydrothermal alteration such as chlorization, silicitication, sericitization and carbonitization can be observed around the quartz veins. 4 vein stages can be distinguished based on its paragenetic sequence, vein structure, alteration features and ore minerals. Microthermometry of the fluid inclusion assemblages occur in the veins are conducted to reconstruct a hydrothermal P-T evolution. Fluid inclusions in clean and barren quartz vein in stage 1 have Th of $270{\sim}342^{\circ}C$ and salinity of 1.7~6.4 (NaCl eqiv.) wt%. Euhedral quartz crystal in stage 2 have Th of $108{\sim}350^{\circ}C$ and salinity of 0.5~7.5 wt%. Barren milky quartz vein in stage 3 have Th of $174{\sim}380^{\circ}C$ and salinity of 0.8~7.5 wt%. Calcite vein in stage 4 have Th of $103{\sim}265^{\circ}C$ and salinity of 0.7~6.4 wt%. Calculated paleodepth about 0.5~1.5 km (hydrostatic pressure) indicate epithermal ore-forming condition. Shallow depth but relatively high-T hydrothermal fluids possibly create a steep geothermal gradient, sufficient for base metal precipitation in the Inseong deposit.