• Economic and Environmental Geology
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• v.34 no.6
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• pp.507-522
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• 2001

At the Tongyeong mine, quartz, rhodochrosite (kutnahorite), muscovite, illite, pyrite, galena, chalcopyrite. sphalerite, acanthite, and hessite are the principal vein minerals. They were deposited under epithermal conditions in two stages. Ore mineral assemblages and associated gangue phases in stage can be clearly divided into two general associations: an early cycle (band) that appeared with introduction of most of the sulfides and electrum, and a later cycle in which base metal and carbonate-bearing assemblages (mostly rhodochrosite) became dominant. Tellurides and some electrum occur as small rounded grains within subhedral-to euhedral pyrite or anhedral galena in stageII. Sulfide mineralization is zoned from pyrite to galena and sphalerite. We have used computer modeling to simulate formation of four stages of vein genesis. The reaction of a single fluid with andesite host rock at 28$0^{\circ}C$, isobaric cooling of a single fluid from 26$0^{\circ}C$ to 12$0^{\circ}C$, and boiling and mixing of a fluid with both decreasing pressure and temperature were studied using the CHILLER program. Calculations show that the precipitation of alteration minerals is due to fluid-andesite interaction as temperature drops. Speciation calculations confirm that the hydrothermal fluids with moderately high salinities and pH 5.7 (acid), were capable of transporting significant quantities of base metals. The abundance of gold in fluid depends critically on the ratio of total base metals and iron to sulfide in the aqueous phase because gold is transported as an Au(HS)$_2$- complex, which is sensitive to sulfide activity. Modeling results for Tongyeong mineralization show strong influence of shallow hydrogenic processes such as boiling and fluid mixing. The variable handing in stageII mineralization is best explained by maltiple boilings of hydrothermal fluid followed by lateral mixing of the fluid with overlying diluted, steam-heated ground water. The degree of similarity of calculated mineral assemblages and observed electrum composition and field relationships shows the utility of the numerical simulation method in identifying chemical processes that accompany boiling and mixing in Te-bearing Au-Ag system. This has been applied in models to narrow the search area for epithermal ores.

• Economic and Environmental Geology
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• v.17 no.1
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• pp.17-34
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• 1984

The Ordovician limestone and dolomite was mineralized by the intrusion of quartz porphyry to form hydrothermal ore deposit along the fault shear zone, which trends $N30^{\circ}-40^{\circ}W$ dipping $60^{\circ}-70^{\circ}SW$. The primary manganese carbonates in the upper part of the deposit were oxidized to form supergene manganese ore deposits. The quartz porphyry is plotted mainly in granite region of the triangular diagram of normative composition. The granite phase contains more copper and lead, but less zinc, nickel and chromium than the granodiorite phase which occupies the northwestern part of the quartz porphyry. The content of copper, lead, zinc, nickel and chromium in the quartz porphyry is lower compared with the granitic rocks from the copper province in the Gyeongsang basin. But the granitic rocks from the lead-zinc province has lower content of copper and nickel than the quartz porphyry. The primary distribution pattern of trace elements in the country rock of limestone and dolomite has close relation with the hydrothermal mineralization, showing anomalous or high content near the fault shear zone. The secondary distribution pattern of trace elements in soils shows close relation with the solubility of the carbonates of the elements under weathering condition.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.305-313
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• 2010

Mineralogical characteristics of Cu-Co ores from the Central African Copperbelt in the Democratic Repblic of Congo are studied using powder X-ray diffractometer, general area detector X-ray diffractometer, and electron proble microanalyzer. Black ores are mainly composed of heterogenite (cobalt oxide/hydroxide mineral) and malachite (copper carbonate mineral), whereas green ores are only composed of malachite. Heterogenite shows very bright white color under the reflected microscope, and belongs to 3R polytype, because it has d-spacings at $4.39{\AA}$ and $2.316{\AA}$. Since NiO and $Fe_20_3$ content of heterogenite are lower than those of 3R polytype from other localities, it cannot completely exclude the presence of 2H polytype in heterogenite from this study. Malachite is light grey color under the reflected microscope with approximate chemical formula of $Cu_{1.97}Co_{0.02}Fe^{2+}{_{0.01}}CO_3(OH)_2$. Heterogenite and malachite were probably formed at the supergene emichment stage, the last mineralization stage in the Central African Copperbelt. Cobalt seems to be much more emiched in the black supergene (oxy)hydroxide ore than those in the primary sulfide ore.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.363-379
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• 2014

The Haenam Pb-Zn skarn deposit is located at the Hwawon peninsula in the southwestern part of the Ogcheon Metamorphic Belt. The deposit is developed along the contact between limestone of the Ogcheon group and Cretaceous quartz porphyry. Petrography of ore samples, chemical composition of skarn and ore minerals, and geochemistry of the related igneous rocks were investigated to understand the characteristics of the skarn mineralization. Skarn zonation consists of garnet${\pm}$pyroxene${\pm}$calcite${\pm}$quartz zone, pyroxene+garnet+quartz${\pm}$calcite zone, calcite+pyroxene${\pm}$garnet zone, quartz+calcite${\pm}$pyroxene zone, and calcite${\pm}$chlorite zone in succession toward carbonate rock. Garnet commonly shows zonal texture comprised of andradite and grossular. Pyroxene varies from Mn-hedenbergite to diopside as away from the intrusive rock. Chalcopyrite occurs as major ore mineral near the intrusive rock, and sphalerite and galena tend to increase as going away. Electron probe microanalyses revealed that FeS contents of sphalerite become decreased from 5.17 mole % for garnet${\pm}$pyroxene${\pm}$calcite${\pm}$quartz zone to 2.93 mole %, and to 0.40 mole % for calcite+pyroxene${\pm}$garnet zone, gradually. Ag and Bi contents also decreased from 0.72 wt.% and 1.62 wt.% to <0.01 wt.% and 0.11 wt.%, respectively. Thus, the Haenam deposit shows systematic variation of species and chemical compositions of ore minerals with skarn zoned texture. The related intrusive rock, quartz porphyry, expresses more differentiated characteristics than Zn-skarn deposit of Meinert(1995), and has relatively high$SiO_2$ concentration of 72.76~75.38 wt.% and shows geochemical features classified as calc-alkaline, peraluminous igneous rock and volcanic arc tectonic setting.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.2
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• pp.125-140
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• 2022

The Xiquegou Pb-Zn deposit is located at the Qingchengzi orefield which is one of the largest Pb-Zn mineralized zone in the northeast of China. The geology of this deposit consists of Archean granulite, Paleoproterozoinc migmatitic granite, Paleo-Mesoproterozoic sodic granite, Paleoproterozoic Liaohe group, Mesozoic diorite and Mesozoic monzoritic granite. The Xiquegou deposit which is a Triassic magma-hydrothermal type deposit occurs as vein ore filled fractures along fault zone in unit 3 (dolomitic marble and schist) of Dashiqiao formation of the Paleoproterozoic Liaohe group. Xiquegou Pb-Zn deposit consists of quartz, apatite, calcite, pyrite, arsenopyrite, pyrrhotite, marcasite, sphalerite, chalcopyrite, stannite, galena, tetrahedrite, electrum, argentite, native silver and pyrargyrite. Wallrock alteration of this deposit contains silicification, pyritization, dolomitization, chloritization and sericitization. Based on mineral petrography and paragenesis, dolomites from this deposit are classified two type (1. dolomite (D₀) as wallrock, 2. dolomite (D₁) as wallrock alteration in Pb-Zn mineralization quartz vein ore). The structural formulars of dolomites are determined to be Ca_1.03-1.01Mg_0.95-0.83Fe_0.12-0.02Mn_0.02-0.00(CO₃)₂(D₀) and Ca_1.16-1.00Mg_0.79-0.44Fe_0.53-0.13Mn_0.03-0.00As_0.01-0.00(CO₃)₂(D₁), respectively. It means that dolomites from the Xiquegou deposit have higher content of trace elements compared to the theoretical composition of dolomite. The dolomite (D₁) from quartz vein ore has higher content of these trace elements (FeO, PbO, Sb₂O₅ and As₂O₅) than dolomite (D₀) from wallrock. Dolomites correspond to Ferroan dolomite (D₀), and ankerite and Ferroan dolomite (D₁), respectively. The structural formular of chlorite from quartz vein ore is (Mg_1.65-1.08Fe_2.94-2.50Mn_0.01-0.00Zn_0.01-0.00Ni_0.01-0.00Cr_0.02-0.00V_0.01-0.00Hf_0.01-0.00Pb_0.01-0.00Cu_0.01-0.00As_0.03-0.00Ca_0.02-0.01Al_1.68-1.61)_5.77-5.73(Si_2.84-2.76Al_1.24-1.16)_4.00O₁₀(OH)₈. It indicated that chlorite of quartz vein ore is similar with theoretical chlorite and corresponds to Fe-rich chlorite. Compositional variations in chlorite from quartz vein ore are caused by mainly octahedral Fe²⁺ <-> Mg²⁺ (Mn²⁺) substitution and partly phengitic or Tschermark substitution (Al^3+,VI+Al^3+,IV <-> (Fe²⁺ 또는 Mg²⁺)^VI+(Si⁴⁺)^IV).

• Economic and Environmental Geology
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• v.25 no.1
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• pp.51-60
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• 1992

The pluton rocks in Kwangyang-Seungju area consist of two mica granite, hornblende diorite, Rimunri quartz diorite, grnodiorite porphyry and granophyre. The analysis of the geochronological data by the methods of K-Ar for the hornblende from Rimunri quartz diorite and hornblende diorite show that the ages are found to be $86{\pm}3.3$ Ma and $108{\pm}4$ Ma, respectively, and K-Ar age for chlorite from the altered two mica granite which intruded by the hornblende diorite of the Bonjeong mine shows $108{\pm}4$ Ma; K-Ar age for sericite from the greisenized hornblende diorite, which is closely associated with the Bonjeong ore deposits, is dated as $94.2{\pm}2.4$ Ma. They correspond to the igneous activity of the Bulgugsa Disturbance periods in the area. In chemical feature for oxides versus silica and AFM triagular diagrams of the pluton rocks in the study area, there is a suggestion of the possibility that these rock facies area a Calc-alkali series of differentiated products by low-pressure crystal fractionation processes in $SiO_2$-undersaturated suites. Compared with hornblende diorite, andesite and granodiorite porphyry, two mica granite, Rimunri quartz diorite and granophyre exhibit a wider range of normalized REE abundance and negative Eu anomalies. Such anomalies imply more extensive feldspar fractionation during crystallization. The Rimunri quartz diorite and hornblende diorite occurring in the margin of four mines(Bonjeong, Okdong, Soungchei and Saungyeul) of this area have high contents of As, Sb, Cu and Zn which have been shown as the best indicators in hypogene gold deposits and low contents of Ba, Cr served as more sensitive indicators. And the granitoids are regarded as the rocks associated with gold and sulfide mineralization of the area.

• Economic and Environmental Geology
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• v.53 no.4
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• pp.363-381
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• 2020

The polymetallic Co, Ni, Cu, As, Au, and Ag deposits of Bou Azzer East are located in the western part of the Bou Azzer inlier in the Central Anti Atlas, Morocco. Six stages of emplacement of the mineralization have been identified. Precious metals (native gold and electrum) are present in all stages of this deposit except the early nickeliferous stage. From the Statistical analysis of the Co, As, Ni, Au, and Ag contents of a set of 501 samples, shows that the Pearson correlation coefficient between As-Co elements (0.966) is the highest followed by that of the Au-Ag couple (0.506). Principal component analysis (PCA) and hierarchical ascending classification (HAC) of the grades show, that Ni is associated with the pair (As-Co) and Cu is rather related to the pair (Au-Ag). The kriging maps show that the highest values of the Co, As and Ni appear in the contact of the serpentinite with other facies, as for those of Au and Ag, in addition to anomalous zones concordant with those of Co, Ni and As, they show anomalies at the extreme South and North of the study area. The development of the anomalous Au and Ag zones is mainly along the N40-50°E and N145°E directions.

• The Journal of Engineering Geology
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• v.15 no.1
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• pp.19-27
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• 2005

The Sambo mine is located in Hae-je Myeon, Moo-an Gun, Chollanamdo, which consists of host gneiss and rhyolite possessing quartzite veins with other compositions such as gold, silver, and sublimated sulfur. The ore grade estimated from the core was 0.05～10.9g/t or less in gold and 0.05～389g/t or less in silver, indicating a partial mineralization. The purpose of this paper is to understand the subsurface structures and the distribution of mineralized bodies in the Sambo mine using a combined method of Schlumberger, Wenner, and Dipole-di-pole resistivity surveys on the surface and the resistivity tomography survey in boreholes. The result of three-dimensional resistivity inversion showed that the mineralized body is extended to 240m long in the N10°～20°E direction, with 30m wide and 80 m thick from the surface. The low resistivity zones (<1,000ohm-m) determined from the resistivity image were in good agreement with the mineralized bodies and weak zones identified from the logged cores.

• Economic and Environmental Geology
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• v.27 no.4
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• pp.363-373
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• 1994

The Cretaceous granitic rocks show differences in rock types and chemical compositions according to metallogenic provinces of copper, lead zinc and molybdenum in the Gyeongsang basin. Jindong granites are of granodiorite~quartz diorite~diorite in Cu-province; Makeunsan/Yucheon-Eonyang granites, granodiorite~granite in Pb Zn-province; Onjeongri-Yeonghae granites, granodiorite~quartz diorite in Mo-province, and there is a trend that productive masses are less differenciated than barren masses in Cu and Pb-Zn provinces whereas productive masses are more differenciated than barren masses in Mo province. Metallogenic provinces are distinguishable by variations of major and trace elements. The Cretaceous granitic rocks are highest in the content of Ca, Mg and other basic major elements and lowest in the content of K and Na in Cu provicne; the variation trends are vice versa in Pb-Zn province. Trace elements such as Rb and Sr show variations related to K and Ca, and metallogenic provinces are also distinguishable by their ratios. The granitic rocks of Mo province have intermediate content of major and trace elements, but are clearly distinguishable from Jindong granites and partly overlapped by Yucheon-Eonyang granites. Chlorine content in biotites is higher in a productive mass than in a barren mass in Cu province. Therefore, the mineralogical and chemical compositions are applicable as geochemical index to distinguish the types of mineralizaion, and productive and barren masses of the Cretaceous granitic rocks in the Gyeongsang basin.

• Economic and Environmental Geology
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• v.21 no.3
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• pp.257-268
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• 1988

The Mugeug gold deposits is consisted of more than fourteen gold and silver-bearing quartz veins emplaced in Mesozoic granodiorite mass. In the Samhyungje vein, one of the representative vein in the mine, six stages of mineralizatidns are recognized: Stage I, deposition of base-metal sulfides and gray quartz; stage II, deposition of base-metal sulfides, electrum and white quartz with pinkish tint; stage m, deposition of base-metal sulfides and dark gray quartz; stage N, deposition of native silver, argentite, Ag-tetrahedrite, polybasite, arsenpolybasite and quartz; stage V, deposition of nearly barren quartz; stage VI, deposition of transparent quartz veinlets with minor pyrite. Ag contents of electrum increase steadily from stage II to stage N; 57.25-61.44 atom. % for stage II, 62.85-69.66 atom. % for stage m, 69.79-74.12 atom. % for stage N. Homogenization temperatures of fluid inclusions are as follows; stage II, from $194^{\circ}$ to $287^{\circ}C$; stage V, from $137^{\circ}$ to $171^{\circ}C$, stage VI, from $192^{\circ}$ to $232^{\circ}C$. Salinities of fluid inclusions range from 3.7 to 7.9 wt.% equivalent NaCl in stage II and from 0.8 to 4.3 wt.% equivalent Nael in stage V. Ore mineralogy suggest that temperature and sulfur fugacity declined steadily from $290^{\circ}$ to $150^{\circ}C$ and from $10^{-10.5}$ to $10^{-19.0}$atm. through stage II into stage N. Fluid pressure during stage II inferred from data of mineral assemblages and fluid inclusions is 370bar.