This paper presents the morphologic,chemical and other typomorphic characteristics of native gold from four placer deposits(basins of the Lev.Nora,Skalistaya and Golysheva rivers,and Loginova brook),four placer occurr...This paper presents the morphologic,chemical and other typomorphic characteristics of native gold from four placer deposits(basins of the Lev.Nora,Skalistaya and Golysheva rivers,and Loginova brook),four placer occurrences(basins of the Lagernaya,Nizh.Litke and Prokhodimaya rivers,and Tikhiy brook),and the alluvial deposit of cape Mordovin on Bolshevik island of the Severnaya Zemlya archipelago(Russia).Optical microscopy,scanning electron microscopy and electron-probe microanalysis were used in this study.Placer gold from the Lagernaya,Golysheva,Nizh.Litke and Skalistaya rivers,Tikhiy brook and cape Mordovin is characterized by a very high fineness(>988‰)in the rims and a lower fineness(860‰–970‰)in the center.Gold particles from the placers of the Lev.Nora and Prokhodimaya rivers and Loginova brook are low fineness and widely vary in the center(from 647‰to 920‰)and are high fineness(950‰–980‰)in the rims.In some gold particles from the placers of the Lev.Nora and Skalistaya rivers,zones with Cu up to 1.2 wt.%and Hg up to 2.6 wt.%are observed.Titanite,monazite,cobaltite,ulmannite,brannerite,rutile,zircon,Y-xenotime,bismuthite,native bismuth and bismuthinite,garnet(almandine),Cu-or Ni-pyrrhotite were found in the native gold from the Skalistaya and Lev.Nora placers.Native gold from the Skalistaya river placer contains mineral micro-inclusions of cobaltite,Cu,Cd-bearing sphalerite and Fe,Cu-ullmannite.Native gold from the Lev.Nora river placer differs in the presence of brannerite and bismuth minerals.On the basis of the obtained results,available metallogenic characteristics of Bolshevik island and literature data,the following types of primary sources are predicted for these locations:(1)Lev.Nora river deposits of gold-copper rare metal and porphyry gold-copper formations;(2)Skalistaya river deposits of porphyry gold-copper and gold-quartz formation;(3)all the other locations:deposits of gold-quartz and gold-sulfide-quartz formations(hosted in terrigenous carbonaceous complexes).The presence of intermediate reservoirs near some of these locations is probable.展开更多
The tabular beryl found in Huya Country, Sichuan Province is a rare and special member among beryls. Chemical analysis reveals that the beryl is a new type of Cs-rich Na-Li beryl, and the content of alkalis （Li20, Na...The tabular beryl found in Huya Country, Sichuan Province is a rare and special member among beryls. Chemical analysis reveals that the beryl is a new type of Cs-rich Na-Li beryl, and the content of alkalis （Li20, Na2O, K2O, Rb2O, Cs2O） is up to 2.41%. The CCD system on the SMART APEX four circle single crystal diffractometer was used in this experiment to determine the structure of the sample accurately. The beryl belongs to the hexagonal system; its space group is P6/mcc. The dimensions of the unit cell are as follows： a = 0.91961（3） nm, c = 0.91969（7） nm, c/a = 1.0000, V= 0.67357 nm3, 7 = 120°, α= 90°, β = 90°. The accurate atomic coordinates of alkali metal ions and other crystallographic parameters are also obtained： Z = 2, the calculated density D = 2.754 g/cm^3 and final R （ I 〉 2 σ （/3）= 0.046 for 5597 reflections. The crystal structure was described by coordination polyhedron. Based on the data gained, a three-dimensional graph of the crystal structure of tabular beryl was made with the ATOMS 6.0 software. The refinement of crystal structure indicates that there are two main reasons for the cause of the tabular configuration： （1） The substitution of Be by Li into the tetrahedral framework weakened the stacked six-sided rings [Si6O18]^12- of the tetrahedral Si; （2） Alkalis （mainly Na and Cs） are too large to substitute in four-fold or six-fold coordination within the structure and are accommodated in the vacant channel. The accommodation of these alkalis strengthened the structure of six-sided rings of the tetrahedral Si. And other alkali metal ions and free volatile molecules such as H2O and CO2 occupy variable positions in the channel. The equation of the electrovalence is Li＋＋Na＋→Be^2＋. According to structural and compositional differences, the monoclinic crystal of tabular beryl is considered to be a new member of the beryl group. Chemical constraints of the environment, namely, the bulk-rock chemistry and the fluid-phase composition and physical-chemical conditions during the growth of the mineral may account for these occurrences of rare elements. In addition, that Li and Be have appro^mate physical parameters is also the key factor for the substitution. The direction of the mineralized hydrothermal liquid and the special occurrence conditions of the beryl such as the pH, temperature and pressure are also considered to be the main causes of the configuration of the tabular beryl.展开更多
Utilizing theories of minerageny and prospecting mineralogy, the authors studied the attitude, morphotype and chemical composition of metallic minerals of pyrite, gold, chalcopyrite, galena and sphalerite, non-metalli...Utilizing theories of minerageny and prospecting mineralogy, the authors studied the attitude, morphotype and chemical composition of metallic minerals of pyrite, gold, chalcopyrite, galena and sphalerite, non-metallic minerals of quartz, carbonate, dolomite and rutile in the Puziwan gold deposit. The study shows the following results. （1） The mineral assemblage is complex and the species of sulfide are abundant with occurrences of sulfosalt minerals. （2） The composition in the minerals is complex and there rich micro elements, including As, Sb, Bi, Se, Te, Au, Ag, Cu, Pb, Zn, and Cr, Ni, V. The typomorphic characteristics of the association of the elements and their specific value suggest that gold mineralization is associated with shallow magmatic hydrothermal activity, the oreforming fluid is the mixture of abundant rising alkali magmatic water originating from the mantle or the lower crust and the descending acid atmospheric water. （3） Ankerite, Fe-rich sphalerite, granular Ti-rich rutile are widely distributed, which indicate great denudation depths, high mineralization temperature. The deposit is found in the middle and shallow positions of the porphyry series. The deep layers are not favorable for gold mineralization. （4） Copper minerals are rich in the ores and sulfides have high content of copper, suggesting possible porphyry-type Cu （Au） mineralization in deep positions and the surrounding areas.展开更多
Arsenopyrite is one of very important and common auriferous minerals in endogenetic gold deposits. In seven gold deposits, the prospecting typomorphic characteristics of arsenopyrite, such as morphological typomorphis...Arsenopyrite is one of very important and common auriferous minerals in endogenetic gold deposits. In seven gold deposits, the prospecting typomorphic characteristics of arsenopyrite, such as morphological typomorphism, composition typomorphism, pyroelectricity typomorphism and so on, were established. The crystal form of arsenopyrite is simple, and the form symbols mainly are {101}, {120}, {210}, {140}, {230}, {012}, etc. The smaller grain and poor crystal form arsenopyrite indicates the better auriferous characteristics. The major elements (Fe, As and S) of gold-bearing arsenopyrite usually show Fe/As+S>0.5,As/S<1 which deviates from its theoretical value. The most important trace element is Au and next is Ag in arsenopyrite, and they often show the positive correlation. The pyroelectricity of arsenopyrite can reflect the mineralization epoch, and it also is related to the crystal form and granudarity.展开更多
The morphology, REE geochemistry and U-Pb geochronology of zircons from quartz monzodiorite in the Sunzhuang area, Fanshi County, Shanxi Province are presented in this study. The zircon crystals can be classified into...The morphology, REE geochemistry and U-Pb geochronology of zircons from quartz monzodiorite in the Sunzhuang area, Fanshi County, Shanxi Province are presented in this study. The zircon crystals can be classified into four main types as： AB, L, S and P, and 24 subtypes such as AB4, ABs, Ls, and S3. The maximum crystallization temperature of zircon was estimated as 850℃, with the minimum of 550℃. The peak temperatures of the zircon crystallization range from 650℃ to 700℃. The abundances of Th and U in the zircon grains show large variation with the Th/U values 〉 0.4. The Th and U values also show a positive correlation in most zircons. The REE abundance of zircon in the quartz monzodiorite ranges from 280.4 ppm to 2143 ppm with an average of 856.4 ppm. The chondrite normalized zircon REE patterns show two types, one is characterized by HREE enrichment and LREE depletion with positive Ce-anomaly and negative Eu-anomaly whereas the other is HREE enriched and LREE depleted with negative Eu-anomaly but without positive Ce-anomaly, and relatively flat patterns. The LA-ICP-MS U-Pb geochronology on the zircons yields a mean age of 133-0.87 Ma. Our data on zircon morphology, composition and U-Pb geochronology reveal that the parent magma of the quartz monzodiorite which was emplaced during late Yanshanian had a mixed crust-mantle source, with crustal components dominating. The magma is inferred to have been water rich and alkaline with initial high oxygen fugacity. Post-magmatic hydrothermal activity occurred under relatively reducing conditions which was conductive for gold precipitation in the Yixingzhai gold deposit.展开更多
基金The work was carried out within the framework the State assignment of the Federal Agency for Subsoil Use of 27.12.2023№049-00003-24-00a State Assignment of the Sobolev Institute of Geology and Mineralogy,Russian Academy of Sciences(project no.122041400237-8).
文摘This paper presents the morphologic,chemical and other typomorphic characteristics of native gold from four placer deposits(basins of the Lev.Nora,Skalistaya and Golysheva rivers,and Loginova brook),four placer occurrences(basins of the Lagernaya,Nizh.Litke and Prokhodimaya rivers,and Tikhiy brook),and the alluvial deposit of cape Mordovin on Bolshevik island of the Severnaya Zemlya archipelago(Russia).Optical microscopy,scanning electron microscopy and electron-probe microanalysis were used in this study.Placer gold from the Lagernaya,Golysheva,Nizh.Litke and Skalistaya rivers,Tikhiy brook and cape Mordovin is characterized by a very high fineness(>988‰)in the rims and a lower fineness(860‰–970‰)in the center.Gold particles from the placers of the Lev.Nora and Prokhodimaya rivers and Loginova brook are low fineness and widely vary in the center(from 647‰to 920‰)and are high fineness(950‰–980‰)in the rims.In some gold particles from the placers of the Lev.Nora and Skalistaya rivers,zones with Cu up to 1.2 wt.%and Hg up to 2.6 wt.%are observed.Titanite,monazite,cobaltite,ulmannite,brannerite,rutile,zircon,Y-xenotime,bismuthite,native bismuth and bismuthinite,garnet(almandine),Cu-or Ni-pyrrhotite were found in the native gold from the Skalistaya and Lev.Nora placers.Native gold from the Skalistaya river placer contains mineral micro-inclusions of cobaltite,Cu,Cd-bearing sphalerite and Fe,Cu-ullmannite.Native gold from the Lev.Nora river placer differs in the presence of brannerite and bismuth minerals.On the basis of the obtained results,available metallogenic characteristics of Bolshevik island and literature data,the following types of primary sources are predicted for these locations:(1)Lev.Nora river deposits of gold-copper rare metal and porphyry gold-copper formations;(2)Skalistaya river deposits of porphyry gold-copper and gold-quartz formation;(3)all the other locations:deposits of gold-quartz and gold-sulfide-quartz formations(hosted in terrigenous carbonaceous complexes).The presence of intermediate reservoirs near some of these locations is probable.
基金This investigation was supported financially by the Ministry of Education of China （Nos. 01037 and 03178）the National Natural Science Foundation of China （Nos. 40304007 and 40172036） the Fund of State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences （Nos. GPMR0530）.
文摘The tabular beryl found in Huya Country, Sichuan Province is a rare and special member among beryls. Chemical analysis reveals that the beryl is a new type of Cs-rich Na-Li beryl, and the content of alkalis （Li20, Na2O, K2O, Rb2O, Cs2O） is up to 2.41%. The CCD system on the SMART APEX four circle single crystal diffractometer was used in this experiment to determine the structure of the sample accurately. The beryl belongs to the hexagonal system; its space group is P6/mcc. The dimensions of the unit cell are as follows： a = 0.91961（3） nm, c = 0.91969（7） nm, c/a = 1.0000, V= 0.67357 nm3, 7 = 120°, α= 90°, β = 90°. The accurate atomic coordinates of alkali metal ions and other crystallographic parameters are also obtained： Z = 2, the calculated density D = 2.754 g/cm^3 and final R （ I 〉 2 σ （/3）= 0.046 for 5597 reflections. The crystal structure was described by coordination polyhedron. Based on the data gained, a three-dimensional graph of the crystal structure of tabular beryl was made with the ATOMS 6.0 software. The refinement of crystal structure indicates that there are two main reasons for the cause of the tabular configuration： （1） The substitution of Be by Li into the tetrahedral framework weakened the stacked six-sided rings [Si6O18]^12- of the tetrahedral Si; （2） Alkalis （mainly Na and Cs） are too large to substitute in four-fold or six-fold coordination within the structure and are accommodated in the vacant channel. The accommodation of these alkalis strengthened the structure of six-sided rings of the tetrahedral Si. And other alkali metal ions and free volatile molecules such as H2O and CO2 occupy variable positions in the channel. The equation of the electrovalence is Li＋＋Na＋→Be^2＋. According to structural and compositional differences, the monoclinic crystal of tabular beryl is considered to be a new member of the beryl group. Chemical constraints of the environment, namely, the bulk-rock chemistry and the fluid-phase composition and physical-chemical conditions during the growth of the mineral may account for these occurrences of rare elements. In addition, that Li and Be have appro^mate physical parameters is also the key factor for the substitution. The direction of the mineralized hydrothermal liquid and the special occurrence conditions of the beryl such as the pH, temperature and pressure are also considered to be the main causes of the configuration of the tabular beryl.
文摘Utilizing theories of minerageny and prospecting mineralogy, the authors studied the attitude, morphotype and chemical composition of metallic minerals of pyrite, gold, chalcopyrite, galena and sphalerite, non-metallic minerals of quartz, carbonate, dolomite and rutile in the Puziwan gold deposit. The study shows the following results. （1） The mineral assemblage is complex and the species of sulfide are abundant with occurrences of sulfosalt minerals. （2） The composition in the minerals is complex and there rich micro elements, including As, Sb, Bi, Se, Te, Au, Ag, Cu, Pb, Zn, and Cr, Ni, V. The typomorphic characteristics of the association of the elements and their specific value suggest that gold mineralization is associated with shallow magmatic hydrothermal activity, the oreforming fluid is the mixture of abundant rising alkali magmatic water originating from the mantle or the lower crust and the descending acid atmospheric water. （3） Ankerite, Fe-rich sphalerite, granular Ti-rich rutile are widely distributed, which indicate great denudation depths, high mineralization temperature. The deposit is found in the middle and shallow positions of the porphyry series. The deep layers are not favorable for gold mineralization. （4） Copper minerals are rich in the ores and sulfides have high content of copper, suggesting possible porphyry-type Cu （Au） mineralization in deep positions and the surrounding areas.
文摘Arsenopyrite is one of very important and common auriferous minerals in endogenetic gold deposits. In seven gold deposits, the prospecting typomorphic characteristics of arsenopyrite, such as morphological typomorphism, composition typomorphism, pyroelectricity typomorphism and so on, were established. The crystal form of arsenopyrite is simple, and the form symbols mainly are {101}, {120}, {210}, {140}, {230}, {012}, etc. The smaller grain and poor crystal form arsenopyrite indicates the better auriferous characteristics. The major elements (Fe, As and S) of gold-bearing arsenopyrite usually show Fe/As+S>0.5,As/S<1 which deviates from its theoretical value. The most important trace element is Au and next is Ag in arsenopyrite, and they often show the positive correlation. The pyroelectricity of arsenopyrite can reflect the mineralization epoch, and it also is related to the crystal form and granudarity.
基金supported by the Key Program of National Natural Science Foundation of China (Grand No.90914002)the China State Administrative Office of Ore-Prospecting Project for Critical Mines (Grant No.20089937)+1 种基金Nuclear energy research project:study on Sandstone-type uranium deposits prediction technology in Junggar superimposed large basin (Grant No.DH1142)the Introducing Talents of Discipline to Universities Program (B07011)
文摘The morphology, REE geochemistry and U-Pb geochronology of zircons from quartz monzodiorite in the Sunzhuang area, Fanshi County, Shanxi Province are presented in this study. The zircon crystals can be classified into four main types as： AB, L, S and P, and 24 subtypes such as AB4, ABs, Ls, and S3. The maximum crystallization temperature of zircon was estimated as 850℃, with the minimum of 550℃. The peak temperatures of the zircon crystallization range from 650℃ to 700℃. The abundances of Th and U in the zircon grains show large variation with the Th/U values 〉 0.4. The Th and U values also show a positive correlation in most zircons. The REE abundance of zircon in the quartz monzodiorite ranges from 280.4 ppm to 2143 ppm with an average of 856.4 ppm. The chondrite normalized zircon REE patterns show two types, one is characterized by HREE enrichment and LREE depletion with positive Ce-anomaly and negative Eu-anomaly whereas the other is HREE enriched and LREE depleted with negative Eu-anomaly but without positive Ce-anomaly, and relatively flat patterns. The LA-ICP-MS U-Pb geochronology on the zircons yields a mean age of 133-0.87 Ma. Our data on zircon morphology, composition and U-Pb geochronology reveal that the parent magma of the quartz monzodiorite which was emplaced during late Yanshanian had a mixed crust-mantle source, with crustal components dominating. The magma is inferred to have been water rich and alkaline with initial high oxygen fugacity. Post-magmatic hydrothermal activity occurred under relatively reducing conditions which was conductive for gold precipitation in the Yixingzhai gold deposit.
