Cu-Zn Ore Research Articles

Fluid evolution and ore genesis of the Weilasituo Li-Sn-Cu-Zn polymetallic deposit in Inner Mongolia: Evidence from fluid inclusion and C-H-O-Li isotopes

The Weilasituo Li-Sn-Cu-Zn polymetallic deposit is located in the southwestern Great Xing'an Range (GXR), and crypto-explosive breccia-type and hydrothermal vein-type mineralization are developed in the mining area. With the Early Cretaceous amazonite granite as the mineralization center, the greisen-type Li(-Rb) mineralization is developed in the crypto-explosive breccia pipe above the granite, and the quartz vein-type Sn(-W-Mo) and Cu-Zn(-Ag) mineralization is successively developed in the surrounding Paleoproterozoic Xilinguole complex, forming mineralization zoning. The polymetallic metallogeny comprises early Li (Rb) through Sn(-W-Mo) to late Cu-Zn(-Ag) mineralization, and can be divided into six stages: (I) zinnwaldite–topaz–fluorite, (II) quartz–arsenopyrite–cassiterite–sphalerite–wolframite, (III) quartz–molybdenite–polymetallic sulfides, (IV) quartz–arsenopyrite–pyrite–chalcopyrite, (V) quartz–chalcopyrite–pyrrhotite–sphalerite–galena ± pyrite, and (VI) quartz–calcite–fluorite.Fluid inclusions (FIs) in the zinnwaldite, topaz and fluorite of Li(-Rb) ore phase contain high-temperature medium-salinity (348–404℃; 5.09–9.60 wt%) vapor–liquid two–phase aqueous type (vapor–liquid ratio: 35–70 %), similar to intermediate-density (ID) type FIs, and represent a single-phase fluid directly exsolved from the magma; FIs in the Sn(-W-Mo) ore phase quartz contain daughter mineral-bearing three-phase (SVL), vapor (V), vapor-rich two-phase aqueous (LV) and liquid-rich two-phase aqueous (VL) type, reflecting fluid boiling; FIs in the Cu-Zn(-Ag) ore phase quartz contain CH4 ± CO2 two-phase FIs and VL-type FIs, indicating fluid immiscibility. Lithium isotope data show that the Li ore-forming material was crustal derived, while H-O isotope data indicate that the ore fluid was derived from magmatic water and mixed with meteoric water in the late Cu-Zn(-Ag) ore phase; Carbon isotope data suggest that the CH4 and CO2 in the FIs were sourced from the fluid-rock reaction between the hydrothermal fluid and with the Xilinguole Complex graphite-bearing wallrocks. Raman spectroscopy shows that stage Ⅱ-Ⅴ FIs contain CH4 and CO2, whose content increased markedly from the Sn(-W-Mo) to Cu-Zn(-Ag) stage, indicating that CH4 and CO2 are enriched continuously with fluid migration and fluid-rock reaction.We conclude tha the initial single-phase ID Li-Rb-W-Sn-rich fluid was exsolved from the magma, and formed the Li(-Rb) mineralization in the crypto-explosive breccia pipe as the temperature dropped. Subsequently, the fluid entered the faults and the pressure dropped, causing fluid boiling, and triggered the proximal Sn(-W-Mo) vein-type mineralization. With the fluid migration and more water–rock reaction, CH4 and CO2 are continuously enriched and fluid immiscibility occurred, forming the distal Cu-Zn(-Ag) vein-type mineralization.

Geological, geochemical and fluid inclusion features of Kömürlükdere and Göçükdibi Cu-Zn ore (Central Pontides, Turkey): Implications for their genesis

The Kömürlükdere and Göçükdibi Cu-Zn ores are located in the Central Pontide orogenic belt, where Besshi-type deposits (such as Hanönü, Zeybek, Sayyayla [Kastamonu]) have been discovered in last two decades. The Göçükdibi and Kömürlükdere ores are hosted in metabasites and quartz schist that belong to the Middle Jurassic Kunduz metamorphic rocks in the accretionary complex in the Central Pontides. The ore bodies show stratiform features, parallel to schistosity, within an alternation of metabasite and quartz schist succession. The average thicknesses of the ore zone and ore levels within the ore zone are 12 m and 3 cm, respectively. The ore bodies contain chalcopyrite, sphalerite, and magnetite, with dominant pyrite formed during the ore formation phase. Meanwhile, hematite, covellite, malachite, and goethite minerals formed during the supergene processes.Microprobe studies showed that the Fe and Cd content of sphalerite varies from 0.08 to 1.12 wt%, indicating Fe-poor sphalerite, and 0.08–0.27 wt%, respectively. The Zn/Cd ratios (average 274.4 for Kömürlükdere, 288.6 for Göçükdibi) of the sphalerite are comparable to those of the worldwide volcanogenic-massive sulfide (VMS) ore system related to andesitic-basaltic source rocks. The Co/Ni ratio (mean 3.2) of pyrite shows volcanogenic pyrite.The average δ34S of the stratiform pyrites is 3.9 ‰ (ranging from 2.06 ‰ to 5.34 ‰), indicating that the sulfur comes from a large homogeneous source, possibly magmatic. The average homogenization temperature (Th) and salinity of fluid inclusions obtained from quartz and sphalerite are 313 °C and 7.7 % equiv. NaCl, respectively, and similar to those of the global VMS deposits.The metabasites contain an average of 164 ppm Cu, 127 ppm Zn, and 2.2 ppm Sb, which shows enrichment several times greater than the background value of the basalts. Meanwhile the ore levels contain an average 0.23 % and 0.83 % Cu and Zn values, respectively. The trace metal enrichment of associated metabasites and the ore zones is evident for elements such as Cu, Zn, Cd, As, and Sb, indicating that they both precipitated in the same basin as syngenetic, and that there was repeated pulses of metal-rich fluids exhaled into the basin.Field observations and analytical data (mineral chemistry, sulfur isotope, fluid inclusion, etc.) show that the Kömürlükdere and Göçükdibi Cu-Zn ore bodies occurred as Besshi-type deposits within the Middle Jurassic Central Pontide Supercontinent, which developed in the marine environment appropriate to the accretionary complex located along the southern margin of Eurasia.

Sphalerite as a non-traditional critical metal source: Correlative microscopy (EPMA, EBSD, and APT) of cobalt-enriched sulfides from the sediment-hosted copper-cobalt Dolostone Ore Formation deposit, Namibia

Sphalerite from the sediment-hosted Dolostone Ore Formation (DOF) Cu-Co-Zn deposit, in northwestern Namibia, has previously been shown to contain extremely high concentrations of the critical metal Co (up to 1 wt%). These concentrations are the highest reported in sphalerite to date, and the how and why of sphalerite being able to incorporate such high concentrations of Co are poorly understood. We use correlative electron probe microanalysis, electron backscattered diffraction, and atom probe to reconstruct the likely incorporation mechanisms and modes of occurrence of such high Co concentrations in natural sphalerite. While over twenty samples were studied, the comprehensive analytical workflow was executed on one representative sample to gain a detailed understanding of Co enrichment. The sulfides of the studied sample are Co-rich pyrite, chalcopyrite, Co-rich sphalerite, linnaeite, cobaltpentlandite, and cobaltite, mentioned in order of abundance. Detailed petrography of these sulfides indicates that they formed through three stages during the main Cu-Co-Zn ore stage of the DOF. Cobalt was initially contained in pyrite that grew during Ore Stage 1 and was later affected by oxidizing fluids (Ore Stage two). This led to remobilization and growth of linnaeite (Co2+Co3+2S4). A later change in fO2 (Ore Stage three) led to the breakdown of linnaeite and the further growth of accessory cobaltite along with the Co-rich sphalerite and chalcopyrite. The hyper-enriched Co-sphalerite then is the last major sink for Co in the DOF deposit. A low Fe and Co and high Zn sub-grain boundary network within the Co-rich sphalerite was identified by EPMA and EBSD. This sub-grain network is believed to have formed during a later, secondary metamorphic stage (Cu-Zn (-Pb) Ore Stage 4), which developed during ductile deformational mineralization styles such as pressure shadows and veins. Our APT data reconstructions show no evidence for Co-inclusions within the Co-sphalerite, and spatial ion correlation analyses of the data suggest that Co occurs in the sphalerite through simple substitution of Zn. This study demonstrates that sphalerite may contain significant concentrations of the Co through simple substitution, potentially representing an important non-traditional Co source in future critical metal exploration.

Enrichment mechanisms and occurrence regularity of critical minerals resources in the Yaojialing Zn skarn polymetallic deposit, Tongling district, eastern China

Critical minerals resources are widely used in emerging industries, and their mineralization characteristics and metallogenic regularity are of high importance. Skarn deposits are one of the important sources of critical minerals resources. Yaojialing deposit is a typical large skarn zinc polymetallic deposit in Tongling district of the Middle and Lower Yangtze River metallogenic belt. The ore bodies are mainly lenticular and veined occurrence along the proximal skarn zone and structural or lithologic contacts, respectively. We recognize five hydrothermal stages in the deposit: skarn stage, oxide stage, early sulfide stage, late sulfide stage and carbonate stage. The early and late sulfide stages are the main ore-forming stages. In addition to the production of zinc, gold and copper, the deposit also contains critical element resources such as cadmium, cobalt, selenium, and tellurium. Taking the Yaojialing deposit as an example, this paper shows the occurrence and distribution of critical minerals resources in a typical skarn deposit by using scanning electron microscope, TESCAN integrated mineral analyzer (TIMA), and sulfide LA-ICP MS analysis. Although there are no cadmium minerals in Yaojialing deposit, cadmium can incorporated in the sphalerite lattice, and sphalerite in veins has elevated cadmium content (average 5478.78 ppm). Tellurium content in various sulfides is very low, and it does not enter into the sulfide lattice. It mainly forms tellurobismuthite, hessite and tetradymite, which occur in Cu-Zn ore formed in the early sulfide stage, there are 227 tetradymite grains in a single rock section. Selenium occurs as naumannite in vein ore in the distal of the deposit; selenium can also incorporated the lattice of chalcopyrite and sphalerite, and the selenium content is elevated in sphalerite formed in the early sulfide stage (average 226.80 ppm). The cobalt mineral glaucodot is only found in skarn ore; cobalt easily incorporated the lattice of pyrite and sphalerite, and pyrite and sphalerite formed in the early sulfide stage are enriched in cobalt (average 1962.18 ppm). The characteristics of trace elements in pyrite and sphalerite show that temperature is the main factor affecting the distribution of critical minerals resources, high temperature is conducive to the enrichment of cobalt, selenium and tellurium, while low temperature is conducive to the enrichment of cadmium. Cadmium, cobalt, selenium, and tellurium have high content in specific parts of the deposit, which makes them potentially amenable to recovery.

Modelling effects of dissolved ions in process water on flotation performance

The mining and mineral processing industries need water in all of their operations, from exploration, through mining and processing to closure. Flotation is the most affected by the quality of the process water in all of mineral beneficiation applications. Process water contains dissolved ions of almost all types depending on ore characteristics such as surface chemistry, mineralogy and surface oxidation. There is a general understanding about influence of individual ions on flotation performance in literature. However, it is crucial to demonstrate interactive effects of the major ions in a process water quantitatively using mathematical modelling to control the upper limits of ion contaminations. In this study the major ions affecting flotation performance of a complex Cu-Zn ore were determined to be Ca2+, Cu2+ and S2O32−. An experimental design has been done by using Design Expert Software. The statistical experimental design allowed derivation of mathematical models expressing grade and recovery as a function of water chemistry. These models were used to estimate critical concentration of the dissolved ions for an efficient flotation process.

A Special Issue on Volcanogenic Massive Sulfide Deposits of the Trans-Hudson Orogen: Preface

Paleoproterozoic volcanogenic massive sulfide (VMS) deposits are hosted in greenstone belts that formed during assembly of Earth’s first supercontinent, Nuna, at 2.1 to 1.7 Ga. These deposits account for a significant component of the world’s VMS tonnage and, thus, are an important global exploration target. Among these Paleoproterozoic belts, the 1.92 to 1.80 Ga Trans-Hudson orogen of Canada is the largest and best endowed in Laurentia, with over 29 deposits totaling 320 Mt of Cu-Zn (±Au, Ag, Pb) ore. Study of its deposits, districts, and tectonostratigraphic evolution enables greater understanding of metallogenic and geodynamic processes during the Paleoproterozoic. We briefly overview the Trans-Hudson orogen, its VMS deposits, and their exploration history, and illustrate that various distinct types of volcanogenic massive sulfide deposits form in predictive tectonostratigraphic sequences associated with both pre- and postaccretion volcanism. We present results from a four-year program to investigate the deposits and evolution of the Trans-Hudson orogen, highlighting various approaches at district and belt scales to improve exploration models for other structurally complex and covered Precambrian terranes.

Boron-polymetallic metallogeny of the north and northeast of the Sino-Korean Craton

Based on published data and original investigations, it has been shown that the combination of widely known Ag, Fe, and Fe-Mn ore deposits, as well as boron and Pb-Zn world-class deposits, is typical for metallogenic zones in the north and northeast of the Sino-Korean Craton. The ore genesis was spatially inherited and lasted from the Archean to Mesozoic. The Archean metallogenic zones are related to the protocontinental margin terranes of the craton basement and they comprise banded iron ore and Cu-Zn sulfide deposits. The proterozoic-Early Paleozoic metallogenic zones are related to rift basins, where the ore-bearing Archean folded basement is overlain by volcanic and sedimentary complexes. The Proterozoic metallogenic zones host quartz veins and schistosity zone-related Au deposits, banded iron and Cu-Zn ore deposits, large sedimentary-metamorphogenic borate and magnesite deposits, Cu-W deposits in tourmalinites, exhalation-sedimentary Pb-Zn ore deposits, and large polygenic REE-Fe-Nb ore deposits. The Riphean-Cambrian terrigenous-carbonate strata are represented by stratiform Pb-Zn and fluorite deposits. Mesozoic metallogenic zones related to volcano-plutonic complexes of intraplate series coincide with zones where the folded basement is made of Precambrian ore-bearing series. Gold deposits are typical of all the metallogenic zones, but most of them are related to Mesozoic volcano-plutonic complexes.

Flotation Experimental Study of High-Sulfur Cu-Zn Ore in Yunnan

The experimental ore belongs to high-sulfur Cu-Zn poly-metallic ore, the mineral composition of ore is complex, cupriferous pyrite most are disseminated. The Cu grade of raw ore is 0.76%, Zn grade is 1.48% and S about 25.02%. on the basis of best reagent system and control flotation time, the author did closed circuit process. the results of closed circuit process as follows: the copper concentrate grade is 20.35% and recovery rate is 86.081%; the zinc concentrate grade is 54.32% and recovery rate is 84.20%.

Validation of the efficient application of the electrochemical water processing in ore heap leaching

The article theoretically and experimentally validates the effective applicability of the electrochemically treated acid wastedump water as a leaching agent for low-grade copper-zinc ores instead of sulphuric acid solutions. The authors have found the way to intensify the Cu-Zn ore leaching by adding 20 mg/l of NaCl in the electrochemically treated wastedump water, which allows the active chlorine concentration of 1.5 g/l and accelerates dissolution of copper and zinc to product solution by a factor of 2.8–6.

Trace Elements and Rare Earth Elements Geochemistry and Its Metallogenic Significance for Cu-Zn Ore Deposits in Tongbai Area, Henan Province, China

There are some Cu-Zn polymetallic ore deposits that are of volcanic hosted massive sulfide (VHMS) deposits located in Tongbai region, Henan Province, China. The trace elements and rare earth elements (REEs) geochemistry of ores of Liushanyan Cu-Zn ore deposit, Dalishu–Fanglaozhuang Cu-Zn ore deposit and Yangjuan Cu-mineralizing spot were analyzed by using inductively coupled plasma mass spectrometry (ICP-MS) method to discuss the genesis of these deposits. Four types have been identified on the basis of study on trace elements and REEs geochemistry: the ores of the first type show light rare earth elements (LREE)-enriched REE patterns and have no Eu anomalies and weak negative Ce anomalies, with a weak depleted high field strength elements (HFSE) and smaller anomalies at Zr and Ti relative to normal mid-ocean ridge basalts (N-MORB); the ores of the second type show LREE-enriched REE patterns and have negative Eu anomalies and weak negative Ce anomalies; the ores of the third type show LREE-enriched REE patterns and have positive Eu anomalies and negative Ce anomalies, with a depleted HFSE and small negative anomalies at Zr and Ti relative to N-MORB; and the ores of the fourth type show horizontal distribution REE patterns, have positive Eu anomalies and weak negative Ce anomalies, with a depleted HFSE and no anomalies at Zr and Ti relative to N-MORB. The first type and the second type have similar characteristics to the basic volcanic rocks and acid volcanic rocks, respectively. Characteristics of the third type indicate that the convective mixing of a little amount of sea water with hydrothermal fluids had happened with a lot of minerals which is not dissolved in the solvents in the residual phase. The fourth type has a depleted mantle source. These characteristics indicate that the mineralization material has the same source with wall rocks of the Liushanyan Formation, which is the product of mantle partial melting that experienced early multiple melting events.

The Lithologic, Stratigraphic, and Structural Setting of the Giant Antamina Copper-Zinc Skarn Deposit, Ancash, Peru

Antamina, located at latitude 9° 32' S and longitude 77° 03' W in the Ancash Department of north-central Peru, is the largest known Cu-Zn skarn ore deposit. It incorporates a mineral reserve of 561 Mt, which has an average grade of 1.24 percent Cu, 1.03 percent Zn, 13.71 g/t Ag and 0.029 percent Mo, calculated at a 0.7 percent Cu equiv cutoff grade. The grandite-dominated calcic skarn formed in and around an upper Miocene porphyritic monzogranite stock emplaced into Upper Cretaceous carbonate strata that had experienced thin-skinned, northeast-verging thrusting and folding in the late Eocene Incaic orogeny. The exoskarn Cu-Zn ore is discordant to the strata of the Jumasha and overlying Celendin Formations, which comprise, respectively, massive to thick-bedded, relatively pure limestones and thin-bedded, predominantly marly limestones. The Jumasha Formation, the upper contact of which is locally defined as the top of the uppermost thick-bedded limestone or marble unit, hosts approximately three-quarters of the known exoskarn. Approximately the same fraction of the contiguous endoskarn Cu ore occurs adjacent to this formation. The overlying Celendin Formation is less extensively mineralized but, because it is widely metamorphosed to hornfels and locally converted to diopsidic skarnoid, may have inhibited the upward and outward migration of hydrothermal fluids, thereby promoting the development of the unusually large endoskarn ore zone. Ore also occurs in late hydrothermal breccias emplaced during the formation of mineralized endoskarn. The preskarn thermal metamorphic aureole around the ore deposit is expressed differently in the two host formations. Jumasha Formation limestone is coarsened and bleached to banded gray marble and locally to white marble peripheral to the intrusion and skarn. Minor scapolite occurs in dark gray bands in marble, concentrated in a discontinuous halo tens of meters wide and commonly separated from the skarn by tens of meters. Three facies of calc-hornfels are recognized in the marl beds of the Celendin Formation adjacent to the intrusion extending hundreds of meters beyond sulfide-bearing skarn: a peripheral, very fine grained, light brown phlogopitic facies; an intermediate, fine-grained, gray tremolitic facies; and a proximal, medium-grained, light green diopsidic facies. At an XCO2 of 0.1 to 0.9 and P = 100 MPa, these zones reflect temperatures increasing to circa 495°C adjacent to the intrusion. In addition, in nodular beds of the Celendin Formation that have been metamorphosed to hornfels, diagenetic calcite nodules are selectively replaced by diopside for distances of tens of meters beyond the skarn front. Such calc-silicate formation through both metamorphism and metasomatism, together with a 9 km2 cluster of Pb-Zn-Ag vein deposits, provides district-scale vectors to ore. The Antamina deposit lies on a newly recognized cross-strike structural discontinuity in the segmented Incaic Maranon thrust and fold belt, the northeast-trending Querococha arch. Southeast of the arch, Incaic folds and thrust faults strike north-northwest, but northwest of the arch they strike northerly. The plunge of fold axes concomitantly changes from south-southeast to north. Stratigraphic relationships indicate that the arch was a paleohigh, at least in the Jurassic and possibly throughout the late Paleozoic-early Mesozoic interval. The middle Miocene Carhuish pluton is exposed on the arch 30 km southwest of Antamina, whereas coeval Calipuy Supergroup volcanic units lie at similar altitudes to the north and south. Only scattered hydrothermal centers of late Miocene age are known in the Cordillera Negra, but an apparent swarm of intrusions, including the Antamina stock, occurs along the Querococha arch. Antamina is situated where the locus of changes in the strike of folds and faults and the plunge of folds steps left along the arch. At Antamina, a pair of fault-bend folds above frontal thrust ramps show approximately 500 m of dextral apparent offset across the deposit and are inferred to have been separated by a northeast-striking transfer fault or lateral ramp, itself localized by a left-stepping jog in the Valley fault, an underlying, similarly oriented transverse structure. The jog in the Valley fault is inferred to have also controlled intrusion and skarn development. This local-scale jog in the Valley fault mimics the regional step along the arch. The arch may reflect a transform segment of the originally jagged, rifted continental margin, which persisted as a transverse basement weakness. Northeast-striking, originally sinistral, basement structures affected regional-scale sedimentation and structural patterns, including articulation of the thrust and fold belt. At a local scale, they influenced lateral ramp formation and related fracture development in the overlying thrust sheets. In the proposed model, they also localized later uplift and the rapid transit of small volumes of productive melt into a shallow crustal setting, conditions favorable for formation of a giant magmatic-hydrothermal ore deposit.

Wall-rock alteration at the Millenbach Cu-Zn mine, Noranda, Quebec

Pipe-shaped zones of altered rock containing disseminated and stockwork vein mineralization underlie each of the several Archean volcanogenic Cu-Zn ore lenses at the Millenbach mine. The rocks and mineralization have been metamorphosed first to hornblende hornfels assemblages, then retrograded to greenschist facies assemblages, but the metamorphism has not significantly affected the bulk composition of the rocks. The alteration pipes show a distinct mineralogical zoning in which a core zone containing either anthophyllite-bearing assemblages or massive chlorite grades outward into a biotite-rich zone characterized by a spotted texture. Normative calculations were used to show that alteration pipes initially had a chlorite core which graded laterally and vertically into a sericite-rich outer zone and finally into unaltered rocks. Similar zoning is present on the selvedges of individual sulfide veins within the alteration pipes. Volume was conserved, and a distinctive metasomatic trend developed across the alteration pipes and vein selvedges during the alteration process. The most characteristic features of the altered rocks are increased Fe and Mg, and decreased Ca and Na, relative to fresh rocks. K and Al have generally been added at the margins and leached at the cores of pipes. Chemical zoning across vein selvedges is similar. The zoning of alteration types on vein borders, and to a certain extent in the pipes as a whole, is interpreted as due to the progressive reaction of an initially homogeneous hydrothermal solution with the rocks as the fluid moved upward in, and outward from, permeable channelways in the discharge conduit of a submarine, sea water-dominated hydrothermal system. However, an additional cause of vertical, and to a lesser extent lateral, zoning is thought to have been the existence of a strong vertical thermal gradient, as well as lateral variations in the permeability in the pipes. The thermal gradient could have been caused by the discharge fluid column being under hydrostatic pressure and everywhere at its boiling point. The fluid was probably evolved sea water which was in equilibrium with the rocks at depth in the system and then degenerated, causing alteration and sulfide deposition as a result of cooling and chemical changes associated with boiling as it rose in the conduit systems.

Cu-Zn-Pb ores in the Aijala-Orijarvi area, southwest Finland

The Aijala Cu-Zn ore deposit, the Metsaemonttu Zn-Pb ore deposit, and the Orijaervi Zn-Cu ore deposit are located in the leptite zone of southwest Finland. The sulfide ores of central Sweden belong to the same metallogenic province. The zone can be interpreted as a mid-Precambrian island-arc structure.The volcanic rocks in the Aijala-Orijaervi area are predominantly volcanoclastic, although units of lava origin are also encountered. In chemical composition they are predominantly calc-alkalic, although basaltic volcanite layers of tholeiitic composition are also met with. The lower section of the volcanite formation is composed of a silicic volcanic group whose composition varies from rhyolite to dacite. The chemical composition of the intermediate-basic and basic volcanite groups in the upper section varies from basaltic to andesitic. They often show primary volcanic structures, such as pillow lavas, volcanoclastic structures, and phenocrysts. The volcanites are overlain by argillaceous and arenitic weathering sediments that exhibit primary sedimentary structures such as graded bedding and slumping.The rocks in the area were metamorphosed in the lower-pressure amphibolite facies. In the Aijala-Orijaervi zone the rocks were folded in two phases, F 1 and F 2 . The general regional folding, F 1 , is often isoclinal with a gently plunging fold axis. The younger crossfolding, F 2 , is more local and shows subvertical fold axes.The Cu-Zn deposit of Aijala and the Zn-Pb deposit of Metsaemontttu are both sulfide disseminations or breccias in the upper part of the acid volcanite group in a pyroclastic unit with quartz and plagioclase phenocrysts. The Orijaervi Zn-Cu ore deposit consists of sulfide disseminations, breccias, and veins of massive sulfides in a zone of cordierite-sericite and cordierite-anthophyllite rocks. The wall rocks of the ores include chlorite-bearing skarns, dolomitic limestones, quartz rocks, and cordierite-anthophyllite rocks.The mineralization took place after the decline of intense acid pyroclastic volcanism. All three ore deposits are severely deformed and partly remobilized. They are composed of several minor orebodies which in detail cut and brecciate the wall rock but as a whole are stratabound in relation to the country rock.Each ore deposit has alteration zones whose rocks exhibit dolomitization, silicification, sericitization, and magnesium-iron metasomatism. Associated with the ore deposits at Metsaemonttu and Aijala there are alteration pipes of cordierite-anthophyllite rocks and a blanket type of alteration zone. As a rule the alteration around the ores has depleted the rocks in sodium and increased the abundances of magnesium, iron, manganese and titanium. The behavior of silicon, aluminum, calcium, and potassium varies when compared with the presumed primary composition.Even though the proportion on massive sulfides is low, the Aijala Cu-Zn, Metsaemonttu Zn-Pb, and Orijaervi Zn-Cu ores may be allied with massive Precambrian volcanic-exhalative sulfide ores as their proximal ore types.

The Cu-Zn Obrazek ore deposit, Czechoslovakia: A volcanogenic deposit included in the Ransko intrusive complex

The Cu-Zn Obrazek ore deposit is reinterpreted as metamorphosed volcanogenic-type rather than epigenetic vein-type. Enclosed by undeformed, non-metamorphosed mafic-ultramafic rocks of the Ransko complex, the ore is a highly folded, intensely metamorphosed (Zn-rich) association of banded, massive sphalerite-barite-pyrite-pyrrhotite-chalcopyrite and (Cu-rich)pyrite-chalcopyrite-pyrrhotite. Cu-rich ores are disseminated in deformed metamorphic assemblages of quartz, sillimanite, cordierite, anthophyllite, orthopyroxene and gahnite. Textural and compositional features in the metamorphic rocks suggest that the cordierite-anthophyllite assemblage was produced by regional metamorphism of rocks associated with the ore deposit. Inclusion of the Cu-Zn deposit and associated rocks in the Ransko intrusive complex produced contact metamorphic hornfelses of quartz, cordierite, orthopyroxene and Al-spinel. The occurrence and compositions of Zn-rich chromian spinel and minor intercumulus sulfides in anorthosite, troctolite and norite of the Ransko complex near the Obrazek ore body are interpreted to result from contamination of the Ransko parent magma by the Cu-Zn deposit and associated rocks.

銅‐亜鉛鉱の分離に対する問題点とその対策について

It is well known that the separation of copper and zinc minerals in the complex sulphide ores flotation is very difficult. On the other hand, it is also important to recover sphalerite entrained in the copper concentrate which is produced from the concentrators treating Cu-Pyrite ores and to recover chalcopyrite entrained in the zinc concentrate which is produced from the concentrators treating the Pb-Zn ores. Thus, the separation technique of Cu-Zn ores includes many difficult problems which have to improve.In this paper, the authors considered on many problems for the separation of Cu-Zn ores and discussed on how to separate the above minerals from the research works of the previous papers of the authors and others. There are many reasons why the separation of Cu-Zn ores is very difficult. One of them is the copper ions existing in the flotation pulp. Accordingly, the prevention and deactivation of the copper-activated sphalerite were discussed in order to separate the Cu-Zn ores.Among the previous research works which were carried out by the authors, the prevention and deactivation of copper activation for sphalerite were most effective by the use of sodium sulphide and ferric ion solution containing sulphuric acid. The effect of sodium sulphide on the prevention of copper activation for sphalerite was studied in the presence of sulphurous acid or sodium cyanide used as a depressant of sphalerite. From the results obtained, it may be considered that the copper activation of sphalerite is prevented perfectly by the use of sodium sulphide. Then the deactivation of the copper-activated sphalerite was investigated in a series of the laboratory experiments by the use of ferric ion solution containing sulphuric acid. From the results obtained, it was recognized that the deactivation of copper-activated sphalerite could be attained remarkably by the treatment of 980 mg/l Fe+++ solution containing over 4 vol. % of H2SO4. O2 gas accelerates the deactivation of the copper-activated sphalerite by the treatment of the above both solution. The temperature is one of the important factors for the deactivation. Using the flotation machine, the differential flotation test of Cu-Zn ore were carried out. The separation of Cu-Zn ore was successful by the deactivation treatment for Cu-Zn ore.From the recent paper by R. M. Manser and P. R. A. Andrews, a new reagent, Kr6D, as a depressant for sphalerite in a differential sulphide flotation stage was introduced in this paper. Small-scale laboratory flotation tests on such pure sulphide minerals as sphalerite and chacopyrite indicated that the Kr6D is capable of depressing sphalerite when used in small doses. At higher concentrations, chalcopyrite is also depressed. Single-stage batch-scale flotation tests were carried out on bulk concentrates containing the sulphide minerals. The Kr6D was compared with starch as a depressant both in the presence and in the absence of sulphur dioxide. In each case the new modifier was shown to be more effective.In addition to the above methods for the separation of Cu-Zn ores, the authors considered the possibility of improving selective flotation of bulk flotation concentrates from the previous papers of some other authors, including the abrasive action of high temperature and electric current for the adsorption collector layer on sphalerite and chalcopyrite. The desorption of collector layer on the Cu-Zn bulk concentrate by the use of sodium sulphide was discussed.

On cassiterite and stannite from some ore deposits in Naegi District, Gifu Prefecture

Naegi district, the southeastern margin of Gifu Prefecture, is one of the most famous localities for its pegmatite minerals. So-called Naegi mineralogical province includes many metallic ore deposits and pegmatites which distributions are zonally arranged. Stannite and cassiterite are found in some Cu-Zn ore deposits belonged to the outermost zone of the district. Stannites occur mainly as unmixing minerals from chalcopyrite and sphalerite, but a little stannite are formed for reaction of cassiterite and chalcopyrite. In addition stannites are classified into four varieties by microscopic properties.