Rich Sulfide Research Articles

Sulfide-sulfate metasomatism and nickel release in the suprasubduction mantle

Metasomatic replacement of olivine by orthopyroxene under the influence of SiO2-rich melts is a widespread process in mantle conditions responsible for the formation of pyroxenite from mantle peridotite. However, the behavior of nickel in this process remains unclear. The reaction of Ni-containing olivine with silica- and sulfur-rich metasomatic agents in the suprasubduction mantle may release nickel from olivine and subsequently form a rock containing orthopyroxene and nickeliferous sulfides. Xenoliths of mantle wedge harzburgite from the Shiveluch volcano (Kamchatka continental arc) contain abundant globules of Ni-rich MSS, pentlandite and smaller amount of copper sulfides, totaling up to 0.75 wt.% (∼2600 ppm S2–), in association with Ca-sulfates (up to 7900 ppm S6+). The process accounting for the observed mineral association can be described via simplified reactions (the coefficients are approximate): (Mg,Fe,Ni)2SiO4 + 2xH+ +SiO2 = 2(Mg,Fe)SiO3 + xNi2+ + xH2O; Ni2+ + S2– = NiS. The influx of both oxidized and reduced sulfur may account for the coexistence of sulfide and sulfate phases. The presence of low-Ti chrome spinel with high Fe(II)/Fe(III) ratios, low Al, Ca and Ti in olivine, and no evidence of deserpentinization confirms the mantle origin of the sulfide/sulfate-bearing xenoliths. The mean isotopic composition of sulfur in the sulfide-sulfate assemblage, δ34S = +4.5‰, supports the contribution of slab-derived sulfur. The accumulations of Ni-(Cu)-rich sulfides and Ca-sulfate in metasomatized peridotites can serve as an intermediate host for sulfur and chalcophile metals, thereby generating magmas containing sulfur at the level of sulfide saturation and simultaneously enriched in Ni and Cu during the subsequent partial melting of the mantle.

Orogenic Au deposits with atypical metal association (Cu, Co, Ni): Insights from the Pohjanmaa Belt, western Finland

The Laivakangas Au-Cu metallogenic area is characterised by orogenic Au deposits with both Au-only and with atypical (Au ± Cu, Co, Ni) metal associations. Here we study and compare four examples to better constrain the parameters controlling enrichment in base metals in addition to Au. We selected two typical Au-only deposits, the Laivakangas and the Huhta deposits and two orogenic Au deposits with atypical metal association, the Jouhineva Au-Cu-Co-Ag and the Kurula Au-Co deposits. All four deposits record multiple successive mineralisation events with local variations in their respective metal association. Two auriferous mineralisation events are identified, (1) a ubiquitous As-Au-(Co, Ni) event close to peak metamorphism (620–430 °C) where Au occurs either as invisible Au in arsenides or as inclusion in arsenopyrite; (2) a later Cu(-Au)-rich sulfide event on the retrograde path where Au locally occurs as free, native grains along with chalcopyrite. From S isotope studies of the sulfide and sulfarsenide minerals and relations between the deposits and surrounding rocks, we propose that the variation in metal association of the ore fluid is linked to the diversity of lithologies involved in metamorphic fluid production. Multi-event hydrothermal mineralisation and relatively reduced redox conditions appear critical to increase the Au endowment in a deposit and to introduce atypical metals. Results of this study provide a new comprehension of the variability of metal association in orogenic Au deposits of the Laivakangas Au-Cu metallogenic area and elsewhere.

Evaluation of deformation characteristics of brittle rocks beyond the limit of strength in the mode of uniaxial servohydraulic loading

One of the most reliable methods for assessing the physical and mechanical properties of rocks as a result of their destruction are laboratory tests using hard or servo-driven test presses. They allow to obtain reliable information about changes in these properties beyond the limit of compressive strength. The results of laboratory tests of rich sulfide ore samples are presented, which made it possible to obtain graphs of their extreme deformation. Both monolithic samples and samples with stress concentrators in the form of circular holes with a diameter of 3, 5 and 10 mm were tested. It was revealed that during the destruction of the samples, the modules of elasticity and deformation decrease by 1.5-2 times, and in the zone of residual strength – by 5-7 times.

Mobilisation of deep crustal sulfide melts as a first order control on upper lithospheric metallogeny

Magmatic arcs are terrestrial environments where lithospheric cycling and recycling of metals and volatiles is enhanced. However, the first-order mechanism permitting the episodic fluxing of these elements from the mantle through to the outer Earth’s spheres has been elusive. To address this knowledge gap, we focus on the textural and minero-chemical characteristics of metal-rich magmatic sulfides hosted in amphibole-olivine-pyroxene cumulates in the lowermost crust. We show that in cumulates that were subject to increasing temperature due to prolonged mafic magmatism, which only occurs episodically during the complex evolution of any magmatic arc, Cu-Au-rich sulfide can exist as liquid while Ni-Fe rich sulfide occurs as a solid phase. This scenario occurs within a ‘Goldilocks’ temperature zone at ~1100–1200 °C, typical of the base of the crust in arcs, which permits episodic fractionation and mobilisation of Cu-Au-rich sulfide liquid into permeable melt networks that may ascend through the lithosphere providing metals for porphyry and epithermal ore deposits.

Перспективы развития геотехнологий подземной добычи руд на глубоких рудниках Талнахского и Октябрьского месторождений

Rich sulphide, cuprous and impregnated ores are currently mined in the underground mines of the Talnakh and Oktyabrskoye deposits at the depths from 250 to 1,700 m. The reserves of rich ores are depleted, and therefore the growth of cuprous and impregnated ores is gaining importance. Their share may reach 80% of the total production by 2030. A distinctive feature of such deposits is the occurrence of cuprous and impregnated ores above the rich sulphide ore, which reserves have been mined out using mining systems with curing backfill mixtures. In this context, mining of impregnated ores will be done in the undermined zones, which will lead to significant rock mass deformation, opening of existing natural and formation of new cracks, will affect the stability of mining structures and will require special measures to control rock pressure in the mines. The paper presents the results of assessing the stress-and-strain condition of the undermined mass of impregnated ores mined using the room-and-pillar cut-and-fill method at the depths of 500, 1000 and 2000 m. The assessment shows that no dangerous stress concentrations arise in the mining structures at great depths which creates preconditions for the safe development of such deposits. A significant increase in ore extraction will require upgrading of existing underground facilities. It is proposed to carry out pre-concentration of the mined ore in the underground conditions using modern crushing complexes, high-capacity mine separators to remove waste rock, which can subsequently be used as the backfill material. In this way, a closed-loop mining system is created that meets the efficiency requirements of mining production and integrated subsoil development.

Forecasting criteria for sulphide PGE-copper-nickel deposits of the Noril’sk province (In English)

Research subject. World-class sulphide platinum-group-element (PGE)-Cu-Ni deposits occur within the Noril’sk-Talnakh region of northern Siberia, Russia. The signifcance of these deposits presents opportunities to determine the most effective approaches for the search of similar deposits using commercial PGE-Cu-Ni deposit examples. Materials and methods. Petrological and geochemical analysis of the ultramafc-mafc intrusions of the Noril’sk province ranks them into three types in terms of sulphide mineralization style and economic signifcance: 1) economic intrusions containing unique and large sulphide PGE-Cu-Ni deposits (Oktyabr’sk, Talnakh and Noril’sk-1); 2) subeconomic intrusions that contain small- to medium-sized Cu-Ni sulphide deposits, and medium-sized to large PGE deposits (Chernogorsk, Zub-Marksheider, Vologochan, etc.); 3) uneconomic intrusions that contain low-grade disseminated Cu-Ni ores with ≈0.2 wt % of Cu and Ni, and low Cr and PGE (Nizhny Talnakh, Zelyonaya Griva, etc.). Results and conclusions. Principal sources used in exploration for rich sulphide PGE-Cu-Ni ores include structural, magmatic, stratigraphic-lithological, geochemical, mineralogical, metamorphic and some others. Based on an analysis of isotope-geochemical data, new indicators for locating sulphide PGE-Cu-Ni mineralization are suggested. A restricted range of S-isotope values, and a negative trend for coupled S-Cu isotope compositions can be employed as useful guides to assess the economic potential of a PGE-Cu-Ni sulphide deposit. It is proposed that the Chernogorsk ultramafc-mafc intrusion of the Noril’sk province is the most promising target in a search for rich PGE-Cu-Ni ores. It is suggested that the previously known mineralogical-geochemical and novel isotope-geochemical characteristics of sulphide and silicate minerals are important indicators in assessing the potential ore content of ultramafc-mafc intrusions of the Noril’sk province.

Hydrogeochemical Variability of the Acidic Springs in the Rio Tinto Headwaters

Peña de Hierro, located in southwest Spain, encompasses the springs and headwaters for the Rio Tinto River that emerge above normal faults and has been mined for its rich sulfide ore since 2500 BC. The springs are typically characterized by an orange coloration, typical pH of ~2.33, and contain elevated concentrations of heavy metals that are produced by acid rock drainage (ARD). ARD is a natural phenomenon that results from chemolithoautotrophs metabolizing the sulfide ore. Mining has amplified the magnitude of the acidity and concentrations of heavy metals evidenced within sedimentary cores from the Huelva estuary. Acidity, redox state, hydrochemistry and isotopic analyses were examined for the purpose of characterizing the subsurface flows and determining the interconnectivity of the groundwaters. Previous studies have documented the geochemistry of the springs, dating a select few, yet many springs remain uncharacterized. Acidity presented spatial variability throughout the field area, caused by extensive sulfide interactions which generated and modified the pH. Redox exhibited a large range of values due to oxygen diffusivity though the fracture network. The surrounding geology is highly heterogeneous because of intensive deformation during the Variscan and Tertiary periods, and this heterogeneity is shown in the varied aqueous chemistry. Fractionation patterns observed in δ2H and δ18O values predominantly reflected enrichment by intensive evaporation and depletion in δ18O as a result of the proposed sulfatic-water model for Rio Tinto’s hydrogeology. The analysis illustrates minimal hydrologic interconnectivity, evidenced by the extensive physical and chemical contrasts within such a small proximity.

To the question of raw material sources of mining and smelting centers of the Paleometal Epoch in Central Kazakhstan

The subject of this research is the copper deposits, copper-ore resource, and sources of alloying raw materials for mining and smelting production of the Paleometal Epoch in Central Kazakhstan, namely within the Kazakhstan mining and smelting region and Zhezkazgan-Ulytau mining and smelting center. The article provides the interim results of comprehensive research of geoarchaeological production facilities in the territory of copper deposits within the Zhezkazgan-Ulytau mining and smelting center, which allow determining the peculiarities of metallogenic complexes that used to be potential objects of the development of copper-ore reserves during the establishment of copper metallurgy, as well as making a predictive assessment of mineral raw materials potential of the region. The initial premise of this research lies in the authors' pursuit to integrate natural scientific methods of research into the field of humanities to the maximum effect via studying smelting slags and ore relics from the ancient settlements of the region for the purpose of reconstructing the mining and smelting process of the Bronze Age in Central Kazakhstan. The authors offer the variants of localization of the mineral raw materials complex of Zhezkazgan-Ulytau mining and smelting center within the Kazakhstan mining and smelting region. Based on examination of the ores and smelting slags of Bronze Age settlements in Central Kazakhstan, the authors believe that the main copper raw materials in the Zhezkazgan-Ulytau region were the oxidized malachite-azurite and rich sulfide ores, as well as the zones of secondary sulfide enrichment of copper sandstones of the Zhezkazgan ore region. The conducted research allow to get closer to establishing patterns of localization of various types of copper deposits and development of copper-ore resources for mining and smelting production of Zhezkazgan-Ulytau region during the Paleometal Epoch.

Application of layered double hydroxide enriched with electron rich sulfide moieties (S2O42−) for efficient and selective removal of vanadium (V) from diverse aqueous medium

The preparation of an adsorbent with highest efficiency, selectivity and stability is usually a challenging task. Herein, we prepared a thio functionalized layered double hydroxide (LDH) denoted as S2O4 LDH by intercalating a strong reducing agent (S2O42−) in the interlayers of trimetallic LDH and was applied to capture vanadium (V(V)) oxyanions from aqueous medium of diverse conditions. The successful preparation of the adsorbent was first confirmed using XRD, FTIR, EDX and CHS analyses. The results revealed that the modified LDH showed excellent performance at a wider pH range which can avoid the tedious work of adjusting pH in actual industrial wastewater treatment. The adsorption capacity was increased with temperature and obtained 379.55 mg/g at 323 K comparing to 112.3 mg/g at 293 K. The adsorption isotherm was better fitted to Langmuir model which suggested monolayer adsorption behavior. At lower temperature (293 K), the sorption kinetics were fitted to a pseudo-first order reaction model which implied physisorption reaction while at higher temperatures (303 and 323 K), the reaction order fitted to pseudo-second order reaction model which highlighted the chemisorption reaction mechanism. As confirmed using XRD, FTIR, EDX and XPS instrumental techniques, the dominant removal mechanism of V(V) involved ion-exchange and partial reduction reactions to nontoxic and less soluble V(IV) and V(III) species due to the low valent sulfur group and followed adsorption in S2O4 LDH. The prepared adsorbent showed very good selectivity towards V(V) in the presence of different co-existing ions both in synthetic wastewater and spiked real water samples. This novel adsorbent also exhibited high recyclability and obtained >90.0% removal of V(V) after four consecutive adsorption–desorption cycles due to the unique memory effect of the LDH. We believe that this strategy provides a new direction to find highly efficient and selective materials for capturing vanadium ions from wastewater of diverse conditions.

Bronze Age metallurgical slags from the South Urals: types, mineralogy and copper sources

In the paper, an investigation of copper metallurgical slags found in the South Urals and dating to the Bronze Age between 4000 and 1300 BCE is carried out. Four main mineralogical types are distinguished according to their mineral composition: Cr-rich spinel containing olivine, sulphide-containing olivine, sulphide containing glassy and pyroxene type. First type of slags is composed of zoned olivine, magnetite and glass having relicts of Cr-rich spinels and serpentinites that indicate the use of azurite-malachite ores from ultrabasic rocks. These finds were determined in sites of the Early Yamna period in the Cis-Urals and are widespread in Sintashta culture. The second type is composed of skeletal olivine crystals, magnetite and wustite with copper sulphides droplets. It type belongs to Alakul period. The raw material sources are sulphide ores from a secondary enrichment zone of VMS, skarn and Cu-porphyry deposits. The sulphide containing glassy type is mainly composed of glass with copper and sulphide droplets. The slags were recovered in the Srubna sites. The raw material sources were rich sulphide ores of cupriferous sandstones. The pyroxene type is composed of augite, pigeonite and/or wollastonite with a small amount of glass and sulphide inclusions. According to the composition of glass, slags can be distinguished into the Cis-Uralian type, including cupriferous sandstones, and Trans-Uralian type having various volcanogenic-hydrothermal deposits as raw materials. Essential Ca, P, Ba and REE impurities in slag glass demonstrate the use of barite, calcite and bone fluxes. The phase diagrams, crystallisation temperatures and experimental data revealed that slag melt temperatures ranged between 1150–1300 ° C.

Об опасности возникновения областей с пониженным содержанием кислорода в подземных выработках при разработке сульфидных руд

At the underground development of the sulfide deposits by the systems with a consolidating stowing, the temperature of the ore mass and the mine atmosphere increases due to the heat released during the hydration reaction of the hardening mixtures. This facilitates the activation of the oxidizing processes occurring in the sulfide ores. As a result, the areas with a reduced oxygen content are formed in the extended upstream workings. A decrease of the oxygen content in the working atmosphere below the critical values is a source of mortal danger for the underground mine personnel. These assumptions were confirmed when analyzing the causes of the emergency at the Taimyrsky mine of PJSC «MMC «Norilsk Nickel». The production here is carried out with the application of slicing and chamber mining systems with the filling of the mined-out space by the consolidating stowing. Main ore minerals: pyrrhotite, chalcopyrite, cubanite, talnakhite and pentlandite, which chemical activity testifies to their potential fire hazard. Solid (rich) sulfide copper-nickel ores are prone in the fragmentary and crushed state to oxidation by air oxygen accompanied by the formation of heat. More intensive oxidation occurs in the presence of moisture and air flow through the crushed ore. The calculations showed that the high air temperature, along with the presence of wet ore dust and fines in the dead-end mine where the accident occurred, contributed to the occurrence of critical deoxygenation of the atmosphere, which was the objective cause of the incident. In order to avoid the recurrence of this situation, it is required to control the oxygen content in the dead-end mine workings located near the filling mass. In addition, accidental penetration of people into these workings should be completely excluded.

The geological setting of arsenic enrichment in groundwater of the shallow aquifers of the Tista Floodplain, Rangpur, Bangladesh

Arsenic is present in water samples within the studied active floodplain areas of the Tista river, Rangpur Division, Bangladesh. All the water samples contain less arsenic than the WHO prescribed limit of 10 μg/L. 93.33% groundwater samples have higher Mn content than the permissible limit of 0.01 mg/L of WHO. The heavy metal concentrations of water can be expressed as Fe>Mn>Zn>As on the basis of their mean content. The heavy metals are negatively correlated with the well depth which is indicative of the influence of the anthropogenic activities on the concentrations of heavy metals. The arsenic concentration in water samples is higher in the central part of the study area. The coarser grain size, dominance of physical weathering, elevated topography and the effective flushing of groundwater resulted low concentration of arsenic in the groundwater. The EDS study reveals that arsenic occurs as coating materials of the silicate minerals. The river waters also have arsenic content lower than WHOs permissible limit. The factor analysis reveals that the iron and arsenic is released by the chemical weathering of arsenic bearing minerals like pyrite and arsenopyrite. The Fe and Mn derived in the groundwater by the chemical weathering of iron and manganese bearing minerals such as iron rich clay, silicate minerals and iron sulfides. Â

Mechanisms for Pd[sbnd]Au enrichment in porphyry-epithermal ores of the Elatsite deposit, Bulgaria

Porphyry Cu can contain significant concentrations of platinum-group elements (PGE: Os, Ir, Ru, Rh, Pt, Pd). In this study, we provide a comprehensive in situ analysis of noble metals (PGE, Au, Ag) for (CuFe)-rich sulfides from the Elatsite, one of the world's PGE-richest porphyry Cu deposits. These data, acquired using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), indicate that Pd was concentrated in all the (CuFe)-rich sulfides at ppm-levels, with higher values in pyrite (~6 ppm) formed at the latest epithermal stage (i.e., quartz–galena–sphalerite assemblage) than in bornite and chalcopyrite (<5 ppm) from the hypogene quartz–magnetite–bornite–chalcopyrite ores. Likewise, Au is significantly more concentrated in pyrite (~5 ppm) than in the (CuFe)-rich sulfides (≤0.08 ppm). In contrast, Ag reaches hundreds of ppm in pyrite and bornite (~240 ppm) but is in much lesser amounts in chalcopyrite (<25 ppm). The inspection of the time-resolved spectra collected during LA-IPC-MS analyses indicates that noble metals are present in the sulfides in two forms: (1) structurally bound (i.e., solid solution) in the lattice of sulfides and, (2) as nano- to micron-sized inclusions (PdTe and Au). These observations are further confirmed by careful investigations of the PGE-rich (CuFe)-rich sulfides by combining high-spatial resolution of field emission scanning electron microscope (FESEM) and focused ion beam and high-resolution transmission electron microscopy (FIB/HRTEM). A typical Pd-bearing mineral includes the composition PdTe2 close to the ideal merenskyite but with a distinct crystallographic structure, whereas Au is mainly found as native element. Our detailed mineralogical study coupled with previous knowledge on noble-metal inclusions in the studied ores reveals that noble metal enrichment in the Elatsite porphyry ores was mainly precipitated from droplets of Au-Pd-Ag telluride melt (s) entrained in the high-temperature hydrothermal fluid. These telluride melts could separate at the time of fluid unmixing from the silicate magma or already be present in the latter either derived from deep-seated crustal or mantle sources. Significant enrichment in Pd and Au (the latter correlated with As) in low-temperature pyrite is interpreted as remobilization of these noble metals from pre-existing hypogene ores during the epithermal overprinting.

The Occurrence and Origin of Pentlandite-Chalcopyrite-Pyrrhotite Loop Textures in Magmatic Ni-Cu Sulfide Ores

Abstract Pentlandite is the dominant Ni-hosting ore mineral in most magmatic sulfide deposits and has conventionally been interpreted as being entirely generated by solid-state exsolution from the high-temperature monosulfide solid solution (MSS) (Fe,Ni)1–xS. This process gives rise to the development of loops of pentlandite surrounding pyrrhotite grains. Recently it has been recognized that not all pentlandite forms by exsolution. Some may form as the result of peritectic reaction between early formed MSS and residual Ni-Cu–rich sulfide liquid during differentiation of the sulfide melt, such that at least some loop textures may be genuinely magmatic in origin. Testing this hypothesis involved microbeam X-ray fluorescence mapping to image pentlandite-pyrrhotite-chalcopyrite intergrowths from a range of different deposits. These deposits exemplify slowly cooled magmatic environments (Nova, Western Australia; Sudbury, Canada), globular ores from shallow-level intrusions (Norilsk, Siberia), extrusive komatiite-hosted ores from low and high metamorphic-grade terranes, and a number of other deposits. Our approach was complemented by laser ablation-inductively coupled plasma-mass spectrometry analysis of palladium in varying textural types of pentlandite within these deposits. Pentlandite forming coarse granular aggregates, together with loop-textured pentlandite where chalcopyrite also forms part of the loop framework, consistently has the highest Pd content compared with pentlandite clearly exsolved as lamellae from MSS or pyrrhotite. This is consistent with much of granular and loop pentlandite being formed by peritectic reaction between Pd-rich residual sulfide liquid and early crystallized MSS, rather than forming entirely by subsolidus grain boundary exsolution from MSS, as has hitherto been assumed. The wide range of Pd contents in pentlandite in individual samples reflects a continuum of processes between peritectic reaction and grain boundary exsolution. Textures in metamorphically recrystallized ores are distinctly different from loop-textured ores, implying that loop textures cannot be regenerated (except in special circumstances) by metamorphic recrystallization of original magmatic-textured ores. The presence of loop textures can therefore be taken as evidence of a lack of penetrative deformation and remobilization at submagmatic temperatures, a conclusion of particular significance to the interpretation of the Nova deposit as having formed synchronously with the peak of regional deformation at temperatures within the sulfide melting range.

A First-Principles Exploration of NaxSy Binary Phases at 1 atm and Under Pressure

Interest in Na-S compounds stems from their use in battery materials at 1 atm, as well as the potential for superconductivity under pressure. Evolutionary structure searches coupled with Density Functional Theory calculations were employed to predict stable and low-lying metastable phases of sodium poor and sodium rich sulfides at 1 atm and within 100–200 GPa. At ambient pressures, four new stable or metastable phases with unbranched sulfur motifs were predicted: Na2S3 with C 2 / c and Imm2 symmetry, C 2 -Na2S5 and C 2 -Na2S8. Van der Waals interactions were shown to affect the energy ordering of various polymorphs. At high pressure, several novel phases that contained a wide variety of zero-, one-, and two-dimensional sulfur motifs were predicted, and their electronic structures and bonding were analyzed. At 200 GPa, P 4 / m m m -Na2S8 was predicted to become superconducting below 15.5 K, which is close to results previously obtained for the β -Po phase of elemental sulfur. The structures of the most stable M3S and M4S, M = Na, phases differed from those previously reported for compounds with M = H, Li, K.

Mass balance and origin of fluids associated to smectite and chlorite/smectite alteration in Seival Mine Cu–Mineralization – Camaquã Basin – Brazil (Part II)

The Seival Mine, located in the Camaquã Basin, hosts several small Cu and Ag ore deposits in volcano–sedimentary sequence surrounding the Lavras do Sul Intrusive Complex. Alteration minerals consist of calcite, sulfate, smectite and chlorite/smectite associated with Cu–rich sulfides. The mass balance calculations from less altered to altered volcanic rocks show large chemical changes with the mobility of mettallic elements in major or trace amounts. Mass balance calculations for similar volcanic protoliths, with different degrees of alteration or textural variations, indicate that increasing proportions of clay minerals reflects higher degrees of alteration. This alteration did not mobilize Si, Al, Fe, and Mg and had a small effect on other metallic elements such as Cu, Zn, Ni, and Au. Consequently, fluids associated with propylitic to argillic alteration with chlorite–smectite precipitation did not participate in the transport of base metals and ore deposition. Interpretations of oxygen stable–isotopes for magmatic, late magmatic and hydrothermal minerals show decreasing proportion magmatic fluid (δ18Ofluid of andesine labradorite ca. 5 to 7‰), toward a predominance of meteoric fluid (δ18Ofluid of quartz and calcite) between −12 and 0‰ for the low–temperature alteration (250 to 80 °C). Carbon stable isotopes result suggest a mixture of inorganic carbon ca. −7 to −5‰ from volcanic CO2 with late carbonate precipitation with atmospheric signatures ca. −4 to −1‰. These mass balance and stable isotopes interpretations suggest that high–temperature late–magmatic fluid/rock interaction (650 to 350 °C) has promoted the base metal enrichment.

Source and Assessment of Metal Pollution at Khetri Copper Mine Tailings and Neighboring Soils, Rajasthan, India.

We present here the results of the study on metal pollution by identifying source, abundance and distribution in soil and tailings of Khetri copper complex (KCC) mines, Rajasthan India. The region is highly contaminated by copper (Cu) with higher values in the soil near overburden material (1224mg/kg) and tailings (111mg/kg). The average Cu (231mg/kg) concentration of soil is ~9, 5 and 32 times higher than upper crust, world average shale (WAS) and local background soil (LS), respectively. However this reaches to ~82, 46 and 280 times higher in case of tailing when compared. The correlation and principal component analysis for soil reveals that the source of Cu, Zn, Co, Ni, Mn and Fe is mining and Pb and Cd could be result of weathering of parent rocks and other anthropogenic activities. The source for Cr in soil is both mining activities and weathering of parent rocks. The values of index of geo-accumulation (Igeo) and pollution load index for soil using LS as background are higher compared to values calculated using WAS. The metal rich sulphide bearing overburden material as well as tailings present in the open environment at KCC mines region warrants a proper management to minimize their impact on the environment.

Chapter 27 Lead–zinc–silver deposits of Myanmar

Before 1960 the Pb–Zn–Ag mines in Myanmar were an important source of foreign exchange. Almost the entire output of lead and zinc came from the Bawdwin Mine which, before 1942, was ranked as the sixth-largest producer of lead in the world (Ministry of Mines 1970). In 1938 Myanmar's output of refined lead, zinc concentrates and silver was 76 590 tons, 65 928 tons and 6 230 000 ounces, respectively. By 1986 output levels had fallen to 5948 tons of lead, 7393 tons of zinc and 576 000 ounces of silver. These figures represent a dramatic decline in production from the Bawdwin Mine and Namtu Processing Plant, which Soe Win (1994) has considered to be due to the failure to identify new reserves and inadequate investment in mine facilities. In the past, the Namtu–Bawdwin mining complex produced refined silver, lead and zinc concentrates, copper matte, nickel speiss and antimonial lead. The rich sulphide ore, previously mined underground at Bawdwin and treated at Namtu, yielded a lead concentrate averaging 51.3% Pb, 14.1% Zn and 1.16% Cu and a zinc concentrate averaging 26.1% Zn and 18.1% Pb. Currently, the oxide ore (‘halo ore’) from the open pit only is processed at Bawdwin, to yield a concentrate averaging 41.73% Pb, 9.03% Zn and 3.06% Cu. The lower ore grades present a problem for the old Namtu smelter, which was designed for processing sulphide ore and requires lead concentrates to have a minimum content of 57% Pb with 10–15% Zn and 1–2% Cu. A new blast furnace has been installed capable of smelting lead concentrates as low as 40% Pb, with a tolerance of up to 8% Zn and 3% Cu and with a rated capacity of 50 tons/day (Than Htay 2002). In addition, a zinc fuming plant will produce zinc oxide from zinc slags. …

Actively forming Kuroko-type volcanic-hosted massive sulfide (VHMS) mineralization at Iheya North, Okinawa Trough, Japan

Modern seafloor hydrothermal systems provide important insights into the formation and discovery of ancient volcanic-hosted massive sulfide (VHMS) deposits. In 2010, Integrated Ocean Drilling Program (IODP) Expedition 331 drilled five sites in the Iheya North hydrothermal field in the middle Okinawa Trough back-arc basin, Japan. Hydrothermal alteration and sulfide mineralization is hosted in a geologically complex, mixed sequence of coarse pumiceous volcaniclastic and fine hemipelagic sediments, overlying a dacitic to rhyolitic volcanic substrate. At site C0016, located adjacent to the foot of the actively venting North Big Chimney massive sulfide mound, massive sphalerite-(pyrite-chalcopyrite±galena)-rich sulfides were intersected (to 30.2% Zn, 12.3% Pb, 2.68% Cu, 33.1ppm Ag and 0.07ppm Au) that strongly resemble the black ore of the Miocene-age Kuroko deposits of Japan. Sulfide mineralization shows clear evidence of formation through a combination of surface detrital and subsurface chemical processes, with at least some sphalerite precipitating into void space in the rock. Volcanic rocks beneath massive sulfides exhibit quartz-muscovite/illite and quartz-Mg-chlorite alteration reminiscent of VHMS proximal footwall alteration associated with Kuroko-type deposits, characterized by increasing MgO, Fe/Zn and Cu/Zn with depth. Recovered felsic footwall rocks are of FII to FIII affinity with well-developed negative Eu anomalies, consistent with VHMS-hosting felsic rocks in Phanerozoic ensialic arc/back-arc settings worldwide.Site C0013, ∼100m east of North Big Chimney, represents a likely location of recent high temperature discharge, preserved as surficial coarse-grained sulfidic sediments (43.2% Zn, 4.4% Pb, 5.4% Cu, 42ppm Ag and 0.02ppm Au) containing high concentrations of As, Cd, Mo, Sb, and W. Near surface hydrothermal alteration is dominated by kaolinite and muscovite with locally abundant native sulfur, indicative of acidic hydrothermal fluids. Alteration grades to Mg-chlorite dominated assemblages at depths of >5mbsf (metres below sea floor). Late coarse-grained anhydrite veining overprints earlier alteration and is interpreted to have precipitated from down welling seawater as hydrothermal activity waned. At site C0014, ∼350m farther east, hydrothermal assemblages are characterized by illite/montmorillonite, with Mg-chlorite present at depths below ∼30mbsf. Recovered lithologies from distal, recharge site C0017 are unaltered, with low MgO, Fe2O3 and base metal concentrations.Mineralization and alteration assemblages are consistent with the Iheya North system representing a modern analogue for Kuroko-type VHMS mineralization. Fluid flow is focussed laterally along pumiceous volcaniclastic strata (compartmentalized between impermeable hemipelagic sediments), and vertically along faults. The abundance of Fe-poor sphalerite and Mg-rich chlorite (clinochlore/penninite) is consistent with the lower Fe budget, temperature and higher oxidation state of felsic volcanic-hosted hydrothermal systems worldwide compared to Mid Ocean Ridge black smoker systems.

Composition and properties of highly dispersed particles generated under sulfide ore milling

Laser diffraction analysis and dynamic light scattering method are used to study highly dispersed particles generated during milling of lead–zinc ore (Gorevsky deposit), rich sulfide and impregnated copper–nickel ore (Norilsk and Kingash deposits), as well as Gorevsky Pb concentrate and Sorsky deposit Cu and Mo concentrates. Zeta-potentials of particles are measured in clarified (colloid) solution above precipitation; surface composition of ores and their fine sizes is analyzed using X-ray photoelectron spectroscopy. The highest yield of particles under 5 μm size grade (to 3 total percent) was observed in case of Kingash ore; moreover, zeta-potential of these particles was positive at pH 9.5 and surface compositions of precipitation and colloid particles were nearly the same. Comparatively high content of ultra dispersed fractions was observed in case of Gorevsky ore and Pb concentrate. Clarified solutions contained mostly aggregates of nano-size particles, first of all, Si and Mg minerals, with the hydrodynamic diameter of 500–1200 nm, which shows little changes with time. Sulfide component of hydrosols contains many nano-size particles of minerals that better resist oxidation (sphalerite, molybdenite, pentlandite, chalcopyrite) and, in particular, can transfer metals within the ambient medium.