scholarly journals Gold Partitioning in a Model Multiphase Mineral-Hydrothermal Fluid System: Distribution Coefficients, Speciation and Segregation

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 890 ◽  
Author(s):  
Sergey Lipko ◽  
Vladimir Tauson ◽  
Valeriy Bychinskii

The characteristics of Au partitioning in a multiphase, multicomponent hydrothermal system at 450 °C and 1 kbar pressure were obtained using experimental and computational physicochemical modelling and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. Sphalerite and magnetite contained 0.1–0.16 ± 0.02 µg/g Au and coexisted with galena and bornite which contained up to 73 ± 5 and 42 ± 10 µg/g Au, respectively. Bornite and chalcopyrite were the most effective Au scavengers with cocrystallization coefficients Au/Fe and Au/Cu in mineral-fluid system n–n × 10−2. Sphalerite and magnetite were the weakest Au absorbers, although Fe impurity in sphalerite facilitated Au uptake. Using the phase composition correlation principle, Au solubility in minerals was estimated (µg/g Au): low-Fe sphalerite = 0.7, high-Fe sphalerite = 5, magnetite = 1, pyrite = 3, pyrite-Mn = 7, pyrite-Cu = 10, pyrrhotite = 21, chalcopyrite = 110, bornite = 140 and galena = 240. The sequence reflected increasing metallicity of chemical bonds. Gold segregation occurred at crystal defects, and on surfaces, and influenced Au distribution due to its segregation at crystal interblock boundaries enriched in Cu-containing submicron phases. The LA-ICP-MS analysis of bulk and surficial gold admixtures revealed elevated Au content in surficial crystal layers, especially for bornite and galena, indicating the presence of a superficial nonautonomous phase (NAP) and dualism in the distribution of gold. Thermodynamic calculations showed that changes in experimental conditions, primarily in sulfur regime, increased the content of the main gold species (AuCl2− and AuHS0) and decreased the content of FeCl20, the prevailing form of iron in the fluid phase. The elevation of S2 and H2S fugacity affected Au partitioning and cocrystallization coefficients. Using Au content in pyrite, chalcopyrite, magnetite and bornite from volcanic-sedimentary, skarn-hosted and magmatic-hydrothermal sulfide deposits, the ranges of metal ratios in fluids were estimated: Au/Fe = n × 10−4−n × 10−7 and Au/Cu = n × 10−4−n × 10−6. Pyrite and magnetite were crystallized from solutions enriched in Au compared to chalcopyrite and bornite. The presence of NAP, and associated dualism in distribution coefficients, strongly influenced Au partitioning, but this effect does not fully explain the high gold fractionation into mineral precipitates in low-temperature geothermal systems.

2019 ◽  
Vol 85 (4) ◽  
pp. 110-113
Author(s):  
Olexandr Ponomarenko ◽  
Anatolyi Samchuk ◽  
Kateryna Vovk ◽  
Igor Shvaika ◽  
Ganna Grodzinskaya

The analytical technologies of sample preparation of rocks and mushrooms using the microwave field for the determination of germanium by the method of mass spectrometry with inductively coupled plasma (ICP-MS analysis) have been developed. Germanium is a rare element. Germanium is homology of silicon and carbon. To date, the definition of low content of germanium in geological objects is a rather complex analytical task, which requires its concentration - extraction, co-precipitation, ion exchange. At present, the harmonious combination of the method of natural objects decomposition in the microwave field and germanium determination using ICP-MS analysis is particularly promising. Sample preparation of silicate rocks for ICP-MS determination of germanium was carried out by decomposition in a mixture of hydrofluoric, phosphate and nitric acids (5: 5: 2) in a microwave oven program at 240°C for 30 min. Sample preparation of mushrooms for ICP-MS germanium determination was carried out according to the following scheme. Initially, the dried sample was sealed in the presence of CaO, after dissolving it in a mixture of HNO3+HF+H3PO4 (6:6:1). Ge solution was extracted by Nazarenko V.A. extraction method. The developed analytical schemes have made it possible to significantly reduce the duration and labor intensity of sample preparation. The obtained solutions were analyzed using an inductively coupled plasma mass spectrometer. The developed method for determining germanium by ICP-MS analysis has been successfully tested on standard rock samples. The obtained results are in accordance with the accepted attribute, the relative standard deviation Sr ranges from 0.7-0.9. The data on the content and distribution of germanium in the Boletales fungi are obtained. They indicate wild mushrooms contain high levels of germanium, especially Boletus and Mushroom biospores. These studies are necessary because the essential properties of germanium and its compounds attract special attention of scientists today. Complementary Ge compounds which have hypotensive, bactericidal, antiviral and antitumor effects have already been synthesized.


2020 ◽  
Vol 58 (3) ◽  
pp. 293-311 ◽  
Author(s):  
Zeinab Azadbakht ◽  
David R. Lentz

ABSTRACT Biotite grains from 22 felsic intrusions in New Brunswick were mapped in situ using a laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS). We investigated the extent to which biotite can retain its magmatic zoning patterns and, where zoning does exist, how it can be used to elucidate early to late stage, syn-magmatic to post-crystallization processes. Although the major element and halogen contents of the examined biotite phenocrysts are homogeneous, two-thirds of the grains display trace-element zoning for Ba, Rb, and Cs. The results also indicated that zoning is better retained in larger grains (i.e., > 500 × 500 μm) with minimal alteration and mineral inclusions. An exceptionally well-zoned Li-rich siderophyllite from the Pleasant Ridge topaz granite in southwestern New Brunswick shows Ti, Ta, Sn, W, Cs, Rb, and V (without Li or Ba) zoning. Cesium values increase from 200 to 1400 ppm from core to rim. Conversely, Sn and W values decrease toward the rim (50 to 10 and 100 to 10 ppm, respectively). Tantalum and Ti values show fewer variations but drop abruptly close to the rim of the grain (100 to 20 and 2000 to 500 ppm, respectively). These observations may indicate crystallization of mineral phases with high partition coefficients for these highly incompatible elements (except Ti) (e.g., cassiterite and rutile) followed by fractionation of a fluid phase at a later stage of magma crystallization. The preservation of zoning may indicate rapid cooling post-crystallization of the parent magma.


2019 ◽  
Vol 104 (8) ◽  
pp. 1092-1116 ◽  
Author(s):  
Jun-Yi Pan ◽  
Pei Ni ◽  
Ru-Cheng Wang

Abstract Granite-related wolframite-quartz veins are the world's most important tungsten mineralization and production resource. Recent progress in revealing their hydrothermal processes has been greatly facilitated by the use of infrared microscopy and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of both quartz- and wolframite-hosted fluid inclusions. However, owing to the paucity of detailed petrography, previous fluid inclusion studies on coexisting wolframite and quartz are associated with a certain degree of ambiguity. To better understand the fluid processes forming these two minerals, free-grown crystals of intergrown wolframite and quartz from the giant Yaogangxian W deposit in South China were studied using integrated in situ analytical methods including cathodoluminescence (CL) imaging, infrared microthermometry, Raman microspectroscopy, and fluid inclusion LA-ICP-MS analysis. Detailed crystal-scale petrography with critical help from CL imaging shows repetition of quartz, wolframite, and muscovite in the depositional sequence, which comprises a paragenesis far more complex than previous comparable studies. The reconstruction of fluid history in coexisting wolframite and quartz recognizes at least four successive fluid inclusion generations, two of which were entrapped concurrently with wolframite deposition. Fluctuations of fluid temperature and salinity during precipitation of coexisting wolframite and quartz are reflected by our microthermometry results, according to which wolframite-hosted fluid inclusions do not display higher homogenization temperature or salinity than those in quartz. However, LA-ICP-MS analysis shows that both primary fluid inclusions in wolframite and quartz-hosted fluid inclusions associated intimately with wolframite deposition are characterized by strong enrichment in Sr and depletion in B and As compared to quartz-hosted fluid inclusions that are not associated with wolframite deposition. The chemical similarity between the two fluid inclusion generations associated with wolframite deposition implies episodic tungsten mineralization derived from fluids exhibiting distinct chemical signatures. Multiple chemical criteria including incompatible elements and Br/Cl ratios of fluid inclusions in both minerals suggest a magmatic-sourced fluid with the possible addition of sedimentary and meteoric water. Combined with microthermometry and Raman results, fluid chemical evolution in terms of B, As, S, Sr, W, Mn, Fe, and carbonic volatiles collectively imply fluid phase separation and mixing with sedimentary fluid may have played important roles in wolframite deposition, whereas fluid cooling and addition of Fe and Mn do not appear to be the major driving factor. This study also shows that fluid inclusions in both wolframite and coexisting quartz may contain a substantial amount of carbonic volatiles (CO2 ± CH4) and H3BO3. Ignoring the occurrence of these components can result in significant overestimation of apparent salinity and miscalculation of LA-ICP-MS elemental concentrations. We suggest that these effects should be considered critically to avoid misinterpretation of fluid inclusion data, especially for granite-related tungsten-tin deposits.


2019 ◽  
Vol 20 (3) ◽  
pp. 280-298
Author(s):  
Paul A. Morris ◽  
Alex Christ ◽  
Edward J. Mikucki

The <10, <4, <2.5 and <1 µm fractions of eight regolith samples have been extracted as aerosols, then analysed for more than 60 elements by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Precision and accuracy rivals that of conventional digestion and ICP-MS analysis for most elements, but the aerosol extraction and ablation approach can be completed within 30 min, avoids compromising the sample by screening, column settling, fusion and/or digestion, and includes data for elements such as Br, Cl, I and Se that are conventionally analysed by individual procedures. Major element chemistry and scanning electron microscope (SEM) imagery show that the aerosol fractions of regolith are dominated by kaolinite, with quartz in aeolian regolith. The aerosol fractions of Si- and Ca-rich regolith have higher trace element concentrations than the coarser fraction (0.45–2 mm), but chalcophile elements are depleted in the aerosols of Fe-rich regolith relative to the coarser fraction. Improvements in in-field analytical technology coupled with aerosol extraction mean that fine and ultrafine fraction chemistry can be used to guide mineral exploration programmes in close to real time.Supplementary material: The results of the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of filter papers are available at https://doi.org/10.6084/m9.figshare.c.4562807


2015 ◽  
Vol 98 (1) ◽  
pp. 218-224 ◽  
Author(s):  
Shuo Wang ◽  
Xv Dong ◽  
Bingye Dai ◽  
Mingfei Pan ◽  
Shaoyuan He ◽  
...  

Abstract A method was developed for detection of V, Cr, Cu, As, and Pb in water and biological samples by combining online flow injection and preconcentration with inductively coupled plasma-MS. The 2-nitroso-1-naphthol-4-sulfonic acid (Nitroso-S) impregnated MCI GEL CHP20P resin was prepared as an enrichment sorbent. Some parameters affecting the efficiency of the preconcentration process were investigated in the experiment, including the pH and volume of sample solution, the flow rate for sample loading, the type and concentration of eluent, and the influence of co-existing ions. Under the optimal experimental conditions, the enrichment factor and LOD (3s) of chosen metal ions V, Cr, Cu, As, and Pb were in the ranges of 71–268 and 4.89–23.76 ng/L, respectively. Based on 11 repeated measurementsof standard solutions (1.0 μg/L), the RSD ofthe ions ranged from 1.2 to 2.9%. The detection procedure was also performed for analyzing two certifiedreference materials, GBW 08607 (water) and GBW 10052 (green tea), as well as environmental water and biological samples. Good agreement with certified valuesand high recoveries have demonstrated improved accuracy of the proposed method.


2012 ◽  
Vol 1475 ◽  
Author(s):  
E. Myllykylä ◽  
M. Tanhua-Tyrkkö ◽  
A. Bouchet

ABSTRACTThis study aims at gaining a better understanding of the behaviour of montmorillonite in contact with different ground waters; alteration of montmorillonite and possible formation of secondary minerals. Batch experiments were conducted with purified Swy-2 montmorillonite in simulated fresh (I=0.05 M, pH 8) and saline (I=0.1 M, pH 11) waters at 25 and 60ºC in anaerobic (Ar(g)) conditions. The concentrations of Al, Fe; Mg and Si were analysed from ultra-filtered solution samples with HR-ICP-MS (High Resolution Inductively Coupled Plasma Mass Spectrometry). The amount of released Si depended strongly on the experimental conditions. The Si concentrations at 60oC in the saline and fresh waters showed a difference greater than an order of magnitude. The initial purified montmorillonite and the solid materials from experiments were analysed with XRD. The analysis indicated that the nature of smectite did not change, but the experimental conditions, more or less, modified the structure of montmorillonite, e.g., in fresh waters the XRD spectra showed peaks typical of mixed layer minerals, which can refer to the presence of either randomly ordered illite/smectite or randomly ordered collapsed smectite/ hydrated smectite layers. The dissolution of montmorillonite was studied also by modelling with TOUGHREACT. The experimental and modelled results were compared revealing a need to develop the model e.g. in respect of the evolution of pH.


2020 ◽  
Author(s):  
N.S. Medvedev ◽  
A.V. Volzhenin ◽  
A.I. Saprykin

High purity molybdenum and its compounds are used for the synthesis of ionizing radiation detectors for search for dark matter and double beta decay. Properties of these detectors largely depend on their trace composition. The new mass-spectrometry with inductively coupled plasma (ICP-MS) and electrothermal vaporization (ETV) method was developed for the analysis of high-purity molybdenum. The samples were introduced into the ICP using the ETV device. The vaporization curves of matrix element (molybdenum) and trace elements were studied in detail. The dependence of analytical signal and limits of detection (LODs) of analytes versus ETV-ICP-MS instrumental parameters (ICP power, transport flow, ion optics settings) was established. The proposed method of ETV-ICP-MS analysis allowed us to control the content of 28 trace elements in high-purity molybdenum with a purity of 6N (99.9999% wt.) and provided LODs from 0.3 to 200 ng g-1. Using of ETV for ICP-MS analysis of molybdenum led to decreasing of the LODs of trace elements from 3 to 200 times comparing with ICP-MS analysis with standard sample introduction system. The validation of proposed ETV-ICP-MS method was performed by spike experiment and by comparing the results of ETV-ICP-MS, ICP-MS, and atomic absorption spectrometry with electrothermal vaporization (GFAAS) analysis.


2021 ◽  
Vol 9 ◽  
Author(s):  
Zhaoping Yang ◽  
Simon Edward Jackson ◽  
Thomas Skulski

Laser ablation inductively coupled plasma multi-collector mass spectrometry (LA-MC-ICP-MS) allows rapid, in situ, highly precise measurements of Cu isotope ratios of native Cu and Cu-bearing minerals. However, the National Institute of Standards and Technology Cu-metal isotope standard NIST SRM976 that is commonly used to calibrate LA-MC-ICP-MS Cu isotope measurements of native Cu is no longer available. We have investigated the suitability of four Cu metal materials, SSC-1, SSC-3 and SSC-4 (cathode Cu metal rods) and CUPD-1 (Cu anode sawings), originally developed by the Canada Centre for Mineral and Energy Technology (CANMET) as certified reference materials for trace element analysis, as Cu isotope reference materials for LA-MC-ICP-MS analysis and solution nebulization (SN) of Cu. The Cu isotopic composition and homogeneity of these four materials were characterised by SN- and LA-MC-ICP-MS, and are reported for the first time. The bulk Cu isotopic compositions, expressed as δ65CuSRM976 in per mil (‰) relative to NIST SRM976 with combined uncertainties (U, k = 2), of SSC-1, SSC-3 and SSC-4, determined utilizing SN-MC-ICP-MS, are identical within analytical uncertainty at 0.03 ± 0.07‰ (n = 29), 0.04 ± 0.04‰ (n = 28), and 0.05 ± 0.08‰ (n = 29), respectively; the composition of CUPD-1 is 2.14 ± 0.08‰ (n = 28). The compositions are 0.01 ± 0.07‰ (n = 29), 0.04 ± 0.06‰ (n = 29), 0.03 ± 0.06‰ (n = 28) and 2.15 ± 0.06‰ (n = 28), respectively, relative to the European Reference Material ERM®-AE633 Cu isotope standard. The Cu isotope homogeneity of the four new reference materials was assessed by determining whether multiple individual in situ Cu isotope measurements made by LA-MC-ICP-MS analysis (43 µm spot size), using each of the other three reference materials as a calibrator, approximate a single normal distribution. We also investigate whether there are statistically significant differences between the mean δ65Cu values of three independent data sets for each of the Cu isotope reference materials using one-way analysis of variance (ANOVA). Normality tests (graphical assessment of normal distribution quantile-quantile plots, and the Shapiro-Wilk, Jarque-Bera and reduced chi-squared statistic tests) show that: 1) the Cu isotope data acquired on SSC-1, SSC-3, SSC-4 and CUPD-1 do not depart significantly from a normal distribution, 2) the scatter of the Cu isotope data is due to analytical uncertainty with 95% confidence, and 3) there are no other significant sources of scatter; e.g. heterogeneity of the reference materials. The results of one-way ANOVA reveal that the mean difference of the δ65Cu value for each of the reference materials SSC-1, SSC-3, SSC-4 and CUPD-1 is statistically not significant at the 0.05 level. The mean δ65CuSRM976 values with combined uncertainties (U, k = 2) of SSC-1, SSC-3, SSC-4 and CUPD-1, determined by LA-MC-ICP-MS using each of the other three reference materials as a calibration standard, are 0.03 ± 0.09‰ (n = 132), 0.05 ± 0.09‰ (n = 154), 0.03 ± 0.09‰ (n = 144) and 2.14 ± 0.10‰ (n = 106), respectively. These values are in agreement with those determined by SN-MC-ICP-MS analysis at the 95% confidence level and have excellent precision (2 s.d. ≤ 0.10‰). These results suggest that SSC-1, SSC-3, SSC-4 and CUPD-1 can be considered isotopically homogeneous at a spatial resolution of 43 μm, and they are suitable reference materials for calibration and quality control of in situ and solution nebulization Cu isotope analyses of Cu.


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