Galena Ore Research Articles

The paragenesis of silver minerals in the Pb-Zn Stan Terg deposit, Kosovo - an example of precious metal epithermal mineralization.

This study reports silver mineral association found recently in the Stan Terg lead and zinc mine, located in the Vardar Zone (in the northern Kosovo). The described mineralization comprises pyrargyrite, freieslebenite, high-Ag bearing tetrahedrite, freibergite and native compounds (electrum, native silver, native antimony). Ag-minerals occur in vuggs and cracks in massive galena ore, and have signs of the latest precipitated minerals in the deposit. The chemical composition of those minerals was confirmed by the electron microprobe. Freibergite from the Stan Terg deposit reveals zonality and contains between 13.91-20.28 at. % of Ag. High Ag solutions are indicated also by relatively high silver content in electrum, which is between 47.02 and 73.19 at. % of Ag. The Ag association is supposed to be an epithermal equivalent of precious metal mineralization which could be located in the external part of the Stan Terg hydrothermal system. This association occurs in low temperatures, below 200˚C. The Ag-minerals can be part of epithermal veins from the external part of the Stan Terg hydrothermal system. Similarly to the other know Pb-Zn-Ag hydrothermal system, silver association is related to formation of the rhodochrosite banded ore and Ag-Au-Sb±Hg dominated mineralization.

Identifying evidence for past mining and metallurgy from a record of metal contamination preserved in an ombrotrophic mire near Leadhills, SW Scotland, UK

This study presents a new 3600-year record of past metal contamination from a bog located close to the Leadhills and Wanlockhead orefield of southwest Scotland. A peat core, collected from Toddle Moss, was radiocarbon (14C) dated and analysed for trace metal concentrations (by EMMA) and lead isotopes (by ICP-MS) to reconstruct the atmospheric deposition history of trace metal contamination, in particular, lead. The results show good agreement with documented historical and archaeological records of mining and metallurgy in the region: the peak in metal mining during the 18th century, the decline of lead mining during the Anglo-Scottish war and lead smelting during the early medieval period. There may also have been earlier workings during the Late Bronze and Iron Ages indicated by slight increases in lead concentrations, the Pb/Ti ratio and a shift in 206Pb/207Pb ratios, which compare favourably to the signatures of a galena ore from Leadhills and Wanlockhead. In contrast to other records across Europe, no sizeable lead enrichment was recorded during the Roman Iron Age, suggesting that the orefield was not a significant part of the Roman lead extraction industry in Britain. These findings add to the various strands of archaeological evidence that hint at an early lead extraction and metallurgical industry based in southern Scotland. The results also provide further evidence for specific regional variations in the evolution of mining and metallurgy and an associated contamination signal during prehistoric and Roman times across Europe.

Solvent extraction of Pb(II) and Zn(II) from a Nigerian galena ore leach liquor by tributylphosphate and bis(2,4,4-trimethylpentyl)phosphinic acid

Physico-chemical conditions for the optimal separation of Pb(II) and Zn(II) from a galena ore leachate using a combination of tributylphosphate (TBP) and bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex®272) have been investigated. The results of fundamental studies using synthetic solution of Pb(II) showed that the extraction efficiency increased with increasing pH, extractant concentration and temperature. An extraction yield of 92.1±0.2% for Pb(II) at pH 5.0 by 1mol/L TBP in 100% MIBK and 94.6±0.2% for Zn(II) at pH 3.0 by 0.032mol/L Cyanex®272 in kerosene was obtained from an initial galena leach liquor containing 1705.1mg/L Pb, 98.7mg/L Zn and 130.2mg/L total iron as major constituents at 25±2°C at a stirring time of 30 and 25min, respectively. Iron was also effectively removed by precipitation using 1mol/L ammoniacal solution at pH 3.5. The stoichiometry of the lead-extractable species was found to be HPbCl3·TBP. Values of 52.7±0.01 kJmol−1, −5.05 kJmol−1, 159.6±0.01JK−1mol−1 and 0.127±0.003M−2 were calculated for the apparent standard molar enthalpy (ΔH°), Gibb’s free energy (ΔG°), molar entropy (ΔS°) and extraction constant, respectively. About 94.5±0.2% Pb(II) and 94.6±0.2% Zn(II) were stripped from the TBP and Cyanex®272, respectively using 0.1mol/L HCl solution. Finally, a compact extraction scheme has been provided.

Ecotoxicological Assessment of Contaminated River Sites as a Proxy for the Water Framework Directive: an Acid Mine Drainage Case Study

Metal contamination of freshwater bodies resulting from mining activities or deactivated mines is a common problem worldwide such as in Portugal. Bracal (galena ore) and Palhal (pyrrhotite, chalcopyrite, galena, sphalerite, and pyrite ore), located in a riverside position, are both examples of deactivated mining areas lacking implemented recovery plans since their shutdown in the early mid-1900s. In both mining areas, effluents still flow into two rivers. The purpose of this work was to evaluate the potential hazard posed by the mining effluents to freshwater communities. Therefore, short- and long-term ecotoxicological tests were performed on elutriates from river sediments collected at each site using standard test organisms that cover different functional levels (Vibrio fischeri, Pseudokirchneriella subcapitata, Lemna minor, and Daphnia sp.). The results show that elutriates from the sediments of Palhal were very toxic to all tested species, while in contrast, elutriates from Bracal showed generally no toxicity for the tested species. Our study highlights the usefulness of using an ecotoxicological approach to help in the prioritization/scoring of the most critical areas impacted by deactivated mines. This ecotoxicological test battery can provide important information about the ecological status of each concerning site before investing in the application of time-consuming and costly methods defined by the Water Framework Directive or can stand as a meaningful complementary analysis.

Effect of galvanic contact on the flotability of galena in the presence and absence of a collector

In this paper, the effect of various electrochemical environments in the galena flotation is investigated. The electrochemical environments consisted of a ball mill for grinding of galena ore and a Denver flotation cell for flotation of galena in the laboratory scale. In order to achieve the maximum recovery with sodium hyposulfite, the concentrations of 0.06 and 0.12M of air and nitrogen gases have been used to control the pulp potential in the Denver flotation cell. The galena sample was from the “Era mine” which is located in the Kiyasar area, north of Iran. This mine contains: Galena (PbS) at least 22%, Fluorite (CaF2) 73.37%, Quartz (SiO2) 2.54% and other minerals such as Cerussite (PbCO3) and Kaolinite (Al2Si2O5(OH)4). Flotation of Galena was conducted in a 0.12M of sodium hyposulfite solution. It was found that the amount of recovery by this process was 85% and 63% in the presence and absence of potassium amyl xanthate (KAX) and at an estimated potential of 280 to 350mV respectively while the recovery was 70% and 52% at an approximate potential of 175 to 210mV in water in the presence and absence of collector (KAX).

Bioleaching of Zn(II) and Pb(II) from Nigerian sphalerite and galena ores by mixed culture of acidophilic bacteria

Zn(II) and Pb(II) from Nigerian sphalerite and galena ores were bioleached by a mixed culture of acidophilic bacteria. The influences of pH and ferric ion on the bioleaching rates of sphalerite and galena were examined. The result shows that pH 2.1 and 2.7 are favourable for the leaching of Zn(II) and Pb(II) from sphalerite and galena, respectively. It was observed that the use of agarose-simulated media caused cells to excrete exopolymers containing ferric ions which enhanced oxidation. The oxidation equilibrium for sphalerite and galena took 3 and 4 d, respectively. About 38.3% sphalerite and 34.2% galena were leached within 1 d and approximately 92.0% Zn(II) and 89.0% Pb(II) were recovered in 5 d, respectively. The unleached residual products were examined by X-ray diffraction for sphalerite, revealing the presence of elemental sulphur(S), zinc sulphate (ZnSO 4) and few traces of calcium aluminate (Ca 3Al 2O 6). The XRD pattern also indicates the presence of elemental sulphur (S), lead sulphate (PbSO 4) and few traces of itoite [Pb(S,Ge)(O,OH) 4] and cobalt lead silicate [Pb 8Co(Si 2O 7) 3] in the unleached galena ore.

Le champ filonien à Zn-(Pb, Cu, As, Hg) du district minier de Fedj Hassène (Nord Ouest de la Tunisie): Minéralogie, Eléments en traces, Isotopes du Soufre et Inclusions Fluides

Le district minier de Fedj Hassène est situé à proximité de la frontière algéro-tunisienne, à 10 Km au sud de la ville de Ghardimaou. Il regroupe plusieurs filons à Pb-Zn, localement accompagnés par des sulfures de Cu, d’As et d’Hg. Les réserves sont estimées à 370.000 t à 10% de Zn et 0,2% de Pb. Les minéralisations remplissent des fractures subparallèles à la faille d’Ain Kohla de direction ESEWNW et des fentes d’extension qui recoupent les calcaires marneux du Turonien moyen. Le filon principal est formé par de la sphalérite massive brune et accessoirement par de la galène et de la barytine. Le minerai peut se présenter sous forme massive ou sous la forme de ciment de brèche. L’association minérale est composée par de la sphalérite, galène, chalcopyrite, pyrite et orpiment. La gangue est formée par de la calcite massive et localement par de la barytine et du quartz. L’analyse des éléments en trace dans la sphalérite révèle des teneurs en poids de 0,84% Fe, 0,14% Cd et 0,02% Mn. L’étude des inclusions fluides dans la calcite et la sphalérite montre l’existence d’un fluide caractérisé par une salinité de l’ordre de 23% poids équiv. NaCl à température décroissante lors de la mise en place des minéralisations (194 °C lors du dépôt de la calcite et 133 °C lors du dépôt de la sphalérite). Ce fluide est caractérisé par une densité comprise entre 1,00 g/cm3 et 1,11 g/cm3 avec une pression de piégeage estimée de 200 bars. La précipitation des sulfures parait être contrôlée par une chute de la température. Les mesures des isotopes du soufre dans la sphalérite donnent des valeurs de δ34S toutes positives et variant dans une gamme très restreinte comprise entre + 4,6‰ et 6,4‰ VCDT (moyenne=5,6‰). Ces valeurs indiquent une origine commune du soufre réduit qui est formé par les processus de ré duction thermique de sulfates. La source des sulfates admet les évaporites triasiques de la région comme reservoir potentiel. Les études géologiques et minéralogiques couplées à la microthermométrie des inclusions fluides et la géochimie des éléments en traces et des isotopes du soufre permettent de classer le gisement filonien de Fedj Hassène dans le groupe des gisements polymétalliques (Pb-Zn-As, Hg) typiques de la zone des nappes de la Tunisie du Nord et de l’Algérie nord-orientale.

A study of dissolution kinetics of a Nigerian galena ore in hydrochloric acid

The results of experimental investigation on the study of dissolution kinetics of a Nigerian galena ore in hydrochloric acid solution were discussed. The influence of acid concentration, temperature, particle size, stirring speed and solid/liquid ratio on the extent of dissolution was examined. The elemental analysis by XRF showed that the galena ore is composed mainly of PbS with metals such as Sn, Fe and Zn occurring as minor elements and Mn, Rb, Sr and Nb as traces. The XRD analysis indicated galena as the dominant mineral phase, with the presence of associated minerals, such as α-quartz (SiO2), sphalerite (ZnS), cassiterite (SnO2), pyrite (FeS2) and manganese oxide (MnO2).Results of leaching studies showed that galena dissolution in HCl solution increases with increasing acid concentration and temperature; while it decreases with particle diameter and solid/liquid ratio at a fixed stirring rate of 450 rpm. The study showed that 94.8% of galena was dissolved by 8.06 M HCl at 80 °C within 120 min with initial solid/liquid ratio of 10 g/L. The corresponding activation energy, Ea was calculated to be 38.74 kJ/mol. Other parameters such as reaction order, Arrhenius constants, reaction and dissociation constants were calculated to be 0.28, 73.69 s−1, 1.73 ± 0.13 × 103 and 1.37 ± 0.024 × 104 mol L−1 s−1, respectively. The mechanism of dissolution of galena was established to follow the shrinking core model for the diffusion controlled mechanism with surface chemical reaction as the rate controlling step for the dissolution process. Finally, the XRD analysis of the post-leaching residue showed the presence of elemental sulphur, lead chloride and α-quartz.

Comparative analysis of the dissolution kinetics of galena in binary solutions of HCl/FeCl3 and HCl/H2O2

A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl3/HCl and H2O2/HCl has been undertaken. The dissolution kinetics of the galena was found to depend on leachant concentration, reaction temperature, stirring speed, solid-to-liquid ratio, and particle diameter. The dissolution rate of galena ore increases with the increase of leachant concentration, reaction temperature, and stirring speed, while it decreases with the increase of solid-to-liquid ratio and particle diameter. The activation energy (E a) of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl3/8.06 M HCl, and it suggests the surface diffusion model for the leaching reaction, while the E a value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H2O2/8.06 M HCl, which suggests the surface chemical reaction model for the leaching reaction. Furthermore, the linear relationship between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface reaction in the two cases. Finally, the rate of reaction based on the reaction-controlled process has been described by a semiempirical mathematical model. The Arrhenius and reaction constants of 11.023 s−1, 1.25×104 and 3.65×102 s−1, 8.02×106 were calculated for the 0.3 M FeCl3/8.06 M HCl and 8.06 M H2O2/8.06 M HCl binary solutions, respectively.

The producing of lead and elemental sulfur by new technologies from galenite ores

These investigations have developed an effective hydrometallurgical method to recover high-purity lead metal and elemental sulfur from simulated galena synthetic mixures eliminating sulfur gases and lead emissions, in contrast to the current high-temperature smelting technology. The method consists of different operations: oxidative leaching with production of solution with residue containing elemental sulfur., electrowinning by the solution with metal production. The obtained results determined the optimal parameters for possible processing of natural domestic galena ores.

Performance of Three Aquatic Plant Species in Bench-scale Acid Mine Drainage Wetland Test Cells

We investigated pollutant removal from acid mine drainage (AMD) by three different aquatic plant species (Typha angustifolia, Desmostachya bipinnata, and Sacharum bengalense) in bench-scale wetland test cells of 1 m3. AMD was generated in the laboratory using chalcopyrite, galena, and sphalerite ore. A substrate containing 75% soil, 20% powdered goat manure, and 5% wood shavings was used in each cell. The performance of the system was evaluated for different water column heights (100, 150, and 200 mm) and for different retention periods (24, 48, 72, 96, and 168 hrs). The performance of the plant species was different for the various metals of AMD; therefore, multi-species plantings should be considered in constructed wetlands.

Pb isotope signatures of sediments from Guanabara Bay, SE Brazil: Evidence for multiple anthropogenic sources

Sediments from Guanabara Bay and two rivers were analyzed for Pb isotope composition. The results define linear groups interpreted as different sources of Pb. The samples from Iriri and Surui rivers present different Pb compositions probably resulting from two active pollutants which are transported in the waters to the Guanabara Bay, where they are mixed. The 206Pb/ 207Pb values of 1.151 and 1.091 presented here are in the range of Brazilian galena ore signature.

Geochemical and mineralogical distribution of germanium in the Khusib Springs Cu–Zn–Pb–Ag sulfide deposit, Otavi Mountain Land, Namibia

The Khusib Springs deposit in the Otavi Mountain Land, Namibia, is a small though high-grade carbonate-hosted Cu–Zn–Pb–Ag–(As–Sb–Ge) deposit of the “Tsumeb-type” containing approximately 300,000 t of ore grading 10% Cu, 1.8% Pb and 584 ppm Ag. A lens-shaped sulfide orebody, up to 10 m thick and elongated parallel to bedding, replaces limestone, locally brecciated, of the lower Tsumeb Subgroup (Damara Supergroup) in the northern limb of a large NE-trending synclinal structure. A prominent zone of dolomite alteration surrounds the orebody. In a drill core through the orebody, the uppermost 2 m are enriched in Zn (up to 5%) and Ag (up to 3350 ppm), but lower in Ge (< 30 ppm) than the central and lower parts of the orebody, which are in turn enriched in Ge (up to 200 ppm) and Pb (up to 7%). Massive ore consists of a texturally complex mineral assemblage dominated by Zn-rich tennantite, enargite, galena and pyrite. Fe-poor sphalerite is abundant only in the uppermost part of the orebody and in the footwall where it forms a prominent zone of disseminated sphalerite ± chalcopyrite ± galena ± pyrite. The upper zone of the massive ore is further characterized by a general lack of enargite, and the occurrence of a variety of late-stage phases including tetrahedrite, Ag-bearing tennantite, pearceite–polybasite and native silver. The central and lower parts of the orebody are composed of tennantite–enargite–galena ore with variable proportions of pyrite, but lacking sphalerite. Most Ge is hosted in Ge-bearing colusite [Cu 26V 2(As,Ge) 6S 32] forming small (usually < 50 μm in size) grains along the margins of ore layers and veinlets. With the notable exception of enargite, the major sulfides contain only trace amounts of Ge (< 100 ppm). Trace element analyses reveal a wide range of Ge concentrations in enargite, averaging to 500 ppm. Frequently, colusite is associated with deformed trails of phengitic, F-rich muscovite, rutile, apatite, tourmaline, dolomite and pyrite. Such trails are interpreted as former stylolites in the carbonate host rock, which has been replaced by sulfide ore. Colusite carries on average 4.0 wt.% Ge, up to 4.7 wt.% W and up to 4.4 wt.% Sn, and is occasionally accompanied by small amounts of Mo–W sulfides. Additional minerals identified in the ore include W-bearing germanite, Ge-bearing stannoidite, chalcopyrite, bornite, stromeyerite, minerals of the chalcocite-group, and covellite. Geochemical and mineralogical features of sulfide ores from Khusib Springs resemble some sulfide ores of the pipe-shaped polymetallic Ge-rich Tsumeb deposit. Similar to the latter, ore formation probably occurred during D 2 deformation and metamorphism and involved highly saline, hot brines (up to 370 °C [Chetty, D., Frimmel, H.E., 2000. The role of evaporites in the genesis of base metal sulfide mineralization in the Northern Platform of the Pan-African Damara Belt, Namibia: geochemical and fluid inclusion evidence from carbonate wall rock alteration. Mineralium Deposita 35, 364–376]) carrying sulfur derived from evaporite sequences. A polyphase mineralization involving three successive stages is proposed: early sphalerite–pyrite–(chalcopyrite–bornite) mineralization is replaced by tennantite, enargite, galena and Ge-bearing colusite. A late stage mineralization overprints parts of the orebody at lower temperatures leading to precipitation of ‘schalenblende’ (Cu- and Ag-rich), digenite, tetrahedrite and pearceite–polybasite. The occurrence of small, but high-grade Ge-rich Cu–Zn–Pb–Ag deposits in the lower Tsumeb Subgroup has important consequences on the mineral potential of the area, because prospecting for Cu-rich ores has been traditionally performed in the uppermost Tsumeb Subgroup only, in relation to paleokarst structures.

Atypical and typical zinc geochemistry in a carbonate setting, Sä Dena Hes Mine, Yukon Territory, Canada

The Sä Dena Hes Mine produced Pb and Zn concentrates from a polymetallic Manto deposit in 1991 and 1992. Ownership of the mine was assumed by Sä Dena Hes Operating Corporation (Teck Cominco Ltd and Pan-Pacific Metal Mining Corporation) in 1994. Sphalerite and galena ore bodies with negligible Fe sulphide were processed by conventional flotation methods resulting in carbonate-rich tailings. This paper presents evaluations of atypical and typical Zn geochemistry under non-acidic conditions using laboratory testing, mineralogy and simple modelling. Atypical behaviour is shown by drainage containing 40 mg/l Zn from a short adit. The Zn load contained in the mine drainage is not apparent in a spring-fed stream a few hundred metres down-gradient. Results of an attenuation test to mimic field conditions showed that Zn was removed to concentrations of less than 0.001 mg/l. Spherical aggregates containing 40% Zn were found in the column residues using scanning electron microscopy. The aggregates are likely a Zn hydroxide or basic carbonate based on the Zn concentration, though the exact mineralogical form was not determined. Similarly, elevated Zn concentrations (up to 56 mg/l) have been found in pH-neutral porewaters near the water table in the tailings deposit. Zinc concentrations generally decrease to below 1 mg/l just below the water table and below 0.1 mg/l in seepage from the tailings dam. However in this case, simple dilution modelling and thermodynamic equilibrium modelling of the tailings porewater chemistry showed that the decrease in Zn concentrations could be attributed to the formation of Zn carbonate. Electron microscopy confirmed the presence of smithsonite (ZnCO 3 ) in the tailings; in addition Zn also occurred as a trace element in Mg–Mn–Ca carbonate phases.

Cyclic voltammetry and dielectric studies on PbS–potassium ethyl xanthate–dextrine system under flotation and depression conditions

Froth flotation technique continues to be one of the most important concentration processes to float ores in a selective form specifically for PbS–ZnS, PbS–CuFeS 2 and PbS–ZnS, PbS–CuFeS 2 ores. There is an interest in doing research on a clean reagent (biodegradable reagent) to depress lead sulfide ore to control this process and have the appropriate knowledge about the interactions that can occur among galena and dextrine reagent. Cyclic voltammetry, high impedance and flotation test results are compared on a PbS–KEX–C 6H 8O 5 (galena–ethyl xanthate–dextrine) system to obtain the responsible collector and depression products and the suitable conditions to float and depress galena ores. Cyclic voltammetry studies showed the reaction products responsible for the shrink galena ore, in this case the PbC 6H 8O 5 organometallic. Measurements of complex permittivity and dielectric constant, at 100 MHz, by high impedance technique suggested that it is possible to obtain from isotherm adsorption the adequate industrial depressor this being in the range of 20–30 ppm.

Barite-silica mineralization at the inter-Ordovician unconformity in southwestern Sardinia (Italy): a fluid inclusion study

¶Data from secondary fluid inclusions in barite and quartz occurring in strongly silicified lithologies (“Quarzite”) along the inter-Ordovician unconformity in SW Sardinia suggest that two distinct fluids are recorded in the mineral phases. (A), a high temperature (250–360 °C) – low salinity (0–6% NaCl equiv.) fluid, measured in quartz, (B), a high salinity (6–20% NaCl equiv.) – low temperature (<80–200 °C) fluid, measured in barite. Fluid (B), though less abundant than A, has also been recorded in quartz, whereas traces of fluid (A) were found in barite. The characteristics of fluid (B) make it akin to the well known saline formation waters responsible for the deposition of the post-Variscan barite and galena ores in SW Sardinia.

Determination of low concentrations of the flotation reagent ethyl xanthate by sampled DC polarography and flow injection with amperometric detection

A polarographic DC tast method with the static mercury drop electrode, SMDE, was developed for determination of the flotation collector ethyl xanthate (EtX) in the concentration range from 1×10 −5 to 8×10 −5 M. The potentiality of the method was demonstrated by evaluating the capacity of powdered galena ore (PbS) to adsorb EtX in a titration-like procedure. Sulfide could be determined simultaneously with EtX because in NaOH electrolyte their anodic waves are well separated ( E 1/2≅−0.72 and −0.42 V versus Ag/AgCl, respectively). In addition, a new FIA method was developed by adapting a simple device to the tip of the glass capillary of a mercury electrode and doing amperometric detection at a fixed potential of −0.1 V, always in the DC tast mode. No oxygen removal was required. Reproducible results were obtained at a frequency of 72 injections per h, with automatic renewal of the SMDE every second. The calibration curve for freshly prepared EtX standards rendered a straight line from 5×10 −6 to 8×10 −5 M with correlation coefficient of 0.997, suitable for real applications in flotation processes and its effluents.

Fluid Chemistry and Depositional Mechanism of the Epigenetic, Discordant Ores of the Proterozoic, Carbonate-Hosted, Zawarmala Pb-Zn Deposit, Udaipur District, India

The Proterozoic, carbonate-hosted, Zawarmala Pb-Zn deposit has stratiform, banded pyrite-sphalerite ore, as well as discordant, sphalerite-galena veins and rich massive galena ore shoots. The mechanisms of deposition of discordant vein and massive ores have been studied using speciation and solubility calculations based on ore fluid characteristics and physical parameters inferred from petrography, fluid inclusion studies, and leachate analysis. Massive galena ore, which is the economic ore type, cuts across the earlier, F2-related, vein-type ore and is distinct from the vein-type ore in terms of mineralogy, texture, and fluid inclusion characteristics. Fluid inclusions in quartz associated with the ores show that fluids forming vein-type ore are low-salinity (4.3–14.7 wt % NaCl equiv) H2O-NaCl fluids. The trapping temperature of vein-type ore fluid was estimated to be in the range of 395° to 290°C at a pressure of about 1,450 bars. Fluids associated with massive galena ore are H2O-CO2-NaCl fluids of lower salinity (about 3–4 wt % NaCl equiv). The wide variation in XCO2 of fluid inclusions that occur in close proximity to each other within the same sample of massive ore suggests heterogeneous entrapment of the low-salinity H2O-CO2-NaCl fluids. From the intersection of isochores of local, homogeneously entrapped CO2 and aqueous biphase fluids of unmixed CO2-H2O-NaCl fluid, trapping temperature fluid was estimated to be between 250° and 150°C at pressures of 2,000 to 750 bars. Despite the low salinity of the ore fluids, speciation studies show that chloride complexes are dominant over most of the temperature range of interest in both ore fluids. The only bisulfide complex of importance is \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(Pb(HS)_{2}^{0}\) \end{document}, which is dominant below 175°C in fluids associated with massive galena ore. Data from fluid inclusions and solubility calculations reveal that cooling is the important mechanism of vein-type ore deposition. In contrast, physicochemical data indicate that an increase in reduced sulfur, by mixing a regional, high metal content, low sulfur fluid with a local, high sulfur fluid at the site of deposition, was the mechanism for massive galena ore deposition. The difference in oxidation state (and therefore also in metal content) of the two fluids is inferred to be a significant factor that caused differences in the modes of deposition of the two ore types and the relatively high value of XCO2 (0.2033) in fluids associated with massive galena ore.

Formation of Chloropyromorphite from Galena (PbS) in the Presence of Hydroxyapatite

Transformation of unstable lead [Pb(II)] forms into sparingly soluble pyromorphite [Pb5(PO4)3(OH, Cl, F, ...)] by the addition of phosphate to Pb-contaminated soil has been proposed as a remediation technology to reduce the mobility and bioavailability of Pb. Galena, an insoluble lead sulfide mineral (PbS) frequently found in mining wastes, becomes unstable upon exposure to oxidizing conditions causing it to become a source of liable Pb forms in soils. Thus, a galena ore was reacted with synthetic hydroxyapatite [Ca5(PO4)3OH] under various pH conditions to determine the formation rate of pyromorphite and the solubility of galena under the ambient condition. In a 6-day reaction period, the dissolution rate of galena increased with pH due to the oxidation of dissolved sulfide. Hence, formation of chloropyromorphite became apparent in the galena−apatite suspensions with increasing pH. The insignificant effect of mineral P/Pb molar ratio on the formation of chloropyromorphite implied that dissolution/oxidation of galena was the rate-limiting step.

Crystallographic preferred orientation and microstructure of experimentally deformed Braubach galena ore with emphasis on the relation to diffusional processes

Sample cylinders of two galena ore hand specimens from Braubach, Germany were axially shortened in the strain rate range 5 × 10−5 s−1–5 × 10−7 s−1 at a confining pressure of 200 (300) MPa and at temperatures of 20 °C–600 °C. Neutron diffraction analyses of the crystallographic preferred orientation (texture) were carried out before and after experimental deformation on the same sample cylinder. Up to a deformation temperature of 300 °C and a strain rate of 5 × 10−6 s−1 a more or less complete fiber texture develops, the strength of the fiber texture only depending on strain and the strength of the original preferred orientation. At slower strain rate and higher temperature, there is a distinct decrease of the fiber texture development. Diffusional mass transfer starts to become a significant deformation mechanism. Deformation at 500 °C changes the original texture only slightly, which indicates a rapid increase of importance of diffusional flow processes. The alteration of the accompanying sulfosalts indicates that the temperature is high enough for the movement of atoms. The microstructure only reveals remarkable deformation structures at higher strains and in areas of locally higher stresses.