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The phase equilibria in the pseudoternary systems CuSbS2-MS (M = Pb, Eu, Yb) have been studied, and their phase diagrams have been mapped out. The systems contain MCuSbS3 sulfides with an orthorhombic lattice, isostructural with the mineral bournonite (sp. gr. Pmn21, Z = 4). PbCuSbS3: a = 8.162, b = 8.71, c = 7.81 A; EuCuSbS3: a = 8.156, b = 8.682, c = 7.786 A; YbCuSbS3: a = 8.150, b = 8.664, c = 7.78 A.

Newly discovered assemblages of numerous ore minerals disseminated in schists, amphibolites and mylonites at their contacts with a dolomite lens exploited at Redziny, in the northeastern Bohemian Massif, Western Sudetes, Poland, was used in an evaluation of the thermochemical conditions under which specific, and in some cases rare, phases formed. Arsenopyrite, cassiterite and associated base-metal sulfides crystallized at temperatures lower than 550°C. The Ag-bearing sulfosalts pavonite, benjaminite, makovickyite, gustavite, berryite, matildite, giessenite, izoklakeite, cosalite, freibergite and tetrahedrite crystallized along with Ag-bearing galena in the temperature range ca. 350–280°C. They preceded the Cu–Pb–Bi(Sb) sulfosalts wittichenite, bournonite, aikinite-group minerals, emplectite and Ag-poor tennantite, which crystallized from about 300°C to even below 200°C. Kesterite and cernýite crystallized at temperatures about 350°C, cernýite occurring only in Zn-depleted environments. Ferrokesterite and petrukite, occurring with Zn-enriched chalcopyrite as inclusions within (Fe,Cd,Cu,Sn)-enriched sphalerite, are products of decomposition at 340–270°C of a higher-temperature (Zn,Cd,Cu,Fe,Sn) sulfide. Chatkalite formed as a metastable phase at the SnO 2 –SnS equilibrium at temperatures of about 270–260°C; stannoidite crystallized from 270°C to 250–240°C, at which point mawsonite began to crystallize. Unknown Sn-bearing sulfides, with compositions varying between Cu 4 Fe 3 SnS 8 and Cu 10 SnS 8 , crystallized at probably still lower temperatures. Bismuth sulfides (bismuthinite and an unknown Pb–Bi–S phase), sulfoselenides (ikunolite) and sulfotellurides (tetradymite, joseite-A, joseite-B and an unknown Bi–Te–S phase) crystallized under varying conditions: tetradymite at about 300°C, ikunolite at 270–240°C, bismuthinite from about 300 to 220°C, and joseite-A and joseite-B clearly below 240°C.

Oriented single-crystals of stibnite, bismuthinite, kermesite, stephanite and bournonite were investigated by polarized Raman spectroscopy. The obtained spectra were compared to those of the sulfosalt minerals tetrahedrite and pyrargyrite. Whereas the latter show isolated SbS 3 groups with ideal trigonal symmetry, the former show distorted XS 3 (X = Sb,Bi) groups with lower symmetry. Moreover, in stibnite and isostructural bismuthinite the pyramidal groups are interconnected to infinite ribbons, and even to sheets in kermesite. The internal vibrations, i.e. the stretching and bending modes, of the SbS 3 groups occur at ~340–180 cm −1 , those of the BiS 3 groups in bismuthinite at ~280–150 cm −1 . The higher mass and the longer bond distances of the BiS 3 groups readily explain the lower wavenumbers of the latter. However, even for the SbS 3 groups a negative correlation between bond distances and vibrational wavenumbers is observed. Moreover, in those minerals with a wide range of pyramidal bond distances, i.e. stibnite, kermesite, bismuthinite, a more extended range of vibrational modes is observed. A clear distinction between Raman spectra of separated and interconnected SbS 3 groups is not observed.

Carbonate-replacement Pb–Zn–Ag ± Au deposits in the Kamariza area, Lavrion district, Attica, Greece, are genetically related to the emplacement of Miocene andesitic dikes within a rapidly extending continental back-arc basin, which formed during exhumation of the Attic-Cycladic Crystalline Belt. Replacement veins as well as chimneys and mantos of massive sulfides are the major orebody types with mantos grading into chimneys and veins. Ore minerals are similar among the various types of orebodies in the Kamariza area and consist of sulfides and sulfarsenides (pyrite, arsenopyrite, chalcopyrite, galena, sphalerite, gersdorffite, marcasite), native metals (Au and Bi), Sn-bearing phases (petrukite), sulfosalts and sulfbismuthites of Ag, Bi, Cu, Pb, As, Sb (tetrahedrite-group minerals, bournonite, boulangerite, stephanite, pyrargyrite, semseyite, enargite, bismuthinite, lillianite homologues, Cu-matildite, aikinite, Ag-aikinite, mummeite, emplectite, wittichenite). The elemental association of Bi, Au, and Ag is common. The assemblages gersdorffite-bismuthinite-native gold and native gold-native bismuth are evidence for a contribution of magmatic components to the hydrothermal system. A fluctuation in the sulfidation states of the ore fluid during the evolution of the Kamariza system is evident from the deposition of early arsenopyrite, as well as of enargite-luzonite and both low-Fe and Fe-rich sphalerite in the same samples. Microthermometry of fluid inclusion assemblages show that carbonate replacement mineralization was deposited from a warm to hot (100°C to 400°C), low to moderately saline (1.8 to 17.3 wt% NaCl equiv) fluid. Eutectic temperatures of fluid inclusions as low as −55°C suggest the presence of CaCl2 in addition to NaCl, in the ore fluid. The Kamariza deposit occurs distal to the Plaka granodiorite intrusion and the associated porphyry-Mo mineralization, but is likely to be genetically related to a granitoid buried at depth.

The intrusion-centered, polymetallic Plaka ore system, Lavrion, Greece, is genetically related to the emplacement of a Miocene biotite ± hornblende granodioritic body and granodiorite porphyry dikes/sills within metamorphic Mesozoic rocks of the Attic-Cycladic Crystalline Belt. The ore system includes porphyry, breccia-type, skarn, skarn-free carbonate replacement and vein-type ores enriched in Mo, W, Pb, Zn, Cu, As, Sb, Bi and Ag. Early pyrite-molybdenite (±chalcopyrite ± pyrrhotite) mineralization was deposited in multidirectional and sheeted quartz veins within the silicically and sericitically altered granodiorite intrusive. The emplacement of granodiorite porphyry dikes/sills was followed by the introduction of base metal sulphides during hydrothermal brecciation of the porphyritic rocks. Skarn- and skarn-free carbonate replacement ores developed contemporaneously with these magmatic-hydrothermal events and are characterized by the presence of pyrrhotite, pyrite, Fe-rich sphalerite and Bi-Ag-rich galena. A late Pb-As-Sb-Cu-Ag-rich banded vein (Filoni 80) is composed of pyrrhotite, chalcopyrite, arsenopyrite, sphalerite (both Fe-rich and Fe-poor), lollingite, argentian tetrahedrite, bournonite, pyrargyrite, miargyrite, native arsenic, semseyite, heteromorphite, veenite, falkmanite and fluorite, quartz and siderite. The ore mineralogy of the Plaka deposit is generally consistent with reducing and low sulphidation fluid conditions during metal deposition. Fluid inclusion data indicate that molybdenite deposition was associated with boiling between 270 and 360 °C and at a pressure of 50–200 bars, corresponding to a depth of approximately 1 km. Dilution of a saline fluid by mixing with less saline water resulted in the formation of a moderately saline (14–18 wt% NaCl equiv.), low-temperature (190–220 °C) fluid and the precipitation of sulphides and sulphosalts in the Filoni 80 vein. The evolution from early porphyry-style mineralization to the later vein ores likely formed either as a result of continuous syn-mineralization uplift of the Plaka granodiorite in relation to post-orogenic regional uplift during the Upper Miocene, or as a simple cooling of the high-temperature hydrothermal system.

The occurrence and the chemical compositions of ore minerals (especially the silver-bearing minerals) and fluid inclusions of the El Zancudo mine in Colombia were investigated in order to analyze the genetic processes of the ore minerals and to examine the genesis of the deposit. The El Zancudo mine is a silver–gold deposit located in the western flank of the Central Cordillera in Antioquia Department. It consists mainly of banded ore veins hosted in greenschist and lesser disseminated ore in porphyritic rocks. The ore deposit is associated with extensive hydrothermally altered zones. The ores from the banded veins contain sphalerite, pyrite, arsenopyrite, galena, Ag-bearing sulfosalts, Pb-Sb sulfosalts, and minor chalcopyrite, electrum, and native silver. Electrum is included within sphalerite, pyrite, and arsenopyrite, and is also partially surrounded by pyrite, arsenopyrite, sphalerite, and tetrahedrite. Native silver is present in minor amounts as small grains in contact with Ag-rich sulfosalts. Silver-bearing sulfosalts are argentian tetrahedrite–freibergite solid solution, andorite, miargyrite, diaphorite, and owyheeite. Pb-Sb sulfosalts are bournonite, jamesonite, and boulangerite. Two main crystallization stages are recognized, based on textural relations and mineral assemblages. The first-stage assemblage includes sphalerite, pyrite, arsenopyrite, galena and electrum. The second stage is divided into two sub-stages. The first sub-stage commenced with the deposition and growth of sphalerite, pyrite, and arsenopyrite. These minerals are characterized by compositional growth banding, and seem to have crystallized continuously until the end of the second sub-stage. Tetrahedrite, Pb-Cu sulfosalts, Ag-Sb sulfosalt, and Pb-Ag-Sb sulfosalts crystallized from the final part of the first sub-stage and during the whole second sub-stage. However, one Pb-Ag-Sb sulfosalt, diaphorite, was formed by a retrograde reaction between galena and miargyrite. The minimum and maximum genetic temperatures estimated from the FeS content of sphalerite coexisting with pyrite and the silver content of electrum are 300°C and 420°C, respectively. These estimated genetic temperatures are similar to, but slightly higher than the homogenization temperatures (235–350°C) of primary fluid inclusions in quartz. The presence of muscovite in the altered host rocks and gangue suggest that the pH of the hydrothermal solutions was close to neutral. Most of the sulfosalts in this deposit have previously been attributed as the products of epithermal mineralization. However, El Zancudo can be classified as a xenothermal deposit, in view of the low pressure and high temperature genetic conditions identified in the present study, based on the mineralogy of sulfosalts and the homogenization temperatures of the fluid inclusions.

Tetrahedrite fahlores from the Galena Mine of the Coeur d’Alene Mining District (Wallace, Idaho) have been found to be enriched in Ag by the Ag-Cu exchange reaction: \[{1/10\ Cu_{10}(Zn,Fe)_{2}Sb_{4}S_{13}_{Cu-fahlore}^{}}\ +\ {AgSbS_{2}_{in\ galena}^{}}\ +\ {PbS_{galena}^{}}\ =\ {CuPbSbS_{3}_{bournonite}^{}}\ +\ {1/10\ Ag_{10}(Zn,Fe)_{2}Sb_{4}S_{13}_{Ag-fahlore}^{}}\] which occurred during cooling following fahlore mineralization. This solid-state reaction produced a distinct population of high-Ag fahlores found in galena-rich samples, quantitatively removed Ag (in an AgSbS 2 component) from galena, and accounts for all of the bournonite mineralization. This reaction has produced the most argentian fahlore yet found [molar Ag/(Ag + Cu) = 0.443] in the district, and forms a secondary overprint on any primary fahlore zoning that may have existed. The results obtained here indicate that the galena and fahlore-siderite stages of mineralization were virtually synchronous, as this reaction has produced the same result despite the opposite relative age relationships of these mineralization stages exhibited in two of the mines studied. Multiple lines of evidence suggest a temperature between 320 and 350 °C for this “stage.” Based on the Ag/(Ag + Cu) of fahlores and Fe-Zn partitioning between fahlore and sphalerite, we estimate that fahlore compositions were frozen in by about 235 °C, roughly 40 °C above corresponding temperatures obtained for the Gold Hunter vein of the Lucky Friday Mine. This result and the absence of readily detectable diaphorite (~Pb 2 Ag 3 Sb 3 S 8 ) in the Galena Mine sample containing the highest Ag fahlore indicate a faster cooling rate for the terrane in the vicinity of the Galena Mine.

Mineralogical features and compositional data on bournonite from epithermal vein deposit of Varatec, Baiuţ mine field in the Baia Mare district, Romania are presented. Bournonite is disposed in quartz matrix or it is associated with chalcopyrite and tetrahedrite. SEM images demonstrate the absence of intergrown derivates with distinct compositions. Variations of chemical composition of bournonit have been recorded using electron probe microanalyses. The negative correlation of Sb – As contents indicates a substitution process between the two elements and the presence of limited solid solution towards seligmanite.

The sulphide ores from the Julcani mining district (Peru) display many retrograde reactions that may be attributed to solid-state processes accompanying cooling. Fahlores [˜(Cu,Ag)10(Zn,Fe)2(Sb,As)4S13] from the Herminia mine exhibit pronounced downstream enrichments in molar Ag/(Ag+Cu) ratios that are strongly correlated with the abundance of PbS-AgSbS2-AgBiS2 phases. These correlations, discontinuous core to rim Sb/(Sb+As) enrichments in bournonites, and prominent reaction textures involving fahlores, bournonites and galenas provide strong evidence that the fahlores in these ores have been enriched in Ag by the Ag–Cu exchange reactionwhich occurred during cooling following mineralization of a PbS-AgSbS2-AgBiS2 galena and has been documented elsewhere. Secondary PbS-AgSbS2-AgBiS2 minerals aramayoite, bismuthian diaphorite [Pb2Ag3(Bi,Sb)3S8], and diaphorite were produced from primary galenas with cooling of ores with high Pb/Cu and Bi/Sb; pyrargyrite formed from the breakdown of the Ag10Zn2Sb4S13 component in the most Ag-rich fahlores, as an exsolution product of galena, and from replacement of aramayoite and galena with the evolution of semimetal sulphides. Based on mineral compositions, phase equilibria, a thermochemical database for sulphides and sulphosalts, and the reintegrated composition for primary grains of Ag-rich PbS-AgSbS2-AgBiS2 phases, we estimate that the primary temperature of hydrothermal mineralization was >320±10°C, that these reactions ceased to affect fahlore Ag/(Ag+Cu) ratios and Bi/(Bi+Sb) ratios of aramayoite and miargyrite after cooling through 220±10°C. Galenas, however, appear to have continued to adjust their compositions to reflect even lower temperatures by continued exsolution of semimetals and production a diverse suite of sulphosalts that occur in fine intergrowths with galena.

Laser sulfur combustion in the presence of O 2 is the most commonly used method of in situ sulfur isotope analysis. Previous workers indicated that a small but reproducible fractionation of 34 S/ 32 S exists between the product SO 2 gas and the mineral. The magnitude of this fractionation varies with bond strength, as reflected in Gibbs free energy of formation at 298.15K. The correction factors are known for common sulfides and anhydrite but not, hitherto, for stibnite and the sulfosalt minerals, which are important constituents of many classes of ore deposits. We present the correction factors for the following chemically and crystallographically well-characterized minerals: stibnite (weighted mean = −1.2‰), bournonite (+0.6‰), tetrahedrite (+1.3‰), and boulangerite (+1.4‰). The Gibbs free energies of formation of these phases have been approximated by the sulfide summation method, and the correlation of ΔG 298 0 with the correction factor for the sulfosalts fits well with the trend previously established for simple sulfides. There is an excellent correlation between the fractionation factor and mineral composition, a parameter that does result in bond strength variations (e.g., mol fraction of PbS in sulfosalts), allowing estimation of the correction factors for simple intermediate compositions. Finally, bond strength also varies with variation in interatomic distances, and we have, therefore, investigated the behaviour of stibnite, a strongly anisotropic mineral. Our results indicate that there is a significant variation in fractionation factor, depending on crystal orientation. The fractionation factor along the prismatic b-axis, which displays the strongest chemical bonds (as monitored by the shortest bond lengths), is more negative (−1.7‰) than along the other crystallographic directions (−0.7 to −1.0‰), which is in full agreement with theoretical predictions. We demonstrate the application of the technique in unravelling source- and process-related sulfur isotope systematics in two hydrothermal vein systems in the classic mining area of the NE Rhenish Massif, both studies requiring resolution beyond the scale of conventional sulfur isotope analysis.

The Maronia copper-molybdenum deposit is hosted by a porphyritic microgranite, located 30 km south-east of Komotini in Thrace (north-eastern Greece) in the Rhodope metallogenic province. The geology of the area is dominated by metamorphosed Mesozoic sedimentary and volcanic rocks, and Tertiary plutonic and subvolcanic intrusions. The metamorphic rocks belong to the Makri Unit of the Circum Rhodope Belt and consist mainly of marbles and calc-schists in the lower part and schists in the upper part. The marbles and schists of the Makri Unit are intruded by the Oligocene Maronia pluton of gabbroic-monzogabbroic-monzonitic composition and a younger porphyry microgranite, which is the host of the copper-molybdenum mineralisation. Three hydrothermal alteration zones have been recognised in the porphyritic microgranite: an argillic zone, a phyllic zone, and a propylitic zone which extends into the surrounding rocks. Additionally, three highly silicified zones crop out at the north-eastern, south-eastern and southern parts of the microgranite. Chalcopyrite-pyrite-molybdenite mineralisation, concentrated mainly in the silicified zones and associated with areas of phyllic and propylitic alteration, occurs as disseminations, veinlets and segregations. Surface samples of altered rock contain as much as 7,600 ppm Mo, 5,460 ppm Cu and 1 ppm Au. Geochemical data from a drill core revealed a 10-m-thick horizon containing as much as 12 ppm Au, 17 ppm Ag and 2.00% Cu. Argillic and phyllic alteration zones are characterised by relatively low REE abundances (average total: 88 and 95 ppm respectively) and negative Eu anomalies, compared to rocks in the propylitic alteration zone where REE contents are higher (average total: 177 ppm) and there is a positive Eu anomaly. The ore-related mineral assemblage consists of sulphides (pyrite, chalcopyrite, cubanite, pyrrhotite, pentlandite, molybdenite, sphalerite, galena and bismuthinite), sulphosalts (tetrahedrite, tennantite, zinkenite, chalcostibite, famatinite, bournonite, boulangerite, meneghinite) and oxides (magnetite). The molybdenites revealed unusually high and variable rhenium concentrations, from 0.12 to 4.21 wt%. Microthermometric investigation of four types of fluid inclusions in ore-related quartz revealed salinities from 5 to 55 wt% NaCl equiv, with homogenisation temperatures varying mainly from 280 to 460 °C. The application of the chlorite geothermometer yielded temperatures between 308 and 331 °C for lowest-temperature propylitic alteration. The estimated trapping pressures of the ore-forming fluids range from 150 to 510 bar. Boiling is considered to be the main process of ore formation. Sulphur isotopic compositions for the pyrite and molybdenite suggest an igneous derivation of sulphur. Ascending melts and hydrothermal fluids interacted with the sulphide-bearing metavolcanic rocks, incorporating sulphur and ore metals (including Cu, Mo, Pb, Zn and Au) from the lithosphere. Geological, mineralogical and geochemical data indicate that the Maronia deposit has the potential of containing economic quantities of exceptionally high-grade porphyry Cu-Mo ores, with economic gold grades, in an easily accessible, yet under-explored region.

Tetrahedrite fahlores from the Coeur d’Alene mining district (Idaho) have been found to be enriched in Ag by the Ag–Cu exchange reaction \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \begin{eqnarray*}&&{\frac{1}{10}Cu\_{10}(Zn,Fe)\_{2}Sb\_{4}S\_{13}\_{Cu-fahlore}^{}}\ +\ {AgSbS\_{2}\_{in\ galena}^{}}\ +\ {Pbs\_{galena}^{}}\ =\ \\&&{CuPbSbS\_{3}\_{bournonite}^{}}\ +\ {\frac{1}{10}Ag\_{10}(Zn,Fe)\_{2}Sb\_{4}S\_{13}_{Ag-fahlore}^{}}\end{eqnarray*} \end{document} which occurred during cooling following galena mineralization. This solid–state reaction resulted in quantitative removal of Ag (in a AgSbS2 component) from galena and development of bournonite coronas on fahlore grains. The reaction produced a distinct population of high-Ag fahlores found in galena-rich samples and accounts for all of the bournonite mineralization. The most argentian of these high-Ag fahlores examined in this study (molar Ag/(Ag+Cu) = 0.303±0.011 and 0.336±0.011) are found in samples which achieved saturation with respect to other Ag-sulfosalts, namely pyrargyrite and polybasite and diaphorite, respectively. Multiple lines of evidence for the Ag-Cu exchange reaction are presented in this paper which applies mass-balance constraints and a thermodynamic database for sulfides/sulfosalts to microprobe analyses and textural observations, and to bulk production data. This solid-state reaction may explain why previous district studies have been unable to demonstrate convincingly primary fahlore zoning. Based on the Ag/(Ag+Cu) of fahlores coexisting with other Ag-sulfosalts and Fe-Zn partitioning between fahlore and sphalerite, we estimate that fahlore compositions were frozen in by 175°C. Examining the composition data for other Ag tetrahedrite fahlores found in the Coeur d’Alene district and elsewhere, we conclude that the thermodynamic database provides an accurate description of phase equilibria, except possibly for very Fe-rich systems where further studies of the Fe-Zn partitioning between fahlore and Fe-rich (Zn,Fe)S phases and of the thermodynamics of Fe-rich (Zn,Fe)S phases are warranted.

Mesothermal vein-type Sb mineralization in the Rheinisches Schiefergebirge, Germany, is characterized by two different mineralization styles, which are (1) extensional quartz-stibnite vein systems, and (2) (Cu)–Pb–Sb sulphosalt assemblages in overprinted pre-existing Pb–Zn veins. A detailed Pb isotope study of 52 representative samples from both mineralization types indicates distinct compositional patterns. (Cu)–Pb–Sb sulphosalts (meneghinite, boulangerite, bournonite) formed by reaction/remobilization are characterized by Pb isotope compositions (206Pb/204Pb=18.179–18.223), which are identical to the precursor galena (206Pb/204Pb=18.168–18.223). The Pb isotope composition of sulphosalt minerals in these vein systems was controlled by lead inherited from pre-existing galena. Stibnite and Pb-sulphosalts (zinkenite, semseyite, plagionite) formed in quartz–stibnite vein systems display Pb isotope ratios (206Pb/204Pb=18.250–18.354), which are more radiogenic than galenas from Variscan Pb–Zn ore veins (206Pb/204Pb=18.162–18.303). Detailed small-scale investigation of thrust zones hosting Pb–Zn ores and crosscutting quartz–ankerite fissure veins (Ramsbeck deposit) indicates that the Pb isotope compositions of recrystallized (galena) and remobilized phases (boulangerite, semseyite, bournonite) are arranged along a linear trend. This is interpreted as mixing between primary galena with 206Pb/204Pb≅18.206 and overprinting hydrothermal fluids with a more radiogenic composition (206Pb/204Pb≥18.354), expressed by intermediate compositions (206Pb/204Pb=18.256–18.334) of newly-formed sulphosalts. The Pb isotope systematics of the vein-type Sb mineralization is in accordance with a model of Pb extraction from similar crustal sources (Palaeozoic sedimentary sequences) at different times.

Syntectonic hydrothermal Pb-Zn vein systems of the Ramsbeck deposit, Germany, have been extensively overprinted by late-stage fluids responsible for fissure vein mineralisation. This has caused remobilisation of vein components, notably of sphalerite and galena, as well as the formation of various Sb sulphosalt minerals, including boulangerite, semseyite, tetrahedrite and bournonite. A detailed sulphur isotope study of sphalerite, galena and sulphosalts related to different stages of recrystallisation, remobilisation and reaction has been carried out using an insitu laser combustion technique. Primary sphalerite-galena ores from flat-lying thrust zones are characterised by homogeneous positive δ34S values in the range +6.5 to +7.7‰. In contrast, recrystallised and remobilised sphalerite and galena from both overprinted thrust zones and extensional fissure veins show δ34S values in the range –1.1 to +2.9‰ and –0.7 to +8.7‰ respectively. Sulphosalt minerals show a similar variation in their sulphur isotope compositions, which range between –1.7 and +7.7‰. Fissure vein hosted sphalerite and sulphosalts display significantly more negative δ34S values than the primary Pb-Zn ores. Sphalerite which recrystallised in situ and boulangerite which formed by reactive replacement of primary galena show slightly more positive δ34S values than fissure vein hosted minerals. The compositional range of remobilised mineral phases can be best explained by varying contributions (variable mixing) of sulphur derived from (1) the primary sphalerite-galena ores of the flat thrust systems, and (2) the hydrothermal fluid responsible for the fissure vein mineralisation. Equilibrium fractionation temperatures calculated for sphalerite-galena pairs contrast strongly with fluid inclusion data. Isotopic fractionation related to the remobilisation has to be interpreted in terms of kinetic processes.

Although falkmanite of the ideal composition proposed by Ramdohr & Odman (1940), Pb 3 Sb 2 S 6 , could not be synthesized even with the help of halide fluxes, a phase with composition similar to boulangerite, (Pb 5 Sb 4 S 11 ) but with dissimilar X-ray diffraction pattern was synthesized by sulfidation of bournonite at 400 and 500° C. This phase has been provisionally referred to as falkmanite in this study. Molar PbS:Sb 2 S 3 ratio in boulangerite varied from 2.41 to 2.47 and that in falkmanite varied from 2.51 to 2.57. Powder X-ray-diffraction pattern for boulangerite furnished an orthorhombic cell with a = 23.443 A, b = 21.183 A and c = 4.505 A, while that for falkmanite gave a monoclinic cell with a = 21.626 A, b = 11.409 A, c = 7.876 A and β = 96.19°. This raises doubts as to the identity of falkmanite as a member of the boulangerite homologous series, as proposed by Mozgova et al. , (1983). At 530° C, Cu-free meneghinite co-existed with falkmanite, signifying that the meneghinite solid solution field in the ternary Cu 2 S-PbS-Sb 2 S 3 touched the PbS-Sb 2 S 3 binary between 500 and 530°C. From 530 to 560° C, the proportion of Cu-free meneghinite gradually increased relative to that of falkmanite implying increased overlap of the meneghinite solid solution field with the PbS-Sb 2 S 3 binary. Falkmanite and boulangerite synthesized at 500° C and heated at 560° C for 2 hours provided similar X-ray-diffraction patterns, which corresponded with that of Cu-free meneghinite.

Ag-Sb deposits of a new economic district that occurs on the boundary of the southeastern Altay Republic of eastern Russia and northeast Mongolia are herein described. Mineralization of this region is divided into two periods—(1) Late Hercynian (Mo-W deposits) and (2) Mesozoic (Sn-W, as well as Ni-Co-As, Ag-Sb, and Sb-Hg deposits). The deposits of main economic interest, silver-antimony, consist of siderite-sulfosalt veins and vein zones that occur in contact-metamorphosed coal-bearing terrigenous rocks of Devonian age. These veins occur to depths of up to 900 m, and occur along strike for 3 to 3.5 km; their thicknesses range up to 12 m. The deposits are mineralogically and geochemically similar to silver deposits of the Yakutian, Pamir, Slovakian, Coeur D'Alene (USA), and Freiberg (Germany) ore districts. The main ore minerals are quartz, carbonate, and Ag-tetrahedrite, with minor chalcostibnite, chalcopyrite, bournonite, zinkenite, arsenopyrite, and pyrite. Sulfides are characterized by widespread isomo...

Samples of drill core, ore and concentrates from the Proterozoic Suurikuusikko Au deposit, Kittila, Central Lapland were studied by optical microscopy, image analysis, Secondary Ion Mass Spectrometer (SIMS), trace gold analysis by electron microprobe, and diagnostic leaching techniques to characterize the mode of occurrence of the gold. The main ore minerals are pyrite, arsenopyrite and gersdorffite, and the minor ore minerals include chalcopyrite, sphalerite, tetrahedrite, galena, bournonite and rutile. Graphite is found in all samples as microcrystalline grains. Pyrite, arsenopyrite and occasionally gersdorffite occur as disseminated intimately intergrown grains and as large grain aggregates. Diagnostic leaching tests show that an average of only 4.1% of the gold is in cyanide leachable form i.e. free gold, whereas on average 57% of the gold is bound to pyrite and arsenopyrite as inclusions or as lattice gold. The weight percentage of arsenopyrite and pyrite in the concentrate determined with image analysis on backscattered electron images is 65.2 and 34.7, respectively. Trace Au analyses done with EPMA using the Australian CSIRO-TRACE program from the drill core samples and concentrates show that the average gold content in pyrite is 46 ppm (192 analyses) and in arsenopyrite 279 ppm (136 analyses). The CSIRO-TRACE microprobe analyses correspond favourably to SIMS analyses, e.g. 69 ppm for pyrite (16 analyses) and 217 ppm for arsenopyrite (22 analyses). The distribution of gold in concentrates was calculated as free gold 4.1%, gold in pyrite 22.7%, and gold in arsenopyrite 73.2%. Both arsenopyrite and pyrite show strong zoning when treated for 1–2 min with KMnO4 dissolved in sulphuric acid, and trace Au microprobe analyses show that the zonal bands reflect different concentrations of gold in the minerals. Free gold was not found by optical microscopy, but a rare mineral search technique using TURBO-SCAN runs on the drill core samples and concentrates located 111 gold grains. The grains have a large compositional variation from silver-bearing gold to electrum and Au-Ag-amalgam.

Several distinct assemblages of Pb-Sb, Pb-As, Cu-Pb-Sb and Cu-Fe-Zn-Sn sulphosalts are identified in sulphide samples from Bleikvassli mine, Norway. Detailed optical microscopy and electron probe microanalysis have permitted investigation of textural relationships between minerals and compositional variations between different ore types. Tetrahedrite, typically containing 10–16 wt.% Ag (rare freibergite containing 25–30 wt.% Ag has also been identified in two samples), stannite (Cu2(Fe>Zn)SnS4), and meneghinite, CuPb13Sb7S24, are widely distributed as trace constituents throughout massive pyritic and galena-rich ores. Native antimony and pyrargyrite occur in trace amounts in all ore types, as the breakdown products of earlier sulphosalts. Several distinct types of wall-rock mineralisation are present at Bleikvassli. Of considerable mineralogical interest are the coarse-grained sulphide mobilisates within the wall rock which contain a distinct␣and characteristic suite of Pb-As sulphosalts:␣tennantite + jordanite (Pb14As6S23) + seligmannite (CuPbAsS3) ± dufrenoysite (Pb2As2S5). Bournonite (CuPbSbS3) is the only Sb-bearing sulphosalt recognised in significant amounts within the mobilisates, meneghinite and tetrahedrite being conspicuously absent. These mobilisates display considerable Au enrichment; electrum can be confirmed, intimately associated with jordanite and tennantite. Appreciable Sb (up to 3 wt.%) is contained within galena in the mobilisates, in contrast to galena from massive ores which contains only negligible Sb. Contents of Ag and Bi in galena vary considerably in all ore types, but confirm earlier suggestions that galena is a major Ag-carrier at Bleikvassli. Boulangerite (Pb5Sb4S11), jamesonite (FePb4Sb6S14) and gudmundite (FeSbS) occur in trace amounts. Sn-sulphosalts are represented by kesterite, (Cu2(Zn> Fe)SnS4), but commonly zoned with respect to Zn/Fe ratio, in the mobilisates, rather than by stannite. A rare type of mobilisate, also in the wall rock, in which chalcocite and bornite are the main minerals, contains native Ag, stromeyerite (AgCuS), mckinstryite ((Ag,Cu)2 S), Ag-free tetrahedrite, an unnamed Cu-Ag-Fe sulphide (Cu3Ag2FeS4) and native Bi, myrmekitically intergrown with chalcocite. Although a comprehensive genetic model for the wall-rock mineralisation at Bleikvassli is largely impossible given the limitations in the present state of knowledge regarding mechanisms involved in remobilisation processes, a multi-stage model of remobilisation during regional metamorphism is considered to best explain the observations. An interplay of different solid- and liquid-state remobilisation mechanisms, in various combinations, is required to account for the macro- and microscopic observations. Remobilisation probably began during the earlier stages of metamorphism, with crystallisation and further remobilisation taking place during the entire metamorphic cycle, giving rise to the extensive chemical and mineralogical diversity observed today. Preserved mineral assemblages and their textural relationships reflect a complex sequence of replacement and decomposition reactions taking place during the latest phase of late-metamorphic crystallisation and subsequent cooling.

Spectroscopic studies on two naturally occurring minerals bornite and bournonite are carried out by optical absorption and EPR techniques. In both samples doubly ionised copper ion exhibits in tetragonally distorted tetrahedral site symmetry. In the case of bornite triply ionised iron is in the regular tetrahedral site symmetry. Different crystal field and tetragonal parameters are evaluated: Dq = 450, B = 690 and C = 2600 cm−1 for Fe(III) ion in Bornite Dq = 431, Ds = -642 and Dt = 462 cm−1 for Cu(II) ion in Bornite Dq = 433, Ds = -639 and Dt = 468 cm−1 for Cu(II) ion in Bournonite

The Janggun iron deposits, Republic of␣Korea, occur as lens-shaped magnesian skarn, magnetite and base-metal sulfide orebodies developed in the Cambrian Janggun Limestone Formation. Mineralization stage of the deposits can be divided into two separate events. The skarn stage (107 Ma) consists of magnetite, pyrrhotite, base-metal sulfides, carbonates and magnesian skarn minerals. The hydrothermal stage (70 Ma) consists of base-metal sulfides, native bismuth, bismuthinite, tetrahedrite, boulangerite, bournonite and stannite. Mineral assemblages, chemical compositions and thermodynamic considerations indicate that formation temperatures, −log fs2 and −log fo2 values of ore fluids from the skarn stage were 433 to 345 °C, 8.1 to 9.7 bar and 29.4 to 31.6 bar, and the hydrothermal stage was 245 to 315 °C, 10.4 to 13.2 bar and 33.6 to 35.4 bar, respectively. Thermochemical considerations indicate that the XCO2 during magnesian skarnization ranged from 0.06 to 0.09, and the activity of H+ presumably decreased when the fluids equilibrated with host dolomitic limestone which resulted in a pH change from about 6.1 to 7.8, and decreases in fo2 and fs2. The δ34S values of ore sulfides have a wide range from 3.2 to 11.6 ‰ (CDT). Calculated 34SH2 S values of ore fluids are 2.9 to 5.4 ‰ (skarn stage) and 8.7 to 13.5 ‰ (hydrothermal stage). These are interpreted to represent an initial deep-seated, igneous source of sulfur which gave way to influence of oxidized sedimentary sulfur to hydrothermal stage. The δ13C values of carbonates in ores range from −4.6 to −2.5 ‰ (PDB). It is likely that carbon in the ore fluids was a mixture of deep-seated magmatic carbon and dissolved carbon of dolomitic limestone. The δ18OH2 O and δD values (SMOW) of water in the ore fluids were 14.7 to 1.8 and −85 to −73 ‰ during the skarn stage and 11.1 to −0.2 and −87 to −80 ‰ in the hydrothermal stage.

New 40 Ar/ 39 Ar age spectra on sericite and lead isotope data on tetrahedrite, siderite, galena, bournonite, and stibnite, together with previously published isotopic, geochemical, and geologic studies provide evidence for two major vein-forming events in the Coeur d'Alene district and surrounding areas of the Belt basin. The data suggest that the zinc- and lead-rich veins (e.g., Bunker Hill and Star-Morning mines) formed in the Proterozoic (1.0 Ga), whereas the silver-rich veins (e.g., Silver belt mines), antimony veins (e.g., U.S. Antimony mine), and gold-bearing quartz veins (Murry subdistrict) formed in Late Cretaceous to early Tetitary time.

Gold in Early Proterozoic Birimian greenstone at Prestea in Ghana is associated with base metal sulphides and sulphosalts including arsenopyrite, pyrite, sphalerite, chalcopyrite, pyrrhotite, galena, tetrahedrite, bournonite, boulangerite and jamesonite. The occurrence of the gold is intimately associated with arsenopyrite and the sulphosalts, and to a lesser extent with the other sulphides. The tetrahedrites at Prestea constitute the major component of sulphosalts associated with gold and occurring in two distinct types. Type I show ideal stoichiometric composition. Type II tetrahedrites deviated from the ideal stoichiometry and are represented approximately by the average formula (Cu,Ag)9.61(Fe,Zn)2.39(Sb,As)4S13. The tetrahedrites co-precipitated with gold exhibit ideal characteristics indicating an equilibruim state of the mineralizing fluid during precipitation. Three types of pyrites were distinguished by electron-microprobe analyses based on their As, Co and Ni composition. The As content in type I vary from 0.15 to 0.37 wt%, and contain up to 2 wt.% Co.Type II pyrites are As-rich and form the most dominant with As content ranging from 0.2 to 2.69 wt.%. Ni content varies from below-detection to 1000 ppm. Type III pyrites are poor in the trace elements and consistent with the stoichiometric composition. The mineralization occurred in three paragenetic stages from at least a two-phase hydrothermal fluid, with stage II forming a prolonged and main stage of the ore and gold mineralization. Redox changes in ore fluid which were triggered by episodic pressure releases during fissuring and fracturing caused fluctuation of the activity of the As/Ni ratio and subsequent oscillatory zoning of Ni in As-rich ores.

The textural and paragenetic relationships of sulphide and sulphosalt minerals within Cu-Pb-Sb-Bi hydrothermal vein mineralization at the Apollo mine, Siegerland, Germany, are interpreted in terms of various reaction sequences. An earlier primary sulphide mineralization hosted within a siderite vein of the Siegerland type, with pyrite, chalcopyrite, sphalerite and galena as main component phases, has been overprinted by Sb-, Bi- and Cu-rich fluids. This superposition resulted in the formation of new quartz-stibnite veins, and various mineral reactions with the primary sulphides including the formation of the sulphosalt minerals semseyite, tetrahedrite, meneghinite, jaskolskiite, boulangerite, bournonite and zinkenite. Based on microprobe analyses of reaction pairs and determination of mineral proportions in some cases, a series of quantitative data for each mineral reaction may be generated. This, in turn, allows for the construction of isocon diagrams permitting the relative mobility and immobility of all chemical elements involved in each reaction to be discussed. Two stages of reactive replacement are identified, characterized by immobile behaviour of S and supply of Sb and Cu during the first stage and relative immobility of S and Sb with no further supply of metals during the second stage. Formation of sulphosalts inside the siderite vein during the first stage is interpreted as a decrease of disequilibrium between hydrothermal fluids and pre-existing vein minerals. Replacement processes of the second stage are interpreted as an equilibration of geochemical contrasts between different points within the siderite vein and also between the siderite and quartz-stibnite vein systems. The geochemical evolution of fluid composition during the entire mineralizing event may therefore be modelled, based on the transfer of chemical components reflected in the succession of mineral reactions. Such an approach has applications to comparable polyphase mineralization sequences, in which an understanding of fluid evolution patterns may greatly assist in the development of genetic models for mineral deposits. Solid-state diffusion and grain-boundary diffusion are considered to be the dominant mechanisms for short-range mass transport, whereas diffusion of ionic and complex species through the fluid is considered to be of major importance in long-range mass transport.

Investigations of Sb-based chalcogenides, stephanite Ag5SbS 4 and bournonite CuPbSbS 3, have been performed by 121,123Sb nuclear quadrupole resonance (NQR). In stephanite a phase transition at 140 K and internal diffusion motions with an activation energy of 0.29 eV have been experimentally detected. The analysis of experimental results for bournonite revealed two crystal-chemical positions of Sb in the unit cell with distinct local symmetry. The NQR frequencies ν and line-widths Δν data indicate that Sb(A)S3 complex has almost axial symmetry, but Sb(B)S 3 complex is substantially distorted.

The pyritic VMS deposits at Sulitjelma, northern Norway have been regionally metamorphosed at amphibolite facies during the Caledonide Orogen. The deposits contain a wide diversity of sulphide, sulphosalt and related minerals, which are systematically discussed with reference to their occurrence, paragenesis and mineral chemistry. Most of these minerals are, however, rare to absent within the massive deposits, which are dominantly composed of pyrite with subordinate chalcopyrite, sphalerite and pyrrhotite. Galena, arsenopyrite, cubanite, molybdenite, stannite and tetrahedrite occur in minor amounts. Syn-metamorphic mobilisation has, however, resulted in the redistribution of a range of elements, including Cu, Pb, Sb, As, Ni and Au. These elements have been reconcentrated into mobilised segregations, where they have crystallised, under retrograde conditions, into a range of discrete phases. Ore mobilisation, which took place along tectonically-controlled pathways is, however, of a highly localised nature, with a considerable range in mineral textures and parageneses observed in different samples. Typical associations within these mobilisates include a range of CuPbSb and CuPbAs sulphosalts, including bournonite, meneghinite, seligmannite and jordanite, breithauptite, nisbite, costibite, arsenopyrite and gudmundite. Co-existing galena is characterised by elevated concentrations of Ag, Bi and Se. Argentian tetrahedrite (9–17 wt% Ag), the chief Ag-carrier in the deposits, as well as other Ag-bearing phases, including pyrargyrite, hessite and empressite, are strongly enriched in the mobilisates. Gold, as electrum (50–75 wt% Au), and more rarely as aurostibite, is also relatively enriched in the mobilisate samples over those from more massive parts of the deposits. A further range of minerals, including native antimony, native arsenic, allargentum, dyscrasite, argentite, mckinstryite (?), jalpaite (?) and native silver occur as low temperature breakdown products of earlier-formed minerals. Preserved textures do not contradict a model involving more than a one phase of mobilisation during the metamorphic evolution.

The Prestea lode gold deposit occurs in a graphitic shear zone in the Birimian system of Ghana. The Birimian is an Early Proterozoic greenstone assemblage (≈ 2100 Ma) with large gold deposits, consisting of a lower unit predominantly of metasediments and an upper unit of metavolcanics with interbedded sediments. The metamorphic stage is of greenschist facies grade. The gold generally occurs as free gold or closely associated with sulfides, particularly arsenopyrite and sulfosalts. It is usually coarse grained and occurs along grain boundaries, as inclusions and in fractures with the ore minerals. The gold is nearly pure, with analyzed grains containing 95-96 wt% Au, 4-5 wt% Ag, and less than 0.1 wt% Sb, Bi, Zn, or Cu. Associated metallic phases consist of pyrite, arsenopyrite, chalcopyrite, pyrrhotite, sphalerite, galena, and sulfosalts such as tetrahedrite, boulangerite, bournonite, and jamesonite. The fluid associated with the gold mineralization was H2O-CO2-NaCl in composition, with a mean salinity = 3...

Reversed brackets on As and Sb partitioning between tetrahedrite-tennantite fahlores {∼CU10(Fe,Zn)2(Sb,As)4S13} and bournonite-seligmannite solid solutions {CuPb(Sb,As)S3} (400°C evacuated silica tubes, NH4Cl flux) indicate that the maximum nonidealities associated with the As-Sb substitution are about 165 (bournonite) and 250 (fahlore) cal/gfw on a per atom exchange basis. The experimental constraints are consistent with the following calibration of the As-Sb exchange reaction between these phases:where kcal/gfw, X2 = Zn/(Zn + Fe) (or one-half the number of Zn atoms/formula unit) and X3 = As/(As + Sb) refer to atomic ratios in fahlore, and ΔG°23 = ΔH°23 = 2.59 ± 0.14 kcal/gfw (Raabe and Sack, 1984; Sack and Loucks, 1975; O'Leary and Sack, 1987; Sack, 1992).

Huai Kham On gold deposit is located within the Lampang-Phrae volcanic beltof the Sukhothai Fold Belt in northern Thailand. The gold deposit is hosted byTriassic andesitic tuff and intercalated rhyolitic welded tuff. The host sequenceis overlain by sedimentary sequences including Triassic calcareous sandstoneof the Wang Chin Formation and Middle Triassic limestone of the Kang PlaFormation.Gold nuggets and electrum werefound in quartz-richveins with associatedpyrite,chalcopyrite, galena and bournonite cutting across the andesitic tuff andunderlying rhyolitic tuff.Sulfur isotope analyses indicate that the gold-ore forming fluids vary insulfur isotopic values from

The Abakaliki lead-zinc deposit in the lower Benue Trough (Nigeria) represents the largest of a series of fracture controlled base metal deposits within the Lower Cretaceous (Albian) Asu River Group shales. Field evidence, ore microscopy and electron microprobe analysis of the lodes, suggest that the vein mineralization commenced with pre-ore precipitation of diagenetic marcasite, pyrite and minor gel-like colloform textured schalenblende and galena especially at the vein/wall rock contacts. This was succeeded by an ore stage consisting mainly of sphalerite, galena, chalcopyrite and pyrite. Accessories include bournonite and boulangerite. There was also a later introduction of complex intergrowths comprising bornite, chalcocite, enargite, and tennantite. In addition a lead/iron bearing copper sulphide and a copper bismuth sulphide of wittichenite composition (Cu6Bi2SO6), the optical parameters of which do not agree with those of wittichenite, were also introduced. The late stage copper sulphides and sulphosalts were formed as replacements of earlier lower temperature (ca. 170°C) main phase mineralization, when temperature rose in minimum up to 230°C.

In vein material from the abandoned copper mine at Dhurode, County Cork, Republic of Ireland, the sulphosalt meneghinite is partly replaced by later minerals, notably a symplectite of galena and bournonite. Mineral analyses and proportions indicate that the bulk Pb/Sb ratio in the symplectite is almost identical to that of the meneghinite. It is inferred that Pb and Sb were the relatively immobile elements whose short-range segregation controlled the scale of symplectite intergrowth, during a diffusive replacement reaction in which Cu and S were added from the vein-forming fluid. This is the second sulphosalt-bearing symplectite for which immobile elements have been identified. In both cases, the inferred replacement reaction causes a volume increase, approximately 15% in the present example.

Prestea Goldfields occurs in the Precambrian Upper Birimian series which is represented by northeasterly dipping phyllites, metatuffs, metagreywackes and carbonaceous phyllites. The mineralized zone is made up of three channels, namely; the main reef channel, the west reef channel, and the ‘B’ or east reef channel. The ore bodies are localized in these three channels. The occurrence of tectonic movements has resulted in the formation of extensive fault gouges along one or both contacts of the reef and wall rocks, but in places, the fault gouges cut through the reef. Wall rock alteration occurs in the form of pyritization, arsenopyritization, sericitization, chloritization, silicification, and carbonatization. The most abundant ore minerals are pyrite and arsenopyrite, each making up 20–30% of all the ore minerals. Gold is commonly associated with bournonite and bonanza ores are associated with mariposite. This paper analyses the present method of exploration. Initial drilling into the footwall has shown good values in the metavolcanic rocks.

This report deals with a general reexamination of the systematics of sulfosalts. It represents an update of the activity of the Sulfosalt Sub-Committee within the Commission on Ore Mineralogy of the International Mineralogical Association, in connection with the Commission on New Minerals, Nomenclature and Classification (CNMNC-IMA). Part I presents generali- ties of sulfosalt definition and nomenclature. After an extended chemical definition of sulfosalts, attention is focused on "classic" sulfosalts with As 3+ ,S b 3+ ,B i 3+ or Te 4+ as cations, corresponding to the general formula (Me + , Me' 2+ , etc.)x ((Bi, Sb, As) 3+ , Te 4+ )y ((S, Se, Te) 2− )z (Me, Me': various metals). General aspects of their chemistry and classification principles are summarized, especially with regard to chemical substitutions and modular analysis of complex crystal structures. On this basis, Part II presents a review of sulfosalt systematics. Six main crystal-chemical sub-groups are distinguished (plus some unclassified species), con- cerning more than 220 valid mineral species. Among others whose status is questioned are those considered to be varieties of well-defined species; minerals with ill-defined X-ray data; those that are possibly identical species; and those that represent the potential revalidation of old species. More than 50 crystal structures still remain unsolved, among which about a half probably corresponds to new structure types.

Native gold, in association with tetrahedrite, bournonite, bismuthian jamesonite, antimonian bismuth, chalcopyrite, sphalerite, gersdorffite, galena, covelline, yarrowite and acanthite occurs in a NW-SE trending quartz carbonate vein which cuts folded Lower Devonian slates of the Meadfoot Group. The locality, 2.5 km north of the village of Loddiswell, lies in a belt of Devonian thrust and nappe terrain with a roughly E-W trend. The host-rocks are muddy turbiditic sediments interbedded with spilitic lavas, keratophyres and tuffs, together with intrusive dolerites (greenstones) which were deformed together during the Variscan orogeny. The deposit was worked briefly in the nineteenth century but little ore was raised and it is doubtful whether any gold was recovered. Analysis of samples collected in the present study revealed gold values of 5-10 ppm and silver values of 1000-2000 ppm. The relationship between gold-antimony mineralization, the basic igneous rocks in the nappe sequence, and their intersection by a series of major NW-SE fracture zones is discussed in the context of the regional metallogenic evolution of SW England. The mineralization is considered to be the result of fluid extraction during shear movements on the NW-SE structures and shows features in common with mesothermal gold-bearing sulphide veins in other Palaeozoic provinces.

This paper summarizes macrostructures of individual ore bodies, mineral assemblages, mineralization stages, and oxygen isotopic data for quartz from veins and wall rock for copper-lead-zinc mineralization at the Hayakawa and Shakako deposits. Chalcopyrite-pyrite-tetrahedrite-galena-sphalerite-bearing quartz veins (Cu-Pb-Zn quartz veins) and galena-sphalerite-bearing quartz veins (Pb-Zn quartz veins) occur at the Hayakawa and Shakako deposits. The Cu-Pb-Zn quartz veins formed earlier than the Pb-Zn quartz veins. The minerals in the Cu-Pb-Zn quartz veins include chalcopyrite, pyrite, tetrahedrite-tennantite, galena, sphalerite, enargite, bournonite, semseyite, hessite, kesterite, arsenosulvanite, Cu-Fe-Zn-Sn-S mineral, tetradymite, aikinite, quartz and apatite. The minerals in the Pb-Zn quartz veins are galena, sphalerite, pyrite, chalcopyrite, tetrahedrite, electrum and quartz. FeS content of sphalerite decreases from the earlier to later stages of mineralization. Distinct compositional heterogeneity between Sb and As is recognized within a grain of tetrahedrite-tennantite. The δ18O values for quartz in Cu-Pb-Zn quartz veins at the Hayakawa deposit range from 1.4 to 3.1 per mil. The value for quartz in Cu-Pb-Zn-quartz veins at the Shakako deposit is 1.9 per mil. The calculated δ18O values (-10.1 to -3.3 per mil) of ore fluids responsible for the formation of the Hayakawa deposit are lower than sea water and primary magmatic water. Therefore, we suggest that Cu-Pb-Zn quartz veins of the Hayakawa and Shakako deposits originated from ore fluids of meteoric water under a subvolcanic environment.

The Sierra Almagrera vein-type mineralization contains base metal sulphides and Pb-Sb- Cu-Ag sulphosalts. The sulphides possess significant proportions of Ag, Sb (galena), Fe (sphalerite) and Sb, Zn (chalcopyrite). Ore microscopy and electron microprobe have revealed a mineralogical and textural variation and confirmed the presence of bournonite, boulangerite and anomalous tetrahedrite. The average sulphosalt formulas are bournonite Cu 0.98 Pb 0. 96 Sb 0.98 S 3.04 , boulangerite Pb 4.8 Sb 3.8 S 11.34 and anomalous tetrahedrite Ag 0.6 Cu 9.7 Zn 3.6 Fe 0. 44 Sb 3.47 S 13- The sequence of mineral deposition indicates the existance of four mineralizing stages and one supergene alteration: 1) Fe-(As); 2) Zn-Cu-Fe; 3) Pb-Sb-Cu-Ag; 4) Cu-Zn-Fe, and 5) carbonates, sulphates and supergene oxides. In broad terms, it is possible to establish the following conclusions: a) there exist a mineralogical and textural variation with depth, the Pb-Sb-Cu-Ag stage reaching the maximum development; b) a temperature decrease during the formation of sph. 1, linked to the progressive increase in Fe-content of the sphalerite has been detected; c) the compositional homogeneity of the bournonite (and the fair lack of As in the tetrahedrite) could indicate the existance of a possible tendancy to individually crystallise the Sb and As sulphosalts, according to the trend Bi → Sb → As.

The gold-bearing veins from the Piririca region, Ribeira Valley, State of Sao Paulo, Brazil, show epigenetic features and seem to be mainly related to a ductile-brittle shear zone, subordinate to the Agudos Grandes and Ribeira regional tectonic lineaments. Stratigraphically, presents the area a sequence of metavolcano-sedimentary rocks with associated metabasic rocks, characterized by low-grade metamorphism. These rocks are correlated with the Middle Proterozoic Perau Formation. Within the veins, pyrite and arsenopyrite are the most abundant sulphide minerais, with the following minerais having been detected in subordinate quantities: chalcopyrite, boulangerite, bournonite, jamesonite, tetrahedrite, sphalerite, galena, bornite, ilmenite and gold. Milky quartz is the dominat gangue. In the tentative preliminary paragenetic sequence proposed here, coarsegrained pyrite, arsenopyrite and ilmenite are considered as representing the first phase of sulphide deposition and have been affected by a brecciation/mylonitization deformation episode. The other minerais mentioned above represent a post-def ormation phase that occurs in veinlets and fractures, cutting crystals of pyrite and arsenopyrite

Analytical formulation of the phase equilibrium relationship between two sets of representative mineral assemblages (Fe-Zn tetrahedrite ss + sphalerite + pyrite + chalcopyrite and tennantite ss + bournonite ss + galena + boulangerite) from two distinct ore facies of different generations within the same ore deposit at Rajpura-Dariba, India, has been attempted through the Gibbs method. Textural studies and element-partitioning data between coexisting mineral pairs point to a close approach to chemical equilibrium in both the assemblages. There is a marked nonideality in both the mineral systems and the element distribution patterns follow a modified Nernst law.The algebraic approach, comprising a solution of a system of linear equations in matrix form and the relating of mineral compositions to various intensive thermodynamic variables, generates only semischematic mu (sub S 2 ) -T-X i diagrams. This is due to constraints imposed by some simplified assumptions and inadequacies of some input data. Nevertheless, several significant conclusions emerge:1. The Fe-Zn tetrahedrite ss + sphalerite (+pyrite + chalcopyrite) assemblage belonging to the system Cu 2 S-FeS-ZnS-Sb 2 S 3 -S 2 provides a reliable mu (sub S 2 ) and/or T sensor due to steep intersections of compositional isopleths of tetrahedrite ss and sphalerite in mu (sub S 2 ) -T space, provided the Ag concentration in tetrahedrite ss is ignored. In contrast, the assemblage tennantite ss + bournonite ss (+galena + boulangerite) is of little use as an environmental sensor, due to the very low angle intersection of As isopleths of tennantite ss and bournonite ss .2. Near-vertical disposition of analytical data points on the mu (sub S 2 ) -T diagram for the tetrahedrite ss + sphalerite system indicates a virtually constant temperature and variable mu (sub S 2 ) condition for equilibration--a situation expected in metamorphosed sulfide deposits.3. The As partition ratio between tennantite ss and bournonite ss was found to be a linear function of the ratio (dmu (sub S 2 ) /dmu (sub A s ) ) (sub P.T) . This linear dependence is interpreted to be the manifestation of an interactive control of chemical potentials of the two ambient species (S 2 and As) over mineral composition under isothermal-isobaric conditions. The alternative possibility, of the chemical potentials of the ambient species being controlled by the mineral composition on an extensive scale, can be ruled out due to the low concentration of the mineral species in the orebody as a whole--although such a situation may be possible on a microenvironmental scale.

Radioisotopes of technetium and iodine, elements that are present in reactor wastes, are strongly sorbed (100 ≲ KD ≲ 2000) from aqueous solutions by several naturally occurring minerals (bournonite...

In the Janggun lead-zinc-silver ores, bournonite occurs as anhedral grains up to 2mm long, closely associated with galena, minerals of the tetrahedrite-freibergite series, boulangerite, sphalerite, pyrite and rhodochrosite. The bournonite, though minor or trace in amount, tends to occur in the peripheries of the ore pipe. In reflected light, it is light greyish white in colour with greenish tints and exhibits weak bireflectance and distinct anisotropism without any internal reflections. Occasionally, lamellar twinning on {110} plane may be observed. Reflectance: Rmax=37.5, Rmin=33.8 percent at a light with wavelength of 580 nm, and VHN: 175-198kg/mm2 at a 50-g load. The chemical composition on the average from 15 spot analyses by electron microprobe for 5 grains is, Pb 43.3, Sb 24.4, Zn 0.0, Cu 12.9, S 19.7, sum 100.3 (all in weight percent); the corresponding empirical formula on the basis of S=3 is, Cu1.00 Pb1.03 Sb0.99 S3, which is close to the ideal formula CuPbSbS3. The strongest reflections on the X-ray diffraction patterns are; 3.90 A (8) (002), 2.97 A (4) (220), 2.73 A (10) (130), 2.67 A (4) (212), 2.59 A (5) (310), 1.766 A (6) (332), the patterns are identical with those of literature, and in harmony with the space group _??_-Pn 21m. This mineral is considered to have been formed at the latest stage of hydrothermal lead-zinc-silver mineralization. At the beginning of this paper, geologic environments of the ore deposits are briefly described.

Antimony has long been reckoned as a strategic metal. It is used today not only in metallic form, e.g. as an alloying element in lead, but also to an increasing extent in the form of Sb2O3 as a flame retardant filler in plastics. The mineral raw material that provides nearly all the world's supply of antimony is stibnite, Sb2S3. The flotation properties of this mineral are fairly well established. Its crystal structure makes its floatability depend on which surfaces of the mineral are exposed by grinding. Factors of pulp chemistry, however — especially the pH of the pulp — seem to have a more decisive influence on the result of flotation. At about pH 4–5, stibnite floats spontaneously with acceptable recovery, and with collectors it floats very well. Activation with metal salt is needed at neutral pH, while floatability is seriously impaired at pH 10. The beneficiation properties of other antimony minerals have been very little studied. Antimony oxides, pure antimony and jamesonite, Pb4FeSb6S14, are also recovered as values in addition to stibnite. Antimony oxides respond very poorly to flotation with xanthate collectors. The flotation properties of jamesonite are more akin to galena than to stibnite, and this mineral floats best at around natural pH without activation. The high antimony content of some very complex sulphide ores is a problem in beneficiation, giving concentrates heavily contaminated with antimony minerals which, if they cannot be separated, increase the cost of smelting. These impurities can be grouped according to their beneficiation properties: Lead-antimony sulphides jamenosite, Pb4FeSb6S14 boulangerite, Pb5Sb4S11 Lead-antimony-copper sulphide bournonite, CuPbSbS3 Ferrous antimony sulphides gudmundite, FeSbS berthierite, FeSb2S4 The flotation properties of the lead-antimony minerals grow more like those of galena the higher they grade in lead. Bournonite, a fairly common mineral in complex sulphide ores, floats well in process environments where chalcopyrite normally floats; in many cases this makes it impossible to separate from chalcopyrite. Initial studied have indicated that the ferrous antimony minerals have properties resembling those of pyrite and pyrrhotite.

The Driggith vein is representative of the lead-zinc mineralization in the Caldbeck Fells area, with a primary mineral assemblage consisting of quartz, baryte, calcite, chalcedony, pyrite, arsenopyrite, galena, sphalerire, bournonite, argentian tetrahedrite, and native antimony. Broadly similar assemblages are found in Pb-Zn mineralization of Upper Devonian to Permian age else-where in the Lake District. The paragenetic sequence appears to have been early pyrite and minor arsenopyrite associated with quartz; with later baryte, calcite, sphalerite, and chalcopyrite enclosed by galena. Within the galena occur inclusions of tetrahedrite, bournonite, and native antimony. A later stage of baryte mineralization was followed by the alteration of primary sulphides to secondary minerals. Elsewhere in the Lake District, galena occurring in this association also contains inclusions of native antimony, bournonite, and other sulphosalts, and in this respect differs from galena associated with earlier veins composed dominantly of chalcopyrite, pyrite, and arsenopyrite. The inclusions make a major contribution to the high antimony values reported in trace element analyses of galena from the Lake District. The occurrence of these inclusions, which in some cases display preferred orientation within the host galena, is discussed in terms of phase relations involving PbS and AgSbS2.

The recently discovered Salgadinho copper deposit, 7 km NNE of S. Luis, Portugal is located in the southernmost linear belt of outcropping low metamorphic grade deformed Palaeozoic rocks (Famennian) in the SW part of the Iberian Pyrite Belt. The stratabound replacement pyrite-chalcopyrite mineralisation is present in variably altered felsic pyroclastic rocks which are overlain by pyritic graphitic shales and tuffs which have undergone alteration in the lowermost 5m. The altered pyroclastic rocks are characterised by pale green celadonitic fluoro-muscovite and, in the most intense zone of alteration, quartz, ankerite, and ore minerals are present (pyrite, chalcopyrite, sphalerite, tetrahedrite, galena, bournonite). No exhalative Cu-Zn or Zn-Pb ore has been discovered associated with the submarine volcanic stratabound Cu-rich alteration zone. Alteration of feldspars and groundmass has involved a net loss from the system and gains in Fe2+, F, H2O, Mg, Fe3+, Ca, Mn, P, Ti, S, Cu, Zn, Pb, As, Sb, Ag and Au at the expense of Si, K, Al and Na. The great enrichment of F in the altered rocks, the association of zonal alteration facies with coarse grained pyroclastic masses and the intimate association of pale green celadonitic fluoro-muscovite with mineralisation at Salgadinho and most other deposits of the Iberian Pyrite Belt represents a powerful exploration guide for submarine exhalative ores.

Leadzinccopper mineralization in the lower Benue Trough of Nigeria occurs as discordant fracture controlled veins within the Lower Cretaceous shales of the Asu River Group. Three stages of events are proposed for the evolution of the veins in this district: 1. (i) pre-ore fracturing and brecciation of Albian shales accompanied by the precipitation of framboidal and colloform aggregates of pyrite, siderite and quartz; 2. (ii) ore stage formation of sphalerite, galena, copper bearing minerals (e.g. chalcopyrite, bornite, chalcosite, wittichenite and digenite) tetrahedrite, bournonite and boulangerite; and 3. (iii) final deposition of octahedral galena, sphalerite, bravoite and marcasite in the hanging wall of the veins. Quartz precipitation appears to be at several stages although a large amount of quartz accompanied the ore stage sulphide precipitation. A mineralogical zoning from a prite-galena-sphalerite rich top, to chalcopyrite rich base is shown by the larger veins in the district. Post ore oxidation and lateritic weathering of primary vein constituents led to the supergene enrichments of limonite, cerrusite, smithsonite, malachite and azurite which are sometimes preserved with the primary minerals. These mineralogical associations, compositions of the ore and gangue minerals, and the previusly reported temperatures of vein minerals are compatible with those of ore deposits formed from basinal brines. The mineralization is considered to be epigenetic and vein formation appears to have accompanied the Cenomanian tectonic event in the Benue basin.

The Blazna-Guset mining area is located in the Rodna Mountains, Eastern Carpathians, North Romania. It is mostly covered by the metamorphic rocks of the Rebra Series (Upper Precambrian; K/Ar dating gave 800 m.y.). The middle part of this series — called the Carbonate Formation — contains lead-zinc pyrite ores hosted by prevailingly carbonate rocks. The ores form flat and thin lenses occurring together with fine intercalations of silicate-, graphite- and quartz-bearing rocks within the calcite-dominated limestones. Pyrite, ironpoor sphalerite and galena are the main ore minerals. Chalcopyrite, pyrrhotite and magnetite also occur in small amounts. Within the highly deformed and partly recrystallized parts of the ore bodies bournonite, arsenopyrite and pearceitepolybasite were locally encountered. Ba, Ti and Mn are the most significant ore-accompanying elements.