Search

This paper describes the nitric acid dissolution process of natural minerals such as ten-nantite, chalcopyrite and sphalerite, with the addition of Fe (III) ions and FeS2. These minerals are typical for the ores of the Ural deposits. The effect of temperature, nitric acid concentration, time, additions of Fe (III) ions and FeS2 was studied. The highest dissolution degree of sulfide minerals (more than 90%) was observed at a nitric acid concentration of 6 mol/dm3, an experiment time of 60 min, a temperature of 80 °C, a concentration of Fe (III) ions of 16.5 g/dm3, and an addition of FeS2 to the total mass minerals at 1.2:1 ratio. The most significant factors in the break-down of minerals were the nitric acid concentration, the concentration of Fe (III) ions and the amount of FeS2. Simultaneous addition of Fe (III) ions and FeS2 had the greatest effect on the leaching process. It was also estab-lished that FeS2 can be an alternative catalytic surface for copper sulfide minerals during nitric acid leaching. This helps to reduce the influence of the passivation layer of elemental sulfur due to the galvanic linkage formed between the minerals, which was confirmed by SEM-EDX. © 2022 by the author. Licensee MDPI, Basel, Switzerland.

Polymetallic veins (Pb-Zn-Cu-Ag-Au) at the world-class Bingham Canyon, Utah, porphyry Cu-Au-Mo deposit have long been recognised, but poorly understood. They are laterally zoned outward from the centre of the porphyry deposit transitioning from Fe-Cu to Pb-Zn-Cu-Ag-Au mineralisation. Physical and chemical characterisation of these polymetallic veins provide insight into the origin, timing, and controls of ore deposition. These sheared, sulphide-rich, NE/SW- trending veins are dominated by pyrite and multiple generations of quartz, with lesser amounts of other sulphide and gangue minerals. Gold (0.27–4.61 ppm) provides the most value to the ore, though the veins contain substantial Cu and Ag as well. Host rocks include Eocene monzonite and Palaeozoic limestone and quartzite, which contain economic ore lodes. Significant hosts of Ag include galena and tennantite, and Cu is hosted primarily in chalcopyrite, tennantite, and sphalerite. The main host of Au could not be determined, but Au could be focused along fractures or hosted in inclusions found in pyrite. The 34S values of vein pyrite have a narrow range suggestive of a magmatic source. Ore grades (Cu, Ag, Au) improve with distance from the centre of the porphyry deposit; however, this is accompanied by higher concentrations of deleterious elements (Pb, As, Bi) for downstream processing. These polymetallic veins were created sequentially throughout the formation of the deposit. Vein mineralisation appears to postdate all intrusions and the porphyry Cu-Au mineralisation; however, it may be related to the late fluids responsible for Mo mineralisation in the main porphyry orebody., Polymetallic veins (Pb-Zn-Cu-Ag-Au) at the world-class Bingham Canyon, Utah, porphyry Cu-Au-Mo deposit have long been recognised, but poorly understood. They are laterally zoned outward from the centre of the porphyry deposit transitioning from Fe-Cu to Pb-Zn-Cu-Ag-Au mineralisation. Physical and chemical characterisation of these polymetallic veins provide insight into the origin, timing, and controls of ore deposition. These sheared, sulphide-rich, NE/SW- trending veins are dominated by pyrite and multiple generations of quartz, with lesser amounts of other sulphide and gangue minerals. Gold (0.27–4.61 ppm) provides the most value to the ore, though the veins contain substantial Cu and Ag as well. Host rocks include Eocene monzonite and Palaeozoic limestone and quartzite, which contain economic ore lodes. Significant hosts of Ag include galena and tennantite, and Cu is hosted primarily in chalcopyrite, tennantite, and sphalerite. The main host of Au could not be determined, but Au could be focused along fractures or hosted in inclusions found in pyrite. The 34S values of vein pyrite have a narrow range suggestive of a magmatic source. Ore grades (Cu, Ag, Au) improve with distance from the centre of the porphyry deposit; however, this is accompanied by higher concentrations of deleterious elements (Pb, As, Bi) for downstream processing. These polymetallic veins were created sequentially throughout the formation of the deposit. Vein mineralisation appears to postdate all intrusions and the porphyry Cu-Au mineralisation; however, it may be related to the late fluids responsible for Mo mineralisation in the main porphyry orebody.

Luzonite, partially replaced by tennantite, was identified in dump specimens from the historic Levant Mine, west Cornwall, in a paragenetic sequence comprising early cassiterite–quartz–pyrite–arsenopyrite overprinted by Cu–Fe sulphides and followed by luzonite and tennantite. Mineral chemical data indicates that luzonite is a near-end member and tennantite is so-called Cu-excess tennantite, the implication being its Fe content (2.01–4.04 at.%) is present entirely as Fe3+ in the sulphide lattice. Both luzonite and its replacement product, Cu-excess tennantite, indicate that at least one hydrothermal episode in the long-lived Levant mineralising system involved influx of oxidised, high-intermediate sulphidation fluids. The presence of fine bornite and covellite lamellae in Cu-excess tennantite are interpreted to be post-depositional exsolution products. Luzonite has a sulphur isotope 34S of 0 ± 0.3 per mille and it is tentatively proposed that the luzonite–tennantite depositing event represented a pulse of essentially pure magmatic-hydrothermal fluid., Luzonite, partially replaced by tennantite, was identified in dump specimens from the historic Levant Mine, west Cornwall, in a paragenetic sequence comprising early cassiterite–quartz–pyrite–arsenopyrite overprinted by Cu–Fe sulphides and followed by luzonite and tennantite. Mineral chemical data indicates that luzonite is a near-end member and tennantite is so-called Cu-excess tennantite, the implication being its Fe content (2.01–4.04 at.%) is present entirely as Fe3+ in the sulphide lattice. Both luzonite and its replacement product, Cu-excess tennantite, indicate that at least one hydrothermal episode in the long-lived Levant mineralising system involved influx of oxidised, high-intermediate sulphidation fluids. The presence of fine bornite and covellite lamellae in Cu-excess tennantite are interpreted to be post-depositional exsolution products. Luzonite has a sulphur isotope 34S of 0 ± 0.3 per mille and it is tentatively proposed that the luzonite–tennantite depositing event represented a pulse of essentially pure magmatic-hydrothermal fluid.

The common twinning of tetrahedrite and tennantite can be described as an order-disorder (OD) phenomenon. The unit OD layer is a one-tetrahedron-thick (111) layer composed of six-member rings of tetrahedra, with gaps between them filled with Sb(As) coordination pyramids and triangular-coordinated (Cu, Ag). The stacking sequence of six-member rings is ABCABC, which can also be expressed as a sequence of three consecutive tetrahedron configurations, named alpha, beta, and gamma. When the orientation of component tetrahedra is uniform, the alpha, beta, gamma, alpha sequence builds the familiar cage structure of tetrahedrite. However, when the tetrahedra of the beta layer are rotated by 180 degrees against those in the underlying alpha configurations and/or when a rotated alpha configuration follows after the beta configuration (instead of gamma), twinning is generated. If repeated, this could generate the ABAB sequence which would modify the structure considerably. If the rest of the structure grows as a regular cubic tetrahedrite structure, the single occurrence of the described defect sequences creates a twin.

The common twinning of tetrahedrite and tennantite can be described as an order-disorder (OD) phenomenon. The unit OD layer is a one-tetrahedron-thick (111) layer composed of six-member rings of tetrahedra, with gaps between them filled with Sb(As) coordination pyramids and triangular-coordinated (Cu, Ag). The stacking sequence of six-member rings is ABCABC, which can also be expressed as a sequence of three consecutive tetrahedron configurations, named alpha, beta, and gamma. When the orientation of component tetrahedra is uniform, the alpha, beta, gamma, alpha sequence builds the familiar cage structure of tetrahedrite. However, when the tetrahedra of the beta layer are rotated by 180 degrees against those in the underlying alpha configurations and/or when a rotated alpha configuration follows after the beta configuration (instead of gamma), twinning is generated. If repeated, this could generate the ABAB sequence which would modify the structure considerably. If the rest of the structure grows as a regular cubic tetrahedrite structure, the single occurrence of the described defect sequences creates a twin.

The Tsumeb base-metal deposit in NE Namibia contained one of the most diverse examples of mineralogical paragenesis ever observed within a single mineral deposit. From approximately 307 minerals in total, arsenic minerals show the greatest diversity: 63 arsenates, 6 arsenites and 7 arseno-sulphates. Arsenic content was around 1% in the ore zone and intermittently produced as a by-product (white As oxide). Mineralisation is hosted in the Otavi dolomite. Due to the karstic nature of the host dolomite, there has been considerable water flow through the deposit, even during mining. There are strong geochemical relationships observed in the current mine water chemistry and the existing secondary mineral assemblage, which started with oxidation of sulphide minerals, such as tennantite, that generated not only metal ions but also protons that reduced groundwater pH. The resulting acidity was quickly neutralised in dolomite and secondary minerals were deposited in response to changes in solution chemistry. Assessment of current mine waters provides limited insight into the relative stability of the minerals. It appears that metal and As activity have decreased over time in water contacting the oxidised sulphide deposit. The general trend of increasing acidity in the environment since the Cretaceous may explain the higher Cl content of the mine waters but this is by no means certain., The Tsumeb base-metal deposit in NE Namibia contained one of the most diverse examples of mineralogical paragenesis ever observed within a single mineral deposit. From approximately 307 minerals in total, arsenic minerals show the greatest diversity: 63 arsenates, 6 arsenites and 7 arseno-sulphates. Arsenic content was around 1% in the ore zone and intermittently produced as a by-product (white As oxide). Mineralisation is hosted in the Otavi dolomite. Due to the karstic nature of the host dolomite, there has been considerable water flow through the deposit, even during mining. There are strong geochemical relationships observed in the current mine water chemistry and the existing secondary mineral assemblage, which started with oxidation of sulphide minerals, such as tennantite, that generated not only metal ions but also protons that reduced groundwater pH. The resulting acidity was quickly neutralised in dolomite and secondary minerals were deposited in response to changes in solution chemistry. Assessment of current mine waters provides limited insight into the relative stability of the minerals. It appears that metal and As activity have decreased over time in water contacting the oxidised sulphide deposit. The general trend of increasing acidity in the environment since the Cretaceous may explain the higher Cl content of the mine waters but this is by no means certain.

A comprehensive flotation survey was carried out at the Northparkes Cu-Au mine, New South Wales, Australia, in 2012 to allow mass balancing and to evaluate the operation of the flotation circuit. A rudimentary Cu only unsized flotation simulator was developed to evaluate the potential for optimisation, and in 2013 the model was expanded to produce a mineral-based flotability component model to estimate the effect of future concentrator feed source on metallurgical performance. The simulator incorporated the flash flotation circuit and also a Jameson cell flotability model, and allowed various circuit configurations to be simulated to provide a blueprint for long-term planning. Statistical analysis was carried out on the sets of simulation and survey results. After calibration the simulator produced an absolute variance of 0.83% for Cu recovery and 2.83% for concentrate grade between simulated and actual plant performance, and in terms of mineral performance prediction it was accurate for bornite, chalcopyrite, chalcocite and tennantite. Non-sulphide gangue showed higher variance and this was corrected with later development of a size-by-size model., A comprehensive flotation survey was carried out at the Northparkes Cu-Au mine, New South Wales, Australia, in 2012 to allow mass balancing and to evaluate the operation of the flotation circuit. A rudimentary Cu only unsized flotation simulator was developed to evaluate the potential for optimisation, and in 2013 the model was expanded to produce a mineral-based flotability component model to estimate the effect of future concentrator feed source on metallurgical performance. The simulator incorporated the flash flotation circuit and also a Jameson cell flotability model, and allowed various circuit configurations to be simulated to provide a blueprint for long-term planning. Statistical analysis was carried out on the sets of simulation and survey results. After calibration the simulator produced an absolute variance of 0.83% for Cu recovery and 2.83% for concentrate grade between simulated and actual plant performance, and in terms of mineral performance prediction it was accurate for bornite, chalcopyrite, chalcocite and tennantite. Non-sulphide gangue showed higher variance and this was corrected with later development of a size-by-size model.

Flotation studies have been carried out on the use of sodium thiosulphate and oxidation using oxygen for single minerals (chalcopyrite and tennantite) and arseno-copper ore. Zeta potential, XPS, contact angle, and flotability of single minerals were conducted for each treatment. It was shown that the separation is best conducted in alkaline conditions where there will be interaction between thiosulphate and the mineral surface as well as the formation of hydroxide species during the oxidation. Zeta potentials of both thiosulphate and oxidation conditioning showed that the reactivity of tennantite is much higher than chalcopyrite, resulting in a higher rate of depression on both techniques as shown from contact angle and floatability of each mineral after treatment. XPS spectra confirmed qualitatively and quantitatively the existence of species responsible for the depression of each conditioning techniques. Oxidation for 60 minutes gave the best results in the copper ore flotation tests., Flotation studies have been carried out on the use of sodium thiosulphate and oxidation using oxygen for single minerals (chalcopyrite and tennantite) and arseno-copper ore. Zeta potential, XPS, contact angle, and flotability of single minerals were conducted for each treatment. It was shown that the separation is best conducted in alkaline conditions where there will be interaction between thiosulphate and the mineral surface as well as the formation of hydroxide species during the oxidation. Zeta potentials of both thiosulphate and oxidation conditioning showed that the reactivity of tennantite is much higher than chalcopyrite, resulting in a higher rate of depression on both techniques as shown from contact angle and floatability of each mineral after treatment. XPS spectra confirmed qualitatively and quantitatively the existence of species responsible for the depression of each conditioning techniques. Oxidation for 60 minutes gave the best results in the copper ore flotation tests.

Copper sulphides are often found in association with As-bearing Cu minerals such as enargite and tennantite, particularly during the development of deep Cu deposits. Arsenite is highly toxic to biological systems and its effective immobilisation from refinery waste water is an important process. The use of Acidianus brierleyi, was investigated for the oxidation and immobilisation of arsenite from industrial refining waste water containing up to several g/l of As, mainly in the form of As(III), and up to 10 g/l of Fe(II) with pH values in the range 1-2 and temperatures of 50-80 degrees C. Some As(III) oxidation was observed in all A. brierleyi cultures independent of the presence of Fe(II) when the initial As(III) concentration was 500 ppm. The As(III) oxidation rate was maximised by using an initial Fe(II) concentration of 1 000 ppm, which allowed effective As-immobilisation as amorphous ferric arsenate. Initial addition of 1 000 ppm Fe(III) did not have the same effect as Fe(II), indicating the importance of the microbial production of Fe(III) in maximising the As(III) oxidation rate. The mechanism proposed for simultaneous As(III) oxidation and immobilisation involves As(III) oxidation by A. brierleyi cells independently of the presence of Fe, and coupling of As(III) oxidation with Fe(III) reduction within the extracellular polymeric substance region when a certain Fe(IIII) content is achieved. The reaction mechanism is affected by the presence of jarosite, and optimising the initial Fe(II) concentration is critical for maximising the As(III) oxidation rate to enable selective formation of amorphous ferric arsenate., Copper sulphides are often found in association with As-bearing Cu minerals such as enargite and tennantite, particularly during the development of deep Cu deposits. Arsenite is highly toxic to biological systems and its effective immobilisation from refinery waste water is an important process. The use of Acidianus brierleyi, was investigated for the oxidation and immobilisation of arsenite from industrial refining waste water containing up to several g/l of As, mainly in the form of As(III), and up to 10 g/l of Fe(II) with pH values in the range 1-2 and temperatures of 50-80 degrees C. Some As(III) oxidation was observed in all A. brierleyi cultures independent of the presence of Fe(II) when the initial As(III) concentration was 500 ppm. The As(III) oxidation rate was maximised by using an initial Fe(II) concentration of 1 000 ppm, which allowed effective As-immobilisation as amorphous ferric arsenate. Initial addition of 1 000 ppm Fe(III) did not have the same effect as Fe(II), indicating the importance of the microbial production of Fe(III) in maximising the As(III) oxidation rate. The mechanism proposed for simultaneous As(III) oxidation and immobilisation involves As(III) oxidation by A. brierleyi cells independently of the presence of Fe, and coupling of As(III) oxidation with Fe(III) reduction within the extracellular polymeric substance region when a certain Fe(IIII) content is achieved. The reaction mechanism is affected by the presence of jarosite, and optimising the initial Fe(II) concentration is critical for maximising the As(III) oxidation rate to enable selective formation of amorphous ferric arsenate.

Two series of flotation tests that were conducted investigating potential routes for the Rosebery mine in Tasmania to produce low-As copper concentrate. Arsenopyrite (FeAsS) is the predominant As-containing mineral but tennantite (Cu12As4S13), present to a lesser degree, reports through to Cu concentrate and has resulted in a product containing up to 8 000 ppm As when As levels above 5 000 ppm can preclude import to some customer countries. Tennantite is present as the As-rich end of a solid solution series with tetrahedrite (Cu12Sb4S13). The presence of the As-Ag mineral freibergite (Ag12As4S3) complicates As reduction strategies as silver represents a significant source of credits from copper concentrate sales. A low-cost method was sought whereby the As content of Cu concentrate could be reduced whilst retaining the Ag values. The first test series investigated the effect of pulp potential on the recovery of Cu, Ag and As minerals; the second investigated the effect of pH, froth depth and regrind. It was concluded that Cu sulphosalts provided the bulk of As in Cu concentrate, despite the abundance of arsenopyrite in the mill feed stream. Depression of these minerals will, however, reduce the Ag content of Cu concentrate. Further depression of arsenopyrite will reduce the amount of As in Cu concentrate, retain Ag values and may ultimately prove to be the most cost-effective solution in this case. Pulp potential control proved to be non-reproducible and hence will most likely be an ineffective means of controlling the As content of Rosebery Cu concentrates, whereas pH control provided the most effective means but resulted in a loss of Cu., Two series of flotation tests that were conducted investigating potential routes for the Rosebery mine in Tasmania to produce low-As copper concentrate. Arsenopyrite (FeAsS) is the predominant As-containing mineral but tennantite (Cu12As4S13), present to a lesser degree, reports through to Cu concentrate and has resulted in a product containing up to 8 000 ppm As when As levels above 5 000 ppm can preclude import to some customer countries. Tennantite is present as the As-rich end of a solid solution series with tetrahedrite (Cu12Sb4S13). The presence of the As-Ag mineral freibergite (Ag12As4S3) complicates As reduction strategies as silver represents a significant source of credits from copper concentrate sales. A low-cost method was sought whereby the As content of Cu concentrate could be reduced whilst retaining the Ag values. The first test series investigated the effect of pulp potential on the recovery of Cu, Ag and As minerals; the second investigated the effect of pH, froth depth and regrind. It was concluded that Cu sulphosalts provided the bulk of As in Cu concentrate, despite the abundance of arsenopyrite in the mill feed stream. Depression of these minerals will, however, reduce the Ag content of Cu concentrate. Further depression of arsenopyrite will reduce the amount of As in Cu concentrate, retain Ag values and may ultimately prove to be the most cost-effective solution in this case. Pulp potential control proved to be non-reproducible and hence will most likely be an ineffective means of controlling the As content of Rosebery Cu concentrates, whereas pH control provided the most effective means but resulted in a loss of Cu.

This study aimed to construct a projection of Ag-content in the ore to be extracted in the long-term mining plan of the Andina Division. It is possible to define a global trend, using in this case chemical analysis by ICP-MS of 9 636 diamond drilling samples, geological information, mineralogy of 674 head, concentrate and tail samples, QEMSCAN, and metallurgical behaviour of Ag, and complementing it with the use of implicit modelling dynamic software facilitating the construction of 3D envelopes. The average Ag content of the studied samples is 1.5 ppm, max. 15.9 ppm, and 3 ppm for average incoming materials to process. There is a low statistical correlation with other elements, Cu (0.57) being the highest. Ag is associated with sulphosalts pearceite (60% Ag, 4% As), freibergite-argentotennantite, tennantite-tetrahedrite (18% Ag, 20% As) and polybasite (64-72% Ag). 3D modelling obtained a corresponding ore tonnage for areas with a fixed allocation of 3 ppm Ag. For validation, analysis of actual Ag grade versus prediction from the model trend was performed. To project a trend of Ag content in the deposit consistent with recent observations reporting an increased content with depth, more detailed knowledge of the geological processes and a higher sample density are required., This study aimed to construct a projection of Ag-content in the ore to be extracted in the long-term mining plan of the Andina Division. It is possible to define a global trend, using in this case chemical analysis by ICP-MS of 9 636 diamond drilling samples, geological information, mineralogy of 674 head, concentrate and tail samples, QEMSCAN, and metallurgical behaviour of Ag, and complementing it with the use of implicit modelling dynamic software facilitating the construction of 3D envelopes. The average Ag content of the studied samples is 1.5 ppm, max. 15.9 ppm, and 3 ppm for average incoming materials to process. There is a low statistical correlation with other elements, Cu (0.57) being the highest. Ag is associated with sulphosalts pearceite (60% Ag, 4% As), freibergite-argentotennantite, tennantite-tetrahedrite (18% Ag, 20% As) and polybasite (64-72% Ag). 3D modelling obtained a corresponding ore tonnage for areas with a fixed allocation of 3 ppm Ag. For validation, analysis of actual Ag grade versus prediction from the model trend was performed. To project a trend of Ag content in the deposit consistent with recent observations reporting an increased content with depth, more detailed knowledge of the geological processes and a higher sample density are required.

A technical and economic study was made of the value generated by CSIRO's newly developed process for the treatment of high arsenic copper ores, which uses flotation to separate off the arsenic-bearing minerals. Both the conventional and arsenic-removal flowsheets were modelled using the METSIM software package. Based on a series of price and consumable/labour assumptions, the study indicated that the cost of the new process was 17% higher (Aus, A technical and economic study was made of the value generated by CSIRO's newly developed process for the treatment of high arsenic copper ores, which uses flotation to separate off the arsenic-bearing minerals. Both the conventional and arsenic-removal flowsheets were modelled using the METSIM software package. Based on a series of price and consumable/labour assumptions, the study indicated that the cost of the new process was 17% higher (Aus

La Plata has preliminary estimated reserves of 840 000 t at 4.8 g/t Au, 54 g/t Ag, 4.1%t Cu, 0.7% Pb and 4.2% Zn. The deposit displays a typical VHMS vertical zonation from bottom to top of a pyrite stockwork, disseminated sulphides, massive sulphide lenses and a thin red jasper bed with exhalative-sedimentary textures. The massive sulphide lenses are located within footwall andesitic volcanic and volcaniclastic rocks that are pervasively altered to a quartz-pyrite-sericite assemblage, and immediately below a hanging-wall sequence consisting of at least two basaltic to basaltic-andesitic lava flows, each capped by autoclastic breccia intervals. The main ore minerals are pyrite, chalcopyrite, sphalerite, bornite and galena, with minor tennantite and digenite, and the gangue minerals are barite, quartz and sericite. Mineralogical banding, defined by chalcopyrite-rich layers alternating with pyrite- and/or sphalerite-rich layers, is mostly the result of tectonic injection of ductile chalcopyrite, bornite, and galena within shear bands of cataclastic pyrite and sphalerite. Although it is likely that some Au has been re-precipitated during the shear event, the lack of Au in structural positions indicating an epigenetic origin with respect to the VHMS sulphides suggests that Au was present in the original VHMS ore., La Plata has preliminary estimated reserves of 840 000 t at 4.8 g/t Au, 54 g/t Ag, 4.1%t Cu, 0.7% Pb and 4.2% Zn. The deposit displays a typical VHMS vertical zonation from bottom to top of a pyrite stockwork, disseminated sulphides, massive sulphide lenses and a thin red jasper bed with exhalative-sedimentary textures. The massive sulphide lenses are located within footwall andesitic volcanic and volcaniclastic rocks that are pervasively altered to a quartz-pyrite-sericite assemblage, and immediately below a hanging-wall sequence consisting of at least two basaltic to basaltic-andesitic lava flows, each capped by autoclastic breccia intervals. The main ore minerals are pyrite, chalcopyrite, sphalerite, bornite and galena, with minor tennantite and digenite, and the gangue minerals are barite, quartz and sericite. Mineralogical banding, defined by chalcopyrite-rich layers alternating with pyrite- and/or sphalerite-rich layers, is mostly the result of tectonic injection of ductile chalcopyrite, bornite, and galena within shear bands of cataclastic pyrite and sphalerite. Although it is likely that some Au has been re-precipitated during the shear event, the lack of Au in structural positions indicating an epigenetic origin with respect to the VHMS sulphides suggests that Au was present in the original VHMS ore.

The deposit consists of 55 000 000 t of Zn-Pb-Cu massive sulphide overlying a Cu-rich stockwork. The massive ore is overlain by up to 30 m of feldspar-phyric, rhyolitic volcaniclastic rock and locally by a jasper and/or chert layer up to 15 m thick. The orebody consists mainly of pyrite, sphalerite, galena, chalcopyrite, tetrahedrite-tennantite, arsenopyrite and bournonite, together with minor quartz, chlorite, sericite, carbonate, and barite. The orebody is up to 100 m thick and is underlain by a tabular alteration zone of chlorite-dominated, locally silicified, felsic volcanic rock, the upper 30 to 60 m of which contains chalcopyrite-quartz-chlorite-sericite-carbonate-bearing stockwork veins or veinlets that, prior to deformation, were at a shallow angle to the base of the massive orebody. The characteristics of the deposit suggest deposition of the massive sulphide on the sea floor. It shares most of the characteristics of Iberian Pyrite Belt deposits for which a brine-pool origin has been proposed from fluid inclusion data, suggesting a similar depositional origin despite equivocal evidence from fluid inclusions. The sulphate that underwent biogenic reduction may have been derived from mixing with seawater during early filling of the brine pool, diffusion across the brine-seawater interface and sulphate reduction in the footwall volcaniclastic rocks. Stable and radiogenic isotope compositions suggest involvement of modified seawater and crustal fluids convecting due to magmatic heating, but the calculated high fluid pressures in the stockwork may indicate the additional involvement of magmatic fluids., The deposit consists of 55 000 000 t of Zn-Pb-Cu massive sulphide overlying a Cu-rich stockwork. The massive ore is overlain by up to 30 m of feldspar-phyric, rhyolitic volcaniclastic rock and locally by a jasper and/or chert layer up to 15 m thick. The orebody consists mainly of pyrite, sphalerite, galena, chalcopyrite, tetrahedrite-tennantite, arsenopyrite and bournonite, together with minor quartz, chlorite, sericite, carbonate, and barite. The orebody is up to 100 m thick and is underlain by a tabular alteration zone of chlorite-dominated, locally silicified, felsic volcanic rock, the upper 30 to 60 m of which contains chalcopyrite-quartz-chlorite-sericite-carbonate-bearing stockwork veins or veinlets that, prior to deformation, were at a shallow angle to the base of the massive orebody. The characteristics of the deposit suggest deposition of the massive sulphide on the sea floor. It shares most of the characteristics of Iberian Pyrite Belt deposits for which a brine-pool origin has been proposed from fluid inclusion data, suggesting a similar depositional origin despite equivocal evidence from fluid inclusions. The sulphate that underwent biogenic reduction may have been derived from mixing with seawater during early filling of the brine pool, diffusion across the brine-seawater interface and sulphate reduction in the footwall volcaniclastic rocks. Stable and radiogenic isotope compositions suggest involvement of modified seawater and crustal fluids convecting due to magmatic heating, but the calculated high fluid pressures in the stockwork may indicate the additional involvement of magmatic fluids.

The very close association between As, Cu and Au in many Chinese ores, especially from SW China, may lead to poor results from conventional flotation and cyanide leaching. An ore from Sichuan grading 10.12 g/t Au, 0.6% Cu and 0.14% As and characterised by extremely fine grain size, 70. 9% being smaller than 40 micrometres and 34.31% with Au as inclusions in pyrite and tennantite, was processed in two flotation stages and the resulting Au-bearing copper and pyrite concentrates leached sequentially. Four different oxidising and catalysing lixiviants were tested at 300 kPa and 110-115 degrees C on the Cu-Au concentrate, the two metals then being separated from each other in the leach solution. Cyanide leaching of the pyritic Au concentrate yielded an additional sulphur by-product in the leach residue. Test recoveries were up to 88.89% of Cu, 89.18% of Au and 92.64% of S. Of the Ca-, Ca-Cl-, Ca-Cl-NO- and Ca-Cl-NO-CrO3-based lixiviants, the one including both nitric oxide and chromate compounds recovered the most of both Cu and Au., The very close association between As, Cu and Au in many Chinese ores, especially from SW China, may lead to poor results from conventional flotation and cyanide leaching. An ore from Sichuan grading 10.12 g/t Au, 0.6% Cu and 0.14% As and characterised by extremely fine grain size, 70. 9% being smaller than 40 micrometres and 34.31% with Au as inclusions in pyrite and tennantite, was processed in two flotation stages and the resulting Au-bearing copper and pyrite concentrates leached sequentially. Four different oxidising and catalysing lixiviants were tested at 300 kPa and 110-115 degrees C on the Cu-Au concentrate, the two metals then being separated from each other in the leach solution. Cyanide leaching of the pyritic Au concentrate yielded an additional sulphur by-product in the leach residue. Test recoveries were up to 88.89% of Cu, 89.18% of Au and 92.64% of S. Of the Ca-, Ca-Cl-, Ca-Cl-NO- and Ca-Cl-NO-CrO3-based lixiviants, the one including both nitric oxide and chromate compounds recovered the most of both Cu and Au.

An overview is given of techniques for arsenic removal in copper metallurgy from smelting gases, waste waters and flue dusts. A promising route for the pre-treatment of copper-arsenic concentrates by selective flotation and/or alkaline leaching is then presented. Selective flotation of enargite and tennantite from chalcocite and chalcopyrite depends on control of the redox potential of the pulp, or the application of a pre- oxidation stage, but selectivity needs to be improved. Alkaline leaching of the concentrates with sodium sulphide-sodium hydroxide solutions results in the selective dissolution of arsenic and antimony at high extraction with practically no loss of copper. It could provide a route for processing the dirty concentrates from selective flotation and a conceptual flowsheet for high-arsenic copper bulk concentrates utilising both processes is proposed., An overview is given of techniques for arsenic removal in copper metallurgy from smelting gases, waste waters and flue dusts. A promising route for the pre-treatment of copper-arsenic concentrates by selective flotation and/or alkaline leaching is then presented. Selective flotation of enargite and tennantite from chalcocite and chalcopyrite depends on control of the redox potential of the pulp, or the application of a pre- oxidation stage, but selectivity needs to be improved. Alkaline leaching of the concentrates with sodium sulphide-sodium hydroxide solutions results in the selective dissolution of arsenic and antimony at high extraction with practically no loss of copper. It could provide a route for processing the dirty concentrates from selective flotation and a conceptual flowsheet for high-arsenic copper bulk concentrates utilising both processes is proposed.

Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu12-xFexSb4S13) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu12-xFexAs4S13) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I (4) over bar 3 m). The refinement results also confirm that M2 is a split (24g), flat-pyramidal site situated statistically on both sides of the S1-S1-S2 triangle. In tetrahedrite, this split is about 0.6 angstrom, in tennantite about 0.7 angstrom. Trends in bond lengths and magnitude of the M2 split were evaluated by means of linear regression with Fe concentration as the independent variable.

Rietveld refinement of X-ray synchrotron data was performed for two synthetic tetrahedrite samples, with 0.61 and 1.83 Fe atoms, and two synthetic tennantite samples with 0.10 and 1.23 Fe atoms p.f.u. M-12(Sb,As)(4)S-13. Measurements were performed at 25 and 250 degrees C. For both the phases, increased Fe substitution is reflected in the increased tetrahedral 'Cu1'-S distance ('Cu1' is a site of Fe substitution) and Cu2-S distances. Cu2 was refined as a split position; the Cu2-Cu2 split about the plane of the S1(2)S2 triangle is about 0.56 and 0.65 angstrom for tetrahedrite and tennantite, respectively. Cu2-Cu2 distances in the structure cavity are 2.8-2.9 angstrom. Between 25 and 250 degrees C, the lattice parameter a increased by 0.02-0.04 angstrom and the interatomic distances by 0.01 angstrom on an average. Thermal expansion coefficients of little-substituted samples are similar to those of unsubstituted samples, whereas thermal expansion appears to decrease with increasing substitution by Fe. The Cu2-Cu2 split increases at 250 degrees C by about 0.1 angstrom for tetrahedrite and by more than 0.15 angstrom for tennantite but the cage expansion is minimal so that the Cu2-Cu2 distances in the cavity decrease with temperature. Difference Fourier maps indicate that there is little residual electron density left between the two Cu2 half-sites in tetrahedrite but this inter-site density is substantially higher in tennantite. It increases with temperature, especially in the little-substituted tennantite sample.

Rietveld refinement of X-ray synchrotron data was performed for two synthetic tetrahedrite samples, with 0.61 and 1.83 Fe atoms, and two synthetic tennantite samples with 0.10 and 1.23 Fe atoms p.f.u. M-12(Sb,As)(4)S-13. Measurements were performed at 25 and 250 degrees C. For both the phases, increased Fe substitution is reflected in the increased tetrahedral 'Cu1'-S distance ('Cu1' is a site of Fe substitution) and Cu2-S distances. Cu2 was refined as a split position; the Cu2-Cu2 split about the plane of the S1(2)S2 triangle is about 0.56 and 0.65 angstrom for tetrahedrite and tennantite, respectively. Cu2-Cu2 distances in the structure cavity are 2.8-2.9 angstrom. Between 25 and 250 degrees C, the lattice parameter a increased by 0.02-0.04 angstrom and the interatomic distances by 0.01 angstrom on an average. Thermal expansion coefficients of little-substituted samples are similar to those of unsubstituted samples, whereas thermal expansion appears to decrease with increasing substitution by Fe. The Cu2-Cu2 split increases at 250 degrees C by about 0.1 angstrom for tetrahedrite and by more than 0.15 angstrom for tennantite but the cage expansion is minimal so that the Cu2-Cu2 distances in the cavity decrease with temperature. Difference Fourier maps indicate that there is little residual electron density left between the two Cu2 half-sites in tetrahedrite but this inter-site density is substantially higher in tennantite. It increases with temperature, especially in the little-substituted tennantite sample.

Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu12-xFexSb4S13) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu12-xFexAs4S13) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I (4) over bar 3 m). The refinement results also confirm that M2 is a split (24g), flat-pyramidal site situated statistically on both sides of the S1-S1-S2 triangle. In tetrahedrite, this split is about 0.6 angstrom, in tennantite about 0.7 angstrom. Trends in bond lengths and magnitude of the M2 split were evaluated by means of linear regression with Fe concentration as the independent variable.

As-bearing minerals such as enargite and tennantite may be associated with chalcopyrite, chalcocite and bornite and usually report to the Cu concentrate during conventional flotation due to their similar flotation properties. The As in the concentrate results in environmental problems and in problems with subsequent pyrometallurgical processing. Voltammetric studies were carried out to investigate the oxidation characteristics of enargite, tennantite, chalcopyrite, chalcocite and bornite and contact angle measurements and micro-flotation tests were conducted on the flotation characteristics of enargite and chalcopyrite under controlled pulp potentials. The results indicated that the non-As bearing minerals were easier to oxidise than enargite and tennantite in an alkaline solution. Enargite floated well at a potential as high as +0. 45 V vs. SCE while chalcopyrite was completely depressed at a potential higher than +0.43 V vs. SCE. Selective flotation showed that enargite could be successfully removed from chalcopyrite by controlling the pulp potential at +0.30 to about +0.50 V., As-bearing minerals such as enargite and tennantite may be associated with chalcopyrite, chalcocite and bornite and usually report to the Cu concentrate during conventional flotation due to their similar flotation properties. The As in the concentrate results in environmental problems and in problems with subsequent pyrometallurgical processing. Voltammetric studies were carried out to investigate the oxidation characteristics of enargite, tennantite, chalcopyrite, chalcocite and bornite and contact angle measurements and micro-flotation tests were conducted on the flotation characteristics of enargite and chalcopyrite under controlled pulp potentials. The results indicated that the non-As bearing minerals were easier to oxidise than enargite and tennantite in an alkaline solution. Enargite floated well at a potential as high as +0. 45 V vs. SCE while chalcopyrite was completely depressed at a potential higher than +0.43 V vs. SCE. Selective flotation showed that enargite could be successfully removed from chalcopyrite by controlling the pulp potential at +0.30 to about +0.50 V.

This paper describes the leaching of three common copper sulphide minerals in acidic media using Fe(SO4), FeCl3 or O2 as oxidising agents. The dissolution kinetics at different temperatures of tennantite from McIntyre, Timmins, Ontario, synthetic and Ag-bearing tetrahedrite from Tintic Standard, Utah, and enargite from West Colusa, Butte, Montana were investigated., This paper describes the leaching of three common copper sulphide minerals in acidic media using Fe(SO4), FeCl3 or O2 as oxidising agents. The dissolution kinetics at different temperatures of tennantite from McIntyre, Timmins, Ontario, synthetic and Ag-bearing tetrahedrite from Tintic Standard, Utah, and enargite from West Colusa, Butte, Montana were investigated.

The magmatic-hydrothermal evolution of the deposit was reconstructed on the basis of field relationships, scanning electron microscopy cathodoluminescence, petrography and fluid inclusion analysis. Three major stages of mineralisation were observed. Following a barren hydrothermal stage, stage 2 mineralisation is characterised by quartz-anhydrite stockwork veins and breccias with chalcopyrite, bornite, and molybdenite. Quartz-anhydrite veins with chalcopyrite, bornite and molybdenite associated with phyllic alteration represent stage 3, and stage 4 is characterised by breccias and rare veins containing a lower-temperature assemblage with tourmaline, sericite, and lesser tennantite, bornite and chalcopyrite with late gypsum in local vugs. The data indicate that injection from depth of an exceptionally Cu-, Mo-, Li- and probably also S-rich volatile phase into an already actively evolving upper-crustal magmatic-hydrothermal system resulted in the formation of the unusually large and rich Cu deposit., The magmatic-hydrothermal evolution of the deposit was reconstructed on the basis of field relationships, scanning electron microscopy cathodoluminescence, petrography and fluid inclusion analysis. Three major stages of mineralisation were observed. Following a barren hydrothermal stage, stage 2 mineralisation is characterised by quartz-anhydrite stockwork veins and breccias with chalcopyrite, bornite, and molybdenite. Quartz-anhydrite veins with chalcopyrite, bornite and molybdenite associated with phyllic alteration represent stage 3, and stage 4 is characterised by breccias and rare veins containing a lower-temperature assemblage with tourmaline, sericite, and lesser tennantite, bornite and chalcopyrite with late gypsum in local vugs. The data indicate that injection from depth of an exceptionally Cu-, Mo-, Li- and probably also S-rich volatile phase into an already actively evolving upper-crustal magmatic-hydrothermal system resulted in the formation of the unusually large and rich Cu deposit.

The Plavica Cu-Au deposit in Macedonia is hosted by Oligo-Miocene calc- alkaline volcanic rocks. Vein-type and disseminated mineralisation is dominated by pyrite, together with sulphides and sulphosalts of copper, zinc and arsenic. Alteration of the volcanic rocks is intense and consists of advanced argillic alteration in association with massive silica replacement bodies; these overlie zones of sericitic alteration. Fluid inclusions and oxygen isotopes suggest that the mineralisation formed at temperatures around 200-250 degrees C from dilute fluids with a mixed magmatic-meteoric provenance. These fluids underwent periodic boiling at depths of about 400 m. The presence of saline and CO2-rich fluids suggests the occasional, direct input of magmatic fluid. On the basis of its mineralogy, alteration and fluid characteristics, it is concluded that Plavica represents a high-sulphidation epithermal deposit. Although the enargite-rich veins are currently considered uneconomic, the close magmatic association suggests a porphyry Cu deposit may be present at depth., The Plavica Cu-Au deposit in Macedonia is hosted by Oligo-Miocene calc- alkaline volcanic rocks. Vein-type and disseminated mineralisation is dominated by pyrite, together with sulphides and sulphosalts of copper, zinc and arsenic. Alteration of the volcanic rocks is intense and consists of advanced argillic alteration in association with massive silica replacement bodies; these overlie zones of sericitic alteration. Fluid inclusions and oxygen isotopes suggest that the mineralisation formed at temperatures around 200-250 degrees C from dilute fluids with a mixed magmatic-meteoric provenance. These fluids underwent periodic boiling at depths of about 400 m. The presence of saline and CO2-rich fluids suggests the occasional, direct input of magmatic fluid. On the basis of its mineralogy, alteration and fluid characteristics, it is concluded that Plavica represents a high-sulphidation epithermal deposit. Although the enargite-rich veins are currently considered uneconomic, the close magmatic association suggests a porphyry Cu deposit may be present at depth.

The use is described of MLA characterisation in flotation tests on a Cu-Au ore. A Cu concentrate is produced by flotation of bornite and chalcopyrite and methods were investigated for reducing the As content in the final concentrate by depressing the As-bearing minerals during cleaner flotation. Previous data had identified tennantite as the source of the As. The mineralogy data showed that two of the composite ore samples contained a significant portion of Cu as As-bearing Cu mineral (tennantite/tetrahedrite) and that it was mostly the tennantite group minerals, together with arsenopyrite, that would need to be rejected. Mineral grain size data for chalcopyrite showed that fine regrinding would be required to liberate the chalcopyrite from pyrite and the tennantite group minerals to enable a separation to be made. Subsequent cleaner flotation test data showed that, although evaluation of chalcopyrite liberation data indicated that a regrind size of about 20 micrometers should be targeted, there was a danger of overgrinding. When good liberation of the tennantite group minerals was achieved, a significant portion of very fine chalcopyrite was produced in the finer size fractions, which in turn may lead to lower Cu recoveries into the cleaner concentrate., The use is described of MLA characterisation in flotation tests on a Cu-Au ore. A Cu concentrate is produced by flotation of bornite and chalcopyrite and methods were investigated for reducing the As content in the final concentrate by depressing the As-bearing minerals during cleaner flotation. Previous data had identified tennantite as the source of the As. The mineralogy data showed that two of the composite ore samples contained a significant portion of Cu as As-bearing Cu mineral (tennantite/tetrahedrite) and that it was mostly the tennantite group minerals, together with arsenopyrite, that would need to be rejected. Mineral grain size data for chalcopyrite showed that fine regrinding would be required to liberate the chalcopyrite from pyrite and the tennantite group minerals to enable a separation to be made. Subsequent cleaner flotation test data showed that, although evaluation of chalcopyrite liberation data indicated that a regrind size of about 20 micrometers should be targeted, there was a danger of overgrinding. When good liberation of the tennantite group minerals was achieved, a significant portion of very fine chalcopyrite was produced in the finer size fractions, which in turn may lead to lower Cu recoveries into the cleaner concentrate.

The atlas is intended to meet the need for a field reference guide for geologists and students. It describes the deposit environment, crystal system, characteristics in hand specimen and thin section, distinguishing features, associated minerals and mode of occurrence of acanthite/argentite, arsenopyrite, asbestos, azurite, bismuth, bismuthinite, bornite, boulangerite, bournonite, cassiterite, chalcocite, chalcopyrite, chromite, chrysocolla, cinnabar, cobaltite, copper, covellite, cubanite, diamond, digenite, enargite, galena, gersdorffite, goethite, gold, graphite, haematite, ilmenite, jamesonite, magnetite, malachite, marcasite, millerite, molybdenite, nickeline, orpiment, pentlandite, proustite-pyrargyrite, pyrite, pyrochlore, pyrolusite, pyrrhotite, realgar, scheelite, silver, sperrylite, sphalerite, stibnite, tetrahedrite-tennantite, uraninite, violarite, and wolframite. Examples are given of typical deposits for each mineral and their worldwide distribution. Each entry is accompanied by photographs/microphotographs and has a list of further references. There is a table of contents by chemical grouping and a mineral index that includes the various mentions of the different metals and picks up all the entries for associated minerals., The atlas is intended to meet the need for a field reference guide for geologists and students. It describes the deposit environment, crystal system, characteristics in hand specimen and thin section, distinguishing features, associated minerals and mode of occurrence of acanthite/argentite, arsenopyrite, asbestos, azurite, bismuth, bismuthinite, bornite, boulangerite, bournonite, cassiterite, chalcocite, chalcopyrite, chromite, chrysocolla, cinnabar, cobaltite, copper, covellite, cubanite, diamond, digenite, enargite, galena, gersdorffite, goethite, gold, graphite, haematite, ilmenite, jamesonite, magnetite, malachite, marcasite, millerite, molybdenite, nickeline, orpiment, pentlandite, proustite-pyrargyrite, pyrite, pyrochlore, pyrolusite, pyrrhotite, realgar, scheelite, silver, sperrylite, sphalerite, stibnite, tetrahedrite-tennantite, uraninite, violarite, and wolframite. Examples are given of typical deposits for each mineral and their worldwide distribution. Each entry is accompanied by photographs/microphotographs and has a list of further references. There is a table of contents by chemical grouping and a mineral index that includes the various mentions of the different metals and picks up all the entries for associated minerals.

The Lower Carboniferous carbonate rocks of the Irish Midlands host one of the world's major zinc orefields. The deposits were formed where hydrothermal fluids escaped upsection into the Lower Carboniferous carbonate sequence along extensional normal faults. They occur preferentially in the stratigraphically lowest, non-argillaceous carbonate unit. They occur along, or immediately adjacent to, normal faults which formed conduits for ascending hydrothermal fluids. Sphalerite and galena are the principal sulphides. Barite is present in all the deposits. Most deposits contain minor tennantite, chalcopyrite and/or Pb-Cu-Ag-As sulphosalt minerals. They are stratabound and commonly display large-scale statiform morphologies. They display complex sulphide textures., The Lower Carboniferous carbonate rocks of the Irish Midlands host one of the world's major zinc orefields. The deposits were formed where hydrothermal fluids escaped upsection into the Lower Carboniferous carbonate sequence along extensional normal faults. They occur preferentially in the stratigraphically lowest, non-argillaceous carbonate unit. They occur along, or immediately adjacent to, normal faults which formed conduits for ascending hydrothermal fluids. Sphalerite and galena are the principal sulphides. Barite is present in all the deposits. Most deposits contain minor tennantite, chalcopyrite and/or Pb-Cu-Ag-As sulphosalt minerals. They are stratabound and commonly display large-scale statiform morphologies. They display complex sulphide textures.

Chapters are presented on the petrological and mineralogical framework, indium metallogeny, miscellaneous occurrences, spatial and temporal distribution of deposits, a model of ore formation, historical and actual production, the stockpile situation in relation to the different deposit types, and technological applications and consumption by industries. Indium is hosted by vein-stockwork Sn and W deposits, porphyry Sn deposits, volcanic-hosted massive sulphides, active hydrothermal sea-floor vents, sedex deposits, polymetallic vein deposits, epithermal deposits, active magmatic systems, porphyry Cu deposits and skarn deposits. Metallogenic provinces were commonly associated with oceanic or continental plate margins and orogenic belts while most deposits formed towards the ends of geotectonically active periods in the Ordovician, Carboniferous, Cretaceous and Tertiary. As a major source mineral is sphalerite, resources are closely related to those of Zn. Reported reserves are sufficient to meet anticipated demand for a decade. The final chapter in the book consists of tables listing the characteristics of 104 deposits in Japan (9), the Northeast Pacific, Australia (7), the USA (3), Austria (2), Bolivia (9), the Mid-Atlantic Ridge (3), Canada (8), Bulgaria (3), Peru (2), France (5), Czech Republic (7), China (4), Russia and Bashkir (13), the East Pacific Rise (2), Germany (4), Sweden (2), Spain, Kazakhstan (3), Uzbekistan/Tadzhikistan, Greece, the Southwest Pacific, Brazil, Papua New Guinea, South Africa, Indonesia, Hungary, Portugal, Italy, Argentina, England (3), India and Korea. There are 18 pages of references and a subject index., Chapters are presented on the petrological and mineralogical framework, indium metallogeny, miscellaneous occurrences, spatial and temporal distribution of deposits, a model of ore formation, historical and actual production, the stockpile situation in relation to the different deposit types, and technological applications and consumption by industries. Indium is hosted by vein-stockwork Sn and W deposits, porphyry Sn deposits, volcanic-hosted massive sulphides, active hydrothermal sea-floor vents, sedex deposits, polymetallic vein deposits, epithermal deposits, active magmatic systems, porphyry Cu deposits and skarn deposits. Metallogenic provinces were commonly associated with oceanic or continental plate margins and orogenic belts while most deposits formed towards the ends of geotectonically active periods in the Ordovician, Carboniferous, Cretaceous and Tertiary. As a major source mineral is sphalerite, resources are closely related to those of Zn. Reported reserves are sufficient to meet anticipated demand for a decade. The final chapter in the book consists of tables listing the characteristics of 104 deposits in Japan (9), the Northeast Pacific, Australia (7), the USA (3), Austria (2), Bolivia (9), the Mid-Atlantic Ridge (3), Canada (8), Bulgaria (3), Peru (2), France (5), Czech Republic (7), China (4), Russia and Bashkir (13), the East Pacific Rise (2), Germany (4), Sweden (2), Spain, Kazakhstan (3), Uzbekistan/Tadzhikistan, Greece, the Southwest Pacific, Brazil, Papua New Guinea, South Africa, Indonesia, Hungary, Portugal, Italy, Argentina, England (3), India and Korea. There are 18 pages of references and a subject index.

The Ungay-Malabago polymetallic deposit is located on the eastern end of the island of Rapu-Rapu in the Philippines. The Ungay deposit consists of a highly deformed massive sulphide pod consisting predominantly of pyrite with lesser chalcopyrite, covellite and sphalerite. A peripheral halo of disseminated sulphides occurs around the massive sulphides within the adjacent quartz-sericite altered wall rocks. The primary ore resource contains around 6 750 000 t assaying 1.3% Cu, 2.1% Zn, 2.6 g/t Au and 28 g/t Ag. The gossan transition zone contains more than 500 000 t assaying about 3 g/t Au and 30 g/t Ag. The attitude and depth of the deposit makes it suitable for open-pit mining, but the rising topography to the west makes open-pit mining less attractive at the western end of Domain 3 and it is proposed to mine this zone via an adit from the open pit towards the end of the operating life. The major revenue metals are Cu, contained in chalcopyrite, covellite, bornite, tennantite and enargite, and Zn, contained predominantly in low iron bearing sphalerite and as traces in zincian tennantite. Scoping study, preliminary feasibility study, and definitive feasibility study test work which has been conducted is described. The gossan/transitional ore will be removed during the stripping phase and, following primary crushing in a jaw crusher, will be stockpiled separately for subsequent treatment at a rate of about 200 000 tpa in a dedicated carbon-in-pulp plant to produce Dore bullion. The primary sulphide ore will be treated at a rate of about 800 000 tpa by semiautogenous grinding and differential flotation to produce separate Cu and Zn concentrates. The concentrates will be subjected to pressure filtration ready for bulk shipment from the island to smelters in the region. Au solubilised in the Cu-Zn separation circuit will be recovered from the Zn circuit tailings using a thickener. The overflow will pass to the carbon-in-pulp plant and the underflow will combine with the, The Ungay-Malabago polymetallic deposit is located on the eastern end of the island of Rapu-Rapu in the Philippines. The Ungay deposit consists of a highly deformed massive sulphide pod consisting predominantly of pyrite with lesser chalcopyrite, covellite and sphalerite. A peripheral halo of disseminated sulphides occurs around the massive sulphides within the adjacent quartz-sericite altered wall rocks. The primary ore resource contains around 6 750 000 t assaying 1.3% Cu, 2.1% Zn, 2.6 g/t Au and 28 g/t Ag. The gossan transition zone contains more than 500 000 t assaying about 3 g/t Au and 30 g/t Ag. The attitude and depth of the deposit makes it suitable for open-pit mining, but the rising topography to the west makes open-pit mining less attractive at the western end of Domain 3 and it is proposed to mine this zone via an adit from the open pit towards the end of the operating life. The major revenue metals are Cu, contained in chalcopyrite, covellite, bornite, tennantite and enargite, and Zn, contained predominantly in low iron bearing sphalerite and as traces in zincian tennantite. Scoping study, preliminary feasibility study, and definitive feasibility study test work which has been conducted is described. The gossan/transitional ore will be removed during the stripping phase and, following primary crushing in a jaw crusher, will be stockpiled separately for subsequent treatment at a rate of about 200 000 tpa in a dedicated carbon-in-pulp plant to produce Dore bullion. The primary sulphide ore will be treated at a rate of about 800 000 tpa by semiautogenous grinding and differential flotation to produce separate Cu and Zn concentrates. The concentrates will be subjected to pressure filtration ready for bulk shipment from the island to smelters in the region. Au solubilised in the Cu-Zn separation circuit will be recovered from the Zn circuit tailings using a thickener. The overflow will pass to the carbon-in-pulp plant and the underflow will combine with the

The separation by flotation of chalcocite, covellite, and chalcopyrite from the arsenic copper sulphide minerals, enargite and tennantite, was investigated in mixed mineral systems in the presence of hydrogen peroxide as oxidant. Separation was only possible at pH 5.0 after selective oxidation with H2O2, while at pH 11.0 it was only possible after oxidation with H2O2 followed by EDTA addition for selective removal of surface oxidation products. Arsenic oxides are more stable than copper oxides at pH 5.0 but are less soluble than copper oxides in the presence of EDTA at pH 11.0. X-ray photoelectron spectroscopy (XPS) showed that the surface of the arsenic minerals was more oxidised than that of the non-arsenic minerals., The separation by flotation of chalcocite, covellite, and chalcopyrite from the arsenic copper sulphide minerals, enargite and tennantite, was investigated in mixed mineral systems in the presence of hydrogen peroxide as oxidant. Separation was only possible at pH 5.0 after selective oxidation with H2O2, while at pH 11.0 it was only possible after oxidation with H2O2 followed by EDTA addition for selective removal of surface oxidation products. Arsenic oxides are more stable than copper oxides at pH 5.0 but are less soluble than copper oxides in the presence of EDTA at pH 11.0. X-ray photoelectron spectroscopy (XPS) showed that the surface of the arsenic minerals was more oxidised than that of the non-arsenic minerals.

The treatment of arsenical copper ore from the Chilean mine was tested using a benchtop autoclave. Oxidation of concentrates typically extracted around 95% of Cu. Extraction was limited by the reprecipitation of a complex precipitate containing arsenic. Cyanidation of the oxidation residue recovered about 95% of Au, but less than 10% of Ag was extracted due to the formation of argentojarosite in the autoclave. Whole-ore oxidation at low pulp density was more successful, routinely achieving Cu extractions of 98-99% and extracting more than 95% of Au, while Ag extraction could be increased to as high as 95% by lime boiling. The results formed the basis for a proposed process flowsheet, in which the dilute solution from the autoclave discharge would be treated by direct solvent extraction and electrowinning of copper., The treatment of arsenical copper ore from the Chilean mine was tested using a benchtop autoclave. Oxidation of concentrates typically extracted around 95% of Cu. Extraction was limited by the reprecipitation of a complex precipitate containing arsenic. Cyanidation of the oxidation residue recovered about 95% of Au, but less than 10% of Ag was extracted due to the formation of argentojarosite in the autoclave. Whole-ore oxidation at low pulp density was more successful, routinely achieving Cu extractions of 98-99% and extracting more than 95% of Au, while Ag extraction could be increased to as high as 95% by lime boiling. The results formed the basis for a proposed process flowsheet, in which the dilute solution from the autoclave discharge would be treated by direct solvent extraction and electrowinning of copper.

Mineralogical studies of ore, flotation tails and Cu concentrates from Laronde mine were carried out using ore microscopy, electron microscopy, proton-microprobe, image analysis and material balances. The ore was found to contain major amounts of pyrite, sphalerite, chalcopyrite, bornite, galena, tennantite and pyrrhotite. Liberation of pyrite was very high (80-91%); liberation of chalcopyrite, bornite, sphalerite and tennantite was relatively high in the head sample (55-78%) and concentrate (66-88%). Most of the chalcopyrite in the flotation tails was not liberated. Materials balance calculations on the five major sulphide minerals showed that tennantite was the principal carrier of Bi, As and Te. Removal of tennantite would significantly reduce these contaminants, but at a loss of 9% of the Cu, 2% of the Zn and 0.7% of the Ag. The precious metals occur as discrete minerals, and some Ag occurs in solid solution in bornite, tennantite and sphalerite., Mineralogical studies of ore, flotation tails and Cu concentrates from Laronde mine were carried out using ore microscopy, electron microscopy, proton-microprobe, image analysis and material balances. The ore was found to contain major amounts of pyrite, sphalerite, chalcopyrite, bornite, galena, tennantite and pyrrhotite. Liberation of pyrite was very high (80-91%); liberation of chalcopyrite, bornite, sphalerite and tennantite was relatively high in the head sample (55-78%) and concentrate (66-88%). Most of the chalcopyrite in the flotation tails was not liberated. Materials balance calculations on the five major sulphide minerals showed that tennantite was the principal carrier of Bi, As and Te. Removal of tennantite would significantly reduce these contaminants, but at a loss of 9% of the Cu, 2% of the Zn and 0.7% of the Ag. The precious metals occur as discrete minerals, and some Ag occurs in solid solution in bornite, tennantite and sphalerite.

The practical implementation of laboratory results is discussed for lead-zinc and copper-pyrite flotation, gold hydrometallurgy and water purification. General work includes: estimating flotability; control of activation and depression; crystallographic and hydrophobisation modelling of flotation; the role of oxygen; frother analysis and selection; and computerised optimisation of semiconductor mineral flotation. Aspects of Pb-Zn and Cu-Fe selection are Zn activation and depression, cyanide-free selection, electrochemical selection of bulk concentrates, electrochemical control, voltammetry, froth feeding in Denver cells, pulp level control and pyrite depression. Precious metals leaching by ammonium thiosulphate after oxidation at 90-95 degrees C is discussed, with recovery by cementation. An industrial scheme, based on the results of drum separator and iron swarf experiments, is proposed for cementing copper from mine waters and electrochemical methods for cleaning arsenic and organic substances from waste water. The book includes 183 references and tables of physical data and water quality limits., The practical implementation of laboratory results is discussed for lead-zinc and copper-pyrite flotation, gold hydrometallurgy and water purification. General work includes: estimating flotability; control of activation and depression; crystallographic and hydrophobisation modelling of flotation; the role of oxygen; frother analysis and selection; and computerised optimisation of semiconductor mineral flotation. Aspects of Pb-Zn and Cu-Fe selection are Zn activation and depression, cyanide-free selection, electrochemical selection of bulk concentrates, electrochemical control, voltammetry, froth feeding in Denver cells, pulp level control and pyrite depression. Precious metals leaching by ammonium thiosulphate after oxidation at 90-95 degrees C is discussed, with recovery by cementation. An industrial scheme, based on the results of drum separator and iron swarf experiments, is proposed for cementing copper from mine waters and electrochemical methods for cleaning arsenic and organic substances from waste water. The book includes 183 references and tables of physical data and water quality limits.

Arsenic can be volatilised from high-As concentrates in its elemental form or as sulphides or oxides, depending on operating conditions. Results are presented for its volatilisation from Cu concentrates with 4.1% As and from enargite concentrates with 63.58% Cu3AsS4. Over 98% of As can be removed in the absence of oxygen, at 650 degrees C with a roasting time of 60 min. Increasing the temperature to 700 degrees C can effectively reduce the roasting time to 15 min, while the addition of 1% O2 allows similar results to be achieved in half the time or at 600 degrees C. X-ray diffraction analysis of the solid products indicated that As is volatilised as sulphides in inert atmosphere but as a mixture of sulphides and oxides in a slightly oxidising atmosphere. The presence of oxygen contributes to the production of an oxidised calcine suitable for hydrometallurgical treatment., Arsenic can be volatilised from high-As concentrates in its elemental form or as sulphides or oxides, depending on operating conditions. Results are presented for its volatilisation from Cu concentrates with 4.1% As and from enargite concentrates with 63.58% Cu3AsS4. Over 98% of As can be removed in the absence of oxygen, at 650 degrees C with a roasting time of 60 min. Increasing the temperature to 700 degrees C can effectively reduce the roasting time to 15 min, while the addition of 1% O2 allows similar results to be achieved in half the time or at 600 degrees C. X-ray diffraction analysis of the solid products indicated that As is volatilised as sulphides in inert atmosphere but as a mixture of sulphides and oxides in a slightly oxidising atmosphere. The presence of oxygen contributes to the production of an oxidised calcine suitable for hydrometallurgical treatment.

Air pollution caused by smelting ore concentrates from arsenic-rich porphyry copper deposits can be a serious problem. The presence or absence of arsenic minerals, however, does not correlate with the variations in geotectonic setting of the deposit, but is closely related to hydrogen metasomatism. Fluid evolution paths leading to low K+, Na+ and Cu+ versus H+ ion activity ratios promote the deposition of arsenic sulphosalts. Tennantite is a stable phase at low temperatures and low Cu+/H+ activity ratios of the hydrothermal fluid. The As concentrations of hydrothermal fluids are generally sufficiently high to allow precipitation of tennantite at appropriate configurations of other variables (fluid composition and temperature). The presence of arsenic-rich country rock is not envisaged as a necessary condition for the formation of arsenic-rich porphyry copper deposits., Air pollution caused by smelting ore concentrates from arsenic-rich porphyry copper deposits can be a serious problem. The presence or absence of arsenic minerals, however, does not correlate with the variations in geotectonic setting of the deposit, but is closely related to hydrogen metasomatism. Fluid evolution paths leading to low K+, Na+ and Cu+ versus H+ ion activity ratios promote the deposition of arsenic sulphosalts. Tennantite is a stable phase at low temperatures and low Cu+/H+ activity ratios of the hydrothermal fluid. The As concentrations of hydrothermal fluids are generally sufficiently high to allow precipitation of tennantite at appropriate configurations of other variables (fluid composition and temperature). The presence of arsenic-rich country rock is not envisaged as a necessary condition for the formation of arsenic-rich porphyry copper deposits.

The flotation behaviour of minerals depends on the balance between hydrophobic and hydrophilic species present at the mineral surface. The direct characterisation of the interfacial products formed by the interaction of water and an aqueous solution of amyl xanthate with chalcopyrite, tetrahedrite and tennantite was carried out using X-ray photoelectron spectroscopy and infrared reflection spectroscopy. The experimental data allowed the determination of the adsorption products and suggest mechanisms of interaction between the surfactant solution and the mineral surfaces. Two major processes taking place at the mineral surfaces are the interaction with water and oxygen resulting in the formation of mainly hydrophilic oxidation products, and the adsorption of xanthate producing different types of hydrophobic surface products. Differences were found in the composition of the outermost atomic layers of the minerals which account for differences in flotation behaviour. The results provide a basis for separation between copper minerals containing antimony and arsenic, and chalcopyrite., The flotation behaviour of minerals depends on the balance between hydrophobic and hydrophilic species present at the mineral surface. The direct characterisation of the interfacial products formed by the interaction of water and an aqueous solution of amyl xanthate with chalcopyrite, tetrahedrite and tennantite was carried out using X-ray photoelectron spectroscopy and infrared reflection spectroscopy. The experimental data allowed the determination of the adsorption products and suggest mechanisms of interaction between the surfactant solution and the mineral surfaces. Two major processes taking place at the mineral surfaces are the interaction with water and oxygen resulting in the formation of mainly hydrophilic oxidation products, and the adsorption of xanthate producing different types of hydrophobic surface products. Differences were found in the composition of the outermost atomic layers of the minerals which account for differences in flotation behaviour. The results provide a basis for separation between copper minerals containing antimony and arsenic, and chalcopyrite.

The distribution of significant gold mineralisation at the prospect is spatially related to Cu, Pb, Zn, As and Mn mineral zoning, which resulted from different alteration mineralogy relating to changes in the acidity of the mineralising fluids. In general, significant gold mineralisation is associated with tennantite group minerals (rich in Cu and As) in the central parts of the argillic alteration zones and grades outwards into Pb-rich/Au-poor areas in the distal parts. Mn and Zn haloes associated with argillic and propylitic alteration zones envelope the advanced argillic alteration. This geochemical model may be used as an exploration tool to identify blind target areas in large zones of advanced argillic alteration associated with high-sulphur hydrothermal systems that can be tested by drilling., The distribution of significant gold mineralisation at the prospect is spatially related to Cu, Pb, Zn, As and Mn mineral zoning, which resulted from different alteration mineralogy relating to changes in the acidity of the mineralising fluids. In general, significant gold mineralisation is associated with tennantite group minerals (rich in Cu and As) in the central parts of the argillic alteration zones and grades outwards into Pb-rich/Au-poor areas in the distal parts. Mn and Zn haloes associated with argillic and propylitic alteration zones envelope the advanced argillic alteration. This geochemical model may be used as an exploration tool to identify blind target areas in large zones of advanced argillic alteration associated with high-sulphur hydrothermal systems that can be tested by drilling.

Although many techniques for controlling acid mine drainage have been developed and tested, relatively little work has been done on the retreatment of sulphidic wastes for the recovery of their metals content. An industrial pilot study of tailings recycling is being carried out at Manitou-Barvue in Quebec, whose mill treated 14 000 000 tonnes of ore from 1942 to 1989. The tailings are of four kinds: 7 500 000 t from massive pyrite and sphalerite with accessory galena, tennantite and tetrahedrite, 3 600 000 t from zones rich in pyrite and chalcopyrite, 960 000 t from copper ore and 640 000 t fom copper-silver ore. The pH varies fom 4.8 to 6.4 and mean grades are 0.33 ppm Au, 15.4 ppm Ag and 0.07% Cu, with 0.2-1.2% Zn, 8.8% Fe and 7.4% S. The recycling process comprises the following stages: washing for desulphatisation and dissolution of zinc salts, separation of sulphide and oxide phases by flotation, sizing and comminution of the sulphide phase, recovery of gold and silver by cyanidation, selective flotation for sphalerite concentration and zinc extraction, and residue cyanidation, flotation and disposal. Cost-benefit analysis by means of a computer program has confirmed the economic benefits of the technology and the additional advantages of incorporating different biotechnological processes in the pre-oxidation stage for further enhancement of recovery efficiency., Although many techniques for controlling acid mine drainage have been developed and tested, relatively little work has been done on the retreatment of sulphidic wastes for the recovery of their metals content. An industrial pilot study of tailings recycling is being carried out at Manitou-Barvue in Quebec, whose mill treated 14 000 000 tonnes of ore from 1942 to 1989. The tailings are of four kinds: 7 500 000 t from massive pyrite and sphalerite with accessory galena, tennantite and tetrahedrite, 3 600 000 t from zones rich in pyrite and chalcopyrite, 960 000 t from copper ore and 640 000 t fom copper-silver ore. The pH varies fom 4.8 to 6.4 and mean grades are 0.33 ppm Au, 15.4 ppm Ag and 0.07% Cu, with 0.2-1.2% Zn, 8.8% Fe and 7.4% S. The recycling process comprises the following stages: washing for desulphatisation and dissolution of zinc salts, separation of sulphide and oxide phases by flotation, sizing and comminution of the sulphide phase, recovery of gold and silver by cyanidation, selective flotation for sphalerite concentration and zinc extraction, and residue cyanidation, flotation and disposal. Cost-benefit analysis by means of a computer program has confirmed the economic benefits of the technology and the additional advantages of incorporating different biotechnological processes in the pre-oxidation stage for further enhancement of recovery efficiency.

The presence of native copper in many places, the location of the mineral in a relatively soft conglomerate and its almost horizontal disposition at the base of a cliff of white Triassic sandstone were all factors favourable to the early development of a small extractive industry in this relatively temperate region of the Alps. Notable quantities of As-bearing grey copper ores such as tennantite, germanite, enargite, and especially the arsenides domeykite (Cu3As) and algodonite (Cu6As), allowed the production of bronze before alloying with tin was discovered; local smelters' hoards date from 1250-1150 BC, but the first written mention of Cu in the Barrot dome is late 17th century. The height of recorded activity was in the late 19th century, when from 1878 to 1884 the workings at Cerisier employed 90-230 people and annual production was 200-350 tonnes of mattes grading at least 50% Cu. Total production during the mine's life (1860-1886) was 2 500 t Cu metal from about 100 000 t ore, entailing the development of around 5 000 m of galleries at Cerisier and over 1 000 m at Leouve. Location, access, mine workings, history and mineralisation are described, with sketch-maps, historical reproductions and coloured photographs, for the following deposits: Clue de Roua, Pont des Roberts, Tireboeuf, Bancairon, l'Hubac de Jourdan, Leouve, Villaron-La Nougiere and Raton. For Cerisier, details are also given of ore transport, mineral processing, the workforce, financing, operating companies and overall profit/loss., The presence of native copper in many places, the location of the mineral in a relatively soft conglomerate and its almost horizontal disposition at the base of a cliff of white Triassic sandstone were all factors favourable to the early development of a small extractive industry in this relatively temperate region of the Alps. Notable quantities of As-bearing grey copper ores such as tennantite, germanite, enargite, and especially the arsenides domeykite (Cu3As) and algodonite (Cu6As), allowed the production of bronze before alloying with tin was discovered; local smelters' hoards date from 1250-1150 BC, but the first written mention of Cu in the Barrot dome is late 17th century. The height of recorded activity was in the late 19th century, when from 1878 to 1884 the workings at Cerisier employed 90-230 people and annual production was 200-350 tonnes of mattes grading at least 50% Cu. Total production during the mine's life (1860-1886) was 2 500 t Cu metal from about 100 000 t ore, entailing the development of around 5 000 m of galleries at Cerisier and over 1 000 m at Leouve. Location, access, mine workings, history and mineralisation are described, with sketch-maps, historical reproductions and coloured photographs, for the following deposits: Clue de Roua, Pont des Roberts, Tireboeuf, Bancairon, l'Hubac de Jourdan, Leouve, Villaron-La Nougiere and Raton. For Cerisier, details are also given of ore transport, mineral processing, the workforce, financing, operating companies and overall profit/loss.

The Neoproterozoic Bisha deposit is a more than 39 000 000 t, relatively high grade Zn-Cu-Au-Ag deposit with potentially recoverable Pb, Cd and Ga. The deposit is a single, almost inclusion- and dyke-free lens that has been folded and affected by significant near-surface oxidation and supergene processes which have led to the development of four distinct ore types or zones. The haematite-goethite-quartz gossan 0-30 m deep has high Au, Ag and Pb contents, with native Au, argentiferous Au, electrum, anglesite, and lesser cerrusite. The kaolinite-quartz-sulphate zone occurs at a depth of 25-35 m and also is enriched in Au, Ag and Pb and has the same ore mineralogy as the gossan. It also contains minor chalcocite and minor to trace amounts of unusual Zn-Pb- Fe carbonate and sulphate minerals. The supergene sulphide zone is present at 35-55 m and has significant Cu enrichment, with predominant chalcocite, and lesser digenite, covellite and bornite, along with pyrite, minor pyrrhotite, anglesite, and gangue minerals. The primary massive sulphide is at 55- 450m and has a significant volume of Zn-rich ore and a typical VMS sulphide assemblage of pyrite, sphalerite, chalcopyrite, and minor to trace galena, pyrrhotite, tetrahedrite, tennantite, arsenopyrite, barite, and gangue. The model ages for the Bisha area deposits indicate that the deposits and their host rocks formed early during the development of the 850 to 550 Ma Nakfa terrane., The Neoproterozoic Bisha deposit is a more than 39 000 000 t, relatively high grade Zn-Cu-Au-Ag deposit with potentially recoverable Pb, Cd and Ga. The deposit is a single, almost inclusion- and dyke-free lens that has been folded and affected by significant near-surface oxidation and supergene processes which have led to the development of four distinct ore types or zones. The haematite-goethite-quartz gossan 0-30 m deep has high Au, Ag and Pb contents, with native Au, argentiferous Au, electrum, anglesite, and lesser cerrusite. The kaolinite-quartz-sulphate zone occurs at a depth of 25-35 m and also is enriched in Au, Ag and Pb and has the same ore mineralogy as the gossan. It also contains minor chalcocite and minor to trace amounts of unusual Zn-Pb- Fe carbonate and sulphate minerals. The supergene sulphide zone is present at 35-55 m and has significant Cu enrichment, with predominant chalcocite, and lesser digenite, covellite and bornite, along with pyrite, minor pyrrhotite, anglesite, and gangue minerals. The primary massive sulphide is at 55- 450m and has a significant volume of Zn-rich ore and a typical VMS sulphide assemblage of pyrite, sphalerite, chalcopyrite, and minor to trace galena, pyrrhotite, tetrahedrite, tennantite, arsenopyrite, barite, and gangue. The model ages for the Bisha area deposits indicate that the deposits and their host rocks formed early during the development of the 850 to 550 Ma Nakfa terrane.

Economic beneficiation of the high-As regions of the Northparkes, New South Wales, Cu-Au orebody requires that tennantite present in the ore should be rejected to enable Cu concentrates to meet the typical smelter penalty level of 2 000 ppm As. Results obtained from experiments on a composite sample of high-As drill cores with a head grade of 0.11% As and 1.2% Cu showed that tennantite could be selectively separated from chalcopyrite and bornite using controlled-potential flotation. The separation was made on a bulk Cu-As concentrate after reducing the pulp potential to about -150 mV SHE at pH 12. The lower limiting pulp potential threshold for tennantite is lower than that for chalcopyrite and there is a potential window in the reducing region where tennantite is strongly floatable but chalcopyrite is not. A concentrate was obtained containing 52% of the non-tennantite Cu and assaying 2 600 ppm As. Computer simulations showed that, for a feed containing more typical As and Cu levels of 200 ppm As and 1%, respectively, the efficiency of separation should be sufficient to concentrate about 61 % of the Cu in a product assaying less than 2 000 ppm As. A conceptual flowsheet for As rejection is presented., Economic beneficiation of the high-As regions of the Northparkes, New South Wales, Cu-Au orebody requires that tennantite present in the ore should be rejected to enable Cu concentrates to meet the typical smelter penalty level of 2 000 ppm As. Results obtained from experiments on a composite sample of high-As drill cores with a head grade of 0.11% As and 1.2% Cu showed that tennantite could be selectively separated from chalcopyrite and bornite using controlled-potential flotation. The separation was made on a bulk Cu-As concentrate after reducing the pulp potential to about -150 mV SHE at pH 12. The lower limiting pulp potential threshold for tennantite is lower than that for chalcopyrite and there is a potential window in the reducing region where tennantite is strongly floatable but chalcopyrite is not. A concentrate was obtained containing 52% of the non-tennantite Cu and assaying 2 600 ppm As. Computer simulations showed that, for a feed containing more typical As and Cu levels of 200 ppm As and 1%, respectively, the efficiency of separation should be sufficient to concentrate about 61 % of the Cu in a product assaying less than 2 000 ppm As. A conceptual flowsheet for As rejection is presented.

The Huambo quadrangle to the south is dominated by Cretaceous strata and mainly granite-dacite-diorite intrusions, while the Orcopampa area is mainly composed of Tertiary rocks. The whole region is heavily faulted and there are glacial and erosional deposits as well as recently reactivated chains of volanoes. Quartz vein deposits of tennantite and some freibergite with minor galena, sphalerite, chalcopyrite, gold, polybasite and bornite are mined at Orcopampa and stibnite at Santa Rosa. Other metalliferous deposits include gold and silver at Piraucho and massive lead and zinc. Halite, gypsum and travertine are also exploited., The Huambo quadrangle to the south is dominated by Cretaceous strata and mainly granite-dacite-diorite intrusions, while the Orcopampa area is mainly composed of Tertiary rocks. The whole region is heavily faulted and there are glacial and erosional deposits as well as recently reactivated chains of volanoes. Quartz vein deposits of tennantite and some freibergite with minor galena, sphalerite, chalcopyrite, gold, polybasite and bornite are mined at Orcopampa and stibnite at Santa Rosa. Other metalliferous deposits include gold and silver at Piraucho and massive lead and zinc. Halite, gypsum and travertine are also exploited.

The Boyongan and Bayugo porphyry Cu-Au mineral deposits, discovered under postmineralisation cover during the previous decade, are part of an emerging belt of intrusion-centred Au-rich Cu mineral deposits and prospects in the Surigao district of northeast Mindanao. Since their formation in the early Pleistocene, exhumation and weathering of these deposits have led to the development of a 600-m-thick oxidation profile at Boyongan and a modest (30-70 m) oxidation profile at Bayugo. Debris flows, volcanic material, and fluviolacustrine sediments accumulating in the actively extending Mainit graben subsequently covered the weathered deposits, preserving their supergene profiles. The mineral deposits formed in association with a composite diorite complex containing at least 12 discrete intrusive stages. A characteristic progression of vein and K silicate alteration styles affected each of the synmineralisation intrusions. At Boyongan and Bayugo, intense and pervasive illite alteration, in association with pyrite, chalcopyrite, and tetrahedrite-tennantite, developed in narrow structures crosscutting quartz-K-feldspar veins. In both mineral deposits, Cu and Au are associated with intense quartz-vein stockworks composed primarily of K silicate stage 3 veins. The study illustrates the spectrum of metallogenic processes operative over a geologically brief period and highlights some of the key elements responsible for formation of superior grades and for deposit preservation in an extensional setting., The Boyongan and Bayugo porphyry Cu-Au mineral deposits, discovered under postmineralisation cover during the previous decade, are part of an emerging belt of intrusion-centred Au-rich Cu mineral deposits and prospects in the Surigao district of northeast Mindanao. Since their formation in the early Pleistocene, exhumation and weathering of these deposits have led to the development of a 600-m-thick oxidation profile at Boyongan and a modest (30-70 m) oxidation profile at Bayugo. Debris flows, volcanic material, and fluviolacustrine sediments accumulating in the actively extending Mainit graben subsequently covered the weathered deposits, preserving their supergene profiles. The mineral deposits formed in association with a composite diorite complex containing at least 12 discrete intrusive stages. A characteristic progression of vein and K silicate alteration styles affected each of the synmineralisation intrusions. At Boyongan and Bayugo, intense and pervasive illite alteration, in association with pyrite, chalcopyrite, and tetrahedrite-tennantite, developed in narrow structures crosscutting quartz-K-feldspar veins. In both mineral deposits, Cu and Au are associated with intense quartz-vein stockworks composed primarily of K silicate stage 3 veins. The study illustrates the spectrum of metallogenic processes operative over a geologically brief period and highlights some of the key elements responsible for formation of superior grades and for deposit preservation in an extensional setting.

The Wafi-Golpu district of Papua New Guinea contains contrasting high- and intermediate-sulphidation styles of epithermal veins and alteration that have overprinted and partially obscured the giant, high-grade Golpu porphyry Cu-Au deposit. The initial stages of magmatic-hydrothermal activity produced high-grade porphyry-style assemblages that are zoned about the Golpu diorite intrusions, with most mineralisation formed between 8.76 ± 0.02 and 8.73 ± 0.01 Ma. Porphyry mineralisation was followed by the eruption of the Wafi diatreme, after which upward-widening zones of epithermal alteration and mineralisation have overprinted both the mineralised Golpu diorites and the Wafi diatreme. Above the top of the Golpu porphyry, vein and alteration assemblages include quartz (locally vuggy), alunite, pyrophyllite, kaolinite, dickite, and diaspore, with high-sulphidation mineralisation consisting of pyrite-covellite-chalcocite-tennantite ± enargite ± bornite that transitions outward to a distal assemblage of disseminated pyrite-sphalerite ± tennantite. A zone of intermediate-sulphidation epithermal carbonate-sulphide ± quartz ± adularia veins and montmorillonite-chlorite ± muscovite ± illite alteration occurs along the margins of the high-sulphidation domain. Most of the epithermal Au occurs near the transition from the high- to intermediate-sulphidation domains. New geochronological results indicate that the main stage of Golpu porphyry mineralisation to the last stage of Wafi epithermal veins lasted between 120 and 220 k.y. (Authors.), The Wafi-Golpu district of Papua New Guinea contains contrasting high- and intermediate-sulphidation styles of epithermal veins and alteration that have overprinted and partially obscured the giant, high-grade Golpu porphyry Cu-Au deposit. The initial stages of magmatic-hydrothermal activity produced high-grade porphyry-style assemblages that are zoned about the Golpu diorite intrusions, with most mineralisation formed between 8.76 ± 0.02 and 8.73 ± 0.01 Ma. Porphyry mineralisation was followed by the eruption of the Wafi diatreme, after which upward-widening zones of epithermal alteration and mineralisation have overprinted both the mineralised Golpu diorites and the Wafi diatreme. Above the top of the Golpu porphyry, vein and alteration assemblages include quartz (locally vuggy), alunite, pyrophyllite, kaolinite, dickite, and diaspore, with high-sulphidation mineralisation consisting of pyrite-covellite-chalcocite-tennantite ± enargite ± bornite that transitions outward to a distal assemblage of disseminated pyrite-sphalerite ± tennantite. A zone of intermediate-sulphidation epithermal carbonate-sulphide ± quartz ± adularia veins and montmorillonite-chlorite ± muscovite ± illite alteration occurs along the margins of the high-sulphidation domain. Most of the epithermal Au occurs near the transition from the high- to intermediate-sulphidation domains. New geochronological results indicate that the main stage of Golpu porphyry mineralisation to the last stage of Wafi epithermal veins lasted between 120 and 220 k.y. (Authors.)

The Kapan mining district in the southernmost Lesser Caucasus is one of the few locations along the central Tethyan metallogenic belt where ore-forming processes were associated with magmatic arc growth during Jurassic Tethys subduction along the Eurasian margin. Three ore deposits of the Kapan district were investigated in this study: Centralni West, Centralni East, and Shahumyan. The mineralisation consists of veins, subsidiary stockwork, and partial matrix replacement of breccia host rocks, with chalcopyrite, pyrite, tennantite-tetrahedrite, sphalerite, and galena as the main ore minerals. Centralni West is a dominantly Cu deposit, and its host rocks are altered to chlorite, carbonate, epidote, and sericite. At Centralni East, Au is associated with Cu, and the Shahumyan deposit is enriched in Pb and Zn as well as precious metals. Both deposits contain high-sulphidation mineral assemblages with enargite and luzonite. The lead isotope composition of sulphides and alunite (206Pb/204Pb = 18.17-18.32, 207Pb/204Pb = 15.57-15.61, 208Pb/204Pb = 38.17-38.41) indicates a common metal source for the three deposits and suggests that metals were derived from magmatic fluids that were exsolved upon crystallisation of Middle Jurassic intrusive rocks or leached from Middle Jurassic country rocks. The preferred model is that the Centralni West Cu deposit is a volcanogenic massive sulphide deposit and the Shahumyan and Centralni East deposits are parts of porphyryepithermal systems, with the three deposits being broadly coeval or formed within a short time interval in a nascent magmatic arc setting., The Kapan mining district in the southernmost Lesser Caucasus is one of the few locations along the central Tethyan metallogenic belt where ore-forming processes were associated with magmatic arc growth during Jurassic Tethys subduction along the Eurasian margin. Three ore deposits of the Kapan district were investigated in this study: Centralni West, Centralni East, and Shahumyan. The mineralisation consists of veins, subsidiary stockwork, and partial matrix replacement of breccia host rocks, with chalcopyrite, pyrite, tennantite-tetrahedrite, sphalerite, and galena as the main ore minerals. Centralni West is a dominantly Cu deposit, and its host rocks are altered to chlorite, carbonate, epidote, and sericite. At Centralni East, Au is associated with Cu, and the Shahumyan deposit is enriched in Pb and Zn as well as precious metals. Both deposits contain high-sulphidation mineral assemblages with enargite and luzonite. The lead isotope composition of sulphides and alunite (206Pb/204Pb = 18.17-18.32, 207Pb/204Pb = 15.57-15.61, 208Pb/204Pb = 38.17-38.41) indicates a common metal source for the three deposits and suggests that metals were derived from magmatic fluids that were exsolved upon crystallisation of Middle Jurassic intrusive rocks or leached from Middle Jurassic country rocks. The preferred model is that the Centralni West Cu deposit is a volcanogenic massive sulphide deposit and the Shahumyan and Centralni East deposits are parts of porphyryepithermal systems, with the three deposits being broadly coeval or formed within a short time interval in a nascent magmatic arc setting.

Mount Carlton is a Palaeozoic high-sulphidation epithermal deposit located in the northern segment of the Bowen Basin, northeast Queensland. The deposit is hosted in Early Permian volcanic and sedimentary rocks, and an open-pit mining operation includes the Au-rich V2 pit in the northeast and the Ag-rich A39 pit in the southwest. Mineralisation at Mt. Carlton occurred during active rifting, partly contemporaneously with the deposition of volcanic sediments in localised half-graben and graben basins. Steep normal faults and fracture networks related to the rifting acted as fluid conduits and localised cores of silicic alteration. The silicic cores transition outward to zones of quartz-alunite alteration, which are, in turn, enveloped by a zone of quartz-dickite-kaolinite alteration. Epithermal mineralisation at Mt. Carlton developed in three stages: Cu-Au-Ag mineralisation dominated by enargite was overprinted by Zn-Pb-Au-Ag mineralisation dominated by sphalerite, which, in turn, was overprinted by Cu-Au-Ag mineralisation dominated by tennantite. Proximal Au-Cu mineralisation in the V2 pit occurs in networks of steep faults associated with veins and hydrothermal breccias within a massive rhyodacite porphyry. Three distinct ore zones (Eastern, Western, and Link) are aligned, en echelon, along a broadly E trending corridor., Mount Carlton is a Palaeozoic high-sulphidation epithermal deposit located in the northern segment of the Bowen Basin, northeast Queensland. The deposit is hosted in Early Permian volcanic and sedimentary rocks, and an open-pit mining operation includes the Au-rich V2 pit in the northeast and the Ag-rich A39 pit in the southwest. Mineralisation at Mt. Carlton occurred during active rifting, partly contemporaneously with the deposition of volcanic sediments in localised half-graben and graben basins. Steep normal faults and fracture networks related to the rifting acted as fluid conduits and localised cores of silicic alteration. The silicic cores transition outward to zones of quartz-alunite alteration, which are, in turn, enveloped by a zone of quartz-dickite-kaolinite alteration. Epithermal mineralisation at Mt. Carlton developed in three stages: Cu-Au-Ag mineralisation dominated by enargite was overprinted by Zn-Pb-Au-Ag mineralisation dominated by sphalerite, which, in turn, was overprinted by Cu-Au-Ag mineralisation dominated by tennantite. Proximal Au-Cu mineralisation in the V2 pit occurs in networks of steep faults associated with veins and hydrothermal breccias within a massive rhyodacite porphyry. Three distinct ore zones (Eastern, Western, and Link) are aligned, en echelon, along a broadly E trending corridor.

The Northwest quartz-pyrite-gold veins are situated 500 m east of the Lepanto fault in Mankayan. Most vein mineralisation is hosted by the Lepanto metavolcanic basement rocks at an elevation between 700 and 1 050 m. The earliest stage, stage 1, is characterised by sphalerite + chalcopyrite + pyrite ± magnetite veins cutting the host rocks that were altered to chlorite + illite + epidote. Precious metal deposition started in stage 2 as electrum, native gold, and gold-silver tellurides deposited with pyrite, quartz, and carbonate. Deposition of gold and silver tellurides continued in stage 3a with abundant pyrite and tennantite-tetrahedrite solid solution intergrown with chalcopyrite, bornite and minor sphalerite. The stage 3a veins and host-rock alteration are characterised by abundant muscovite and quartz, while the stage 3b veins and alteration consist of quartz, pyrophyllite, alunite, and dickite. Enargite and luzonite are the dominant sulphide minerals in stage 4, which are either disseminated in silicified host rock or within wide quartz veins. Lesser amounts of quartz and abundant pyrite with inclusions of enargite and luzonite were precipitated in stage 5. Fluid inclusions and stable isotope analysis results are compared with available data from nearby well-studied deposits and provide implications for its formation in relation to the surrounding deposits., The Northwest quartz-pyrite-gold veins are situated 500 m east of the Lepanto fault in Mankayan. Most vein mineralisation is hosted by the Lepanto metavolcanic basement rocks at an elevation between 700 and 1 050 m. The earliest stage, stage 1, is characterised by sphalerite + chalcopyrite + pyrite ± magnetite veins cutting the host rocks that were altered to chlorite + illite + epidote. Precious metal deposition started in stage 2 as electrum, native gold, and gold-silver tellurides deposited with pyrite, quartz, and carbonate. Deposition of gold and silver tellurides continued in stage 3a with abundant pyrite and tennantite-tetrahedrite solid solution intergrown with chalcopyrite, bornite and minor sphalerite. The stage 3a veins and host-rock alteration are characterised by abundant muscovite and quartz, while the stage 3b veins and alteration consist of quartz, pyrophyllite, alunite, and dickite. Enargite and luzonite are the dominant sulphide minerals in stage 4, which are either disseminated in silicified host rock or within wide quartz veins. Lesser amounts of quartz and abundant pyrite with inclusions of enargite and luzonite were precipitated in stage 5. Fluid inclusions and stable isotope analysis results are compared with available data from nearby well-studied deposits and provide implications for its formation in relation to the surrounding deposits.

The Tsumeb orebody is a pipe-like structure lying in late Precambrian bedded dolomite. The major economic minerals are tennantite, chalcocite, bornite, galena and sphalerite. Silver is extracted in addition to copper, lead and zinc. The high rock pressures at the deeper levels of the mine have made it necessary to change the mining method and introduce cable-bolting. A thorough investigation of the mechanics of cable bolting has been carried out following the collapse of two cable-bolted stopes., The Tsumeb orebody is a pipe-like structure lying in late Precambrian bedded dolomite. The major economic minerals are tennantite, chalcocite, bornite, galena and sphalerite. Silver is extracted in addition to copper, lead and zinc. The high rock pressures at the deeper levels of the mine have made it necessary to change the mining method and introduce cable-bolting. A thorough investigation of the mechanics of cable bolting has been carried out following the collapse of two cable-bolted stopes.