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Danish people have a relatively high death-rate, compared to other Nordic countries. This has not gone unnoticed. The government has been actively promoting a healthy lifestyle for quite some time now. This promotion is mainly focussed on physical health. With this public condenser project, an architectural interpretation of this healthy lifestyle is provided. Hereby, the focus is not just on physical health. Since mental health and physical health are always connected, the project addresses both subjects. On top of that, a healthcare component is also addressed within the intervention, in order to make sure that nothing is “broken”, and that the physical and mental health can be continuously developed. By taking a very contextual approach to the way that the design is created and structured, it is possible to strengthen the positive qualities of the site, whilst simultaneously tending to the aspects of the site that could be better. Therefore the project is not just conceptually integrated (by the overarching theme), but also contextually., Public Condenser: Copenhagen, Architecture, Urbanism and Building Sciences

The 2492 Ma deposit occurs on the margin of the West African craton in an Archaean carbonate-facies banded iron formation, having formed during regional shearing in upper-greenschist/lower-amphibolite facies rocks. The hydrothermal mineralisation, hosted by breccias and shear zones that focused the ore fluids, comprises magnetite, pyrrhotite, chalcopyrite, Fe- Co-Ni arsenides, arsenopyrite, cobaltite and Bi-Au-Ag-Te minerals. The meta-carbonate has three types of fluid inclusions, which indicate that the IOCG deposit resulted from complex hydrothermal evolution, with Au transported as AuCl2(-) complexes in undersaturated ore fluids and concentrated in co-existing Bi melt-droplets so that an assemblage of Au- Bi was precipitated during cooling., The 2492 Ma deposit occurs on the margin of the West African craton in an Archaean carbonate-facies banded iron formation, having formed during regional shearing in upper-greenschist/lower-amphibolite facies rocks. The hydrothermal mineralisation, hosted by breccias and shear zones that focused the ore fluids, comprises magnetite, pyrrhotite, chalcopyrite, Fe- Co-Ni arsenides, arsenopyrite, cobaltite and Bi-Au-Ag-Te minerals. The meta-carbonate has three types of fluid inclusions, which indicate that the IOCG deposit resulted from complex hydrothermal evolution, with Au transported as AuCl2(-) complexes in undersaturated ore fluids and concentrated in co-existing Bi melt-droplets so that an assemblage of Au- Bi was precipitated during cooling.

The evaluation of typical ore characteristics of 170 bauxite deposits worldwide has led to the identification of ten critical parameters that affect mineral availability in the context of sustainability. Results indicate that a future increase in quality requirements in the environmental category by 50% will result in a reduction of presently available resources by 20%, decreasing the number of producing deposits to 84, whereas a quality increase of 70% will reduce resources substantially to 21% of the present figure., The evaluation of typical ore characteristics of 170 bauxite deposits worldwide has led to the identification of ten critical parameters that affect mineral availability in the context of sustainability. Results indicate that a future increase in quality requirements in the environmental category by 50% will result in a reduction of presently available resources by 20%, decreasing the number of producing deposits to 84, whereas a quality increase of 70% will reduce resources substantially to 21% of the present figure.

The basin formed over a period of 360 Ma. Sedimentation was episodic and pulses occurred between 3086-3074 Ma (Dominion), 2970-2914 Ma (West Rand) and 2894-2714 (Central Rand and Ventersdorp Contact Reef). Detritus was derived from a mixed granite-greenstone source of two distinct ages. Granitoid plutonism occurred during hiatuses in sedimentation throughout the life of the basin, many of the granitoids being characterised by hydrothermal alteration and geochemically anomalous with respect to Au and U. Tectonically the basin evolved within a long Wilson cycle ending in collision of the Zimbabwe and Kaapvaal cratons. Metamorphism occurred at 2500 and 2300 Ma, with progressive loading by Ventersdorp and Transvaal cover sequences, and at 2000 Ma with Bushveld Complex intrusion or Vredefort catastrophism. Mineralisation is concentrated in the conglomerates of the Central Rand Group and represents early accumulation of detrital heavy minerals and at least two stages of mineral reconstitution caused by metahydrothermal fluids. An early event of authigenic pyrite formation was accompanied by the radiolytic fixing of carbonaceous matter around detrital uraninite. This was followed by an event related to peak metamorphism which resulted in widespread redistribution of gold and the formation of various secondary sulphides. Fluid conditions were such that metal solubilities were very low and precipitation mechanisms very effective, resulting in the superimposition of both primary and secondary mineralisation., The basin formed over a period of 360 Ma. Sedimentation was episodic and pulses occurred between 3086-3074 Ma (Dominion), 2970-2914 Ma (West Rand) and 2894-2714 (Central Rand and Ventersdorp Contact Reef). Detritus was derived from a mixed granite-greenstone source of two distinct ages. Granitoid plutonism occurred during hiatuses in sedimentation throughout the life of the basin, many of the granitoids being characterised by hydrothermal alteration and geochemically anomalous with respect to Au and U. Tectonically the basin evolved within a long Wilson cycle ending in collision of the Zimbabwe and Kaapvaal cratons. Metamorphism occurred at 2500 and 2300 Ma, with progressive loading by Ventersdorp and Transvaal cover sequences, and at 2000 Ma with Bushveld Complex intrusion or Vredefort catastrophism. Mineralisation is concentrated in the conglomerates of the Central Rand Group and represents early accumulation of detrital heavy minerals and at least two stages of mineral reconstitution caused by metahydrothermal fluids. An early event of authigenic pyrite formation was accompanied by the radiolytic fixing of carbonaceous matter around detrital uraninite. This was followed by an event related to peak metamorphism which resulted in widespread redistribution of gold and the formation of various secondary sulphides. Fluid conditions were such that metal solubilities were very low and precipitation mechanisms very effective, resulting in the superimposition of both primary and secondary mineralisation.

A mass balance study of bauxite was performed to analyse the first stage of materials flow associated with the aluminium processing cycle. Evaluation of ore characteristics of around 80 bauxite deposits world-wide allowed identification of critical parameters that affect subsequent alumina production. The combining of bauxite characteristics led to the definition of quality parameters which can be used to identify areas where materials flow and waste can be reduced. These parameters include mass ratios of bauxite to alumina and waste to alumina. The high variance of bauxite quality provides options for optimal mine selection. Assessment of bauxite resources shows a trend that indicates a general reduction of ore quality in the future., A mass balance study of bauxite was performed to analyse the first stage of materials flow associated with the aluminium processing cycle. Evaluation of ore characteristics of around 80 bauxite deposits world-wide allowed identification of critical parameters that affect subsequent alumina production. The combining of bauxite characteristics led to the definition of quality parameters which can be used to identify areas where materials flow and waste can be reduced. These parameters include mass ratios of bauxite to alumina and waste to alumina. The high variance of bauxite quality provides options for optimal mine selection. Assessment of bauxite resources shows a trend that indicates a general reduction of ore quality in the future.

Present characteristics of Witwatersrand mineralisation reflect 1 000 Ma of depositional processes and post-burial diagenetic/metamorphic activity. Fluid and mineralogical constraints suggest that the (Au(HS)2)- complex has limited solubility under conditions pertaining to post-burial fluid migration, but the (AuCl2)- complex has potential for gold transport at temperatures greater than 350 degrees C. The ubiquitous uraninite-kerogen association is characterised by a paragenetic sequence involving early detrital uraninite concentration with later fixation of hydrocarbon residues around uraninite accumulations. The present mineral association in the Witwatersrand Basin can best be accommodated by an early accumulation of detrital minerals and subsequent remobilisation probably during a number of different stages., Present characteristics of Witwatersrand mineralisation reflect 1 000 Ma of depositional processes and post-burial diagenetic/metamorphic activity. Fluid and mineralogical constraints suggest that the (Au(HS)2)- complex has limited solubility under conditions pertaining to post-burial fluid migration, but the (AuCl2)- complex has potential for gold transport at temperatures greater than 350 degrees C. The ubiquitous uraninite-kerogen association is characterised by a paragenetic sequence involving early detrital uraninite concentration with later fixation of hydrocarbon residues around uraninite accumulations. The present mineral association in the Witwatersrand Basin can best be accommodated by an early accumulation of detrital minerals and subsequent remobilisation probably during a number of different stages.

The zone, representing a mid-crustal section of an island arc, shows a complex orogenic evolution in a long-lasting E-W compressional environment. Peak metamorphic doming of the granite-gneisses was followed by retrograde exhumation and gold mineralisation at Kochkar, coinciding with the intrusion of Permian granites. This, and the fact that the hypozonal deposit is not hosted by a major shear zone, contradicts a Cordilleran tectonic setting. Instead, a post-collisional slab rollback or delamination of the lithosphere may have provided the heat source for the large-scale Carboniferous to Permian melting event and the fluid plumbing system for gold mineralisation., The zone, representing a mid-crustal section of an island arc, shows a complex orogenic evolution in a long-lasting E-W compressional environment. Peak metamorphic doming of the granite-gneisses was followed by retrograde exhumation and gold mineralisation at Kochkar, coinciding with the intrusion of Permian granites. This, and the fact that the hypozonal deposit is not hosted by a major shear zone, contradicts a Cordilleran tectonic setting. Instead, a post-collisional slab rollback or delamination of the lithosphere may have provided the heat source for the large-scale Carboniferous to Permian melting event and the fluid plumbing system for gold mineralisation.

Structural interpretation of the belt has been enhanced by new U-Pb zircon SHRIMP ages for the syn-tectonic Kavital granitoid and felsic metavolcanic host rocks. It is concluded that two phases of gold mineralisation occurred within 30 m.y. of each other during the belt's evolution within the tectonic framework of the Dharwar craton, India. The Hutti gold mine is still producing ore grading 6.29 g/t from six of its nine reefs., Structural interpretation of the belt has been enhanced by new U-Pb zircon SHRIMP ages for the syn-tectonic Kavital granitoid and felsic metavolcanic host rocks. It is concluded that two phases of gold mineralisation occurred within 30 m.y. of each other during the belt's evolution within the tectonic framework of the Dharwar craton, India. The Hutti gold mine is still producing ore grading 6.29 g/t from six of its nine reefs.

GIS-based mineral potential mapping has successfully yielded two potential Cu-Au prospects in the Inchiri region, El Joul West and Camel Tick, which will be the subject of intense exploration in the near future, and a high-potential zone for the occurrence of Cu-Au prospects in the south. The three stages of the project were: developing exploration information systems for the region; defining an exploration model, using recognition criteria identified from datasets for the Guelb Moghrein iron oxide copper-gold deposit; and mapping the favourability for such deposits. It is concluded that the weights-of-evidence and fuzzy logic methods are powerful tools for mapping mineral potential: although completely different in their methodologies, both independently present similar results for each of the two regions., GIS-based mineral potential mapping has successfully yielded two potential Cu-Au prospects in the Inchiri region, El Joul West and Camel Tick, which will be the subject of intense exploration in the near future, and a high-potential zone for the occurrence of Cu-Au prospects in the south. The three stages of the project were: developing exploration information systems for the region; defining an exploration model, using recognition criteria identified from datasets for the Guelb Moghrein iron oxide copper-gold deposit; and mapping the favourability for such deposits. It is concluded that the weights-of-evidence and fuzzy logic methods are powerful tools for mapping mineral potential: although completely different in their methodologies, both independently present similar results for each of the two regions.

The mine is associated with a Late Archaean shear zone in the Chitradurga greenstone belt. Gold is hosted by a 100 m wide antiform in a banded iron formation, where original magnetite and siderite have been replaced by a peak metamorphic alteration assemblage of chlorite, stilpnomelane, minnesotaite, sericite, ankerite, arsenopyrite, pyrite, pyrrhotite and gold at c.300-350 degrees C. The more reactive Fe-rich layers are enriched to a far greater extent than the wall rocks. Isotope analysis indicates that the ore fluids were formed by metamorphic devolatilisation of the greenstone belt's deeper levels. Spatial, temporal and structural relationships suggest that mineralisation took place when fluids infiltrated a low-strain area within the first-order structure and were transported along this shear zone to relatively shallow crustal levels during lateral terrane accretion and a change from thrust to concurrent tectonics. Exploration should focus on similar low-strain areas or potentially connected higher-order splays., The mine is associated with a Late Archaean shear zone in the Chitradurga greenstone belt. Gold is hosted by a 100 m wide antiform in a banded iron formation, where original magnetite and siderite have been replaced by a peak metamorphic alteration assemblage of chlorite, stilpnomelane, minnesotaite, sericite, ankerite, arsenopyrite, pyrite, pyrrhotite and gold at c.300-350 degrees C. The more reactive Fe-rich layers are enriched to a far greater extent than the wall rocks. Isotope analysis indicates that the ore fluids were formed by metamorphic devolatilisation of the greenstone belt's deeper levels. Spatial, temporal and structural relationships suggest that mineralisation took place when fluids infiltrated a low-strain area within the first-order structure and were transported along this shear zone to relatively shallow crustal levels during lateral terrane accretion and a change from thrust to concurrent tectonics. Exploration should focus on similar low-strain areas or potentially connected higher-order splays.

The geological characteristics of Cu deposits are evaluated. Worldwide, primary Cu production will rise from 13 400 000 t in 2002 to more than 15 000 00 t in 2050. Current world reserves are estimated at 548 000 000 t Cu with an estimated reserve life index of more than 30 years. Most production and reserves are located in North and South America, Indonesia, Poland and Australia: in 2002 Chile produced 4 450 000 t Cu from 26 mines, the USA 1 130 000 t from 19 mines and Indonesia 1 100 000 t from 2 mines, while reserves were estimated as 160 000 000 t Cu in Chile, 35 000 000 t in the USA, 35 000 000 t in Peru, 31 000 000 t in Poland and 28 000 000 t in Indonesia. Porphyry deposits and sulphide ores constitute 70-80% of both production and reserves. On average, prospects contain lower Cu grades than operating mines. Ore grade and by-products such as Au, Ag, Zn and Pb exert an important control on economic performance, polymetallic VHMS and kuroko deposits yielding a higher net smelter return than porphyry and skarn ores., The geological characteristics of Cu deposits are evaluated. Worldwide, primary Cu production will rise from 13 400 000 t in 2002 to more than 15 000 00 t in 2050. Current world reserves are estimated at 548 000 000 t Cu with an estimated reserve life index of more than 30 years. Most production and reserves are located in North and South America, Indonesia, Poland and Australia: in 2002 Chile produced 4 450 000 t Cu from 26 mines, the USA 1 130 000 t from 19 mines and Indonesia 1 100 000 t from 2 mines, while reserves were estimated as 160 000 000 t Cu in Chile, 35 000 000 t in the USA, 35 000 000 t in Peru, 31 000 000 t in Poland and 28 000 000 t in Indonesia. Porphyry deposits and sulphide ores constitute 70-80% of both production and reserves. On average, prospects contain lower Cu grades than operating mines. Ore grade and by-products such as Au, Ag, Zn and Pb exert an important control on economic performance, polymetallic VHMS and kuroko deposits yielding a higher net smelter return than porphyry and skarn ores.

The study is based on data from more than 300 mines that produced almost 95% of world Cu output in 1998. World production in 1998 was 12 100 000 t Cu and total losses during mining and mineral processing were calculated as 4 200 000 t. About 27% of the loss can be attributed to mining and 73% to processing.The amount of unextracted copper is controlled by properties of different deposit types such as orebody depth and shape and ore mineralogy. Porphyry deposits show high beneficiation-related loss whereas a high proportion of losses from stratiform sediment-hosted and VMS deposits are related to underground mining methods. Analysis of relative statistical entropy combined with calculated copper losses proved useful for evaluating geological properties before a background of sustainable development., The study is based on data from more than 300 mines that produced almost 95% of world Cu output in 1998. World production in 1998 was 12 100 000 t Cu and total losses during mining and mineral processing were calculated as 4 200 000 t. About 27% of the loss can be attributed to mining and 73% to processing.The amount of unextracted copper is controlled by properties of different deposit types such as orebody depth and shape and ore mineralogy. Porphyry deposits show high beneficiation-related loss whereas a high proportion of losses from stratiform sediment-hosted and VMS deposits are related to underground mining methods. Analysis of relative statistical entropy combined with calculated copper losses proved useful for evaluating geological properties before a background of sustainable development.

The category of orogenic gold deposits, which generally formed in collisional or accretionary orogenic belts, is taken to include mesothermal, metamorphic, gold-only, lode-gold, shear-zone-hosted and structurally controlled deposits, including the deposits of Archaean greenstone belts and Phanerozoic turbidite-hosted deposits. Detailed investigation of Mindyak and Kochkar in the Urals, Renco in the Limpopo belt and Lega Dembi in the Megado belt has revealed their complex, dynamic histories of mineralisation. Mindyak, Lega Dembi and Renco are hosted by transcrustal shear zones separating different terranes; mineralisation at Mendyak and Lega Dembi shortly postdated the transition from compression to transpression during late-tectonic accretion, while Renco was probably a deep-crustal equivalent. In contrast, Kochkar is hosted by small-scale structures where mafic dykes cross-cut granites; it may have resulted from external heating of the crust due to delamination of the lithosphere and magmatic underplating., The category of orogenic gold deposits, which generally formed in collisional or accretionary orogenic belts, is taken to include mesothermal, metamorphic, gold-only, lode-gold, shear-zone-hosted and structurally controlled deposits, including the deposits of Archaean greenstone belts and Phanerozoic turbidite-hosted deposits. Detailed investigation of Mindyak and Kochkar in the Urals, Renco in the Limpopo belt and Lega Dembi in the Megado belt has revealed their complex, dynamic histories of mineralisation. Mindyak, Lega Dembi and Renco are hosted by transcrustal shear zones separating different terranes; mineralisation at Mendyak and Lega Dembi shortly postdated the transition from compression to transpression during late-tectonic accretion, while Renco was probably a deep-crustal equivalent. In contrast, Kochkar is hosted by small-scale structures where mafic dykes cross-cut granites; it may have resulted from external heating of the crust due to delamination of the lithosphere and magmatic underplating.

Depending on the quality of the bauxite and the technical layout of the Bayer process, between 1.1 and 6.2 tons of red mud are generated per ton of alumina produced. The critical bauxite parameters that influence process conditions during digestion are defined, characterised and quantified and potential ways of optimising the process to reduce red mud output are identified. Models are presented of various geological and technical scenarios, tracing the flow of raw material during alumina production., Depending on the quality of the bauxite and the technical layout of the Bayer process, between 1.1 and 6.2 tons of red mud are generated per ton of alumina produced. The critical bauxite parameters that influence process conditions during digestion are defined, characterised and quantified and potential ways of optimising the process to reduce red mud output are identified. Models are presented of various geological and technical scenarios, tracing the flow of raw material during alumina production.

In order to establish new criteria for hydrothermal deposits in the former alluvial gold province, the controls on ore formation are particularly emphasised in the study of two representative deposits. At Mindyak and adjacent deposits, postcollisional shear movement along a deep suture zone created permeabilities for mineralising fluids, while the specific geochemistry of adjacent wall-rocks controlled precipitation of gold and sulphides. At Kochkar, mineralisation is in hydrothermal quartz veins hosted by basalt dykes in the Plast granitoid massif. The E-W regional stress field induced tectonic movement along the dyke-granitoid interface, creating pathways for mineralising fluids., In order to establish new criteria for hydrothermal deposits in the former alluvial gold province, the controls on ore formation are particularly emphasised in the study of two representative deposits. At Mindyak and adjacent deposits, postcollisional shear movement along a deep suture zone created permeabilities for mineralising fluids, while the specific geochemistry of adjacent wall-rocks controlled precipitation of gold and sulphides. At Kochkar, mineralisation is in hydrothermal quartz veins hosted by basalt dykes in the Plast granitoid massif. The E-W regional stress field induced tectonic movement along the dyke-granitoid interface, creating pathways for mineralising fluids.

Renco is the only known gold deposit in the granulite-facies terrain of the Limpopo Belt's northern marginal zone. Gold mineralisation is restricted to a shear-zone system, which formed as a second-order structure during thrusting of the northern marginal zone over the Zimbabwe Craton. Mineralisation and deformation occurred under retrograde amphibolite-facies conditions and hydration of the granulite-facies host rocks at about 650 degrees C. The mainly free gold is closely associated with pyrrhotite, chalcopyrite and pyrite, while the alteration assemblage includes garnet, biotite, alkali feldspar, quartz and sometimes siderite. Geochemically, the mineralised shear zones are enriched in Au, S, Fe, Cu, Mo, Bi, Te, Ni, Co and H2O. Deposition of gold from hydrothermal phases was caused by dramatic drops in fluid pressure during phases of brittle deformation. Geochemical and stable-isotope data suggest an external source for the mineralising fluids, by metamorphism of subducted greenstone lithologies of the Zimbabwe Craton., Renco is the only known gold deposit in the granulite-facies terrain of the Limpopo Belt's northern marginal zone. Gold mineralisation is restricted to a shear-zone system, which formed as a second-order structure during thrusting of the northern marginal zone over the Zimbabwe Craton. Mineralisation and deformation occurred under retrograde amphibolite-facies conditions and hydration of the granulite-facies host rocks at about 650 degrees C. The mainly free gold is closely associated with pyrrhotite, chalcopyrite and pyrite, while the alteration assemblage includes garnet, biotite, alkali feldspar, quartz and sometimes siderite. Geochemically, the mineralised shear zones are enriched in Au, S, Fe, Cu, Mo, Bi, Te, Ni, Co and H2O. Deposition of gold from hydrothermal phases was caused by dramatic drops in fluid pressure during phases of brittle deformation. Geochemical and stable-isotope data suggest an external source for the mineralising fluids, by metamorphism of subducted greenstone lithologies of the Zimbabwe Craton.

A comparison of past uranium ore reserve estimates with actual production figures for Key Lake, in Saskatchewan, shows that in general ore tonnage was underestimated and ore grade overestimated. The combination of these factors resulted in errors ranging from -20% to +30% in predicting the metal content of the Gaertner orebody and -12% to +9% in predicting the content of the Deilmann orebody. Reserve calculations undertaken with modern Datamine software show much smaller discrepancies. These results indicate that the irregular shape of the orebodies was initially not properly modelled, while ore lenses close to the main orebody, which were recovered during mining, had not been taken into account in the initial calculations. An additional factor in tonnage and grade discrepancies was ore dilution with waste rock. A more reliable reserve calculation can be achieved by using more refined three-dimensional orebody modelling and factoring in both isolated lenses and dilution., A comparison of past uranium ore reserve estimates with actual production figures for Key Lake, in Saskatchewan, shows that in general ore tonnage was underestimated and ore grade overestimated. The combination of these factors resulted in errors ranging from -20% to +30% in predicting the metal content of the Gaertner orebody and -12% to +9% in predicting the content of the Deilmann orebody. Reserve calculations undertaken with modern Datamine software show much smaller discrepancies. These results indicate that the irregular shape of the orebodies was initially not properly modelled, while ore lenses close to the main orebody, which were recovered during mining, had not been taken into account in the initial calculations. An additional factor in tonnage and grade discrepancies was ore dilution with waste rock. A more reliable reserve calculation can be achieved by using more refined three-dimensional orebody modelling and factoring in both isolated lenses and dilution.

The district, with production of more than 300 t Au in over 250 years, is hosted by granite gneisses. Gold mineralisation is associated with tabular quartz lodes developed preferentially along the margins of easterly-trending mafic dykes. Fabric development indicates that the dykes had a profound influence on the development of shear zones in the granitoids. ENE- and SE-trending dykes were reactivated as dextral and sinistral oblique strike-slip zones, forming a set of conjugate shear zones related to regional-scale Permian shortening. The relationships between dykes and shear zones in the Plast massif resulted from strain refraction due to the presence of biotite-rich, incompetent dykes in the granite-gneisses. Brittle fracturing of the granitoids adjacent to the sheared dykes added to the permeability of their layer-normal dilational shear component, promoting the access of mineralising fluids. Both dykes and gold lodes were later overprinted by mainly brittle fault zones and hydrothermal alteration., The district, with production of more than 300 t Au in over 250 years, is hosted by granite gneisses. Gold mineralisation is associated with tabular quartz lodes developed preferentially along the margins of easterly-trending mafic dykes. Fabric development indicates that the dykes had a profound influence on the development of shear zones in the granitoids. ENE- and SE-trending dykes were reactivated as dextral and sinistral oblique strike-slip zones, forming a set of conjugate shear zones related to regional-scale Permian shortening. The relationships between dykes and shear zones in the Plast massif resulted from strain refraction due to the presence of biotite-rich, incompetent dykes in the granite-gneisses. Brittle fracturing of the granitoids adjacent to the sheared dykes added to the permeability of their layer-normal dilational shear component, promoting the access of mineralising fluids. Both dykes and gold lodes were later overprinted by mainly brittle fault zones and hydrothermal alteration.

The deposit, in the Late Proterozoic, meta-volcanosedimentary Megado belt, has an average grade of 3 g/t Au and proven reserves of 60 t Au. It is located in a dilational jog along a shear zone, where gold precipitation in quartz veins was induced by phase separation from a parental fluid as a result of fluid focusing and throttling into dilatant sites of low mean stress, during the waning stages of the Pan-African tectono-thermal event. The preferred localisation of gold-bearing veins in metasediments suggests a further lithological control on ore formation. Four types of quartz veins can be distinguished within three main systems, resulting from five stages of alteration and mineralisation. The ore-controlling factors can be used to formulate regional exploration models for the area, with structural information such as lithology strike changes particularly important and sedimentary rocks the most likely hosts., The deposit, in the Late Proterozoic, meta-volcanosedimentary Megado belt, has an average grade of 3 g/t Au and proven reserves of 60 t Au. It is located in a dilational jog along a shear zone, where gold precipitation in quartz veins was induced by phase separation from a parental fluid as a result of fluid focusing and throttling into dilatant sites of low mean stress, during the waning stages of the Pan-African tectono-thermal event. The preferred localisation of gold-bearing veins in metasediments suggests a further lithological control on ore formation. Four types of quartz veins can be distinguished within three main systems, resulting from five stages of alteration and mineralisation. The ore-controlling factors can be used to formulate regional exploration models for the area, with structural information such as lithology strike changes particularly important and sedimentary rocks the most likely hosts.

The mine is the major gold producer in the Iron Quadrilateral and one of the largest in Brazil. Gold mineralisation is associated with orebodies occurring within the Archaean Cuiaba banded iron formation, which lies beween horizons of greenschist-facies mafic metavolcanic rocks with carbonaceous metasediments and metavolcaniclastic rocks, affected by three deformation stages. The main gold mineralisation is hosted by six orebodies of 1-6 m thickness, containing sulphide-rich material with more than 4 ppm Au, varying from light to dark in colour and in places massive, non-banded or recrystallised. The Au-dominated deposit is characterised by an association of Au, Ag, As and Sb; the fine Au grains are up to 60 micrometres in size and bound to the sulphides. At present, four of eleven planned mining levels are completely exhausted. The mine produces 540 000 t/a of ore averaging 8 g/t Au, with some by-product silver, by open stoping and cut-and-fill methods. Proven reserves exceed 180 t Au, at a cut-off grade of 4.0 g/t Au., The mine is the major gold producer in the Iron Quadrilateral and one of the largest in Brazil. Gold mineralisation is associated with orebodies occurring within the Archaean Cuiaba banded iron formation, which lies beween horizons of greenschist-facies mafic metavolcanic rocks with carbonaceous metasediments and metavolcaniclastic rocks, affected by three deformation stages. The main gold mineralisation is hosted by six orebodies of 1-6 m thickness, containing sulphide-rich material with more than 4 ppm Au, varying from light to dark in colour and in places massive, non-banded or recrystallised. The Au-dominated deposit is characterised by an association of Au, Ag, As and Sb; the fine Au grains are up to 60 micrometres in size and bound to the sulphides. At present, four of eleven planned mining levels are completely exhausted. The mine produces 540 000 t/a of ore averaging 8 g/t Au, with some by-product silver, by open stoping and cut-and-fill methods. Proven reserves exceed 180 t Au, at a cut-off grade of 4.0 g/t Au.

The deposit is dissected by deep erosion valleys, resulting in a discontinuous bauxite blanket with the orebody dismembered into nine isolated blocks. Production planning is further hampered by both vertical and lateral heterogeneity in ore-grade distribution. A computer-based evaluation of four different haulage models shows that in-pit ore transport by trucks from the extraction site to the crusher is by far the best economic solution. Alternative models, employing conveyor belts of various lengths and the installation of a second crusher, result in lower operating and personnel costs but much higher total costs, because of increased capital investment. Comparison of environmental parameters, such as atmospheric emissions from fuel combustion, indicates that alternative transport schemes will reduce total emissions over the period considered by about 35%, compared with truck haulage only., The deposit is dissected by deep erosion valleys, resulting in a discontinuous bauxite blanket with the orebody dismembered into nine isolated blocks. Production planning is further hampered by both vertical and lateral heterogeneity in ore-grade distribution. A computer-based evaluation of four different haulage models shows that in-pit ore transport by trucks from the extraction site to the crusher is by far the best economic solution. Alternative models, employing conveyor belts of various lengths and the installation of a second crusher, result in lower operating and personnel costs but much higher total costs, because of increased capital investment. Comparison of environmental parameters, such as atmospheric emissions from fuel combustion, indicates that alternative transport schemes will reduce total emissions over the period considered by about 35%, compared with truck haulage only.

Computer modelling of the deposit was carried out using DATAMINE in conjunction with graphic support. Cross sections and level plans of the mine were manually digitised on a digitising tablet. Level plans were combined with cross sections for the respective levels and a wire-frame model constructed by correlating and linking fold limbs in adjacent vertical and horizontal sections by triangulation. The 3-D model generated portrays the orebody as a whole, but structural details, such as small-scale faulting and local-scale distortions of the orebody, cannot be adequately represented. A previously unnoticed deflection of the orebody from its projected orientation was identified, which will result in a modification of exploration strategies aimed at identifying further extensions of mineralisation. Additional information such as ore grades and tonnage evaluations, together with further geophysical and lithogeochemical data, can easily be added to the existing model., Computer modelling of the deposit was carried out using DATAMINE in conjunction with graphic support. Cross sections and level plans of the mine were manually digitised on a digitising tablet. Level plans were combined with cross sections for the respective levels and a wire-frame model constructed by correlating and linking fold limbs in adjacent vertical and horizontal sections by triangulation. The 3-D model generated portrays the orebody as a whole, but structural details, such as small-scale faulting and local-scale distortions of the orebody, cannot be adequately represented. A previously unnoticed deflection of the orebody from its projected orientation was identified, which will result in a modification of exploration strategies aimed at identifying further extensions of mineralisation. Additional information such as ore grades and tonnage evaluations, together with further geophysical and lithogeochemical data, can easily be added to the existing model.

The gold is mainly confined to two tectonostratigraphic zones. Those within and in the immediate hanging wall of the Main Uralian Fault had a complex history of earlier thrusting, folding and reverse faulting, and later transcurrent shearing. Gold is hosted by strike-slip faults that developed by reactivation of ealier compressional structures as the passive margin of the east European platform docked with island arcs of the southern Urals during the Upper Permian and Lower Triassic. Mineralisation occurred at relatively shallow levels (2-6 km), mostly after peak metamorphism. In the East Uralian Zone, deposits of up to 300 t Au are hosted by competent Upper Carboniferous and Lower Permian granites intruded during the main phase of regional compression. Controlling structures are E-W-striking hybrid shear-tensional vein systems. Deformation textures and alteration assemblages indicate mineralisation under conditions close to peak metamorphism., The gold is mainly confined to two tectonostratigraphic zones. Those within and in the immediate hanging wall of the Main Uralian Fault had a complex history of earlier thrusting, folding and reverse faulting, and later transcurrent shearing. Gold is hosted by strike-slip faults that developed by reactivation of ealier compressional structures as the passive margin of the east European platform docked with island arcs of the southern Urals during the Upper Permian and Lower Triassic. Mineralisation occurred at relatively shallow levels (2-6 km), mostly after peak metamorphism. In the East Uralian Zone, deposits of up to 300 t Au are hosted by competent Upper Carboniferous and Lower Permian granites intruded during the main phase of regional compression. Controlling structures are E-W-striking hybrid shear-tensional vein systems. Deformation textures and alteration assemblages indicate mineralisation under conditions close to peak metamorphism.

Renco is the only known major gold deposit in the granulite-facies terrain of the northern margin of the Limpopo belt. Mineralisation is confined to a system of high-temperature mylonite zones and has two distinct geometries: shallow SE-dipping, anastomosing, tabular lodes and subvertically inclined E-plunging pipelike lodes. Kinematics and orientation are consistent with the lateral and frontal thrusting of the northern marginal zone on to the Zimbabwe craton during the Late Archaean. Gold is spatially and temporally closely associated with sulphides, especially pyrrhotite. Mineral textures and garnet-biotite thermometry indicate gold deposition at about 600 degrees C under mid-amphibolite conditions, slightly after peak metamorphism. Fluid flow was largely controlled by fracture permeabilities, with transient episodes of brittle fracturing promoted by strain partitioning into ductile and brittle-ductile bands, the latter containing the bulk of the gold., Renco is the only known major gold deposit in the granulite-facies terrain of the northern margin of the Limpopo belt. Mineralisation is confined to a system of high-temperature mylonite zones and has two distinct geometries: shallow SE-dipping, anastomosing, tabular lodes and subvertically inclined E-plunging pipelike lodes. Kinematics and orientation are consistent with the lateral and frontal thrusting of the northern marginal zone on to the Zimbabwe craton during the Late Archaean. Gold is spatially and temporally closely associated with sulphides, especially pyrrhotite. Mineral textures and garnet-biotite thermometry indicate gold deposition at about 600 degrees C under mid-amphibolite conditions, slightly after peak metamorphism. Fluid flow was largely controlled by fracture permeabilities, with transient episodes of brittle fracturing promoted by strain partitioning into ductile and brittle-ductile bands, the latter containing the bulk of the gold.

Gold mineralisation at the mine occurs in high-temperature shear zones, locally referred to as reefs. Two reef geometries can be identified: shallow reefs are a series of shallow southeasterly dipping, NNE- to ENE-trending auriferous shear zones and steep reefs are subvertically inclined, shallow easterly plunging pipe-like lodes. The kinematics and orientation of the mineralised shear zones correspond to a lateral and frontal thrust zone geometry that formed during the late Archaean. Wall-rock alteration associated with gold mineralisation comprises a garnet-biotite-quartz +/- siderite mineral assemblage. Gold is spatially and temporally associated with sulphide mineralisation including pyrrhotite as the dominant sulphide and minor amounts of chalcopyrite and pyrite. Garnet-biotite thermometry and mineral textures within the host structures indicate that gold deposition occurred at temperatures of or above 600 degrees C, corresponding to mid-amphibolite-facies conditions slightly post-dating peak metamorphism. The high-grade metamorphic ore and alteration mineral parageneses are overprinted by lower-greenschist facies parageneses along brittle faults and cataclasites that are related to the mid-Proterozoic tectonism of the Northern Marginal Zone., Gold mineralisation at the mine occurs in high-temperature shear zones, locally referred to as reefs. Two reef geometries can be identified: shallow reefs are a series of shallow southeasterly dipping, NNE- to ENE-trending auriferous shear zones and steep reefs are subvertically inclined, shallow easterly plunging pipe-like lodes. The kinematics and orientation of the mineralised shear zones correspond to a lateral and frontal thrust zone geometry that formed during the late Archaean. Wall-rock alteration associated with gold mineralisation comprises a garnet-biotite-quartz +/- siderite mineral assemblage. Gold is spatially and temporally associated with sulphide mineralisation including pyrrhotite as the dominant sulphide and minor amounts of chalcopyrite and pyrite. Garnet-biotite thermometry and mineral textures within the host structures indicate that gold deposition occurred at temperatures of or above 600 degrees C, corresponding to mid-amphibolite-facies conditions slightly post-dating peak metamorphism. The high-grade metamorphic ore and alteration mineral parageneses are overprinted by lower-greenschist facies parageneses along brittle faults and cataclasites that are related to the mid-Proterozoic tectonism of the Northern Marginal Zone.

During fieldwork in 2008, the Geological Survey of Denmark and Greenland investigated the gold potential of hydrothermal vein systems in the Nuuk region of the Archaean North Atlantic craton. A new gold occurrence grading up to 672 ppb Au was discovered on the island of Qilanngaarsuit. In this study, petrological and geochemical data are presented in order to constrain the conditions for ore formation and transport of elements during fluid-rock interaction. The replacement of regional, metamorphic, amphibolite-facies mineral assemblages by hydrothermal minerals such as garnet, plagioclase, quartz, biotite and sillimanite surrounding the gold-bearing quartz veins, as well as the late timing of quartz-vein formation by ductile, flexural slip folding, indicate that the gold mineralisation and associated hydrothermal alteration formed late in the metamorphic evolution of Qilanngaarsuit. It is therefore interpreted to represent a new example of hypozonal orogenic gold mineralisation in the Godthabsfjord gold province. The alteration systematics, timing and conditions of the gold mineralisation are similar to those of other gold occurrences, in particular Storo, in the Godthabsfjord gold province., During fieldwork in 2008, the Geological Survey of Denmark and Greenland investigated the gold potential of hydrothermal vein systems in the Nuuk region of the Archaean North Atlantic craton. A new gold occurrence grading up to 672 ppb Au was discovered on the island of Qilanngaarsuit. In this study, petrological and geochemical data are presented in order to constrain the conditions for ore formation and transport of elements during fluid-rock interaction. The replacement of regional, metamorphic, amphibolite-facies mineral assemblages by hydrothermal minerals such as garnet, plagioclase, quartz, biotite and sillimanite surrounding the gold-bearing quartz veins, as well as the late timing of quartz-vein formation by ductile, flexural slip folding, indicate that the gold mineralisation and associated hydrothermal alteration formed late in the metamorphic evolution of Qilanngaarsuit. It is therefore interpreted to represent a new example of hypozonal orogenic gold mineralisation in the Godthabsfjord gold province. The alteration systematics, timing and conditions of the gold mineralisation are similar to those of other gold occurrences, in particular Storo, in the Godthabsfjord gold province.

Two stages of gold mineralisation and deformation are distinguished in the shear zones, which are up to 10 m wide. During the first stage, the amphibolite host rock reacted with a hydrothermal fluid enriched in Si, Ca, Na and K, resulting in opposing depletion and enrichment of specific elements, especially Fe, Mg and Si, in proximal and distal alteration zones. The second stage was associated with a fluid enriched in Fe and Mg leaching Si, Na, K and S from the altered rocks and contributing, along with external ore fluid input, to the formation of extensive contemporaneous gold-quartz veins. Fluid compositions and mass transfer estimates from the study are in accordance with results from bulk-rock geochemical and isotope calculations, with the exception of fluid-rock ratios and volume change which cannot be quantified in the open system under discussion., Two stages of gold mineralisation and deformation are distinguished in the shear zones, which are up to 10 m wide. During the first stage, the amphibolite host rock reacted with a hydrothermal fluid enriched in Si, Ca, Na and K, resulting in opposing depletion and enrichment of specific elements, especially Fe, Mg and Si, in proximal and distal alteration zones. The second stage was associated with a fluid enriched in Fe and Mg leaching Si, Na, K and S from the altered rocks and contributing, along with external ore fluid input, to the formation of extensive contemporaneous gold-quartz veins. Fluid compositions and mass transfer estimates from the study are in accordance with results from bulk-rock geochemical and isotope calculations, with the exception of fluid-rock ratios and volume change which cannot be quantified in the open system under discussion.

The Navachab mine is an open-pit operation with an average Au grade of 1.6-2.0 g/t, and has an estimated total Au production of 1 200 000 oz. The deposit is characterised by a polymetallic Au-Bi-As-Cu-Ag ore assemblage, including pyrrhotite, chalcopyrite, sphalerite, arsenopyrite, Bi, Au, bismuthinite and bismuth tellurides. Au is hosted by quartz sulphide veins and semi-massive sulphide lenses which are developed in a near-vertical sequence of shelf-type metasedimentary rocks including marble, calc-silicate rock and biotite schist. The sequence has been intruded by abundant syntectonic lamprophyre, aplite and pegmatite dykes, indicating widespread igneous activity coeval with mineralisation. Au is interpreted to have precipitated in equilibrium with metamorphic fluid at peak metamorphic conditions of about 550 degrees C and 2 kbars, consistent with isotopic fractionations between coexisting calcite, garnet and clinopyroxene in the alteration halos. The most likely source of the mineralising fluid was a mid-crustal fluid in equilibrium with the Damaran metapelites that underwent prograde metamorphism at amphibolite- to granulite-facies grades. Magmatic fluids may have been important in contributing to the overall hydraulic regime and high apparent geothermal gradients in the mine area., The Navachab mine is an open-pit operation with an average Au grade of 1.6-2.0 g/t, and has an estimated total Au production of 1 200 000 oz. The deposit is characterised by a polymetallic Au-Bi-As-Cu-Ag ore assemblage, including pyrrhotite, chalcopyrite, sphalerite, arsenopyrite, Bi, Au, bismuthinite and bismuth tellurides. Au is hosted by quartz sulphide veins and semi-massive sulphide lenses which are developed in a near-vertical sequence of shelf-type metasedimentary rocks including marble, calc-silicate rock and biotite schist. The sequence has been intruded by abundant syntectonic lamprophyre, aplite and pegmatite dykes, indicating widespread igneous activity coeval with mineralisation. Au is interpreted to have precipitated in equilibrium with metamorphic fluid at peak metamorphic conditions of about 550 degrees C and 2 kbars, consistent with isotopic fractionations between coexisting calcite, garnet and clinopyroxene in the alteration halos. The most likely source of the mineralising fluid was a mid-crustal fluid in equilibrium with the Damaran metapelites that underwent prograde metamorphism at amphibolite- to granulite-facies grades. Magmatic fluids may have been important in contributing to the overall hydraulic regime and high apparent geothermal gradients in the mine area.

Enhanced Cr and Ni values in the shales are a reflection of their antiquity and provenance, rather than suggesting preferential uptake during sedimentation and/or diagenesis. The augmentation of biogenically produced sulphide with sulphide from hydrothermal fluids is indicated by excess Fe:pyrite, very variable C:S ratios and wide-ranging S isotope ratios. Interelement correlations suggest that organic carbon does not play a role in hosting significant base and transition metals, which probably reside in illite-hydromuscovite and pyrite/chalcopyrite. The limited syngenetic metal accumulation can be explained by the stable cratonic depositional setting and the absence of submarine hydrothermal springs venting metalliferous fluids into the basin, while other factors may have limited metal concentration in and extraction from sea water. The fact that the shales host significant epigenetic gold deposits, particularly in the Sabie-Pilgrim's Rest field, is largely related to their permeability and high absorption capacities for metals in hydrothermal fluids; they cannot be considered the source rocks for the gold., Enhanced Cr and Ni values in the shales are a reflection of their antiquity and provenance, rather than suggesting preferential uptake during sedimentation and/or diagenesis. The augmentation of biogenically produced sulphide with sulphide from hydrothermal fluids is indicated by excess Fe:pyrite, very variable C:S ratios and wide-ranging S isotope ratios. Interelement correlations suggest that organic carbon does not play a role in hosting significant base and transition metals, which probably reside in illite-hydromuscovite and pyrite/chalcopyrite. The limited syngenetic metal accumulation can be explained by the stable cratonic depositional setting and the absence of submarine hydrothermal springs venting metalliferous fluids into the basin, while other factors may have limited metal concentration in and extraction from sea water. The fact that the shales host significant epigenetic gold deposits, particularly in the Sabie-Pilgrim's Rest field, is largely related to their permeability and high absorption capacities for metals in hydrothermal fluids; they cannot be considered the source rocks for the gold.