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The degassing behavior of St. Nicholas anthracite has been investigated at 25 - 1400C in vacuum. Relevant data have been obtained that could help provide a more complete understanding of the decrepitation phenomenon that precludes the use of anthracites as metallurgical fuel., Rept. no. GIDEP-305.05.00.00-BA-01.

The characteristics are compared of multiple hearth furnaces, rotary kilns, single shaft kilns, parallel flow regenerative kilns, annular shaft kilns and POLCAL gas suspension preheaters, with reference to product particle size and residual CO2 content, maximum daily capacity, off-gas temperature and energy consumption. Selection of kiln type should be based on product specific surface, reactivity and residual CO2 content required, and on the raw material feed grain size and, in particular, its tendency to decrepitation and shattering. Specific tests have been developed for each kiln type, including shatter and decrepitation tests for shaft kilns and a drum test method for rotary kilns., The characteristics are compared of multiple hearth furnaces, rotary kilns, single shaft kilns, parallel flow regenerative kilns, annular shaft kilns and POLCAL gas suspension preheaters, with reference to product particle size and residual CO2 content, maximum daily capacity, off-gas temperature and energy consumption. Selection of kiln type should be based on product specific surface, reactivity and residual CO2 content required, and on the raw material feed grain size and, in particular, its tendency to decrepitation and shattering. Specific tests have been developed for each kiln type, including shatter and decrepitation tests for shaft kilns and a drum test method for rotary kilns.

The extraction was investigated of Li from spodumene obtained from the Belogorsky mine in Kazakhstan. Laboratory results showed that extraction from solution can be achieved by decrepitation at 1 150 degrees C for 0.5 h with stirring. For commercial production it is recommended that the temperature should be reduced to 1 025-1 085 degrees C. The solutions, derived from 200-300 g samples of beta spodumene, contained 6.4-11.6 g/l Li and the resulting cake had Li contents ranging from 0.11%, with 98.6% recovery, up to 1.50%, with 86.0% recovery., The extraction was investigated of Li from spodumene obtained from the Belogorsky mine in Kazakhstan. Laboratory results showed that extraction from solution can be achieved by decrepitation at 1 150 degrees C for 0.5 h with stirring. For commercial production it is recommended that the temperature should be reduced to 1 025-1 085 degrees C. The solutions, derived from 200-300 g samples of beta spodumene, contained 6.4-11.6 g/l Li and the resulting cake had Li contents ranging from 0.11%, with 98.6% recovery, up to 1.50%, with 86.0% recovery.

The evaluation is discussed of limestone and dolomite for use in glass production with regard to decrepitation, a measure of the amount of flyover of ultrafine particles during the CO2 emission stage of the glassmaking process. The results are presented of experiments to measure decrepitation using a shallow Pt dish at 1 100 degrees C in an electrically heated laboratory furnace. Limestone and dolomite with mosaic, microgranular or microcrystalline structures exhibited negligible or low decrepitation, while samples with coarse crystals or that have been recrystallised to form coarse crystals showed marked decrepitation behaviour., The evaluation is discussed of limestone and dolomite for use in glass production with regard to decrepitation, a measure of the amount of flyover of ultrafine particles during the CO2 emission stage of the glassmaking process. The results are presented of experiments to measure decrepitation using a shallow Pt dish at 1 100 degrees C in an electrically heated laboratory furnace. Limestone and dolomite with mosaic, microgranular or microcrystalline structures exhibited negligible or low decrepitation, while samples with coarse crystals or that have been recrystallised to form coarse crystals showed marked decrepitation behaviour.

Limestone and dolostone are used in industries depending on their physicochemical characteristics. They can be used in construction, agricultural, environmental industries and especially in ironmaking and steelmaking as flux. Dolomite is also used in the production of refractory materials. As the properties of products are significantly affected by physicochemical specifications of limestone or dolomite, the characterisation of those materials is important. This study was initiated to analyse the chemical, decrepitation, and degradation properties of dolomite and limestone samples to determine their suitability as flux. Since the degradation indices were found different for the chemically similar samples, the study was expanded to determine the reason. Complete physicochemical and thermal characterisation was performed via X-ray fluorescence, X-ray diffraction, thermogravimetric, Fourier transform infrared and thin-section microscopic analysis. Although two dolomite samples were mineralogically similar, thermal behaviours were determined as different. Microscopic analysis results showed that the crystal structures/sizes affect the thermal behaviour and degradation index of carbonate samples. (Authors.), Limestone and dolostone are used in industries depending on their physicochemical characteristics. They can be used in construction, agricultural, environmental industries and especially in ironmaking and steelmaking as flux. Dolomite is also used in the production of refractory materials. As the properties of products are significantly affected by physicochemical specifications of limestone or dolomite, the characterisation of those materials is important. This study was initiated to analyse the chemical, decrepitation, and degradation properties of dolomite and limestone samples to determine their suitability as flux. Since the degradation indices were found different for the chemically similar samples, the study was expanded to determine the reason. Complete physicochemical and thermal characterisation was performed via X-ray fluorescence, X-ray diffraction, thermogravimetric, Fourier transform infrared and thin-section microscopic analysis. Although two dolomite samples were mineralogically similar, thermal behaviours were determined as different. Microscopic analysis results showed that the crystal structures/sizes affect the thermal behaviour and degradation index of carbonate samples. (Authors.)

Rare earth metals can be recovered from spent fluid cracking catalysts and automobile catalytic converters. Recycling can also be carried out from scraps generated during the manufacture of rare earth permanent magnets or at the end of life of the magnet. The REEs can be recovered as salts by acid dissolution of magnets or as metals by liquid metal extraction or hydrogen decrepitation. Rare earths can also be recycled from alloys (Ni-MH batteries) and phosphors used in fluorescent lamps, cathode ray tubes, and liquid crystal displays. The recycling rate of rare earths is no more than 10% whereas it is between 25% and 50% for other metals. A few commercial recycling plants are in operation but the recycling rate could be improved by improving the logistics of collection, dismantling and transporting of scrap., Rare earth metals can be recovered from spent fluid cracking catalysts and automobile catalytic converters. Recycling can also be carried out from scraps generated during the manufacture of rare earth permanent magnets or at the end of life of the magnet. The REEs can be recovered as salts by acid dissolution of magnets or as metals by liquid metal extraction or hydrogen decrepitation. Rare earths can also be recycled from alloys (Ni-MH batteries) and phosphors used in fluorescent lamps, cathode ray tubes, and liquid crystal displays. The recycling rate of rare earths is no more than 10% whereas it is between 25% and 50% for other metals. A few commercial recycling plants are in operation but the recycling rate could be improved by improving the logistics of collection, dismantling and transporting of scrap.

Compact iron ores are normally considered to be non-hydrated materials. Research has shown that hydrated phases are present in these ores, occuring as very thin inclusions in the ore interior. On heating, decomposition of these phases takes place producing water vapour which is locked under pressure in the interior. From the principles of fracture mechanics, a theoretical model has been developed that shows quantitatively that the mechanism of bursting under pressure of the trapped water vapour is sufficient to produce haematite decrepitation., Compact iron ores are normally considered to be non-hydrated materials. Research has shown that hydrated phases are present in these ores, occuring as very thin inclusions in the ore interior. On heating, decomposition of these phases takes place producing water vapour which is locked under pressure in the interior. From the principles of fracture mechanics, a theoretical model has been developed that shows quantitatively that the mechanism of bursting under pressure of the trapped water vapour is sufficient to produce haematite decrepitation.

A mechanical decrepitation device coupled to a gas chromatograph was used to characterise the molecular composition of hydrocarbons contained in ore minerals. Aliphatic and aromatic hydrocarbons were found in sulphides and gangue quartz from Variscan and post-Variscan base metal occurrences in the Rhenish Massif, Germany. Based on the analysis of 22 samples, Variscan and post-Variscan mineralisation can be distinguished by the associated hydrocarbons. In particular, Variscan ore minerals always contain a high abundance of methane, whereas n-alkanes in the C2-C5 range are dominant for post-Variscan mineralisation. The possible role played by hydrocarbons in ore precipitation is discussed., A mechanical decrepitation device coupled to a gas chromatograph was used to characterise the molecular composition of hydrocarbons contained in ore minerals. Aliphatic and aromatic hydrocarbons were found in sulphides and gangue quartz from Variscan and post-Variscan base metal occurrences in the Rhenish Massif, Germany. Based on the analysis of 22 samples, Variscan and post-Variscan mineralisation can be distinguished by the associated hydrocarbons. In particular, Variscan ore minerals always contain a high abundance of methane, whereas n-alkanes in the C2-C5 range are dominant for post-Variscan mineralisation. The possible role played by hydrocarbons in ore precipitation is discussed.

The decrepitation method is capable of providing information on the abundance of CO2-rich fluid inclusions in quartz samples by the observation of decrepitation at abnormally low temperatures (below 350 degrees C). The method has been used in extensive regional and detailed studies in the Pine Creek goldfields, where a correlation between Au mineralisation and CO2 content was observed by comparing analyses of samples from several existing operating mines with various other quartz samples from unmineralised areas throughout the region. An area of interest, defined by the regional scale sampling, was subjected to detailed study and this work delineated an anomalous zone with high CO2 content which is closely related to a zone of low-level anomalous Au contents in quartz samples. The quartz shows highly variable decrepitation (and consequent CO2 contents) over small distances, due to the presence of growth zoning and multiple stages of quartz emplacement, as is typical of a high level depositional environment., The decrepitation method is capable of providing information on the abundance of CO2-rich fluid inclusions in quartz samples by the observation of decrepitation at abnormally low temperatures (below 350 degrees C). The method has been used in extensive regional and detailed studies in the Pine Creek goldfields, where a correlation between Au mineralisation and CO2 content was observed by comparing analyses of samples from several existing operating mines with various other quartz samples from unmineralised areas throughout the region. An area of interest, defined by the regional scale sampling, was subjected to detailed study and this work delineated an anomalous zone with high CO2 content which is closely related to a zone of low-level anomalous Au contents in quartz samples. The quartz shows highly variable decrepitation (and consequent CO2 contents) over small distances, due to the presence of growth zoning and multiple stages of quartz emplacement, as is typical of a high level depositional environment.

Studies have been carried out of the decrepitation properties of colemanite, ulexite and borax along with their fragmentation patterns on heating. Information obtained from pure systems was applied to the actual ores both for upgrading colemanite and ulexite and also for achieving their selective separation. The mechanism of modification on heat treatment for each mineral is explained on the basis of thermodynamics of the respective minerals. Optimum conditions for pure colemanite samples were found to be 500 degrees C and 15 mins reaction time. Ulexite did not undergo decrepitation but became friable under heat treatment and handling. Colemanite ores assaying 42.97% B2O3 were upgraded to 57.14% B2O3 upon decrepitation followed by screening at 0.5 mm screen. A mixture of colemanite and ulexite could be separated at efficiencies near 90%. Borax underwent expansion under heat treatment, allowing dry separation of borax from gangue minerals. It was upgraded by a process involving calcination followed by fragmentation and air calcination. The major advantages of a dry scheme are that the dry product can be pelletised or briquetted and environmental problems are minimised., Studies have been carried out of the decrepitation properties of colemanite, ulexite and borax along with their fragmentation patterns on heating. Information obtained from pure systems was applied to the actual ores both for upgrading colemanite and ulexite and also for achieving their selective separation. The mechanism of modification on heat treatment for each mineral is explained on the basis of thermodynamics of the respective minerals. Optimum conditions for pure colemanite samples were found to be 500 degrees C and 15 mins reaction time. Ulexite did not undergo decrepitation but became friable under heat treatment and handling. Colemanite ores assaying 42.97% B2O3 were upgraded to 57.14% B2O3 upon decrepitation followed by screening at 0.5 mm screen. A mixture of colemanite and ulexite could be separated at efficiencies near 90%. Borax underwent expansion under heat treatment, allowing dry separation of borax from gangue minerals. It was upgraded by a process involving calcination followed by fragmentation and air calcination. The major advantages of a dry scheme are that the dry product can be pelletised or briquetted and environmental problems are minimised.

Sampling and assaying, followed by magnetic separation, flotation and decrepitation tests have been carried out on concentrate from the Vergenoeg Mining Co./Fine material, currently removed before crushing, was subjected to elutriation and flotation, in order to determine if its addition to the flotation feed would affect the process. It was found that thia material floats easily, and gives concentrates with good CaF2 grades and good recoveries. Decrepitation was found to be inefficient. Insufficient liberation of fluorspar particles is partly responsible for the difficulties in upgrading the concentrate and it is recommended that a high-grade concentrate be removed either by magnetic separation or direct from the first 'half' of the sixth cleaner bank, and that the remaining lower-grade ore should be reground and upgraded by further flotation., Sampling and assaying, followed by magnetic separation, flotation and decrepitation tests have been carried out on concentrate from the Vergenoeg Mining Co./Fine material, currently removed before crushing, was subjected to elutriation and flotation, in order to determine if its addition to the flotation feed would affect the process. It was found that thia material floats easily, and gives concentrates with good CaF2 grades and good recoveries. Decrepitation was found to be inefficient. Insufficient liberation of fluorspar particles is partly responsible for the difficulties in upgrading the concentrate and it is recommended that a high-grade concentrate be removed either by magnetic separation or direct from the first 'half' of the sixth cleaner bank, and that the remaining lower-grade ore should be reground and upgraded by further flotation.

Sulphide-bearing and barren quartz veins from five Archaean and fourteen Palaeoproterozoic gold deposits were sampled and characterised by decrepigrams and fluid inclusion geochemistry. The decrepigrams exhibited different regional characteristics for the different domains, but within these domains or single ore provinces were usually very uniform and coherent. There were recognisable differences in discrimination in areas where this could rarely be determined by visual observation. The highest concentration of Au usually correlated with the peak frequency of gaseous fluid inclusions that decrepitated at temperatures below 350 degrees C, and with the highest amount of other fluid inclusion types that decrepitated at temperatures above 350 degrees C. These results show that careful collection and assessment of decrepitation data may play a small but constructive role in Au exploration., Sulphide-bearing and barren quartz veins from five Archaean and fourteen Palaeoproterozoic gold deposits were sampled and characterised by decrepigrams and fluid inclusion geochemistry. The decrepigrams exhibited different regional characteristics for the different domains, but within these domains or single ore provinces were usually very uniform and coherent. There were recognisable differences in discrimination in areas where this could rarely be determined by visual observation. The highest concentration of Au usually correlated with the peak frequency of gaseous fluid inclusions that decrepitated at temperatures below 350 degrees C, and with the highest amount of other fluid inclusion types that decrepitated at temperatures above 350 degrees C. These results show that careful collection and assessment of decrepitation data may play a small but constructive role in Au exploration.

Thermal-decrepitation mass spectroscopy has revealed extended-chain hydrocarbons in pre- and early syn-Zn mineralisation veins at Elura Ag-Pb-Zn mine in New South Wales. Laser Raman microprobe analysis demonstrates that the n-alkane signatures are from primary fluid inclusions in quartz and sphalerite. The data may have important implications for the transport of metals in low-temperature reduced connate fluids and the study has also confirmed that two fluids with dissimilar temperatures and redox properties were present throughout the pre- and syn-mineralisation paragenesis, supporting a fluid mixing model of ore genesis., Thermal-decrepitation mass spectroscopy has revealed extended-chain hydrocarbons in pre- and early syn-Zn mineralisation veins at Elura Ag-Pb-Zn mine in New South Wales. Laser Raman microprobe analysis demonstrates that the n-alkane signatures are from primary fluid inclusions in quartz and sphalerite. The data may have important implications for the transport of metals in low-temperature reduced connate fluids and the study has also confirmed that two fluids with dissimilar temperatures and redox properties were present throughout the pre- and syn-mineralisation paragenesis, supporting a fluid mixing model of ore genesis.

34 samples of Silurian dolomite from Ohio were crushed, sized and sieved and the identically sized samples analysed for decrepitation in a study seeking correlations between decrepitation and the physical and chemical properties of the dolomite suite. It was found that the degree of decrepitation increases with the size of crystals within dolomite particles, possibly because longer flaws pre-exist along crystal boundaries and because propagation of flaws is less retarded by boundaries, so that explosive fracturing is initiated by rapid heat- induced expansion., 34 samples of Silurian dolomite from Ohio were crushed, sized and sieved and the identically sized samples analysed for decrepitation in a study seeking correlations between decrepitation and the physical and chemical properties of the dolomite suite. It was found that the degree of decrepitation increases with the size of crystals within dolomite particles, possibly because longer flaws pre-exist along crystal boundaries and because propagation of flaws is less retarded by boundaries, so that explosive fracturing is initiated by rapid heat- induced expansion.

The separation of rare earth metals from steel scrap obtained from the mechanical processing of old hard-disc drives is described. An important pre-requisite for their separation is the demagnetisation of rare-earth magnets and two possible methods have been investigated. The first method, pressure hydrogenation, converts bulk neodymium magnets into fine hydride powders by decrepitation, but this technique is unsuccessful with nickel-plated or corroded items or with polymer-bonded magnets from hard-disc-drive brushless direct-current motors. The necessary pretreatment as well as the comparatively high cost of investment and operation of the pressure-hydrogenation treatment mean that it is of dubious economic feasibility. An alternative demagnetisation procedure, thermal treatment beyond the Curie temperature, yields a rare-earth concentrate with higher neodymium content than primary bastnaesite ores and therefore provides a more viable option., The separation of rare earth metals from steel scrap obtained from the mechanical processing of old hard-disc drives is described. An important pre-requisite for their separation is the demagnetisation of rare-earth magnets and two possible methods have been investigated. The first method, pressure hydrogenation, converts bulk neodymium magnets into fine hydride powders by decrepitation, but this technique is unsuccessful with nickel-plated or corroded items or with polymer-bonded magnets from hard-disc-drive brushless direct-current motors. The necessary pretreatment as well as the comparatively high cost of investment and operation of the pressure-hydrogenation treatment mean that it is of dubious economic feasibility. An alternative demagnetisation procedure, thermal treatment beyond the Curie temperature, yields a rare-earth concentrate with higher neodymium content than primary bastnaesite ores and therefore provides a more viable option.

A method was developed for the quantitative estimation of the fluxing ability of silicate-carbonate ores and Cu smelting slags, taking into account their chemical and phase compositions. The fluxing ability can have positive or negative values, depending on the content of the basic SiO2 and CaO flux components and the combination of different compounds in the material. The effect of the Cu content on the fluxing ability of homogeneous slags was investigated using experimental and industrial data. In Kazakhstan, low-grade ore from Balkhash grading 0.10% Cu, 76.94% SiO2, 10.24% Al2O3, 0.43% CaO and 0.24% MgO gives rise to converter slag containing 26% SiO, 40.3% Fe and 1% CaO and furnace slag with 30.2% SiO, 36.2% Fe, 3.6% CaO and 0.6% MgO, while ore from Zhezkazgan grading 1.18% Cu, 61.70% SiO2, 11.60% Al2O3, 2.46% CaO and 1.70% MgO produces converter slag containing 25.2% SiO, 27.5% Fe, 2.5% CaO and 1.0% MgO and furnace slag with 47.2% SiO, 14.2% Fe, 12.19% CaO and 0.75% MgO. A method developed for classifying the fluxing ability of silicate-carbonate materials was based on fluxing ability and decrepitation for ores and fluxing ability and meltability for slags., A method was developed for the quantitative estimation of the fluxing ability of silicate-carbonate ores and Cu smelting slags, taking into account their chemical and phase compositions. The fluxing ability can have positive or negative values, depending on the content of the basic SiO2 and CaO flux components and the combination of different compounds in the material. The effect of the Cu content on the fluxing ability of homogeneous slags was investigated using experimental and industrial data. In Kazakhstan, low-grade ore from Balkhash grading 0.10% Cu, 76.94% SiO2, 10.24% Al2O3, 0.43% CaO and 0.24% MgO gives rise to converter slag containing 26% SiO, 40.3% Fe and 1% CaO and furnace slag with 30.2% SiO, 36.2% Fe, 3.6% CaO and 0.6% MgO, while ore from Zhezkazgan grading 1.18% Cu, 61.70% SiO2, 11.60% Al2O3, 2.46% CaO and 1.70% MgO produces converter slag containing 25.2% SiO, 27.5% Fe, 2.5% CaO and 1.0% MgO and furnace slag with 47.2% SiO, 14.2% Fe, 12.19% CaO and 0.75% MgO. A method developed for classifying the fluxing ability of silicate-carbonate materials was based on fluxing ability and decrepitation for ores and fluxing ability and meltability for slags.

The NE-trending fault cuts biotite granite and K-feldspar porphyroblastic granodiorite. Along its 8 km are four medium-sized deposits, Jiehe, Shangzhuang, Hedong and Fujia, in altered rocks of the fault shatter zone. Ore microscopy has shown that native gold is associated with tetradymite, chalcopyrite and galena in cracks of pyrite crystals; these serve as indicators for Au-mineralised pyrite. The pyroelectricity coefficients of pyrite vary along the fault zone, with N-type dominant and small amounts of P-type pyrite at Fujia and Hedong. From south to north, pyrite with (100) crystal form decreases and pyrite with (111) or (100)+(111) form increases. Trace elements Bi, Te and high Se and Ni are positively related to Au. Average decrepitation temperature increases and frequency decreases from north to south; very high Au is found in pyrite with a decrepitation temperature of 150-200 rather than 230-270 degrees C., The NE-trending fault cuts biotite granite and K-feldspar porphyroblastic granodiorite. Along its 8 km are four medium-sized deposits, Jiehe, Shangzhuang, Hedong and Fujia, in altered rocks of the fault shatter zone. Ore microscopy has shown that native gold is associated with tetradymite, chalcopyrite and galena in cracks of pyrite crystals; these serve as indicators for Au-mineralised pyrite. The pyroelectricity coefficients of pyrite vary along the fault zone, with N-type dominant and small amounts of P-type pyrite at Fujia and Hedong. From south to north, pyrite with (100) crystal form decreases and pyrite with (111) or (100)+(111) form increases. Trace elements Bi, Te and high Se and Ni are positively related to Au. Average decrepitation temperature increases and frequency decreases from north to south; very high Au is found in pyrite with a decrepitation temperature of 150-200 rather than 230-270 degrees C.

Inclusions in gold-sulphide veins and some regional sulphide-bearing veins showed distinctly higher CO2/CH4 ratios than barren quartz-only and quartz-sulphide veins from the deposit environment. Optical techniques also confirmed the occurrence of low-temperature peaks in acoustic decrepigrams from Au-sulphide veins, previously attributed to the presence of CO2-bearing fluid inclusions. This characteristic peak was absent from quartz-sulphide and quartz-only veins. The results suggest that the gas content of fluid inclusions can distinguish gold-bearing from barren quartz veins, and that acoustic decrepitation may provide a rapid and simple means of identifying different generations of quartz and hence potentially productive veins in mesothermal environments., Inclusions in gold-sulphide veins and some regional sulphide-bearing veins showed distinctly higher CO2/CH4 ratios than barren quartz-only and quartz-sulphide veins from the deposit environment. Optical techniques also confirmed the occurrence of low-temperature peaks in acoustic decrepigrams from Au-sulphide veins, previously attributed to the presence of CO2-bearing fluid inclusions. This characteristic peak was absent from quartz-sulphide and quartz-only veins. The results suggest that the gas content of fluid inclusions can distinguish gold-bearing from barren quartz veins, and that acoustic decrepitation may provide a rapid and simple means of identifying different generations of quartz and hence potentially productive veins in mesothermal environments.

Quartz samples were separated from stream sediments draining the Dartmoor granite and chemically analysed using the ICP-linked decrepitation technique. The samples were derived from three environments: an area of tin-iron vein mineralisation; a region of granite peripheral to the mineralised area; and a region of granite devoid of mineralisation. On a local scale, the fluid inclusion decrepitates in samples from the mineralised region show relatively higher concentrations of Rb, B, Sn, Cu and S and lower concentrations of Na, K, Ca, Fe, Li, Ba, Sr and Zn. Principal component analysis of the whole multi-element data set confirms that the elements Rb, B, Sn, Cu and S behave independently from the major constituents of the fluid inclusion decrepitates and possibly represent a "mineralisation" factor. Discriminant function analysis is able to produce an efficient separation of the samples into the three groups. The regional variation in chemistry of the fluid inclusion decrepitates can be explained by invoking two main sources of quartz for the stream sediments: quartz veins associated with the mineralisation and quartz from the unaltered granite. The fluids in quartz from the unaltered granite also show a regional variation. The study indicates that the multi-element chemical analysis of fluid inclusion decrepitates may be a viable method of geochemical exploration for granite-hosted tin deposits., Quartz samples were separated from stream sediments draining the Dartmoor granite and chemically analysed using the ICP-linked decrepitation technique. The samples were derived from three environments: an area of tin-iron vein mineralisation; a region of granite peripheral to the mineralised area; and a region of granite devoid of mineralisation. On a local scale, the fluid inclusion decrepitates in samples from the mineralised region show relatively higher concentrations of Rb, B, Sn, Cu and S and lower concentrations of Na, K, Ca, Fe, Li, Ba, Sr and Zn. Principal component analysis of the whole multi-element data set confirms that the elements Rb, B, Sn, Cu and S behave independently from the major constituents of the fluid inclusion decrepitates and possibly represent a "mineralisation" factor. Discriminant function analysis is able to produce an efficient separation of the samples into the three groups. The regional variation in chemistry of the fluid inclusion decrepitates can be explained by invoking two main sources of quartz for the stream sediments: quartz veins associated with the mineralisation and quartz from the unaltered granite. The fluids in quartz from the unaltered granite also show a regional variation. The study indicates that the multi-element chemical analysis of fluid inclusion decrepitates may be a viable method of geochemical exploration for granite-hosted tin deposits.

High CO2/H2O ratios are related to gold mineralisation in altered rock-hosted deposits but the ratio may be an unreliable guide in vein-hosted deposits because of the variable unmixing pattern of CO2-H2O fluids. Decrepitometry may prove a useful and rapid method for identifying CO2-H2O unmixing and bonanza gold potential., High CO2/H2O ratios are related to gold mineralisation in altered rock-hosted deposits but the ratio may be an unreliable guide in vein-hosted deposits because of the variable unmixing pattern of CO2-H2O fluids. Decrepitometry may prove a useful and rapid method for identifying CO2-H2O unmixing and bonanza gold potential.