Abstract: Indicator minerals are known for many types of base metal deposits but the high temperatures and pressures associated with magmatism and prograde metamorphism are needed to raise mineral density and grain size in order to produce diverse and abundant indicators. Therefore those base metal deposits that are associated with very large magmatic-hydrothermal systems have the most viable indicator mineral suites, in some cases sufficient to produce anomalies in surficial sediments comparable to the regional-scale anomalies associated with kimberlite fields. Two deposits of this type are Ni-Cu-PGE and porphyry Cu. Most sulphide mineral grains dispersed from these deposits are quickly degraded by weathering, increasing the dependence on more stable alteration minerals. The significance and properties of these minerals are described and examples of anomalies are shown for Ni-Cu-PGE indicator minerals in glacial till and post-glacial gravel in Canada and for porphyry Cu indicator minerals in nonglacial sheet wash gravel in Chile.

Abstract: Over the past two decades, the application of indicator mineral methods to mineral exploration has expanded significantly such that they are now used to explore globally for a broad spectrum of commodities. Indicator mineral suites have been identified for a variety of ore deposit types including diamond, Au, Ni-Cu, PGE, metamorphosed volcanogenic massive sulphide, porphyry Cu, U, Sn and W. Indicator minerals, which include ore, accessory and alteration minerals, are sparse in unconsolidated sediments, thus sediment samples must be concentrated in order to recover and examine them. Because most indicator minerals have a moderate to high specific gravity, processing techniques involving density separation, in combination with sizing and magnetic separation, are used to recover them from sediment samples. This paper reviews the commonly used processing methods including panning, hydroseparation, tabling, Knelson concentrators, spiral concentrators, dense media separators, jigs and various types of magnetic separators, as well as mineral selection and mineral chemistry determinations. Monitoring of quality control is essential at each stage in these processing, picking and analytical procedures. When reporting indicator mineral results, processing methods, fraction weights and size ranges, and laboratory name should all be recorded, in addition to indicator mineral abundance data.

Abstract: Porphyry Cu indicator minerals are mineral species in clastic sediments that indicate the presence of mineralization and hydrothermal alteration associated with porphyry Cu and associated skarn deposits. Porphyry Cu indicator minerals recovered from shallow till samples near the giant Pebble Cu-Au-Mo porphyry deposit in SW Alaska, USA, include apatite, andradite garnet, Mn-epidote, visible gold, jarosite, pyrite, and cinnabar. Sulphide minerals other than pyrite are absent from till, most likely due to the oxidation of the till. The distribution of till samples with abundant apatite and cinnabar suggest sources other than the Pebble deposit. With three exceptions, all till samples up-ice of the Pebble deposit contain 40grains/10kg) are in close proximity to smaller porphyry and skarn occurrences in the region. The distribution of Mn-epidote closely mimics the distribution of garnet in the till samples and further supports the interpretation that these minerals most likely reflect skarns associated with the porphyry deposits. All but two till samples, including those up-ice from the deposit, contain some gold grains. However, tills immediately west and down-ice of Pebble contain more abundant gold grains, and the overall number of grains decreases in the down-ice direction. Furthermore, all samples in the immediate vicinity of Pebble contain more than 65 % pristine and modified grains compared to mostly re-shaped grains in distal samples. The pristine gold in till reflects short transport distances and/or liberation of gold during in-situ weathering of transported chalcopyrite grains. Jarosite is also abundant (1–2 500 grains/10kg) in samples adjacent to and up to 7 km down-ice from the deposit. Most jarosite grains are rounded and preliminary Ar/Ar dates suggest the jarosite formed prior to glaciation and it implies that a supergene cap existed over Pebble West. Assuming this interpretation is accurate, it suggests a shallow level of erosion of the Pebble deposit by glacial processes. Overall the results of this study indicate that porphyry Cu indicator minerals in till samples may be useful in the exploration for porphyry deposits in SW Alaska.

Abstract: Using ED(P)-XRFS (Energy Dispersive X-Ray Fluorescence Spectrometry) analytical methodology, iodine is now routinely determined as part of a multi-element XRFS analysis package on samples (soils and stream sediments) collected for regional geochemical baseline mapping in the United Kingdom. For the first time, a high density regional geochemical map of iodine in soils is presented. These new data for iodine greatly increase the worldwide database for iodine in soils and the regional map of iodine offers an opportunity to better understand the factors that control its distribution in the surface environment. Iodine is often cited as the classic example of how a trace element deficiency in the environment affects human health, in the case of iodine endemic diseases collectively referred to as iodine deficiency disorders. The proximity to the sea coast, providing a supply of iodine via the atmosphere, and the organic content of the soil are seen as the two most important factors in determining the iodine status of the soil.

Abstract: Chronic exposure to high concentrations of arsenic (As) in windblown and vehicle-raised dust from tailings sites in Nova Scotia poses a potential health risk to recreational users of these areas and to nearby residents. The exposure may involve inhalation of dust, as well as oral ingestion of particles. It is important to understand the mineralogy and morphology of As-bearing dust particles in order to evaluate the risk posed by near-surface particulates in As-bearing tailings fields, as this will influence the stability and toxicity of As in the wastes. Optical mineralogy, scanning electron microscopy, electron microprobe, X-ray diffraction, synchrotron-based micro-X-ray diffraction (μXRD) and micro-X-ray absorption near edge structure (μXANES), and sequential leach extractions were applied to tailings samples from three sites in eastern Nova Scotia. Arsenic occurs naturally in these gold deposits mainly in arsenopyrite (FeAsS). In the near-surface material of the tailings fields, sulphide minerals have almost completely oxidized to secondary minerals such as scorodite (FeAsO 4 •2H 2 O) and Ca-Fe arsenates. Iron oxyhydroxides contain variable amounts of As 2 O 5 from trace to 30 wt.% and CaO up to 8 wt.%. The presence of multiple As-hosting solid phases, including relatively soluble Ca-Fe arsenates and Fe oxyhydroxides with adsorbed As has important implications for human health risk assessment and remediation design.

Abstract: Results from an indicator mineral survey conducted with till samples in NW Alberta were used to identify a glacial dispersal train of sand-sized sphalerite and minor galena. High concentrations of dark grey to black, angular, brittle grains of sphalerite were found (100 to >1000 grains) in nine of ninety 30 kg till samples. The presence of high sphalerite grain counts in nine samples situated within a geographically restricted area argues against long-distance glacial transport, comminution, and deposition of erratic material from the carbonate-hosted Pine Point Zn-Pb deposits, located 330 km to the NE. The Pb isotopic composition of the galena grains recovered from till is similar to values obtained from Mississippi Valley-type deposits in the northern Canadian Cordillera and Pine Point and indicates that the galena is derived from similar basement sources situated along the Great Slave Lake Shear Zone. Sphalerite grains from the till have a sulphur isotopic composition significantly different from Mississippi Valley-type deposits in the northern and southern Cordillera, and are significantly different than the Pine Point deposits. These results highlight the potential to discover base metal mineralization hosted within the Cretaceous shale bedrock of northern Alberta.

Abstract: The use of inductively coupled plasma-mass spectrometry (ICP-MS) combined with liquid collectors greatly improved the reliability of the ‘Metals-in-soil-gas’ (MSG) technique in the late 1990s. To date, the MSG technique has been successfully applied in several locations varying in: commodity type (e.g. gold, base metals and nickel), depth of burial, and climatic regimes (e.g. from semi-arid through to wet temperate). In this paper, two case studies and a pilot study are reported to illustrate the effectiveness of the technique. The results show that in MSG, a suite of chalcophile elements, similar to the association of commodity and pathfinder elements in the deposits, exhibit sharp anomalies above the known sulphide mineralization. Copper and Zn peaks can reach tens of thousands of ppb over a background of

Abstract: Sampling around the Ni–Cu deposits in the northern Thompson Nickel Belt (TNB), central Canada, was conducted to document Ni–Cu mineralization signatures in till. Samples used in this study include archived material collected in 1996 and new samples collected in 2005 and 2006. During the Late Wisconsinan, the Laurentide Ice Sheet flowed southwestward and subsequently westward across the TNB striating outcrops and transporting metal-rich till. Exploration along the belt and in the surrounding terranes should consider both the older SW and younger westward ice flow events when interpreting and following up till geochemical results. Till geochemistry of the 3 offer further discrimination of significant till geochemical anomalies. Using the deposit signatures in till as a guide, five anomalous till samples outside the belt represent new exploration targets because they contain significant elevated concentrations of, in various combinations, Pt, Pd, Cu, Cr, Mo, Sb, Bi and Fe.

Abstract: An orientation study around the NICO Co-Au-Bi deposit in the Great Bear magmatic zone of NW Territories, Canada, was initiated in 2007 to establish a practical guide to geochemical and mineralogical exploration for iron oxide copper-gold deposits in glaciated terrain. Bedrock and till samples were collected up-ice, proximal and down-ice from mineralization and host rocks, to characterize their indicator mineral signatures. Results demonstrate that gold grain abundance, size and shape, as well as magnetite and hematite composition, have the best potential to fingerprint the mineralization at NICO. Pristine-shaped gold grains indicative of a local bedrock source and a short distance of glacial transport are relatively abundant in till samples collected immediately down-ice from several mineral occurrences at NICO and none were recovered up-ice. Iron oxide composition using preliminary discriminant diagrams shows some potential, using Ni/(Mn+Cr) versus Ti+V plots. In particular, magnetite and hematite from till samples collected over, or directly down-ice of, the NICO deposit have lower Ti+V compositions compared to magnetite and hematite from till collected up-ice from mineralization. Potential non-ferromagnetic indicator minerals are either not chemically stable in surface sediments (arsenopyrite, chalcopyrite, pyrite), not sufficiently coarse-grained or resistant to glacial transport (bismuthinite, tourmaline, ferroactinolite), not abundant enough in the mineralized bedrock (scheelite, molybdenite, cobaltite, allanite), or not sufficiently heavy (tourmaline) to be useful at NICO but may be at other deposits in the region or elsewhere in glaciated terrain. The development of indicator mineral methods, together with till geochemistry, will be tested with further sampling over the Great Bear magmatic zone.

Abstract: Passive systems with constructed wetlands are designed to simulate natural attenuation processes in order to treat mine water in a long-term and cost-effective manner In this way, they are especially appropriate to treat mine water discharging from abandoned mines This paper presents geochemical and mineralogical data obtained from a recently constructed passive system in the Jales abandoned mine, north Portugal It shows the role of fresh ochre-precipitates, formed as waste products from the neutralization process, in the retention of trace elements Chemical analysis of these waste products revealed strong enrichment factors for metals and arsenic, relative to the water from which they precipitate The mineralogical study shows that ochre-precipitates are poorly ordered iron-rich material, such as ferrihydrites, that occur as small spherical aggregates (

Abstract: The Pinguino deposit is characterized by the presence of indium-rich polymetallic vein mineralization representing an atypical epithermal occurrence for the low sulphidation epithermal mineralization from the Deseado Massif, Patagonia, Argentina. Polymetallic veins display high In, Zn, Pb, Ag, Cd, Au, As, Cu, Sn, W and Bi values represented by complex sulphide mineralogy. Mineralization developed in two main stages: a Cu-Au-In-As-Sn-W-Bi stage, and a Zn-Pb-Ag-In-Cd-Sb stage. Correlation coefficients are used to estimate the degree of inter-relation between metals concentrations in each stage and specifically to determinate the behaviour of indium. Indium concentrations show a wide range (3.4–1184 ppm In) and, based on the correlation coefficients of ore geochemistry, in the first stage indium is associated mainly with Sn, present in ferrokesterite and cassiterite, while the highest indium values are related to the late mineralization stage, closely associated with Zn and Cd and present in the Fe-rich sphalerite, the most important In-bearing mineral in the deposit.

Abstract: Peat groundwater compositions at depths of 0.4 and 1.1 m below ground surface in the Attawapiskat region of the James Bay Lowlands are evaluated for diamond exploration applications. Samples were collected along transects that typically extended at least 200 m beyond the margins of Yankee, Zulu, and Golf kimberlites. Locations of upwelling groundwater usually occur at or near kimberlite margins based on hydrogeological measurements and variations in peat groundwater geochemical parameters (pH and EC are high, and the Eh is low relative to ombrotrophic peat groundwaters). Concentrations of the kimberlite pathfinder metals Ni, Cr, light rare earth elements (LREEs), Ba, Mg/Ca, and alkalis are commonly elevated at sample sites at or near kimberlite margins and where groundwaters are upwelling. The presence of elevated kimberlite pathfinders at these sites suggests that fractures along the boundaries between kimberlites and limestone formed during kimberlite emplacement provide dilation for upward movement of groundwater with elevated kimberlite pathfinder metals. Typically, Ni, Cr, LREE, and Ba behave similarly and thus high concentrations of these metals are found at similar locations along transects. On the other hand, locations of elevated alkalis and Mg/Ca vary. The spatial variations among pathfinder metals in peat groundwaters are possibly due to geochemical processes in the peat, such as metal binding to dissolved organic material, adsorption to insoluble organics or Fe-oxyhydroxides, and incorporation into secondary mineral precipitates, which can act to increase or decrease metal solubility. The findings of this study are readily applicable in diamond exploration in wetlands elsewhere.

Abstract: For use in a nationwide geochemical mapping project, 496 stream sediment samples were collected in eastern Japan including the nation9s capital, Tokyo. The 51 elements were determined using ICP-AES and ICP-MS; their spatial distribution maps were created using geographic information system (GIS) software. Spatial distribution patterns of elemental concentrations in stream sediments are consistent with the distribution of surface geology. Heavy metals and toxic elements are highly elevated in the sediments associated with mineral occurrences, but their distributions are limited to a small area. Surveying for nationwide geochemical mapping avoids collection of samples near contamination sources. Nevertheless, high concentrations of P (P 2 O 5 ), Cr, Ni, Cu, Zn, Sn, Sb, Hg, and Pb were found in populated areas. Results of statistical analyses – analysis of variance and a multiple comparison test – suggest that the enrichments are not coincidental phenomena, rather these sediment samples accurately represented contamination.

Abstract: Acid mine drainage (AMD) is a particular focus of environmental research, involving the examination of many pollutants and their reactivity. Special attention must be paid for an accurate characterization of AMD samples in the field and in the laboratory. AMD samples are typically unstable due to the presence of colloidal material such as iron oxyhydroxides and bacteria. They induce physical and chemical transformations that may affect the analytical results. Variations in pH are recorded within days following sample collection, indicating changes in their chemistry. The present work demonstrates evidence of the instability of AMD samples, through the results of monitoring experiments performed under different laboratory conditions. Expeditious indicators, such as pH and electrical conductivity (combined with the analysis of crystallinity, composition and morphology of the resulting precipitates), allow monitoring of the evolution of the samples. The results also provide information about the transformation of the typical ochre products that precipitate from AMD, suggesting the formation of schwertmannite and its evolution to a more crystalline mineral.

Abstract: A preliminary geochemical study on gold mine tailings proposed for marine tailings disposal has been undertaken to identify the potential release of acidity and ecotoxic elements. Laboratory tests investigated the effects of flushing media, temperatures and light-exposure on the reactivity and acid generation potential of the tailing. Based on low sulphide and carbonate concentrations, ambiguous static test results categorized the tailing as ‘uncertain to potential-acid-generating’. Over a 20-week kinetic test programme, tailing leachates remained circum-neutral and metal release rates decreased substantially after the first-flush. However, Canadian Interim Quality guidelines for marine sediment were exceeded for As, Cd, Cr, Cu, Pb and Zn by factors ranging between 1.5 (Zn) and 196 (As) and kinetic leachate concentrations of Cd exceeded Canadian Marine Aquatic Life guidelines suggesting potentially harmful effects might occur upon disposal of the tailing in marine environment. Leaching of ecotoxic elements was enhanced by the use of seawater as flushing medium. Changes in temperature and light exposure had only minor effects. In-situ long-term (>20 weeks) leaching tests are proposed. SUPPLEMENTARY MATERIAL Raw chemical data of kinetic tests and saturation indices of deionized water cells are available at http://www.geolsoc.org.uk/SUP18432.

Abstract: Iron occurs naturally as Fe 2+ , Fe 3+ , and, to a lesser extent, as Fe 0 . Many fundamental (bio)geochemical processes are based on redox cycling between these oxidation states. Mossbauer spectroscopy provides quantitative information about the distribution of Fe among its oxidation states, identification of Fe-bearing phases, and relative distribution of Fe among those phases. Portable, miniaturised Mossbauer spectrometers were developed for NASA9s Mars Exploration Rovers (in operation since 2004) and provide a means for non-destructive, in-situ field investigations. On Mars, these instruments provided evidence for aqueous activity with implications for habitability, were applied in geological mapping of the landing sites, and helped to identify meteorites, for example. On Earth, they were used in field studies of green rust, the identification of air pollution sources, or the study of archaeological artefacts. Their application to in-situ resource utilisation (ISRU) on the Moon has been demonstrated in a recent NASA field test of hardware for oxygen production. A new detector system in an advanced version of these instruments is based on Si Drift Detectors and permits the simultaneous acquisition of X-ray fluorescence spectra to determine elemental compositions.

Abstract: Hydrothermal alteration around the sediment-hosted Elura Zn-Pb-Ag sulphide deposit has produced detectable and systematic chemical changes that are also reflected in subtle mineralogical features (cryptic alteration). Iron carbonate development accompanied by potassic alteration, the destruction of albite and the absence of chlorite are the dominant mineral alteration effects in the surrounding turbidites. Key elements enriched in the primary dispersion zone are Zn, Pb, Ag, As, Rb, Tl, and particularly Sb. Sodium is strongly depleted in the alteration system. Cryptic alteration and primary dispersion can be detected up to 350 m from the orebody below the weathering front. Pearce Element Ratio (PER) and General Element Ratio (GER) techniques more clearly identify and quantify this alteration and could assist in vectoring towards high intensity alteration adjacent to ore during exploration drilling. These data assessment techniques avoid the problems of closure when comparing element contents for altered and unaltered samples and allow modelling of the mineralogical controls on chemical variation. There are important differences in the alteration effects observed in the fine and coarse fractions of the enclosing turbidite units. For vectoring purposes, the best lithotype to sample is the shale component.

Abstract: Water systems from the Padurea Craiului Mountains and the northeastern extremity of the Pannonian Basin (Oradea–Felix) are investigated for deuterium, global salt content, and major solutes. All types of groundwater (springs, wellhead water, domestic wells, karst springs, cave water) display δ D values (−76.1‰ to −62.3) similar to the surface running water (−76.5‰ to −50.7), suggesting that they are meteoric in origin. The global salt content ranges from 49 mg/l to 1300 mg/l for the groundwater and from 46 mg/l to 665 mg/l for the surface water. From the co-variation between the δ D values, the global salt content, and the major solutes, as well as from the seasonal variation of these parameters, genetic links could be established. The mineralization of the groundwater is due to intense underground circulation, mostly in the karst system developed within the Mesozoic deposits of the Padurea Craiului Mountains.

Abstract: Eleven acid-sulphate and quartz-sericite-pyrite altered mine waste samples from the Animas River watershed in SW Colorado were subjected to a series of 5 to 6 successive leaches using the US EPA 1312 leach protocol to evaluate the transport of metals and loss of acidity from mine wastes as a function of time. Multi-acid digestion ICP-AES analyses, X-ray diffraction (XRD) mineral identification, total sulphur, and net acid potential (NAP) determinations were performed on the initial starting materials. Multiple leaching steps generally showed a ‘flushing9 effect, whereby elements loosely bound, presumably as water-soluble salts, were removed. Aluminum, Cd, Fe, Mg, Mn, Sr, Zn, and S showed decreasing concentration trends, whereas Cu concentrations showed initially decreasing trends, followed by increasing trends in later steps. Concentrations of Zn in the first leach step were independent of whole-sample Zn content. Lead and Ba concentrations consistently increased with each step, indicating that anglesite (PbSO 4 ) and barite (BaSO 4 ), respectively, were dissolving in successive leach steps. Comparison of Fe content with NAP resulted in a modest correlation. However, using the S analyses and XRD identification of sulphide minerals to apportion S amongst enargite, barite, anglesite/galena, and sphalerite, and assigning the remaining S to pyrite, provided a useful correlation between estimated pyrite content and NAP. Whole-sample mass loss correlated well with NAP, but individual elements9 behaviors varied between positive correlation (e.g. Al, Fe, Mg), no apparent correlation (Ca, Cd, Pb, Zn), and negative correlation (Cu). Comparison of the summed titrated acidities of the leachates with the whole-sample NAP values yielded an estimate of the fraction of NAP consumed, and led to an estimate of the time it would take to consume the sample acidity by weathering. We estimate, on the basis of these experiments, the acidity in the upper 30 cm would be consumed in 200–1000 years. In addition, calculations suggest that the acidity would be depleted before the complete store of the metals Cu-Cd-Zn in these mine wastes would be released to the environment.

Abstract: Identification of kimberlite indicator mineral dispersal trains in glaciated terrain provides important clues in determining provenance. Complex ice flow history can distribute kimberlite indicator minerals such that dispersal trains are disguised within clusters of till samples containing abundant kimberlite indicator minerals. This study uses GIS with inverse distance weighted interpolation to identify and isolate dispersal trains within areas where large clusters of till samples with abundant kimberlite indicator minerals exhibit no apparent distribution patterns. The method was tested in the Pelly Bay region of Nunavut, Canada, where many areas contain clusters of till samples with abundant kimberlite indicator minerals, the method delineated dispersal trains within these areas. The study identified trains ranging from 1.5–7 km in length, with the heads of some trains ranging in width between 225 m and 3 km. Mg-ilmenite is the most abundant kimberlite indicator mineral in the Pelly Bay area, however, several trains with distinct relative abundances of kimberlite indicator mineral species were identified that suggest the presence of kimberlites with different intrusive phases. Our study suggests that several of the identified dispersal trains likely originated from kimberlite dykes and/or sills occupying NW–SE oriented structures in the bedrock.

Abstract: Soils from the vicinity of the Endeavor Mine, in the Cobar region of western NSW, have been sieved into the (a) 2–4 mm, (b) 1–2 mm, (c) 0.5–1 mm, (d) 250–500 μm, (e) 125–250 μm, (f) 63–125 μm and (g) Elevated Pb and As contents in the coarse or magnetic fraction of soils in the Endeavor Mine area reflect the underlying weathered Pb–Zn mineralization and may give rise to a larger anomaly than that defined by conventional magnetic lag sampling. Within this area of Pb and As anomalism, the fine fraction of the soils directly above the Northern Pods mineralization ( c . 400 m below) exhibit enriched Zn, S and soluble salt contents (the latter measured as electrical conductivity). The association of elevated Zn, S and EC (electrical conductivity) suggests sulphide-derivation and such anomalism appears more prospective than Zn-only anomalism in fine soil fractions from transported material to the SW of the mine. Unfortunately the preparation of the fine soil fraction is time consuming but, because the fine fraction of the Cobar region soils consistently represents 40–50% of the 2 mm soil fraction for determining Pb and As and the

Abstract: Metallophytes have the ability to grow in metal-rich soils without showing signs of toxicity. It is believed that chelating of metals to organic ligands is a mechanism that metal-tolerant plants use for detoxification. To obtain information about metal species, water extracts of roots, stems and leaves from two metallophytes ( Blepharis aspera , and Helicrysum candolleanum ) were analysed using inductively coupled plasma mass spectrometry (ICP-MS) in combination with cation exchange solid-phase extraction (off-line) and on-line with size exclusion chromatography (SEC). The extracts were analysed for 10 metals that were present at higher than normal concentrations and for 8 elements that have physiological functions in plants. The elements studied were Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, P, S, Si, Ti, V and Zn. The total concentration and the percentage of water-extractable metal were determined in all plant parts. For both plants, K had the highest extraction efficiency (>70%), followed by Mg, Mn, Ni, P and Zn. The main elements Ca, K and Mg were found to be present only in cationic form in the extracts of both plants, whereas Al, Co, Cr, Cu, Fe and Ni were present partly in non-cationic form, indicating complex formation. Size exclusion chromatography showed that all the plant parts had a similar size distribution of the dissolved organic matter, exhibiting mainly one broad peak. All the metals co-eluted with the first part of this peak, suggesting that the metals were associated with relatively large organic molecules, and more so for H. candolleanum than for B. aspera , and more pronounced for the stems than for the roots and leaves. Such data indicate that the two plants may have different mechanisms of dealing with high metal concentrations.

Abstract: Indicator minerals are mineral species that, when recovered from surficial sediments, indicate the presence of a specific mineral deposit, hydrothermal alteration, or rock lithology. Ideal indicator minerals are found in few if any rocks other than the host deposit or lithology. Their physical and chemical characteristics allow them to be readily recovered from exploration sample media and make them sufficiently abundant to be useful (McClenaghan 2005). The application of indicator mineral methods to mineral exploration has a long history extending back to Roman times. In more recent times, from the 1960s to the 1980s, indicator mineral methods were commonly used worldwide to explore for tin (Zantop & Nespereira 1979; Ryan et al . 1988), tungsten (e.g. Lindmark 1977; Stendal 1982; Toverud 1984; …

Abstract: For gold deposits, varying combinations of gold grains, sulphides, platinum-group minerals (PGM), tellurides, scheelite and rutile, and some secondary minerals are useful indicator minerals depending on the deposit type, bedrock geology and weathering regime. Gold grain size, shape, and chemical composition for a variety of sediment types, including stream and glacial sediments, have been documented and the data used to determine potential source rocks and distance of transport. Useful indicator minerals for PGE deposits include those oxide and silicate minerals that indicate the host rocks and PGM, gold, sulphides, arsenides and antimonide minerals that indicate mineralization. Composition and morphology of PGM also have been well documented and this information is used to determine their genesis, potential source rocks and transport distance. Gold grains have been recovered from glacial and stream sediments for more than 100 years. PGM grains have a similar long history of recovery from streams, but only a few cases of recovery from glacial sediment have been reported. Research has focused on the development of microchemical characterization techniques for placer gold and PGM, while the focus for indicator minerals from glacial sediments has been the characterization of oxide and silicate suites.

Abstract: Hyperspectral remote sensing data from the Eastern Fold Belt, Mount Isa Inlier, Australia were compared with petrographic and geochemical studies to map the spatial extension and compositional variations of Proterozoic granitoids and endoskarns as well as hydrothermal alteration patterns in adjoining metasedimentary successions. Detailed spatial analysis of spectral remote sensing data shows an almost circular alteration zoning in the Mallee Gap Granite, which was emplaced during a late phase of the Mesoproterozoic Williams event. A combination of hyperspectral images, such as white mica, kaolin and MgOH products, were used to map the alteration zoning. The formation of the endoskarn is presumably related to autometasomatism and interaction with fluids released from the country rocks during a late phase of the emplacement. The intrusion of the Mallee Gap Granite has only a local control on the hydrothermal alteration, but high potassic granites of the southern Mount Angelay Granite might have expelled oxidized mineralizing fluids and possibly had a major impact on regional scale alteration. Hyperspectral remote sensing data may be used to estimate the imprint of single igneous bodies on the Mesoproterozoic hydrothermal evolution of the Eastern Fold Belt and are important for the study of ore-forming hydrothermal processes in general.

Abstract: Exploration for deep-seated mineral deposits in mature mining camps requires integration of large and heterogeneous spatial data-sets. Traditionally, geological, geochemical, and geophysical observations are acquired, processed and analysed independently within separate spatial contexts or more commonly, for geochemical data, in non-spatial feature space. Although methodological developments are still in progress, 3D GIS (geographic information system) technologies already provide powerful tools that can be used to integrate such heterogeneous data-sets to visualize, compare, and characterize geological relationships in a more supportive interpretive environment. Importantly, this technology provides better opportunities to embed all these properties in a more robust geometric framework in which structural history and palaeogeographic setting can be taken into account. We present 3D GIS applications that aid in interpreting relationship patterns amongst faults, folds and geochemical trends. Examples from the Noranda mining region, a classic VMS mining camp, demonstrate the applicability of 3D GIS to support the discovery of new mineral resources at depth.