Continent-scale digital maps of mineral information of the Earth's land surface are now achievable using geoscience-tuned remote sensing systems. Multispectral ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) data and the derived mineral information provide the opportunity for characterization of geological and soil processes including the nature of the regolith (weathered) cover and alteration footprints of hydrothermal ore deposits [1,2]. This paper describes work from the Western Australian (WA) Centre of Excellence for 3D Mineral Mapping, which is part of CSIRO's Minerals Down Under Flagship and supported by Geoscience Australia and other Australian geosurveys, to generate a series of ASTER mineral group maps (both content and composition) for the whole Australian continent at a 30 m pixel resolution.. The input ASTER L1B radiance-at-sensor data were provided by ERSDAC (Japan), NASA and the USGS. These data were corrected for instrument, illumination, atmospheric and geometric effects. About 4000 ASTER scenes from an archive of >30,000 scenes were selected to generate the continent-scale ASTER map and Hyperion scenes were used for reduction and validation of the cross-calibrated ASTER mosaic to reflectance. Band ratios [2] were applied as base algorithms and masked to remove complicating effects, such as green vegetation, clouds and deep shadow. Types of generated geoscience products include (1) mineral group content maps based on continuum-band depths (e.g. Al-OH group content mapping Al-OH clays like muscovite, kaolinite and montmorillonite) and (2) mineral group composition maps (e.g. Al-OH group composition ranging from Si-rich white mica through to well ordered kaolinite) based on ratios but masked using the relevant content products.

The use of airborne hyperspectral imagery for mapping soil surface mineralogy is examined for the semi-arid Tick Hill test site (20 km2) near Mount Isa in north-western Queensland. Mineral maps at 4.5 m pixel resolution include the abundances and physicochemistries (chemical composition and crystal disorder) of kaolin, illite-muscovite, and Al smectite (both montmorillonite and beidellite), as well as iron oxide, hydrated silica (opal), and soil/rock water (bound and unbound). Validation of these hyperspectral mineral maps involved field sampling (34 sites) and laboratory analyses (spectral reflectance and X-ray diffraction). The field spectral data were processed for their mineral information content the same way as the airborne HyMap data processing. The results showed significant spatial and statistical correlation. The mineral maps provide more detailed surface compositional information compared with the published soil and geology maps and other geoscience data (airborne radiometrics and digital elevation model). However, there is no apparent correlation between the published soil types (i.e. Ferrosols, Vertosols, and Tenosols) and the hyperspectral mineral maps (e.g. iron oxide-rich areas are not mapped as Ferrosols and smectite-rich areas are not mapped as Vertosols). This lack of correlation is interpreted to be related to the current lack of spatially comprehensive mineralogy for existing regional soil mapping. If correct, then this new, quantitative mineral mapping data has the potential to improve not just soil mapping but also soil and water catchment monitoring and modeling at local to regional scales. The challenges to achieving this outcome include gaining access to continental-scale hyperspectral data and models that link the surface mineralogy to subsurface soil characteristics/processes.

This two year collaborative project was established in July 2006 with the overall aim of developing, validating, evaluating and delivering a suite of publicly available, pre-competitive mineral mapping products from airborne HyMap hyperspectral imagery and satellite multispectral ASTER imagery. Moreover, it was important to establish whether these mineral maps would complement other precompetitive geological and geophysical data and provide valuable new information regards enhanced mineral exploration for industry. A mineral systems approach was used to appreciate the value of these mineral maps for exploration. That is, unlocking the value from these mineral maps is not simply by looking for the red bulls-eyes. Instead, mineral products need to be selected on the basis of critical parameters, such as what minerals are expected to develop as fluids migrate from source rocks to depositional sites and then into outflow zones with each associated with different physicochemical conditions (e.g. metasomatic metal budget, nature of the fluids, water-rock ratios, lithostatic pressure, pore fluid pressure, REDOX, pH, and temperature). One of the other key messages is to be able to recognise mineral chemical gradients as well as anomalous cross-cutting effects. These principles were tested using a number of case histories including, (1) the Starra iron oxide Cu-Au deposit; (2) the Mount Isa Pb-Zn-Ag and Cu deposits; and (3) Century Zn, all within the Mount Isa Block. These showed that the interpreted mineral alteration footprints of these mineral systems can be traced 10-15 km away from the metal deposition sites. In summary this project has shown that it is possible to generate accurate, large area mineral maps that provide new information about mineral system footprints not seen in other precompetitive geoscience data and that the vision of a mineral map of Australia is achievable and valuable.

Abstract The ability of thermal infrared (TIR) spectroscopy to characterise mineral and textural content was evaluated for soil samples collected in the semi-arid environment of north-western Queensland, Australia. Grain size analysis and separation of clay, silt and sand sized soil fractions were undertaken to establish the relationship between quartz and clay emissivity signatures and soil texture. Spectral band parameters, based on thermal infrared specular and volume scattering features, were found to discriminate fine clay mineral-rich soil from mostly coarser quartz-rich sandy soil, and to a lesser extent, from the silty quartz-rich soil. This study found that there was the potential for quantifying soil mineral and texture content using TIR spectroscopy. Key Words Soil composition, quartz, kaolinite, smectite, grain size, Tick Hill

Identifying and mapping regolith materials at the regional and continental-scale can be facilitated via a new generation of remote sensing methods and standardised geoscience products. The multispectral Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) is the first Earth observation (EO) system to acquire complete coverage of the Australian continent. The Japanese ASTER instrument is housed onboard the USA's Terra satellite, and has 14 spectral bands spanning the visible and near-infrared (VNIR - 500-1,000 nm - 3 bands @ 15 m pixel resolution); shortwave-infrared (SWIR - 1,000-2,500 nm range - 6 bands @ 30 m pixel resolution); and thermal infrared (TIR 8,000-12,000 nm - 90 m pixel resolution) with a 60 km swath. Although ASTER spectral bands do not have sufficient spectral resolution to accurately map the often small diagnostic absorption features of specific mineral species, which can be measured using more expensive 'hyperspectral' systems, current coverage of hyperspectral data is very restricted. The extensive coverage and 30m pixel size of ASTER make it well suited to national scale work. The spectral resolution of ASTER make it best suited to mapping broader 'mineral groups', such as the di-octahedral 'Al-OH' group comprising the mineral sub-groups (and their minerals species) like kaolins (e.g. kaolinite, dickite, halloysite), white micas (e.g. illite, muscovite, paragonite) and smectites (e.g. montmorillonite and beidellite). Extracting mineral group information using ASTER, using specially targeted band combinations, can find previously unmapped outcrop of bedrocks, weathering products, help define soil type and chemistry, and delineate and characterise regolith and landform boundaries over large and remote areas.

Specimens of radioactive ferruginous sandstone from Madigan's Prospect, Bynoe Harbour, N.T., have been examined by autoradiographic, mineragraphic, mineralogical, and petrographic methods, and tested treated, and analysed chemically; radiation measurements have been made at appropriate stages in the investigation to ascertain the behaviour and distribution of the radioactive material.

The Crater Prospect is situated about 4 miles south-south-east of White's workings and 1 mile north-east of the junction of Batchelor Road and the Darwin-Birdum railway line. It is the name assigned to a type area of an extensive radioactive bed of conglomerate. Low grade but wide-spread radioactivity was discovered by R.S. Matheson and D.F. Dyson (geophysicists) in June 1951, while prospecting along the sedimentary beds out-cropping immediately south of the Rum Jungle granite on the south-side of Giant's Reef fault, and on the south side of another major parallel fault. Geiger-Muller traverses along the strike of a grit-conglomerate horizon away from the Crater prospect revealed that the radioactivity extends westwards for 1.5 miles and for half a mile to the east. The radioactivity, which was confined to the conglomerate, was low-grade and discontinuous over this distance of 2 miles. The Crater Prospect, which can be regarded as a type locality, was geologically mapped by the writer on a scale of 200 feet to one inch after the area had been radiometrically contoured, and the plan accompanies this report (Plate 1). [The geology and structure of the prospect, nature of the radioactivity, and prospecting recommendations are discussed].

An enquiry has come from the Melbourne University Ore-Dressing Laboratory concerning the mineralogy of ores from Nos. 1 and 2 orebodies at Rye Park. Mr. K. S. Blaskett, Principal Research Officer at the Laboratory, has done treatment tests on ore from the No. 1 orebody, but is uncertain as to whether the sample investigated is typical of the ore as a whole. Sullivan and Dallwitz (1952) suggested that scheelite is more abundant than wolfram in the ore, but Mr. Blaskett found that the principal tungsten mineral is wolfram; evidence for this was obtained during ore treatment tests, and was confirmed by mineragraphic work. According to the geological report, fluorite is stated to be abundant, but very little fluorite was found in the ore treated in the Laboratory. As the bulk of the ore at Rye Park is in the No. 2 orebody, the question has arisen whether this ore is appreciably different from the sample tested. Differences in mineral association, grain-size, etc., may be very important in ore treatment. The following report describes in a general way what is known at present about the minerals and problems in which Mr. Blaskett is interested.

An examination was made of many of the mines in the Harts Range and Plenty River mica fields during the latter portion of 1951, in the company of Messrs. G.F. Joklik and W. Roberts. The work involved mine surveying and mapping. A great deal of information of a general nature was obtained from Mr. Joklik, who has spent much time studying the regional geology of the area and the mica deposits. The observations here recorded in regard to mining are the writer's responsibility. The geology of the deposits, mining, and exploration, are discussed.

Two million alluvial macrodiamonds recovered from Tertiary deep leads in the Copeton/Bingara (C/B) area of New England (NSW) formed by ultrahigh pressure metamorphism during Phanerozoic subduction - based on unique isotopic composition (?13C>0), unique inclusions and high pressures on inclusions. The techniques used were either destructive or only succeeded on 3% of 200 stones tested with inclusions. Some researchers have suggested that UHP microdiamond (e.g. from Kochetav) lacks the 2nd order Raman spectral pattern (2200-2700cm-1) that is prominent in cratonic diamond. Our work on African cratonic macrodiamond shows this peak is suppressed if the stone is UV fluorescent, but is strong at 15-75× (signal to noise ratio S/N) for a low background (?1100 counts per second). For NSW macrodiamond with a low background, this peak is greatly reduced at 2-14× S/N for C/B (45 stones), Mt Airly (4), Walcha (2), Frenchmans (1 ) and Wenona Diatreme (1), calibrating the test. This new combined technique (UV lamp, 2nd order Raman) is much faster and works on a larger fraction of stones (including those without inclusions; 13% of C/B stones are low background). Strong brittle/plastic deformation during growth of C/B diamond is confirmed by growth textures and Laue Xray photography, indicating growth during subduction - promoting strong nitrogen aggregation, and suppressing the 2nd order Raman spectral signal. This Raman test should apply to all subduction diamond, including superdeep diamond.