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Updated:
27 February 2008
Geochemistry and mineralogy laboratories
IntroductionKnowledge of the composition of the Earth, the changes in rocks resulting from fluid flow and/or processes leading to the accumulation of mineral/oil deposits is of great importance to scientists and engineers. Whether characterising the phases of a suite of granites, stratigraphically correlating rock units over large areas of complex geology, studying the formation of the regolith, exploring for mineral deposits or monitoring man-made or natural pollution, the data must be of research quality. Geoscience Australia's Geochemical Laboratories provide these data in a prompt and cost effective manner. These laboratories specialise in the identification and analysis of rocks, minerals, soils and the fluids trapped in rocks. This information is used to support Geoscience Australia's regional programs, mineral systems and regolith studies. The data also is used to constrain geochemical and related modelling which is carried out as part of Geoscience Australia's mineral systems research. Geochemical facilitiesGeoscience Australia's Geochemical Laboratory uses analytical techniques which are acknowledged as among the most powerful, most sensitive and most cost effective available . Expertise and facilities available for the preparation and analysis of geochemical samples include: Rocklabs hydraulic splitterThis unit is equipped with tungsten carbide blades and is used to clean weathered samples and to split large samples to fit the swing-jaw crusher. Rocklabs swing-jaw crusherThe swing-jaw crusher is used to reduce samples from 100 mm diameter to less than 20 mm diameter. The jaw faces are made of low contaminant mild steel. Boyd crusherThe Boyd crusher with attached rotary sample divider reduces samples from less than 50 mm to less than 4 mm grains. The sample divider can be set to sample between 2% and 50% of the fine crush. Rocklabs vibratory ringmillThis unit is used to produce a very fine powder from the coarse product from the Boyd crusher. Three grinding mediums are available. These are:
A poster paper on Grinding Head Contamination Tests is available as an HTML abstract or a full paper pdf (1.97Mb). X-Ray fluorescence (XRF) spectrometryThe Philips PW 2404 XRF spectrometer with automated sample loader and online data processing is used for analysing fusions and pressed powder samples for elements with an atomic mass greater than 9. The equipment can measure concentrations as low as 1ppm and as high as 100%. A semi-automatic Initiative Scientific Products Fusilux 4X4 Fusion Machine is used in the production of fused discs and an Activon Automated Speca press for producing powder pellets. A poster paper on Grinding Head Contamination Tests is available as an HTML abstract or a full paper pdf (1.97Mb). Laser ablation and solution inductively coupled plasma - mass spectrometry (ICP-MS)The Agilent Technologies 7500 ICP-MS with automated sample loader and online data processing is used in conjunction with the X-ray Fluorescence (XRF) spectrometer for the analysis of a wide range of trace elements. Detection limits down to ppb levels can be obtained routinely. The ICP-MS is traditionally used with solutions, made by acid digestion of fused glass disks. The ICP-MS is also equipped with a Newwave UP-193 solid state laser ablation system for analysis of solid samples. An article from the December 2000 AGSO Research Newsletter.on the ICP-MS preparation method is available as an HTML version or a pdf version (154kb). Leco RC-412 multiphase carbon / hydrogen / moisture analyserThe Leco C/H/moisture analyser is used for the determination of organic and inorganic carbon as well as bound water in rock and soil samples. This instrument not only determines total carbon and hydrogen but also the amount of the two elements given off and the temperature at which the two elements are given off. Volumetric, gravimetric and electrochemical methodsSupplementary analyses such as moisture, ferrous iron, fluoride, loss on ignition and specific gravity also are available. Other specialised techniques may be used upon request. OZCHEM geochemistry databaseOZCHEM is a database of whole-rock and stream-sediment geochemistry for samples which are mainly from Australia, Antarctica, Papua New Guinea and the Solomon Islands. Both major and trace element analyses are included. Analyses are added from:
Geochemical data are most conveniently handled in digital form. Information from OZCHEM, which was known previously as ROCKCHEM, can be grouped as a complete dataset, or as regional/thematic datasets. The plot-it application is no longer available and until a new interface is developed, access to the geochemistry data is via dataset files. Mineralogical and fluid inclusion facilitiesThe following range of petrological and spectroscopic facilities is available for analysing minerals and fluid inclusions. Two sophisticated geochemical modelling software packages also are available for geochemical research. Laser Raman microprobe (LRMP)The HORIBA Jobin Yvon SuperLabram laser Raman microprobe has a fully confocal microscope and is used for the rapid and non-destructive analysis of solids, liquids and gases. The high spatial resolution of this instrument (≥ 1 micron) makes it particularly suitable for the identification of gases and solids in fluid inclusions. The laser Raman microprobe is equipped with a motorised stage also, which allows Raman mapping of selected areas of the sample. An optical-fibre probe can be attached to the spectrometer and used for probing larger samples that do not fit under the microscope, such as hand specimens and drill core. X-ray diffraction spectrometryThe Seimens D500 X-ray diffractometer (XRD) is used to identify and determine the amount of minerals in powdered samples. The Siroquant software package is used to quantitatively determine the amount of each mineral identified by its X-ray diffraction pattern. These data are used in petrological, marine, environmental and regolith studies. Portable infrared mineral analyser (PIMA)The Integrated Spectronics PIMA is a field-portable, shortwave infrared spectrometer which provides rapid data on rocks and minerals. The accompanying software contains a library of PIMA mineral spectra allowing easy interpretation of unknown spectra. Measurements can be made on all types of samples including diamond drill-core, RC and RAB chips, powders and soil samples. It is particularly useful for regolith studies and for delineating alteration systems and understanding alteration-mineralisation relationships. Electron probe micro-analyser (EPMA)The Cameca SX-100 electron probe micro-analyser is a shared Geoscience Australia-Australian National University facility used for the analysis of elements in very small areas such as individual mineral grains. It is equipped with four wavelength dispersive X-ray spectrometers and an energy dispersive spectrometer. Cathodoluminescence and backscattered electron images also may be obtained in the scanning mode. This instrument is primarily used for major element microanalysis with detection limits typically exceeding 50-100 ppm. However, detection limits may be extended into the trace element range by the use of longer counting times and precise background corrections. Heating and freezing stagesThese laboratories contain the following heating and freezing stages which are used mainly for fluid and melt inclusion studies:
Transmitted and reflected light microscopesThese laboratories contain a range of research-grade, polarising microscopes and binocular microscope including:
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