Our special expertise relates to the identification and characterisation of minerals in soils and weathered rocks in Australian landscapes, novel methods of mineral synthesis, and quantitative techniques of mineralogical analysis using X-ray diffraction. Of particular note is the development of methods for detailed characterisation of clay minerals, and accurate methods for quantitative XRD analysis (Rietveld Analysis).
Techniques for mineralogical analysis
Our mineralogical services are based on X-ray powder diffraction (XRD) using techniques largely devised in this laboratory. Analyses can be made of soils, minerals, rocks, ores, industrial products and chemicals. We can also perform a wide range of additional techniques, including, X-ray fluorescence (XRF) scanning electron microscopy (SEM), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), and various wet chemical methods.
X-ray Diffraction (XRD)
XRD is generally the fastest and most reliable method used in the identification and quantification of crystalline materials. The technique utilises the diffraction (reflection) of X-rays from the unique arrangement of atoms in a crystal structure. The technique is particularly useful for materials with grain sizes too small for microscopic identification (ie. clay minerals, soils minerals, dusts etc.).
XRD can be used to identify mineral specimens (ie. individual grains, mineral assemblages, weathering products, clay minerals etc.) and industrial products (ie. chemical products, boiler scales, corrosion products, asbestos minerals, furnace slags and ashes, etc). In fact, just about any type of solid material will produce a diffraction pattern.
Sample size requirements
Typically, for qualitative analysis, amounts of approximately 1g are sufficient. In some instances, such as well crystalline materials, single grains (~1mg) can be analysed using special low background silicon sample holders. Whole soil analysis, where the clay fraction is to be extracted, requires 10-50g of the whole sample (depending on the clay percentage). Clay analysis for supplied <2µm fraction requires approximately 200mg.
Equipment in our mineralogy lab
The laboratory is equipped with two diffractometers, a Philips PW1710 microprocessor controlled PW1050 instrument, and a Philips PW1800 microprocessor controlled instrument.
The laboratory also has a high temperature diffractometer attachment, and a range of photographic equipment including Debye-Scherrer, Gandolfi, Guinier, Weissenberg, and precession cameras for single crystal analysis.
Instrument control is provided by state of the art (in-house) computer software that has been specifically designed with clay mineral analysis in mind. Manipulation and identification of the unknown diffraction pattern is also performed by in-house computer search match software (Xplot). The measured data is compared to a powder diffraction database (ICDD – International Centre for Diffraction Data CD-ROM) of approximately 66,000 standard patterns.