PARTICULATE PHASE IDENTIFICATION USING SCANNING ELECTRON MICROSCOPY, ENERGY DISPERSIVE X-RAY SPECTROSCOPY AND ELECTRON BACKSCATTER DIFFRACTION (SEM/EDS/EBSD): YOU WANT ME TO POLISH WHAT!?!

Electron backscatter diffraction (EBSD) is an advanced microanalytical tool that has become increasingly available over the past decade. The most common geological application of EBSD is for the determination of lattice preferred orientation to help understand rock deformation. EBSD is also an extremely powerful tool for mineral identification when coupled with energy dispersive x-ray spectroscopy (EDS). While the predominant application of EBSD is for the examination of lattice preferred orientation of minerals within a rock, sample preparation for a bulk material plays a critical role in the quality of the data obtained by EBSD. We will show that it is possible to collect useful information from unpolished particulate samples for the purpose of phase discrimination when coupled with chemical information collected by EDS. While previous workers have explored the use of EBSD on particulate, very little work explored the limits of the technique for particulate work. In addition, the previous work was performed on high atomic number materials with high backscatter coefficients and particle diameters greater than 1 μm. Our work was done on silicate minerals with particle diameters less than 1 μm. By modeling the backscatter coefficient from a thin film using Monte Carlo simulations we were able to optimize the operating conditions used during the analysis. The optimum operating conditions for particles are slightly different from those for bulk samples. We will present methodology and results from the analysis of unpolished particulate mineral samples, specifically asbestiform samples. We conclude that EBSD can be accurately used for the characterization of particulate samples even if only lower quality (relative to a polished bulk sample) patterns are collected.