SEM and EDS microbeam images were generated by two methods as described below. Magnification was set so that 50 to 300 silt-sized particles (0.063 - 0.002 mm) were in the field of view. Two hard-copy BSE images at different magnification were printed, the first at low magnification (x10 - 15) to provide an overview image of the sample being examined, including the "V" locator (see image below) and the second at a higher magnification to act as a road map or guide to relocating the detailed examined area. The image on the left displays an epoxy puck about 1 cm thick and 2,5 cm wide. The puck shape was chosen so that further analyses of these sample could be carried out on a Secondary Ion Mass Spectrometer (SIMS) that requires this particular shape. A standard thin section would also work as a sample mount. Dashed lines on the right image correspond to the "V" whereas the solid outlined box corresponds to the area examined for element mapping.

Ten elements were chosen to represent the key components of common rock-forming and secondary minerals, consistent with the geological setting of the examined samples. They include: Si, Al, K, Mg, Na, Ca, Fe, Ti, Mn, and S.

Method 1
Cambridge S-360 SEM - Oxford-Link eXLII EDS

Digital images: 256 x 256 pixels
Dwell time: 500 milliseconds per pixel
Magnification: 125 times
Operating voltage: 20 keV
Working distance: 25 mm
Beam current: 1.3 nA

Method 2
Cambridge SEM - Oxford-Link XP2 EDS and 4PI OS

Digital images: 512 x 512 pixels
Dwell time: 50 milliseconds per pixel
Magnification: 125 times
Operating voltage: 20 keV
Working distance: 25 mm.