Figure 1. Single X-ray CT slices showing the range of size, spatial resolution, and density discrimination of which the UT scanner is capable. (a) 6.5 micron thick slice of a 3.2-mm diameter core of Green sandstone showing ~10-50 micron pores filled with Woods metal (bright). (Sample courtesy of Sid Green, Terratek, and Dr. Larry Meyer, Lawrence Berkeley National Laboratory). (b) 100 micron thick slice of a 21.5-mm diameter limestone core from the Paradox Formation, showing detection by virtue of partial volume effects, of fracture (arrow) measured in thin section to be 5 microns wide. (Sample courtesy of Dr. Brenda Kirkland-George, University of Texas at Austin). (c) 100 micron slice of a 25-mm core of graphic granite, showing ability to differentiate quartz (light gray) from potassium feldspar (dark gray), two materials closely similar in density. (Sample courtesy of Rob Reed, University of Texas at Austin). (d) 1 mm thick slices of a 300-mm diameter saprolite core, showing superb detail of fracture porosity and macrovoids in the large specimen. (Sample courtesy of Dr. Geri Moline, Oak Ridge National Laboratory). Note two orders of magnitude difference in scale between (a) and (d).