X-RAY TOMOGRAPHY: VISUALIZING IN THREE DIMENSIONS

I like to use the Toolkit as a platform to highlight technologies that are showing signifi cant growth in their use by geoscientists or that strike me as having much unexplored potential. With its ten-fold growth in use by geoscientists over the past decade, the fi rst laboratory method that comes to mind as fulfi lling both of these characteristics is X-ray computed tomography (CT), a nondestructive method providing a 3-dimensional (3-D) visualization of nearly any solid material. Modern systems have been developed that specifi cally target mineralogical or petrological applications, often providing volume (or voxel) resolu-tions reaching the micron scale: hence, such technology is commonly referred to as micro-CT. A micro-CT system consists of a fi nely focused X-ray source (FIG. 1) with a diameter typically around a few microns. Anisotropic X-rays are emitted from this quasi–point source, a process that can be visu-alized as a cone of achromatic photons being directed at the targe