We present a novel tablet application, the Natural Materials Browser, that allows a user to interact with volumetric datasets created from a series of natural materials samples. The data samples -- high resolution meso-scale volumetric images of nutshells gathered via micro-computed tomography -- are envisioned as virtual specimens presented many orders of magnitude larger than their characteristic length scale. The user, initially placed in the center of the volumetric dataset and facing orthogonally toward the original 2D image slices, uses an iPad tablet as a magic lens to view and navigate the data via physical rotation and multitouch gestures. The user has simultaneous access to multiple representations of the datasets from any angle or position, and an additional viewport provides real-time, spatial statistics on the current view of the currently loaded dataset. We conducted a preliminary evaluation of the application by collating cognitive walkthroughs given to domain experts in materials science. Their feedback indicated that our tablet application could potentially be an effective tool for enabling insights regarding these data samples and, more generally, that it functions as a low-cost, immersive system with which to explore volumetric datasets.