Reconstructed slices of fine pumice structure (a) and coarse scoria texture (b) in volcanic rocks from Stromboli volcano (Italy). In both images black voids are vesicles, dark and light grey and white objects are crystals, the matrix (glass + fine crystals) is intermediate grey, and the scale bar is 1 mm. (c) and (d) are volume renderings of the samples in (a) and (b), respectively. Pixel size = 9 µm. See text for further details.