Images from 3D X-ray tomographic reconstruction of small (a,b) sample H and (c,d) sample Valt post-peak showing the fracture trace (a,c) in the side view that shows the fracture trace in the direction of fracture propagation from notch to top of sample (y-direction). In (a,c), the bassanite layer direction is indicated by the small yellow arrows. The top view for sample H in (b) shows the fracture trace in the x-direction and mineral bands and gypsum lineations within the bands. (d) The top view of sample Valt contains both layering and the ends of mineral lineations (see Fig. 2f). Scale bars in each image represent 1 mm.