Figure 3 e,f. (e) Epoxy pore cast of microporous grain (M). Density of microporosity is so high that the grain resembles a sponge (SEM image, Saudi Arabia, Berri field, Arab-C). (f) SEM image of fractured rock surface of ooid-skeletal mud-lean packstone. Large sparry calcite cement crystal (C) is nonmicroporous and distinct in appearance from surrounding micritized and microporous grains (Saudi Arabia, Khursaniyah field, Arab-D).