Figure 6. Before abrasion. A) Surface textures of grapestones, as seen using Environmental Scanning Electron Microscopy (ESEM), show aggregate grains held together by a loose mesh of aragonite needles. This cement can incorporate other material, such as the diatom test seen in the lower right hand corner. B) Oolitic samples have both smooth surface textures and highly porous surfaces with microborings and intricate micro-topography. These features cause weaknesses in what would otherwise be a durable, spherical grain.