Plate 10d.: Chert is folded by brecciation into a myriad of fragments, each free to translate or rotate to accommodate the strain. In this sample the fragments are largely uncemented and still retain a high degree of fracture porosity. Transformation from opal-CT (light gray/white) to quartz (black) occurred in isolated fragments, from the center outwards; at this point the quartz chert fragments still retain a thin rim of light gray opal-CT. Field of view = 7 cm.