SEM Photo at lOOOX. This backscattered electron image shows a pyritized fossil, dark gray silica matrix, detrital plagioclase and potassium feldspar grains, and curved carbonate tests (dark gray). The striated gray material in the fossil chambers is gypsum. Some fractures in this specimen also were gypsum filled. Alternating reducing and oxidizing fluids must have permeated this specimen to produce both sulfur-bearing phases.