5. Cherty dolomite mudstone 6. Argillaceous dolomite mudstone
General Atlantic, Tjaden 1A1 WIW # 1, left photo showing gray dolomite mudstone with white chert nodules. Lower nodule is stained with oil due to presence of microporosity. Photo to right is another example of a cherty, argillaceous dolomite mudstone. It contains burrows, wavy, and lenticular bedding suggesting moderate bioturbation. White rounded and small lenticular-shaped chert nodules suggest selective silicification of burrows. Scale bars are 2 cm.