R865 Sample ID R865 • Cabinet D Mud-Cracks in Sandstone 25cm W x 15cm H x 3cm D • 1120g Sample TypeRockRock QualitySedimentaryRock Type CompositionGrain SizeFineGrain ShapeRounded Grain SortingWell sortedAcid ReactionMohs Hardness 4 This specimen preserves a network of mud cracks formed as fine sediment dried and contracted at the surface. Subsequent burial and lithification transformed the original mud into sandstone, retaining the polygonal fracture pattern as a clear record of periodic exposure and drying in a shallow depositional setting. Description of Mohs scale here