R757 Sample ID R757 • Cabinet C Coal 7.843cm W x 7.198cm H x 4.914cm D • 208g Sample TypeRockRock QualitySedimentaryRock TypeOrganic CompositionOrganicsGrain SizeFineGrain ShapeN/A Grain SortingWell sortedAcid ReactionYesMohs Hardness 2 The rock is half shaped like a circle. It has a dull luster and somewhat of a glassy texture to it. Kind of looks like someone took a bite out of it on one end. Description of Mohs scale here