R688 Sample ID R688 • Cabinet B Welded Tuff 3.784cm W x 5.48cm H x 7.971cm D • 308g Sample TypeRockRock QualityIgneousRock TypeExtrusive CompositionFelsicTexturePyroclasticColor IndexLight Clast SizeAcid ReactionMohs Hardness 6 It is somewhat shaped like the tip of a mountain. though more rectangular. It is partly ashy grey-brown in color. Description of Mohs scale here