The typical textural terms employed for rock sorts with regard to the size on the grains or crystals, are provided in the Desk. The particle-dimensions categories are derived from the Udden-Wentworth scale designed for sediment. For igneous and metamorphic rocks, the phrases are commonly employed as modifiers— • Prograde metamorphic https://www.generationgenius.com/videolessons/rocks-and-minerals-video-for-kids/