Quartzite is a non-foliated metamorphic rock. Quartzite is more rigid and is created from changes in pure quartz sandstone. Sandstone is transformed into quartzite by heat and pressure. When sandstone is formed into quartzite, the separate quartz particles recrystallize to form an interconnecting mixture of quartz crystals, which have a different texture and sedimentary structure than the original sandstone. While sandstone is grainy like sandpaper, quartzite is smooth and glassy like marble. Pure quartzite is typically a white or gray shade, however quartzites may occur in a variety of colors depending on the presence of other minerals.