QUARTZITES: Quartzite is sandstone that has been metamorphosed. Unlike sandstone, quartzite breaks through, not around, the quartz grains, producing a smooth surface instead of a rough and granular one. Quartzites are snowy white, less often pink or gray. They yield a thin and very barren soil and, because they weather slowly, tend to project as hills or mountain masses. Many prominent ridges in the Appalachian Mountains are composed of highly resistant tilted beds of quartzite.