Quartzite is a hard, non-foliated metamorphic rock formed by the action of heat and pressure upon sandstone. Usually, the rock is white or grey, but it occurs in other pale colours. It has a grainy, rough surface. Magnification reveals a mosaic of quartz crystals.
Quartzite is a decorative stone and may be used to cover walls, as roofing tiles, as flooring, and stairsteps. Its use for countertops in kitchens is expanding rapidly. It is harder and more resistant to stains than granite.