Quartzite is a metamorphic rock that is formed from sandstone. Quartzite can be of exceptional strength, density, and hardness. The strength, abrasion resistance, and weathering durability of this rock type expand its application possibilities to include most any of the common uses for natural, dimension stone. Quartzite is the only natural stone that offers the marble look with great hardness and durability. They are also one of the most expensive natural stones.