Most commonly used are Flagstone and Sandstone. Flagstone is a generic term for flat slabs naturally derived from quarries. They are available mostly in browns, reds and blues and are irregular in shape. They can be installed on a bed of sand or thin set over concrete depending on the application. Natural stone is as beneficial to a residential application as a commercial application. They are low maintenance and easily replaced if damaged. Natural stone is strong, durable, sun resistant and heat resistant.