Flagstone is a generic description of flat stone that is most often used in building and landscaping. It is a sedimentary stone that is split into thin layers, allowing it to be used in many applications. Flagstone is usually a sandstone containing feldspar and quartz, often cemented together with calcium, silica or iron oxide. Flagstone is not to be confused with slate, which is also a sedimentary rock but composed primarily of clay or volcanic rock.

Flagstone is quarried most any place where there is sedimentary stone: from Texas to Pennsylvania, from Arizona to the west coast of Ireland. Where the stone is formed and what its primary binding materials are determine the stones' predominant color. Among the colors most commonly found in flagstone are red, pink, peach, chocolate, buff, green, blue, gold, beige and white. Some flagstone has a record of its formation with fossilized tracks of marine worms and ancient insects.

The variety of colors, versatility of uses, wide availability, durability and beauty of flagstone make it an ideal material to use in a range of projects. It has a naturally non-slip surface which makes it perfect for both indoor and outdoor uses. Flagstone can be used for paving, roofing, fences, headstones, patios, walkways, pillars and facades. The stone ranges from ½" to 2" thick. The slabs are usually cut or broken into irregular shapes, adding to the beauty many find in the look of the random, less contrived pattern of a flagstone walkway or patio.

A mason or do-it-yourselfer working with flagstone must rely on his or her artistic side to create a one-of-a-kind work of art. Flagstone may also be cut into squares for a more tailored and patterned look. Flagstone may be broken and manipulated fairly easily due to its makeup, but is still surprisingly resilient and durable.