While you may think of slate as a roofing material, it also works well in many hardscaping applications [source: Bradley-Hole]. Slate rocks originally started out as shale that over time metamorphosed into a new rock [source: Harding, Symes and Taylor]. Slate usually comes in a gray, green or blue color, and it easily cracks into thin slabs of rock [source: Bradley-Hole].
Several of slate's natural qualities make it a good choice for specific outdoor applications. Due to the fact that slate naturally breaks into thin pieces, it's a good paving stone [source: Bradley-Hole]. It can also be made into stone tiles that create a floor with a more formal look [source: Walks, Walls & Patios]. Slate's natural water-resistance makes it a good option for near-water features or pools [source: Pools & Spas].