Slate is a metamorphic rock. Metamorphic refers to change under temperature and pressure. Slate can start out as many different rocks: Sandstones, shale, clays, even volcanic ash. Usually the original rock is a sedimentary rock. Sedimentary rocks are deposited in layers. Slate has very thin layers and can run in different directions. Because Slate can come from so many different original rocks and it can come in any color. Slate is a porous stone but not as much as other types of stone. Slate can be used as roof shingles but if water sits on it can peel or delaminate. Slate can be stained but is generally pretty stain resistant. Slate’s unique characteristics are why Slate has some varied and unique uses such as roof shingles, tabletops, pool tables, floor tiles, Flagstone pavers, showers and other uses.