Slate is a rock that has many natural color variations including gray, blue, greenish-grey, dark red, black, tan and even purplish-gray. References to the color “slate” most likely mean a medium-dark grey with blue undertones, because this is the most common color variation of slate rock.
Slate has a natural tendency to break into large, smooth, flat pieces which makes it very easy to build with. Slate has been used for roofing tiles, walkways, blackboards, small writing tablets, billiard tables, laboratory counter tops, tombstones and floor tiles. It is often sealed to maintain its appearance. It is available with a smooth finish suitable for chalkboards or a rougher, non-skid finish that makes for durable non-skid footing.