Slate is a homogeneous metamorphic rock. It consists of many slabs and leaflet-like structures pressed together. Slate is mostly composed of clay minerals (phyllosilicates), quartz and feldspar. Subordinated and in many cases eponymous minerals from the mica group such as chlorite (chlorite schist) and garnet (garnet-mica schist) occur. The color of the slate varies with the composition and the contained minerals from grey to black, green and blue as well as silver and whitish. The rock can be used indoors and outdoors.