Schist is part of the category of metamorphic rocks. Depending on the particularities of its formation, schist can also be considered to be a sedimentary rock (clay). Schist is characterised by a foliar structure with layers of mineral crystals, thus giving it a foliated appearance with a generally smooth and shiny surface. There are several categories of schist ranked according to the dominant mineral. The schist family therefore includes micaschist, chlorite schist and calcschist. The most frequently found type of schist mainly consists of mica and quartz. Schist forms from alluviums having collected in the depths of the oceans. Schist is created when these sediments are transformed under the effect of high pressure and temperatures. Schist can also be found in orogenous regions, particularly in Cévennes. Schist can be used for various purposes. In the 15th century, for example, Italian artists decided to use grey packstone schist as a drawing instrument. The rock was then modelled to act as a pencil. Schist was available as a drawing tool in colours similar to black and grey. Many artists used schist to produce realistic and eye-catching portraits. Slate is part of the schist family. This type of schist forms at moderate pressures and temperatures. Due to these specific characteristics, slate is one variety of schist, which stands out thanks to its fine grains and robust nature. Slate is highly popular for roofing thanks to these properties. The colour of slate traditionally ranges from white to black but grey, dark red and even green specimens can also be found. Depending on individual preferences, slate can come in two forms: rectangular or as tiles, with a thickness of between three and nine millimetres. Slate can be fitted using traditional methods, nails or a hook system. Schist slabs are becoming increasingly popular in interior designs, which is understandable considering schist slabs have some undeniable advantages. Regarding the range of colours for schist, it is quite wide. However, it is important to remember that schist slabs are exclusively available in dark shades, such as black, blue and purple. Laying schist slabs is not complicated since it is a technique that is similar to the one used for laying regular tiles.