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Schist is a strongly foliated medium-grade metamorphic rock. It is characterized by an abundance of platy or elongated minerals (micas, share similarities in appearance (schistosity) but may be highly variable in composition. Individual mineral grains are discernible by the na*ed eye. This property sets it apart from slate. Schist is one of the most widespread rock types in the continental crust. porphyroblasts of garnet, staurolite and kyanite. 2. Graphite schist. 3. Chlorite schist (greenschist). 4. Quartzofeldspathic (gneissic) schist. 5. Staurolite schist with a twinned staurolite porphyroblast. 6. Blueschist (glaucophane schist with garnet and omphacite). Some schists contain no platy minerals like sheet silicates or graphite, but in this case these rocks have to display a linear fabric (elongated minerals in sub-parallel orientation). Amphibole-bearing rocks with a lineated fabric belong to this group. Schistosity is a type of foliation, characterised by the preferred orientation of elongated or platy mineral grains (which are abundant in schistose rocks). Schistosity is a result of pressure in the crust which forces the grains to align perpendicular to the force applied. This force may be compressive (in mountain ranges) or simply caused by the weight of the overlying rocks. Schist can form only if the compressed rock contains lots of elongated or platy grains. Growth of mica crystals during the course of metamorphism makes the schistosity Mica schist is a very common variety. It is nicely glittering in sunshine because mica flakes act as small mirrors. Such rocks often contain garnet porphyroblasts (red crystals). Narvik, Norway. Width of sample 14 cm. Metamorphic reactions between minerals upon increased burial will lead to the loss of schistosity because feldspar increases in abundance as (and gneissose fabric which can be described as a poorly developed schistosity). Sometimes schist is imagined to contain at least 50% of elongated minerals1, but in many cases the distinction between these rocks is just based on the qualitative as*essment of a geologist