Characteristics

Schist originate from regional metamorphism at the continental side of a convergent plate boundaries, which mean it forms under moderate pressure and moderate temperature conditions. A schist can be defined on its behaviour. When it breaks it produces thin flakes of clay minerals that also can be seen by the naked eye. A schist can't be defined on its mineral composition, but only on the fact of enough platy metamorphic minerals present.

Composition

Schist mainly consist of mica minerals such as chlorite, muscovite and biotite. These exist in the rock because they are deformed clay minerals. Moreover are quartz and feldspars present in this type of metamorphic rock. A schist can also be named according to the abundant minerals when the rock is examined. For example a chlorite schist, graphite schist or garnet schist. These extra names need to be a mineral with metamorphic origin.

References

• NEN-EN-ISO 14688-1:2019
• https://geology.com/