How do you classify metamorphic rocks?

Answer 1

Metamorphic rocks are classified as being foliated or being non-foliated. Foliated metamorphic rocks have visible banding or sheet-like layering. Slate, phyllite, gneiss, and schist are foliated metamorphic rocks. Non-foliated metamorphic rocks do not display banding or layering. Marble and quartzite are non-foliated metamorphic rocks. Metamorphic rocks can also be classified as either regional metamorphic rocks or contact metamorphic rocks, depending on their method of formation.

Answer 2

The two classifications of metamorphic rock are foliated and non-foliated:

1. Foliated metamorphic rock such as gneiss display banding and regrouping of its mineral constituents as a result of enormous pressures and heat. The banding forms perpendicularly to the direction of pressure. The pressure is usually related to tectonic plate collisions. Schist is another type of foliated rock that exhibits thin layering of micaceous minerals, once again due to pressure and heat. The difference between these two types of foliated rock lies in the rock from which they were derived.

2. Non-foliated metamorphic rock such as quartzite and marble do not display the banding or layering that are present in foliated rocks. This is because their parent rock was usually sedimentary and more pure in mineral composition than the parent rocks of foliated rocks.


Metamorphic rock can also be classified as regional (from broad processes such as plate tectonics) or contact (from proximity to an invading heat source).

Metamorphic rock is further classified by degree of metamorphism, as increases in heat and pressure can further metamorphose a rock. The degree is expressed in terms of grade: low grade, medium grade, high grade. As an example, the metamorphic rock slate (low grade) can metamorphose to schist (medium grade) and then to gneiss (high grade).

Answer 3

Based on texture, metamorphic rock can be classified as foliated or non-foliated:

1. Foliated metamorphic rock such as gneiss display banding and regrouping of its mineral constituents as a result of enormous pressures and heat. The banding forms perpendicularly to the direction of pressure. The pressure is usually related to tectonic plate collisions. Schist is another type of foliated rock that exhibits thin layering of micaceous minerals, once again due to pressure and heat. The difference between these two types of foliated rock lies in the rock from which they were derived.

2. Non-foliated metamorphic rock such as quartzite and marble do not display the banding or layering that are present in foliated rocks. This is because their parent rock was usually sedimentary and more pure in mineral composition than the parent rocks of foliated rocks.

Metamorphic rock can also be classified as regional (from broad processes such as plate tectonics) or contact (from proximity to an invading heat source).

Metamorphic rock is further classified by degree of metamorphism, as increases in heat and pressure can further metamorphose a rock. The degree is expressed in terms of grade: low grade, medium grade, high grade. As an example, the metamorphic rock slate (low grade) can metamorphose to schist (medium grade) and then to gneiss (high grade).

Answer 4

By their degree of metamorphism, by the means of metamorphism, and by mineral content.

Answer 5

Metamorphic rocks are classified based on texture, such as foliated or non-foliated.