Metamorphic rocks are classified into two main types: foliated metamorphic rocks and non-foliated metamorphic rocks.
Foliated metamorphic rocks are characterized by their layered or banded appearance. This texture occurs when minerals in the rock align parallel to each other due to directional pressure during metamorphism. Common examples of foliated metamorphic rocks include schist and gneiss. Their unique layered structure can often be seen as distinct bands of different minerals.
Non-foliated metamorphic rocks, on the other hand, do not have a layered or banded appearance. Instead, these rocks are typically uniform in texture. This type forms under conditions where pressure is applied uniformly, rather than from a particular direction. Marble, which originates from limestone, and quartzite, derived from sandstone, are common examples of non-foliated metamorphic rocks. Their lack of foliation makes them often more suitable for use in construction and sculpture.
In summary, when discussing metamorphic rocks, it’s crucial to understand the distinction between foliated and non-foliated rocks, as each type results from different conditions and processes during metamorphism.