Here's why:
* Foliation: This refers to the development of a planar or layered structure within a metamorphic rock. This structure is a result of pressure applied during metamorphism, causing the minerals to align themselves in a specific direction.
* Parallel Alignment: The minerals within foliated rocks tend to align themselves perpendicular to the direction of the pressure, creating distinct layers or bands.
Examples of foliated metamorphic rocks:
* Slate: Fine-grained, with a smooth, flat surface due to the parallel alignment of mica flakes.
* Schist: A coarser-grained rock with a more pronounced foliation, often containing larger mica flakes.
* Gneiss: A banded rock with alternating layers of light and dark minerals, indicating a higher degree of metamorphism than slate or schist.
It's important to note that not all metamorphic rocks are foliated. Rocks that lack this parallel alignment are classified as non-foliated.
