They are classified on the basis of texture (foliated vs. Non-foliated), grain-size, and mineral composition. Texture: metamorphic rocks may have either foliated (layered) or non-foliated texture.
On What Basis Can Metamorphic Rocks Be Identified?
Metamorphic rocks are rocks that have been changed by heat, pressure, or other natural forces. The word “metamorphic“ comes from the Greek word metamorphose, which means “to change form.
“ There are three main ways that metamorphic rocks can be identified:
1. The first way is by their texture. Metamorphic rocks can have a wide range of textures, from very fine–grained to very coarse–grained.
2. The second way is by their mineralogy. Metamorphic rocks are typically made up of different minerals than the rocks they started out as.
3. The third way is by their structure. Metamorphic rocks can have a wide range of structures, from simple layering to complex folding. Metamorphic rocks are classified into two main categories:
foliated and non–foliated. Foliated metamorphic rocks have a layered or banded appearance, while non–foliated metamorphic rocks do not.
The most common type of foliated metamorphic rock is slate. Slate is a very fine–grained rock that can be easily split into thin layers. Slate is often used for roofing, flooring, and countertops