Here's why:
* Foliation refers to the parallel arrangement of mineral grains in a metamorphic rock. This layering often occurs due to pressure and heat during the metamorphic process, causing the minerals to align themselves in a specific direction.
* Non-foliated metamorphic rocks form when the minerals recrystallize without a directional pressure. This can happen when the metamorphic environment is more evenly distributed or when the rock is primarily composed of one mineral.
Examples of non-foliated metamorphic rocks include:
* Marble: Formed from limestone or dolostone, typically has a granular texture.
* Quartzite: Formed from sandstone, often has a sugary texture.
* Hornfels: Formed from contact metamorphism, often very hard and dense.
* Anthracite: A type of coal that has undergone extreme metamorphism.
Remember, even within these rock types, there might be some subtle layering, but it's not as pronounced or pervasive as in foliated rocks.
