Here's why they lack the layered structure:
* Lack of pressure: Foliation (the layering) in metamorphic rocks is caused by intense pressure during the metamorphic process. Non-foliated rocks form under conditions where pressure is more evenly distributed.
* Mineral composition: The specific minerals in the rock can also play a role. Some minerals, like quartz and calcite, tend to recrystallize without creating a layered structure.
Examples of Non-foliated Metamorphic Rocks:
* Marble: Forms from the metamorphism of limestone or dolostone.
* Quartzite: Forms from the metamorphism of sandstone.
* Hornfels: Forms when other rocks are metamorphosed by the heat from an igneous intrusion.
* Anthracite: Forms from the metamorphism of bituminous coal.
* Serpentinite: Forms from the metamorphism of ultramafic rocks.
Let me know if you'd like more information about any of these rocks!
