Here's why:

* Foliation: This refers to the parallel alignment of minerals in a metamorphic rock, creating a layered or banded appearance. This happens due to pressure and heat, causing minerals to recrystallize in a specific direction.

* Non-foliated: These rocks lack this layered structure. They form under conditions where pressure is more evenly distributed, or the minerals are more resistant to alignment.

Examples of non-foliated metamorphic rocks:

* Marble: Formed from limestone, often has a uniform texture without banding.

* Quartzite: Formed from sandstone, typically has a granular texture.

* Hornfels: Often forms in contact with igneous intrusions and lacks a distinct layering.

While these rocks might have crystals, they won't be arranged in the distinctive bands that characterize foliated rocks like schist or gneiss.